From f8edf410c4ddd523917f01dfbef4378b4ad4c1b0 Mon Sep 17 00:00:00 2001 From: Mike Pagano Date: Wed, 29 Apr 2015 13:21:43 -0400 Subject: BFQ patchset for 4.0, v7r7. --- 0000_README | 12 + ...roups-kconfig-build-bits-for-BFQ-v7r7-4.0.patch | 104 + ...introduce-the-BFQ-v7r7-I-O-sched-for-4.0.patch1 | 6966 ++++++++++++++++++++ ...rly-Queue-Merge-EQM-to-BFQ-v7r7-for-4.0.0.patch | 1222 ++++ 4 files changed, 8304 insertions(+) create mode 100644 5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r7-4.0.patch create mode 100644 5002_block-introduce-the-BFQ-v7r7-I-O-sched-for-4.0.patch1 create mode 100644 5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r7-for-4.0.0.patch diff --git a/0000_README b/0000_README index 483ca420..bcce9675 100644 --- a/0000_README +++ b/0000_README @@ -83,6 +83,18 @@ Patch: 5000_enable-additional-cpu-optimizations-for-gcc.patch From: https://github.com/graysky2/kernel_gcc_patch/ Desc: Kernel patch enables gcc < v4.9 optimizations for additional CPUs. +Patch: 5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r7-4.0.patch +From: http://algo.ing.unimo.it/people/paolo/disk_sched/ +Desc: BFQ v7r7 patch 1 for 4.0: Build, cgroups and kconfig bits + +Patch: 5002_block-introduce-the-BFQ-v7r7-I-O-sched-for-4.0.patch1 +From: http://algo.ing.unimo.it/people/paolo/disk_sched/ +Desc: BFQ v7r7 patch 2 for 4.0: BFQ Scheduler + +Patch: 5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r7-for-4.0.0.patch +From: http://algo.ing.unimo.it/people/paolo/disk_sched/ +Desc: BFQ v7r7 patch 3 for 4.0: Early Queue Merge (EQM) + Patch: 5010_enable-additional-cpu-optimizations-for-gcc-4.9.patch From: https://github.com/graysky2/kernel_gcc_patch/ Desc: Kernel patch enables gcc >= v4.9 optimizations for additional CPUs. diff --git a/5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r7-4.0.patch b/5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r7-4.0.patch new file mode 100644 index 00000000..468d1573 --- /dev/null +++ b/5001_block-cgroups-kconfig-build-bits-for-BFQ-v7r7-4.0.patch @@ -0,0 +1,104 @@ +From 63e26848e2df36a3c29d2d38ce8b008539d64a5d Mon Sep 17 00:00:00 2001 +From: Paolo Valente +Date: Tue, 7 Apr 2015 13:39:12 +0200 +Subject: [PATCH 1/3] block: cgroups, kconfig, build bits for BFQ-v7r7-4.0 + +Update Kconfig.iosched and do the related Makefile changes to include +kernel configuration options for BFQ. Also add the bfqio controller +to the cgroups subsystem. + +Signed-off-by: Paolo Valente +Signed-off-by: Arianna Avanzini +--- + block/Kconfig.iosched | 32 ++++++++++++++++++++++++++++++++ + block/Makefile | 1 + + include/linux/cgroup_subsys.h | 4 ++++ + 3 files changed, 37 insertions(+) + +diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched +index 421bef9..0ee5f0f 100644 +--- a/block/Kconfig.iosched ++++ b/block/Kconfig.iosched +@@ -39,6 +39,27 @@ config CFQ_GROUP_IOSCHED + ---help--- + Enable group IO scheduling in CFQ. + ++config IOSCHED_BFQ ++ tristate "BFQ I/O scheduler" ++ default n ++ ---help--- ++ The BFQ I/O scheduler tries to distribute bandwidth among ++ all processes according to their weights. ++ It aims at distributing the bandwidth as desired, independently of ++ the disk parameters and with any workload. It also tries to ++ guarantee low latency to interactive and soft real-time ++ applications. If compiled built-in (saying Y here), BFQ can ++ be configured to support hierarchical scheduling. ++ ++config CGROUP_BFQIO ++ bool "BFQ hierarchical scheduling support" ++ depends on CGROUPS && IOSCHED_BFQ=y ++ default n ++ ---help--- ++ Enable hierarchical scheduling in BFQ, using the cgroups ++ filesystem interface. The name of the subsystem will be ++ bfqio. ++ + choice + prompt "Default I/O scheduler" + default DEFAULT_CFQ +@@ -52,6 +73,16 @@ choice + config DEFAULT_CFQ + bool "CFQ" if IOSCHED_CFQ=y + ++ config DEFAULT_BFQ ++ bool "BFQ" if IOSCHED_BFQ=y ++ help ++ Selects BFQ as the default I/O scheduler which will be ++ used by default for all block devices. ++ The BFQ I/O scheduler aims at distributing the bandwidth ++ as desired, independently of the disk parameters and with ++ any workload. It also tries to guarantee low latency to ++ interactive and soft real-time applications. ++ + config DEFAULT_NOOP + bool "No-op" + +@@ -61,6 +92,7 @@ config DEFAULT_IOSCHED + string + default "deadline" if DEFAULT_DEADLINE + default "cfq" if DEFAULT_CFQ ++ default "bfq" if DEFAULT_BFQ + default "noop" if DEFAULT_NOOP + + endmenu +diff --git a/block/Makefile b/block/Makefile +index 00ecc97..1ed86d5 100644 +--- a/block/Makefile ++++ b/block/Makefile +@@ -18,6 +18,7 @@ obj-$(CONFIG_BLK_DEV_THROTTLING) += blk-throttle.o + obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o + obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o + obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o ++obj-$(CONFIG_IOSCHED_BFQ) += bfq-iosched.o + + obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o + obj-$(CONFIG_BLK_CMDLINE_PARSER) += cmdline-parser.o +diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h +index e4a96fb..267d681 100644 +--- a/include/linux/cgroup_subsys.h ++++ b/include/linux/cgroup_subsys.h +@@ -35,6 +35,10 @@ SUBSYS(freezer) + SUBSYS(net_cls) + #endif + ++#if IS_ENABLED(CONFIG_CGROUP_BFQIO) ++SUBSYS(bfqio) ++#endif ++ + #if IS_ENABLED(CONFIG_CGROUP_PERF) + SUBSYS(perf_event) + #endif +-- +2.1.0 + diff --git a/5002_block-introduce-the-BFQ-v7r7-I-O-sched-for-4.0.patch1 b/5002_block-introduce-the-BFQ-v7r7-I-O-sched-for-4.0.patch1 new file mode 100644 index 00000000..a6cfc585 --- /dev/null +++ b/5002_block-introduce-the-BFQ-v7r7-I-O-sched-for-4.0.patch1 @@ -0,0 +1,6966 @@ +From 8cdf2dae6ee87049c7bb086d34e2ce981b545813 Mon Sep 17 00:00:00 2001 +From: Paolo Valente +Date: Thu, 9 May 2013 19:10:02 +0200 +Subject: [PATCH 2/3] block: introduce the BFQ-v7r7 I/O sched for 4.0 + +Add the BFQ-v7r7 I/O scheduler to 4.0. +The general structure is borrowed from CFQ, as much of the code for +handling I/O contexts. Over time, several useful features have been +ported from CFQ as well (details in the changelog in README.BFQ). A +(bfq_)queue is associated to each task doing I/O on a device, and each +time a scheduling decision has to be made a queue is selected and served +until it expires. + + - Slices are given in the service domain: tasks are assigned + budgets, measured in number of sectors. Once got the disk, a task + must however consume its assigned budget within a configurable + maximum time (by default, the maximum possible value of the + budgets is automatically computed to comply with this timeout). + This allows the desired latency vs "throughput boosting" tradeoff + to be set. + + - Budgets are scheduled according to a variant of WF2Q+, implemented + using an augmented rb-tree to take eligibility into account while + preserving an O(log N) overall complexity. + + - A low-latency tunable is provided; if enabled, both interactive + and soft real-time applications are guaranteed a very low latency. + + - Latency guarantees are preserved also in the presence of NCQ. + + - Also with flash-based devices, a high throughput is achieved + while still preserving latency guarantees. + + - BFQ features Early Queue Merge (EQM), a sort of fusion of the + cooperating-queue-merging and the preemption mechanisms present + in CFQ. EQM is in fact a unified mechanism that tries to get a + sequential read pattern, and hence a high throughput, with any + set of processes performing interleaved I/O over a contiguous + sequence of sectors. + + - BFQ supports full hierarchical scheduling, exporting a cgroups + interface. Since each node has a full scheduler, each group can + be assigned its own weight. + + - If the cgroups interface is not used, only I/O priorities can be + assigned to processes, with ioprio values mapped to weights + with the relation weight = IOPRIO_BE_NR - ioprio. + + - ioprio classes are served in strict priority order, i.e., lower + priority queues are not served as long as there are higher + priority queues. Among queues in the same class the bandwidth is + distributed in proportion to the weight of each queue. A very + thin extra bandwidth is however guaranteed to the Idle class, to + prevent it from starving. + +Signed-off-by: Paolo Valente +Signed-off-by: Arianna Avanzini +--- + block/bfq-cgroup.c | 936 ++++++++++++ + block/bfq-ioc.c | 36 + + block/bfq-iosched.c | 3902 +++++++++++++++++++++++++++++++++++++++++++++++++++ + block/bfq-sched.c | 1214 ++++++++++++++++ + block/bfq.h | 775 ++++++++++ + 5 files changed, 6863 insertions(+) + create mode 100644 block/bfq-cgroup.c + create mode 100644 block/bfq-ioc.c + create mode 100644 block/bfq-iosched.c + create mode 100644 block/bfq-sched.c + create mode 100644 block/bfq.h + +diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c +new file mode 100644 +index 0000000..11e2f1d +--- /dev/null ++++ b/block/bfq-cgroup.c +@@ -0,0 +1,936 @@ ++/* ++ * BFQ: CGROUPS support. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ * ++ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ ++ * file. ++ */ ++ ++#ifdef CONFIG_CGROUP_BFQIO ++ ++static DEFINE_MUTEX(bfqio_mutex); ++ ++static bool bfqio_is_removed(struct bfqio_cgroup *bgrp) ++{ ++ return bgrp ? !bgrp->online : false; ++} ++ ++static struct bfqio_cgroup bfqio_root_cgroup = { ++ .weight = BFQ_DEFAULT_GRP_WEIGHT, ++ .ioprio = BFQ_DEFAULT_GRP_IOPRIO, ++ .ioprio_class = BFQ_DEFAULT_GRP_CLASS, ++}; ++ ++static inline void bfq_init_entity(struct bfq_entity *entity, ++ struct bfq_group *bfqg) ++{ ++ entity->weight = entity->new_weight; ++ entity->orig_weight = entity->new_weight; ++ entity->ioprio = entity->new_ioprio; ++ entity->ioprio_class = entity->new_ioprio_class; ++ entity->parent = bfqg->my_entity; ++ entity->sched_data = &bfqg->sched_data; ++} ++ ++static struct bfqio_cgroup *css_to_bfqio(struct cgroup_subsys_state *css) ++{ ++ return css ? container_of(css, struct bfqio_cgroup, css) : NULL; ++} ++ ++/* ++ * Search the bfq_group for bfqd into the hash table (by now only a list) ++ * of bgrp. Must be called under rcu_read_lock(). ++ */ ++static struct bfq_group *bfqio_lookup_group(struct bfqio_cgroup *bgrp, ++ struct bfq_data *bfqd) ++{ ++ struct bfq_group *bfqg; ++ void *key; ++ ++ hlist_for_each_entry_rcu(bfqg, &bgrp->group_data, group_node) { ++ key = rcu_dereference(bfqg->bfqd); ++ if (key == bfqd) ++ return bfqg; ++ } ++ ++ return NULL; ++} ++ ++static inline void bfq_group_init_entity(struct bfqio_cgroup *bgrp, ++ struct bfq_group *bfqg) ++{ ++ struct bfq_entity *entity = &bfqg->entity; ++ ++ /* ++ * If the weight of the entity has never been set via the sysfs ++ * interface, then bgrp->weight == 0. In this case we initialize ++ * the weight from the current ioprio value. Otherwise, the group ++ * weight, if set, has priority over the ioprio value. ++ */ ++ if (bgrp->weight == 0) { ++ entity->new_weight = bfq_ioprio_to_weight(bgrp->ioprio); ++ entity->new_ioprio = bgrp->ioprio; ++ } else { ++ if (bgrp->weight < BFQ_MIN_WEIGHT || ++ bgrp->weight > BFQ_MAX_WEIGHT) { ++ printk(KERN_CRIT "bfq_group_init_entity: " ++ "bgrp->weight %d\n", bgrp->weight); ++ BUG(); ++ } ++ entity->new_weight = bgrp->weight; ++ entity->new_ioprio = bfq_weight_to_ioprio(bgrp->weight); ++ } ++ entity->orig_weight = entity->weight = entity->new_weight; ++ entity->ioprio = entity->new_ioprio; ++ entity->ioprio_class = entity->new_ioprio_class = bgrp->ioprio_class; ++ entity->my_sched_data = &bfqg->sched_data; ++ bfqg->active_entities = 0; ++} ++ ++static inline void bfq_group_set_parent(struct bfq_group *bfqg, ++ struct bfq_group *parent) ++{ ++ struct bfq_entity *entity; ++ ++ BUG_ON(parent == NULL); ++ BUG_ON(bfqg == NULL); ++ ++ entity = &bfqg->entity; ++ entity->parent = parent->my_entity; ++ entity->sched_data = &parent->sched_data; ++} ++ ++/** ++ * bfq_group_chain_alloc - allocate a chain of groups. ++ * @bfqd: queue descriptor. ++ * @css: the leaf cgroup_subsys_state this chain starts from. ++ * ++ * Allocate a chain of groups starting from the one belonging to ++ * @cgroup up to the root cgroup. Stop if a cgroup on the chain ++ * to the root has already an allocated group on @bfqd. ++ */ ++static struct bfq_group *bfq_group_chain_alloc(struct bfq_data *bfqd, ++ struct cgroup_subsys_state *css) ++{ ++ struct bfqio_cgroup *bgrp; ++ struct bfq_group *bfqg, *prev = NULL, *leaf = NULL; ++ ++ for (; css != NULL; css = css->parent) { ++ bgrp = css_to_bfqio(css); ++ ++ bfqg = bfqio_lookup_group(bgrp, bfqd); ++ if (bfqg != NULL) { ++ /* ++ * All the cgroups in the path from there to the ++ * root must have a bfq_group for bfqd, so we don't ++ * need any more allocations. ++ */ ++ break; ++ } ++ ++ bfqg = kzalloc(sizeof(*bfqg), GFP_ATOMIC); ++ if (bfqg == NULL) ++ goto cleanup; ++ ++ bfq_group_init_entity(bgrp, bfqg); ++ bfqg->my_entity = &bfqg->entity; ++ ++ if (leaf == NULL) { ++ leaf = bfqg; ++ prev = leaf; ++ } else { ++ bfq_group_set_parent(prev, bfqg); ++ /* ++ * Build a list of allocated nodes using the bfqd ++ * filed, that is still unused and will be ++ * initialized only after the node will be ++ * connected. ++ */ ++ prev->bfqd = bfqg; ++ prev = bfqg; ++ } ++ } ++ ++ return leaf; ++ ++cleanup: ++ while (leaf != NULL) { ++ prev = leaf; ++ leaf = leaf->bfqd; ++ kfree(prev); ++ } ++ ++ return NULL; ++} ++ ++/** ++ * bfq_group_chain_link - link an allocated group chain to a cgroup ++ * hierarchy. ++ * @bfqd: the queue descriptor. ++ * @css: the leaf cgroup_subsys_state to start from. ++ * @leaf: the leaf group (to be associated to @cgroup). ++ * ++ * Try to link a chain of groups to a cgroup hierarchy, connecting the ++ * nodes bottom-up, so we can be sure that when we find a cgroup in the ++ * hierarchy that already as a group associated to @bfqd all the nodes ++ * in the path to the root cgroup have one too. ++ * ++ * On locking: the queue lock protects the hierarchy (there is a hierarchy ++ * per device) while the bfqio_cgroup lock protects the list of groups ++ * belonging to the same cgroup. ++ */ ++static void bfq_group_chain_link(struct bfq_data *bfqd, ++ struct cgroup_subsys_state *css, ++ struct bfq_group *leaf) ++{ ++ struct bfqio_cgroup *bgrp; ++ struct bfq_group *bfqg, *next, *prev = NULL; ++ unsigned long flags; ++ ++ assert_spin_locked(bfqd->queue->queue_lock); ++ ++ for (; css != NULL && leaf != NULL; css = css->parent) { ++ bgrp = css_to_bfqio(css); ++ next = leaf->bfqd; ++ ++ bfqg = bfqio_lookup_group(bgrp, bfqd); ++ BUG_ON(bfqg != NULL); ++ ++ spin_lock_irqsave(&bgrp->lock, flags); ++ ++ rcu_assign_pointer(leaf->bfqd, bfqd); ++ hlist_add_head_rcu(&leaf->group_node, &bgrp->group_data); ++ hlist_add_head(&leaf->bfqd_node, &bfqd->group_list); ++ ++ spin_unlock_irqrestore(&bgrp->lock, flags); ++ ++ prev = leaf; ++ leaf = next; ++ } ++ ++ BUG_ON(css == NULL && leaf != NULL); ++ if (css != NULL && prev != NULL) { ++ bgrp = css_to_bfqio(css); ++ bfqg = bfqio_lookup_group(bgrp, bfqd); ++ bfq_group_set_parent(prev, bfqg); ++ } ++} ++ ++/** ++ * bfq_find_alloc_group - return the group associated to @bfqd in @cgroup. ++ * @bfqd: queue descriptor. ++ * @cgroup: cgroup being searched for. ++ * ++ * Return a group associated to @bfqd in @cgroup, allocating one if ++ * necessary. When a group is returned all the cgroups in the path ++ * to the root have a group associated to @bfqd. ++ * ++ * If the allocation fails, return the root group: this breaks guarantees ++ * but is a safe fallback. If this loss becomes a problem it can be ++ * mitigated using the equivalent weight (given by the product of the ++ * weights of the groups in the path from @group to the root) in the ++ * root scheduler. ++ * ++ * We allocate all the missing nodes in the path from the leaf cgroup ++ * to the root and we connect the nodes only after all the allocations ++ * have been successful. ++ */ ++static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd, ++ struct cgroup_subsys_state *css) ++{ ++ struct bfqio_cgroup *bgrp = css_to_bfqio(css); ++ struct bfq_group *bfqg; ++ ++ bfqg = bfqio_lookup_group(bgrp, bfqd); ++ if (bfqg != NULL) ++ return bfqg; ++ ++ bfqg = bfq_group_chain_alloc(bfqd, css); ++ if (bfqg != NULL) ++ bfq_group_chain_link(bfqd, css, bfqg); ++ else ++ bfqg = bfqd->root_group; ++ ++ return bfqg; ++} ++ ++/** ++ * bfq_bfqq_move - migrate @bfqq to @bfqg. ++ * @bfqd: queue descriptor. ++ * @bfqq: the queue to move. ++ * @entity: @bfqq's entity. ++ * @bfqg: the group to move to. ++ * ++ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating ++ * it on the new one. Avoid putting the entity on the old group idle tree. ++ * ++ * Must be called under the queue lock; the cgroup owning @bfqg must ++ * not disappear (by now this just means that we are called under ++ * rcu_read_lock()). ++ */ ++static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct bfq_entity *entity, struct bfq_group *bfqg) ++{ ++ int busy, resume; ++ ++ busy = bfq_bfqq_busy(bfqq); ++ resume = !RB_EMPTY_ROOT(&bfqq->sort_list); ++ ++ BUG_ON(resume && !entity->on_st); ++ BUG_ON(busy && !resume && entity->on_st && ++ bfqq != bfqd->in_service_queue); ++ ++ if (busy) { ++ BUG_ON(atomic_read(&bfqq->ref) < 2); ++ ++ if (!resume) ++ bfq_del_bfqq_busy(bfqd, bfqq, 0); ++ else ++ bfq_deactivate_bfqq(bfqd, bfqq, 0); ++ } else if (entity->on_st) ++ bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); ++ ++ /* ++ * Here we use a reference to bfqg. We don't need a refcounter ++ * as the cgroup reference will not be dropped, so that its ++ * destroy() callback will not be invoked. ++ */ ++ entity->parent = bfqg->my_entity; ++ entity->sched_data = &bfqg->sched_data; ++ ++ if (busy && resume) ++ bfq_activate_bfqq(bfqd, bfqq); ++ ++ if (bfqd->in_service_queue == NULL && !bfqd->rq_in_driver) ++ bfq_schedule_dispatch(bfqd); ++} ++ ++/** ++ * __bfq_bic_change_cgroup - move @bic to @cgroup. ++ * @bfqd: the queue descriptor. ++ * @bic: the bic to move. ++ * @cgroup: the cgroup to move to. ++ * ++ * Move bic to cgroup, assuming that bfqd->queue is locked; the caller ++ * has to make sure that the reference to cgroup is valid across the call. ++ * ++ * NOTE: an alternative approach might have been to store the current ++ * cgroup in bfqq and getting a reference to it, reducing the lookup ++ * time here, at the price of slightly more complex code. ++ */ ++static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, ++ struct bfq_io_cq *bic, ++ struct cgroup_subsys_state *css) ++{ ++ struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0); ++ struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1); ++ struct bfq_entity *entity; ++ struct bfq_group *bfqg; ++ struct bfqio_cgroup *bgrp; ++ ++ bgrp = css_to_bfqio(css); ++ ++ bfqg = bfq_find_alloc_group(bfqd, css); ++ if (async_bfqq != NULL) { ++ entity = &async_bfqq->entity; ++ ++ if (entity->sched_data != &bfqg->sched_data) { ++ bic_set_bfqq(bic, NULL, 0); ++ bfq_log_bfqq(bfqd, async_bfqq, ++ "bic_change_group: %p %d", ++ async_bfqq, atomic_read(&async_bfqq->ref)); ++ bfq_put_queue(async_bfqq); ++ } ++ } ++ ++ if (sync_bfqq != NULL) { ++ entity = &sync_bfqq->entity; ++ if (entity->sched_data != &bfqg->sched_data) ++ bfq_bfqq_move(bfqd, sync_bfqq, entity, bfqg); ++ } ++ ++ return bfqg; ++} ++ ++/** ++ * bfq_bic_change_cgroup - move @bic to @cgroup. ++ * @bic: the bic being migrated. ++ * @cgroup: the destination cgroup. ++ * ++ * When the task owning @bic is moved to @cgroup, @bic is immediately ++ * moved into its new parent group. ++ */ ++static void bfq_bic_change_cgroup(struct bfq_io_cq *bic, ++ struct cgroup_subsys_state *css) ++{ ++ struct bfq_data *bfqd; ++ unsigned long uninitialized_var(flags); ++ ++ bfqd = bfq_get_bfqd_locked(&(bic->icq.q->elevator->elevator_data), ++ &flags); ++ if (bfqd != NULL) { ++ __bfq_bic_change_cgroup(bfqd, bic, css); ++ bfq_put_bfqd_unlock(bfqd, &flags); ++ } ++} ++ ++/** ++ * bfq_bic_update_cgroup - update the cgroup of @bic. ++ * @bic: the @bic to update. ++ * ++ * Make sure that @bic is enqueued in the cgroup of the current task. ++ * We need this in addition to moving bics during the cgroup attach ++ * phase because the task owning @bic could be at its first disk ++ * access or we may end up in the root cgroup as the result of a ++ * memory allocation failure and here we try to move to the right ++ * group. ++ * ++ * Must be called under the queue lock. It is safe to use the returned ++ * value even after the rcu_read_unlock() as the migration/destruction ++ * paths act under the queue lock too. IOW it is impossible to race with ++ * group migration/destruction and end up with an invalid group as: ++ * a) here cgroup has not yet been destroyed, nor its destroy callback ++ * has started execution, as current holds a reference to it, ++ * b) if it is destroyed after rcu_read_unlock() [after current is ++ * migrated to a different cgroup] its attach() callback will have ++ * taken care of remove all the references to the old cgroup data. ++ */ ++static struct bfq_group *bfq_bic_update_cgroup(struct bfq_io_cq *bic) ++{ ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ struct bfq_group *bfqg; ++ struct cgroup_subsys_state *css; ++ ++ BUG_ON(bfqd == NULL); ++ ++ rcu_read_lock(); ++ css = task_css(current, bfqio_cgrp_id); ++ bfqg = __bfq_bic_change_cgroup(bfqd, bic, css); ++ rcu_read_unlock(); ++ ++ return bfqg; ++} ++ ++/** ++ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st. ++ * @st: the service tree being flushed. ++ */ ++static inline void bfq_flush_idle_tree(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *entity = st->first_idle; ++ ++ for (; entity != NULL; entity = st->first_idle) ++ __bfq_deactivate_entity(entity, 0); ++} ++ ++/** ++ * bfq_reparent_leaf_entity - move leaf entity to the root_group. ++ * @bfqd: the device data structure with the root group. ++ * @entity: the entity to move. ++ */ ++static inline void bfq_reparent_leaf_entity(struct bfq_data *bfqd, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ BUG_ON(bfqq == NULL); ++ bfq_bfqq_move(bfqd, bfqq, entity, bfqd->root_group); ++ return; ++} ++ ++/** ++ * bfq_reparent_active_entities - move to the root group all active ++ * entities. ++ * @bfqd: the device data structure with the root group. ++ * @bfqg: the group to move from. ++ * @st: the service tree with the entities. ++ * ++ * Needs queue_lock to be taken and reference to be valid over the call. ++ */ ++static inline void bfq_reparent_active_entities(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, ++ struct bfq_service_tree *st) ++{ ++ struct rb_root *active = &st->active; ++ struct bfq_entity *entity = NULL; ++ ++ if (!RB_EMPTY_ROOT(&st->active)) ++ entity = bfq_entity_of(rb_first(active)); ++ ++ for (; entity != NULL; entity = bfq_entity_of(rb_first(active))) ++ bfq_reparent_leaf_entity(bfqd, entity); ++ ++ if (bfqg->sched_data.in_service_entity != NULL) ++ bfq_reparent_leaf_entity(bfqd, ++ bfqg->sched_data.in_service_entity); ++ ++ return; ++} ++ ++/** ++ * bfq_destroy_group - destroy @bfqg. ++ * @bgrp: the bfqio_cgroup containing @bfqg. ++ * @bfqg: the group being destroyed. ++ * ++ * Destroy @bfqg, making sure that it is not referenced from its parent. ++ */ ++static void bfq_destroy_group(struct bfqio_cgroup *bgrp, struct bfq_group *bfqg) ++{ ++ struct bfq_data *bfqd; ++ struct bfq_service_tree *st; ++ struct bfq_entity *entity = bfqg->my_entity; ++ unsigned long uninitialized_var(flags); ++ int i; ++ ++ hlist_del(&bfqg->group_node); ++ ++ /* ++ * Empty all service_trees belonging to this group before ++ * deactivating the group itself. ++ */ ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) { ++ st = bfqg->sched_data.service_tree + i; ++ ++ /* ++ * The idle tree may still contain bfq_queues belonging ++ * to exited task because they never migrated to a different ++ * cgroup from the one being destroyed now. No one else ++ * can access them so it's safe to act without any lock. ++ */ ++ bfq_flush_idle_tree(st); ++ ++ /* ++ * It may happen that some queues are still active ++ * (busy) upon group destruction (if the corresponding ++ * processes have been forced to terminate). We move ++ * all the leaf entities corresponding to these queues ++ * to the root_group. ++ * Also, it may happen that the group has an entity ++ * in service, which is disconnected from the active ++ * tree: it must be moved, too. ++ * There is no need to put the sync queues, as the ++ * scheduler has taken no reference. ++ */ ++ bfqd = bfq_get_bfqd_locked(&bfqg->bfqd, &flags); ++ if (bfqd != NULL) { ++ bfq_reparent_active_entities(bfqd, bfqg, st); ++ bfq_put_bfqd_unlock(bfqd, &flags); ++ } ++ BUG_ON(!RB_EMPTY_ROOT(&st->active)); ++ BUG_ON(!RB_EMPTY_ROOT(&st->idle)); ++ } ++ BUG_ON(bfqg->sched_data.next_in_service != NULL); ++ BUG_ON(bfqg->sched_data.in_service_entity != NULL); ++ ++ /* ++ * We may race with device destruction, take extra care when ++ * dereferencing bfqg->bfqd. ++ */ ++ bfqd = bfq_get_bfqd_locked(&bfqg->bfqd, &flags); ++ if (bfqd != NULL) { ++ hlist_del(&bfqg->bfqd_node); ++ __bfq_deactivate_entity(entity, 0); ++ bfq_put_async_queues(bfqd, bfqg); ++ bfq_put_bfqd_unlock(bfqd, &flags); ++ } ++ BUG_ON(entity->tree != NULL); ++ ++ /* ++ * No need to defer the kfree() to the end of the RCU grace ++ * period: we are called from the destroy() callback of our ++ * cgroup, so we can be sure that no one is a) still using ++ * this cgroup or b) doing lookups in it. ++ */ ++ kfree(bfqg); ++} ++ ++static void bfq_end_wr_async(struct bfq_data *bfqd) ++{ ++ struct hlist_node *tmp; ++ struct bfq_group *bfqg; ++ ++ hlist_for_each_entry_safe(bfqg, tmp, &bfqd->group_list, bfqd_node) ++ bfq_end_wr_async_queues(bfqd, bfqg); ++ bfq_end_wr_async_queues(bfqd, bfqd->root_group); ++} ++ ++/** ++ * bfq_disconnect_groups - disconnect @bfqd from all its groups. ++ * @bfqd: the device descriptor being exited. ++ * ++ * When the device exits we just make sure that no lookup can return ++ * the now unused group structures. They will be deallocated on cgroup ++ * destruction. ++ */ ++static void bfq_disconnect_groups(struct bfq_data *bfqd) ++{ ++ struct hlist_node *tmp; ++ struct bfq_group *bfqg; ++ ++ bfq_log(bfqd, "disconnect_groups beginning"); ++ hlist_for_each_entry_safe(bfqg, tmp, &bfqd->group_list, bfqd_node) { ++ hlist_del(&bfqg->bfqd_node); ++ ++ __bfq_deactivate_entity(bfqg->my_entity, 0); ++ ++ /* ++ * Don't remove from the group hash, just set an ++ * invalid key. No lookups can race with the ++ * assignment as bfqd is being destroyed; this ++ * implies also that new elements cannot be added ++ * to the list. ++ */ ++ rcu_assign_pointer(bfqg->bfqd, NULL); ++ ++ bfq_log(bfqd, "disconnect_groups: put async for group %p", ++ bfqg); ++ bfq_put_async_queues(bfqd, bfqg); ++ } ++} ++ ++static inline void bfq_free_root_group(struct bfq_data *bfqd) ++{ ++ struct bfqio_cgroup *bgrp = &bfqio_root_cgroup; ++ struct bfq_group *bfqg = bfqd->root_group; ++ ++ bfq_put_async_queues(bfqd, bfqg); ++ ++ spin_lock_irq(&bgrp->lock); ++ hlist_del_rcu(&bfqg->group_node); ++ spin_unlock_irq(&bgrp->lock); ++ ++ /* ++ * No need to synchronize_rcu() here: since the device is gone ++ * there cannot be any read-side access to its root_group. ++ */ ++ kfree(bfqg); ++} ++ ++static struct bfq_group *bfq_alloc_root_group(struct bfq_data *bfqd, int node) ++{ ++ struct bfq_group *bfqg; ++ struct bfqio_cgroup *bgrp; ++ int i; ++ ++ bfqg = kzalloc_node(sizeof(*bfqg), GFP_KERNEL, node); ++ if (bfqg == NULL) ++ return NULL; ++ ++ bfqg->entity.parent = NULL; ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) ++ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; ++ ++ bgrp = &bfqio_root_cgroup; ++ spin_lock_irq(&bgrp->lock); ++ rcu_assign_pointer(bfqg->bfqd, bfqd); ++ hlist_add_head_rcu(&bfqg->group_node, &bgrp->group_data); ++ spin_unlock_irq(&bgrp->lock); ++ ++ return bfqg; ++} ++ ++#define SHOW_FUNCTION(__VAR) \ ++static u64 bfqio_cgroup_##__VAR##_read(struct cgroup_subsys_state *css, \ ++ struct cftype *cftype) \ ++{ \ ++ struct bfqio_cgroup *bgrp = css_to_bfqio(css); \ ++ u64 ret = -ENODEV; \ ++ \ ++ mutex_lock(&bfqio_mutex); \ ++ if (bfqio_is_removed(bgrp)) \ ++ goto out_unlock; \ ++ \ ++ spin_lock_irq(&bgrp->lock); \ ++ ret = bgrp->__VAR; \ ++ spin_unlock_irq(&bgrp->lock); \ ++ \ ++out_unlock: \ ++ mutex_unlock(&bfqio_mutex); \ ++ return ret; \ ++} ++ ++SHOW_FUNCTION(weight); ++SHOW_FUNCTION(ioprio); ++SHOW_FUNCTION(ioprio_class); ++#undef SHOW_FUNCTION ++ ++#define STORE_FUNCTION(__VAR, __MIN, __MAX) \ ++static int bfqio_cgroup_##__VAR##_write(struct cgroup_subsys_state *css,\ ++ struct cftype *cftype, \ ++ u64 val) \ ++{ \ ++ struct bfqio_cgroup *bgrp = css_to_bfqio(css); \ ++ struct bfq_group *bfqg; \ ++ int ret = -EINVAL; \ ++ \ ++ if (val < (__MIN) || val > (__MAX)) \ ++ return ret; \ ++ \ ++ ret = -ENODEV; \ ++ mutex_lock(&bfqio_mutex); \ ++ if (bfqio_is_removed(bgrp)) \ ++ goto out_unlock; \ ++ ret = 0; \ ++ \ ++ spin_lock_irq(&bgrp->lock); \ ++ bgrp->__VAR = (unsigned short)val; \ ++ hlist_for_each_entry(bfqg, &bgrp->group_data, group_node) { \ ++ /* \ ++ * Setting the ioprio_changed flag of the entity \ ++ * to 1 with new_##__VAR == ##__VAR would re-set \ ++ * the value of the weight to its ioprio mapping. \ ++ * Set the flag only if necessary. \ ++ */ \ ++ if ((unsigned short)val != bfqg->entity.new_##__VAR) { \ ++ bfqg->entity.new_##__VAR = (unsigned short)val; \ ++ /* \ ++ * Make sure that the above new value has been \ ++ * stored in bfqg->entity.new_##__VAR before \ ++ * setting the ioprio_changed flag. In fact, \ ++ * this flag may be read asynchronously (in \ ++ * critical sections protected by a different \ ++ * lock than that held here), and finding this \ ++ * flag set may cause the execution of the code \ ++ * for updating parameters whose value may \ ++ * depend also on bfqg->entity.new_##__VAR (in \ ++ * __bfq_entity_update_weight_prio). \ ++ * This barrier makes sure that the new value \ ++ * of bfqg->entity.new_##__VAR is correctly \ ++ * seen in that code. \ ++ */ \ ++ smp_wmb(); \ ++ bfqg->entity.ioprio_changed = 1; \ ++ } \ ++ } \ ++ spin_unlock_irq(&bgrp->lock); \ ++ \ ++out_unlock: \ ++ mutex_unlock(&bfqio_mutex); \ ++ return ret; \ ++} ++ ++STORE_FUNCTION(weight, BFQ_MIN_WEIGHT, BFQ_MAX_WEIGHT); ++STORE_FUNCTION(ioprio, 0, IOPRIO_BE_NR - 1); ++STORE_FUNCTION(ioprio_class, IOPRIO_CLASS_RT, IOPRIO_CLASS_IDLE); ++#undef STORE_FUNCTION ++ ++static struct cftype bfqio_files[] = { ++ { ++ .name = "weight", ++ .read_u64 = bfqio_cgroup_weight_read, ++ .write_u64 = bfqio_cgroup_weight_write, ++ }, ++ { ++ .name = "ioprio", ++ .read_u64 = bfqio_cgroup_ioprio_read, ++ .write_u64 = bfqio_cgroup_ioprio_write, ++ }, ++ { ++ .name = "ioprio_class", ++ .read_u64 = bfqio_cgroup_ioprio_class_read, ++ .write_u64 = bfqio_cgroup_ioprio_class_write, ++ }, ++ { }, /* terminate */ ++}; ++ ++static struct cgroup_subsys_state *bfqio_create(struct cgroup_subsys_state ++ *parent_css) ++{ ++ struct bfqio_cgroup *bgrp; ++ ++ if (parent_css != NULL) { ++ bgrp = kzalloc(sizeof(*bgrp), GFP_KERNEL); ++ if (bgrp == NULL) ++ return ERR_PTR(-ENOMEM); ++ } else ++ bgrp = &bfqio_root_cgroup; ++ ++ spin_lock_init(&bgrp->lock); ++ INIT_HLIST_HEAD(&bgrp->group_data); ++ bgrp->ioprio = BFQ_DEFAULT_GRP_IOPRIO; ++ bgrp->ioprio_class = BFQ_DEFAULT_GRP_CLASS; ++ ++ return &bgrp->css; ++} ++ ++/* ++ * We cannot support shared io contexts, as we have no means to support ++ * two tasks with the same ioc in two different groups without major rework ++ * of the main bic/bfqq data structures. By now we allow a task to change ++ * its cgroup only if it's the only owner of its ioc; the drawback of this ++ * behavior is that a group containing a task that forked using CLONE_IO ++ * will not be destroyed until the tasks sharing the ioc die. ++ */ ++static int bfqio_can_attach(struct cgroup_subsys_state *css, ++ struct cgroup_taskset *tset) ++{ ++ struct task_struct *task; ++ struct io_context *ioc; ++ int ret = 0; ++ ++ cgroup_taskset_for_each(task, tset) { ++ /* ++ * task_lock() is needed to avoid races with ++ * exit_io_context() ++ */ ++ task_lock(task); ++ ioc = task->io_context; ++ if (ioc != NULL && atomic_read(&ioc->nr_tasks) > 1) ++ /* ++ * ioc == NULL means that the task is either too ++ * young or exiting: if it has still no ioc the ++ * ioc can't be shared, if the task is exiting the ++ * attach will fail anyway, no matter what we ++ * return here. ++ */ ++ ret = -EINVAL; ++ task_unlock(task); ++ if (ret) ++ break; ++ } ++ ++ return ret; ++} ++ ++static void bfqio_attach(struct cgroup_subsys_state *css, ++ struct cgroup_taskset *tset) ++{ ++ struct task_struct *task; ++ struct io_context *ioc; ++ struct io_cq *icq; ++ ++ /* ++ * IMPORTANT NOTE: The move of more than one process at a time to a ++ * new group has not yet been tested. ++ */ ++ cgroup_taskset_for_each(task, tset) { ++ ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE); ++ if (ioc) { ++ /* ++ * Handle cgroup change here. ++ */ ++ rcu_read_lock(); ++ hlist_for_each_entry_rcu(icq, &ioc->icq_list, ioc_node) ++ if (!strncmp( ++ icq->q->elevator->type->elevator_name, ++ "bfq", ELV_NAME_MAX)) ++ bfq_bic_change_cgroup(icq_to_bic(icq), ++ css); ++ rcu_read_unlock(); ++ put_io_context(ioc); ++ } ++ } ++} ++ ++static void bfqio_destroy(struct cgroup_subsys_state *css) ++{ ++ struct bfqio_cgroup *bgrp = css_to_bfqio(css); ++ struct hlist_node *tmp; ++ struct bfq_group *bfqg; ++ ++ /* ++ * Since we are destroying the cgroup, there are no more tasks ++ * referencing it, and all the RCU grace periods that may have ++ * referenced it are ended (as the destruction of the parent ++ * cgroup is RCU-safe); bgrp->group_data will not be accessed by ++ * anything else and we don't need any synchronization. ++ */ ++ hlist_for_each_entry_safe(bfqg, tmp, &bgrp->group_data, group_node) ++ bfq_destroy_group(bgrp, bfqg); ++ ++ BUG_ON(!hlist_empty(&bgrp->group_data)); ++ ++ kfree(bgrp); ++} ++ ++static int bfqio_css_online(struct cgroup_subsys_state *css) ++{ ++ struct bfqio_cgroup *bgrp = css_to_bfqio(css); ++ ++ mutex_lock(&bfqio_mutex); ++ bgrp->online = true; ++ mutex_unlock(&bfqio_mutex); ++ ++ return 0; ++} ++ ++static void bfqio_css_offline(struct cgroup_subsys_state *css) ++{ ++ struct bfqio_cgroup *bgrp = css_to_bfqio(css); ++ ++ mutex_lock(&bfqio_mutex); ++ bgrp->online = false; ++ mutex_unlock(&bfqio_mutex); ++} ++ ++struct cgroup_subsys bfqio_cgrp_subsys = { ++ .css_alloc = bfqio_create, ++ .css_online = bfqio_css_online, ++ .css_offline = bfqio_css_offline, ++ .can_attach = bfqio_can_attach, ++ .attach = bfqio_attach, ++ .css_free = bfqio_destroy, ++ .legacy_cftypes = bfqio_files, ++}; ++#else ++static inline void bfq_init_entity(struct bfq_entity *entity, ++ struct bfq_group *bfqg) ++{ ++ entity->weight = entity->new_weight; ++ entity->orig_weight = entity->new_weight; ++ entity->ioprio = entity->new_ioprio; ++ entity->ioprio_class = entity->new_ioprio_class; ++ entity->sched_data = &bfqg->sched_data; ++} ++ ++static inline struct bfq_group * ++bfq_bic_update_cgroup(struct bfq_io_cq *bic) ++{ ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ return bfqd->root_group; ++} ++ ++static inline void bfq_bfqq_move(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct bfq_entity *entity, ++ struct bfq_group *bfqg) ++{ ++} ++ ++static void bfq_end_wr_async(struct bfq_data *bfqd) ++{ ++ bfq_end_wr_async_queues(bfqd, bfqd->root_group); ++} ++ ++static inline void bfq_disconnect_groups(struct bfq_data *bfqd) ++{ ++ bfq_put_async_queues(bfqd, bfqd->root_group); ++} ++ ++static inline void bfq_free_root_group(struct bfq_data *bfqd) ++{ ++ kfree(bfqd->root_group); ++} ++ ++static struct bfq_group *bfq_alloc_root_group(struct bfq_data *bfqd, int node) ++{ ++ struct bfq_group *bfqg; ++ int i; ++ ++ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node); ++ if (bfqg == NULL) ++ return NULL; ++ ++ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) ++ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; ++ ++ return bfqg; ++} ++#endif +diff --git a/block/bfq-ioc.c b/block/bfq-ioc.c +new file mode 100644 +index 0000000..7f6b000 +--- /dev/null ++++ b/block/bfq-ioc.c +@@ -0,0 +1,36 @@ ++/* ++ * BFQ: I/O context handling. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ */ ++ ++/** ++ * icq_to_bic - convert iocontext queue structure to bfq_io_cq. ++ * @icq: the iocontext queue. ++ */ ++static inline struct bfq_io_cq *icq_to_bic(struct io_cq *icq) ++{ ++ /* bic->icq is the first member, %NULL will convert to %NULL */ ++ return container_of(icq, struct bfq_io_cq, icq); ++} ++ ++/** ++ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd. ++ * @bfqd: the lookup key. ++ * @ioc: the io_context of the process doing I/O. ++ * ++ * Queue lock must be held. ++ */ ++static inline struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd, ++ struct io_context *ioc) ++{ ++ if (ioc) ++ return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue)); ++ return NULL; ++} +diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c +new file mode 100644 +index 0000000..97ee934 +--- /dev/null ++++ b/block/bfq-iosched.c +@@ -0,0 +1,3902 @@ ++/* ++ * Budget Fair Queueing (BFQ) disk scheduler. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ * ++ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ ++ * file. ++ * ++ * BFQ is a proportional-share storage-I/O scheduling algorithm based on ++ * the slice-by-slice service scheme of CFQ. But BFQ assigns budgets, ++ * measured in number of sectors, to processes instead of time slices. The ++ * device is not granted to the in-service process for a given time slice, ++ * but until it has exhausted its assigned budget. This change from the time ++ * to the service domain allows BFQ to distribute the device throughput ++ * among processes as desired, without any distortion due to ZBR, workload ++ * fluctuations or other factors. BFQ uses an ad hoc internal scheduler, ++ * called B-WF2Q+, to schedule processes according to their budgets. More ++ * precisely, BFQ schedules queues associated to processes. Thanks to the ++ * accurate policy of B-WF2Q+, BFQ can afford to assign high budgets to ++ * I/O-bound processes issuing sequential requests (to boost the ++ * throughput), and yet guarantee a low latency to interactive and soft ++ * real-time applications. ++ * ++ * BFQ is described in [1], where also a reference to the initial, more ++ * theoretical paper on BFQ can be found. The interested reader can find ++ * in the latter paper full details on the main algorithm, as well as ++ * formulas of the guarantees and formal proofs of all the properties. ++ * With respect to the version of BFQ presented in these papers, this ++ * implementation adds a few more heuristics, such as the one that ++ * guarantees a low latency to soft real-time applications, and a ++ * hierarchical extension based on H-WF2Q+. ++ * ++ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with ++ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N) ++ * complexity derives from the one introduced with EEVDF in [3]. ++ * ++ * [1] P. Valente and M. Andreolini, ``Improving Application Responsiveness ++ * with the BFQ Disk I/O Scheduler'', ++ * Proceedings of the 5th Annual International Systems and Storage ++ * Conference (SYSTOR '12), June 2012. ++ * ++ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf ++ * ++ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing ++ * Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689, ++ * Oct 1997. ++ * ++ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz ++ * ++ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline ++ * First: A Flexible and Accurate Mechanism for Proportional Share ++ * Resource Allocation,'' technical report. ++ * ++ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf ++ */ ++#include ++#include ++#include ++#include ++#include ++#include ++#include ++#include ++#include "bfq.h" ++#include "blk.h" ++ ++/* Max number of dispatches in one round of service. */ ++static const int bfq_quantum = 4; ++ ++/* Expiration time of sync (0) and async (1) requests, in jiffies. */ ++static const int bfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; ++ ++/* Maximum backwards seek, in KiB. */ ++static const int bfq_back_max = 16 * 1024; ++ ++/* Penalty of a backwards seek, in number of sectors. */ ++static const int bfq_back_penalty = 2; ++ ++/* Idling period duration, in jiffies. */ ++static int bfq_slice_idle = HZ / 125; ++ ++/* Default maximum budget values, in sectors and number of requests. */ ++static const int bfq_default_max_budget = 16 * 1024; ++static const int bfq_max_budget_async_rq = 4; ++ ++/* ++ * Async to sync throughput distribution is controlled as follows: ++ * when an async request is served, the entity is charged the number ++ * of sectors of the request, multiplied by the factor below ++ */ ++static const int bfq_async_charge_factor = 10; ++ ++/* Default timeout values, in jiffies, approximating CFQ defaults. */ ++static const int bfq_timeout_sync = HZ / 8; ++static int bfq_timeout_async = HZ / 25; ++ ++struct kmem_cache *bfq_pool; ++ ++/* Below this threshold (in ms), we consider thinktime immediate. */ ++#define BFQ_MIN_TT 2 ++ ++/* hw_tag detection: parallel requests threshold and min samples needed. */ ++#define BFQ_HW_QUEUE_THRESHOLD 4 ++#define BFQ_HW_QUEUE_SAMPLES 32 ++ ++#define BFQQ_SEEK_THR (sector_t)(8 * 1024) ++#define BFQQ_SEEKY(bfqq) ((bfqq)->seek_mean > BFQQ_SEEK_THR) ++ ++/* Min samples used for peak rate estimation (for autotuning). */ ++#define BFQ_PEAK_RATE_SAMPLES 32 ++ ++/* Shift used for peak rate fixed precision calculations. */ ++#define BFQ_RATE_SHIFT 16 ++ ++/* ++ * By default, BFQ computes the duration of the weight raising for ++ * interactive applications automatically, using the following formula: ++ * duration = (R / r) * T, where r is the peak rate of the device, and ++ * R and T are two reference parameters. ++ * In particular, R is the peak rate of the reference device (see below), ++ * and T is a reference time: given the systems that are likely to be ++ * installed on the reference device according to its speed class, T is ++ * about the maximum time needed, under BFQ and while reading two files in ++ * parallel, to load typical large applications on these systems. ++ * In practice, the slower/faster the device at hand is, the more/less it ++ * takes to load applications with respect to the reference device. ++ * Accordingly, the longer/shorter BFQ grants weight raising to interactive ++ * applications. ++ * ++ * BFQ uses four different reference pairs (R, T), depending on: ++ * . whether the device is rotational or non-rotational; ++ * . whether the device is slow, such as old or portable HDDs, as well as ++ * SD cards, or fast, such as newer HDDs and SSDs. ++ * ++ * The device's speed class is dynamically (re)detected in ++ * bfq_update_peak_rate() every time the estimated peak rate is updated. ++ * ++ * In the following definitions, R_slow[0]/R_fast[0] and T_slow[0]/T_fast[0] ++ * are the reference values for a slow/fast rotational device, whereas ++ * R_slow[1]/R_fast[1] and T_slow[1]/T_fast[1] are the reference values for ++ * a slow/fast non-rotational device. Finally, device_speed_thresh are the ++ * thresholds used to switch between speed classes. ++ * Both the reference peak rates and the thresholds are measured in ++ * sectors/usec, left-shifted by BFQ_RATE_SHIFT. ++ */ ++static int R_slow[2] = {1536, 10752}; ++static int R_fast[2] = {17415, 34791}; ++/* ++ * To improve readability, a conversion function is used to initialize the ++ * following arrays, which entails that they can be initialized only in a ++ * function. ++ */ ++static int T_slow[2]; ++static int T_fast[2]; ++static int device_speed_thresh[2]; ++ ++#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \ ++ { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 }) ++ ++#define RQ_BIC(rq) ((struct bfq_io_cq *) (rq)->elv.priv[0]) ++#define RQ_BFQQ(rq) ((rq)->elv.priv[1]) ++ ++static inline void bfq_schedule_dispatch(struct bfq_data *bfqd); ++ ++#include "bfq-ioc.c" ++#include "bfq-sched.c" ++#include "bfq-cgroup.c" ++ ++#define bfq_class_idle(bfqq) ((bfqq)->entity.ioprio_class ==\ ++ IOPRIO_CLASS_IDLE) ++#define bfq_class_rt(bfqq) ((bfqq)->entity.ioprio_class ==\ ++ IOPRIO_CLASS_RT) ++ ++#define bfq_sample_valid(samples) ((samples) > 80) ++ ++/* ++ * We regard a request as SYNC, if either it's a read or has the SYNC bit ++ * set (in which case it could also be a direct WRITE). ++ */ ++static inline int bfq_bio_sync(struct bio *bio) ++{ ++ if (bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC)) ++ return 1; ++ ++ return 0; ++} ++ ++/* ++ * Scheduler run of queue, if there are requests pending and no one in the ++ * driver that will restart queueing. ++ */ ++static inline void bfq_schedule_dispatch(struct bfq_data *bfqd) ++{ ++ if (bfqd->queued != 0) { ++ bfq_log(bfqd, "schedule dispatch"); ++ kblockd_schedule_work(&bfqd->unplug_work); ++ } ++} ++ ++/* ++ * Lifted from AS - choose which of rq1 and rq2 that is best served now. ++ * We choose the request that is closesr to the head right now. Distance ++ * behind the head is penalized and only allowed to a certain extent. ++ */ ++static struct request *bfq_choose_req(struct bfq_data *bfqd, ++ struct request *rq1, ++ struct request *rq2, ++ sector_t last) ++{ ++ sector_t s1, s2, d1 = 0, d2 = 0; ++ unsigned long back_max; ++#define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */ ++#define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */ ++ unsigned wrap = 0; /* bit mask: requests behind the disk head? */ ++ ++ if (rq1 == NULL || rq1 == rq2) ++ return rq2; ++ if (rq2 == NULL) ++ return rq1; ++ ++ if (rq_is_sync(rq1) && !rq_is_sync(rq2)) ++ return rq1; ++ else if (rq_is_sync(rq2) && !rq_is_sync(rq1)) ++ return rq2; ++ if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META)) ++ return rq1; ++ else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META)) ++ return rq2; ++ ++ s1 = blk_rq_pos(rq1); ++ s2 = blk_rq_pos(rq2); ++ ++ /* ++ * By definition, 1KiB is 2 sectors. ++ */ ++ back_max = bfqd->bfq_back_max * 2; ++ ++ /* ++ * Strict one way elevator _except_ in the case where we allow ++ * short backward seeks which are biased as twice the cost of a ++ * similar forward seek. ++ */ ++ if (s1 >= last) ++ d1 = s1 - last; ++ else if (s1 + back_max >= last) ++ d1 = (last - s1) * bfqd->bfq_back_penalty; ++ else ++ wrap |= BFQ_RQ1_WRAP; ++ ++ if (s2 >= last) ++ d2 = s2 - last; ++ else if (s2 + back_max >= last) ++ d2 = (last - s2) * bfqd->bfq_back_penalty; ++ else ++ wrap |= BFQ_RQ2_WRAP; ++ ++ /* Found required data */ ++ ++ /* ++ * By doing switch() on the bit mask "wrap" we avoid having to ++ * check two variables for all permutations: --> faster! ++ */ ++ switch (wrap) { ++ case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ ++ if (d1 < d2) ++ return rq1; ++ else if (d2 < d1) ++ return rq2; ++ else { ++ if (s1 >= s2) ++ return rq1; ++ else ++ return rq2; ++ } ++ ++ case BFQ_RQ2_WRAP: ++ return rq1; ++ case BFQ_RQ1_WRAP: ++ return rq2; ++ case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */ ++ default: ++ /* ++ * Since both rqs are wrapped, ++ * start with the one that's further behind head ++ * (--> only *one* back seek required), ++ * since back seek takes more time than forward. ++ */ ++ if (s1 <= s2) ++ return rq1; ++ else ++ return rq2; ++ } ++} ++ ++static struct bfq_queue * ++bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root, ++ sector_t sector, struct rb_node **ret_parent, ++ struct rb_node ***rb_link) ++{ ++ struct rb_node **p, *parent; ++ struct bfq_queue *bfqq = NULL; ++ ++ parent = NULL; ++ p = &root->rb_node; ++ while (*p) { ++ struct rb_node **n; ++ ++ parent = *p; ++ bfqq = rb_entry(parent, struct bfq_queue, pos_node); ++ ++ /* ++ * Sort strictly based on sector. Smallest to the left, ++ * largest to the right. ++ */ ++ if (sector > blk_rq_pos(bfqq->next_rq)) ++ n = &(*p)->rb_right; ++ else if (sector < blk_rq_pos(bfqq->next_rq)) ++ n = &(*p)->rb_left; ++ else ++ break; ++ p = n; ++ bfqq = NULL; ++ } ++ ++ *ret_parent = parent; ++ if (rb_link) ++ *rb_link = p; ++ ++ bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d", ++ (long long unsigned)sector, ++ bfqq != NULL ? bfqq->pid : 0); ++ ++ return bfqq; ++} ++ ++static void bfq_rq_pos_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct rb_node **p, *parent; ++ struct bfq_queue *__bfqq; ++ ++ if (bfqq->pos_root != NULL) { ++ rb_erase(&bfqq->pos_node, bfqq->pos_root); ++ bfqq->pos_root = NULL; ++ } ++ ++ if (bfq_class_idle(bfqq)) ++ return; ++ if (!bfqq->next_rq) ++ return; ++ ++ bfqq->pos_root = &bfqd->rq_pos_tree; ++ __bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root, ++ blk_rq_pos(bfqq->next_rq), &parent, &p); ++ if (__bfqq == NULL) { ++ rb_link_node(&bfqq->pos_node, parent, p); ++ rb_insert_color(&bfqq->pos_node, bfqq->pos_root); ++ } else ++ bfqq->pos_root = NULL; ++} ++ ++/* ++ * Tell whether there are active queues or groups with differentiated weights. ++ */ ++static inline bool bfq_differentiated_weights(struct bfq_data *bfqd) ++{ ++ BUG_ON(!bfqd->hw_tag); ++ /* ++ * For weights to differ, at least one of the trees must contain ++ * at least two nodes. ++ */ ++ return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) && ++ (bfqd->queue_weights_tree.rb_node->rb_left || ++ bfqd->queue_weights_tree.rb_node->rb_right) ++#ifdef CONFIG_CGROUP_BFQIO ++ ) || ++ (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) && ++ (bfqd->group_weights_tree.rb_node->rb_left || ++ bfqd->group_weights_tree.rb_node->rb_right) ++#endif ++ ); ++} ++ ++/* ++ * If the weight-counter tree passed as input contains no counter for ++ * the weight of the input entity, then add that counter; otherwise just ++ * increment the existing counter. ++ * ++ * Note that weight-counter trees contain few nodes in mostly symmetric ++ * scenarios. For example, if all queues have the same weight, then the ++ * weight-counter tree for the queues may contain at most one node. ++ * This holds even if low_latency is on, because weight-raised queues ++ * are not inserted in the tree. ++ * In most scenarios, the rate at which nodes are created/destroyed ++ * should be low too. ++ */ ++static void bfq_weights_tree_add(struct bfq_data *bfqd, ++ struct bfq_entity *entity, ++ struct rb_root *root) ++{ ++ struct rb_node **new = &(root->rb_node), *parent = NULL; ++ ++ /* ++ * Do not insert if: ++ * - the device does not support queueing; ++ * - the entity is already associated with a counter, which happens if: ++ * 1) the entity is associated with a queue, 2) a request arrival ++ * has caused the queue to become both non-weight-raised, and hence ++ * change its weight, and backlogged; in this respect, each ++ * of the two events causes an invocation of this function, ++ * 3) this is the invocation of this function caused by the second ++ * event. This second invocation is actually useless, and we handle ++ * this fact by exiting immediately. More efficient or clearer ++ * solutions might possibly be adopted. ++ */ ++ if (!bfqd->hw_tag || entity->weight_counter) ++ return; ++ ++ while (*new) { ++ struct bfq_weight_counter *__counter = container_of(*new, ++ struct bfq_weight_counter, ++ weights_node); ++ parent = *new; ++ ++ if (entity->weight == __counter->weight) { ++ entity->weight_counter = __counter; ++ goto inc_counter; ++ } ++ if (entity->weight < __counter->weight) ++ new = &((*new)->rb_left); ++ else ++ new = &((*new)->rb_right); ++ } ++ ++ entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter), ++ GFP_ATOMIC); ++ entity->weight_counter->weight = entity->weight; ++ rb_link_node(&entity->weight_counter->weights_node, parent, new); ++ rb_insert_color(&entity->weight_counter->weights_node, root); ++ ++inc_counter: ++ entity->weight_counter->num_active++; ++} ++ ++/* ++ * Decrement the weight counter associated with the entity, and, if the ++ * counter reaches 0, remove the counter from the tree. ++ * See the comments to the function bfq_weights_tree_add() for considerations ++ * about overhead. ++ */ ++static void bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_entity *entity, ++ struct rb_root *root) ++{ ++ /* ++ * Check whether the entity is actually associated with a counter. ++ * In fact, the device may not be considered NCQ-capable for a while, ++ * which implies that no insertion in the weight trees is performed, ++ * after which the device may start to be deemed NCQ-capable, and hence ++ * this function may start to be invoked. This may cause the function ++ * to be invoked for entities that are not associated with any counter. ++ */ ++ if (!entity->weight_counter) ++ return; ++ ++ BUG_ON(RB_EMPTY_ROOT(root)); ++ BUG_ON(entity->weight_counter->weight != entity->weight); ++ ++ BUG_ON(!entity->weight_counter->num_active); ++ entity->weight_counter->num_active--; ++ if (entity->weight_counter->num_active > 0) ++ goto reset_entity_pointer; ++ ++ rb_erase(&entity->weight_counter->weights_node, root); ++ kfree(entity->weight_counter); ++ ++reset_entity_pointer: ++ entity->weight_counter = NULL; ++} ++ ++static struct request *bfq_find_next_rq(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct request *last) ++{ ++ struct rb_node *rbnext = rb_next(&last->rb_node); ++ struct rb_node *rbprev = rb_prev(&last->rb_node); ++ struct request *next = NULL, *prev = NULL; ++ ++ BUG_ON(RB_EMPTY_NODE(&last->rb_node)); ++ ++ if (rbprev != NULL) ++ prev = rb_entry_rq(rbprev); ++ ++ if (rbnext != NULL) ++ next = rb_entry_rq(rbnext); ++ else { ++ rbnext = rb_first(&bfqq->sort_list); ++ if (rbnext && rbnext != &last->rb_node) ++ next = rb_entry_rq(rbnext); ++ } ++ ++ return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last)); ++} ++ ++/* see the definition of bfq_async_charge_factor for details */ ++static inline unsigned long bfq_serv_to_charge(struct request *rq, ++ struct bfq_queue *bfqq) ++{ ++ return blk_rq_sectors(rq) * ++ (1 + ((!bfq_bfqq_sync(bfqq)) * (bfqq->wr_coeff == 1) * ++ bfq_async_charge_factor)); ++} ++ ++/** ++ * bfq_updated_next_req - update the queue after a new next_rq selection. ++ * @bfqd: the device data the queue belongs to. ++ * @bfqq: the queue to update. ++ * ++ * If the first request of a queue changes we make sure that the queue ++ * has enough budget to serve at least its first request (if the ++ * request has grown). We do this because if the queue has not enough ++ * budget for its first request, it has to go through two dispatch ++ * rounds to actually get it dispatched. ++ */ ++static void bfq_updated_next_req(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ struct request *next_rq = bfqq->next_rq; ++ unsigned long new_budget; ++ ++ if (next_rq == NULL) ++ return; ++ ++ if (bfqq == bfqd->in_service_queue) ++ /* ++ * In order not to break guarantees, budgets cannot be ++ * changed after an entity has been selected. ++ */ ++ return; ++ ++ BUG_ON(entity->tree != &st->active); ++ BUG_ON(entity == entity->sched_data->in_service_entity); ++ ++ new_budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)); ++ if (entity->budget != new_budget) { ++ entity->budget = new_budget; ++ bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu", ++ new_budget); ++ bfq_activate_bfqq(bfqd, bfqq); ++ } ++} ++ ++static inline unsigned int bfq_wr_duration(struct bfq_data *bfqd) ++{ ++ u64 dur; ++ ++ if (bfqd->bfq_wr_max_time > 0) ++ return bfqd->bfq_wr_max_time; ++ ++ dur = bfqd->RT_prod; ++ do_div(dur, bfqd->peak_rate); ++ ++ return dur; ++} ++ ++/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */ ++static inline void bfq_reset_burst_list(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct bfq_queue *item; ++ struct hlist_node *n; ++ ++ hlist_for_each_entry_safe(item, n, &bfqd->burst_list, burst_list_node) ++ hlist_del_init(&item->burst_list_node); ++ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); ++ bfqd->burst_size = 1; ++} ++ ++/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */ ++static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ /* Increment burst size to take into account also bfqq */ ++ bfqd->burst_size++; ++ ++ if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) { ++ struct bfq_queue *pos, *bfqq_item; ++ struct hlist_node *n; ++ ++ /* ++ * Enough queues have been activated shortly after each ++ * other to consider this burst as large. ++ */ ++ bfqd->large_burst = true; ++ ++ /* ++ * We can now mark all queues in the burst list as ++ * belonging to a large burst. ++ */ ++ hlist_for_each_entry(bfqq_item, &bfqd->burst_list, ++ burst_list_node) ++ bfq_mark_bfqq_in_large_burst(bfqq_item); ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ ++ /* ++ * From now on, and until the current burst finishes, any ++ * new queue being activated shortly after the last queue ++ * was inserted in the burst can be immediately marked as ++ * belonging to a large burst. So the burst list is not ++ * needed any more. Remove it. ++ */ ++ hlist_for_each_entry_safe(pos, n, &bfqd->burst_list, ++ burst_list_node) ++ hlist_del_init(&pos->burst_list_node); ++ } else /* burst not yet large: add bfqq to the burst list */ ++ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list); ++} ++ ++/* ++ * If many queues happen to become active shortly after each other, then, ++ * to help the processes associated to these queues get their job done as ++ * soon as possible, it is usually better to not grant either weight-raising ++ * or device idling to these queues. In this comment we describe, firstly, ++ * the reasons why this fact holds, and, secondly, the next function, which ++ * implements the main steps needed to properly mark these queues so that ++ * they can then be treated in a different way. ++ * ++ * As for the terminology, we say that a queue becomes active, i.e., ++ * switches from idle to backlogged, either when it is created (as a ++ * consequence of the arrival of an I/O request), or, if already existing, ++ * when a new request for the queue arrives while the queue is idle. ++ * Bursts of activations, i.e., activations of different queues occurring ++ * shortly after each other, are typically caused by services or applications ++ * that spawn or reactivate many parallel threads/processes. Examples are ++ * systemd during boot or git grep. ++ * ++ * These services or applications benefit mostly from a high throughput: ++ * the quicker the requests of the activated queues are cumulatively served, ++ * the sooner the target job of these queues gets completed. As a consequence, ++ * weight-raising any of these queues, which also implies idling the device ++ * for it, is almost always counterproductive: in most cases it just lowers ++ * throughput. ++ * ++ * On the other hand, a burst of activations may be also caused by the start ++ * of an application that does not consist in a lot of parallel I/O-bound ++ * threads. In fact, with a complex application, the burst may be just a ++ * consequence of the fact that several processes need to be executed to ++ * start-up the application. To start an application as quickly as possible, ++ * the best thing to do is to privilege the I/O related to the application ++ * with respect to all other I/O. Therefore, the best strategy to start as ++ * quickly as possible an application that causes a burst of activations is ++ * to weight-raise all the queues activated during the burst. This is the ++ * exact opposite of the best strategy for the other type of bursts. ++ * ++ * In the end, to take the best action for each of the two cases, the two ++ * types of bursts need to be distinguished. Fortunately, this seems ++ * relatively easy to do, by looking at the sizes of the bursts. In ++ * particular, we found a threshold such that bursts with a larger size ++ * than that threshold are apparently caused only by services or commands ++ * such as systemd or git grep. For brevity, hereafter we call just 'large' ++ * these bursts. BFQ *does not* weight-raise queues whose activations occur ++ * in a large burst. In addition, for each of these queues BFQ performs or ++ * does not perform idling depending on which choice boosts the throughput ++ * most. The exact choice depends on the device and request pattern at ++ * hand. ++ * ++ * Turning back to the next function, it implements all the steps needed ++ * to detect the occurrence of a large burst and to properly mark all the ++ * queues belonging to it (so that they can then be treated in a different ++ * way). This goal is achieved by maintaining a special "burst list" that ++ * holds, temporarily, the queues that belong to the burst in progress. The ++ * list is then used to mark these queues as belonging to a large burst if ++ * the burst does become large. The main steps are the following. ++ * ++ * . when the very first queue is activated, the queue is inserted into the ++ * list (as it could be the first queue in a possible burst) ++ * ++ * . if the current burst has not yet become large, and a queue Q that does ++ * not yet belong to the burst is activated shortly after the last time ++ * at which a new queue entered the burst list, then the function appends ++ * Q to the burst list ++ * ++ * . if, as a consequence of the previous step, the burst size reaches ++ * the large-burst threshold, then ++ * ++ * . all the queues in the burst list are marked as belonging to a ++ * large burst ++ * ++ * . the burst list is deleted; in fact, the burst list already served ++ * its purpose (keeping temporarily track of the queues in a burst, ++ * so as to be able to mark them as belonging to a large burst in the ++ * previous sub-step), and now is not needed any more ++ * ++ * . the device enters a large-burst mode ++ * ++ * . if a queue Q that does not belong to the burst is activated while ++ * the device is in large-burst mode and shortly after the last time ++ * at which a queue either entered the burst list or was marked as ++ * belonging to the current large burst, then Q is immediately marked ++ * as belonging to a large burst. ++ * ++ * . if a queue Q that does not belong to the burst is activated a while ++ * later, i.e., not shortly after, than the last time at which a queue ++ * either entered the burst list or was marked as belonging to the ++ * current large burst, then the current burst is deemed as finished and: ++ * ++ * . the large-burst mode is reset if set ++ * ++ * . the burst list is emptied ++ * ++ * . Q is inserted in the burst list, as Q may be the first queue ++ * in a possible new burst (then the burst list contains just Q ++ * after this step). ++ */ ++static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ bool idle_for_long_time) ++{ ++ /* ++ * If bfqq happened to be activated in a burst, but has been idle ++ * for at least as long as an interactive queue, then we assume ++ * that, in the overall I/O initiated in the burst, the I/O ++ * associated to bfqq is finished. So bfqq does not need to be ++ * treated as a queue belonging to a burst anymore. Accordingly, ++ * we reset bfqq's in_large_burst flag if set, and remove bfqq ++ * from the burst list if it's there. We do not decrement instead ++ * burst_size, because the fact that bfqq does not need to belong ++ * to the burst list any more does not invalidate the fact that ++ * bfqq may have been activated during the current burst. ++ */ ++ if (idle_for_long_time) { ++ hlist_del_init(&bfqq->burst_list_node); ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ } ++ ++ /* ++ * If bfqq is already in the burst list or is part of a large ++ * burst, then there is nothing else to do. ++ */ ++ if (!hlist_unhashed(&bfqq->burst_list_node) || ++ bfq_bfqq_in_large_burst(bfqq)) ++ return; ++ ++ /* ++ * If bfqq's activation happens late enough, then the current ++ * burst is finished, and related data structures must be reset. ++ * ++ * In this respect, consider the special case where bfqq is the very ++ * first queue being activated. In this case, last_ins_in_burst is ++ * not yet significant when we get here. But it is easy to verify ++ * that, whether or not the following condition is true, bfqq will ++ * end up being inserted into the burst list. In particular the ++ * list will happen to contain only bfqq. And this is exactly what ++ * has to happen, as bfqq may be the first queue in a possible ++ * burst. ++ */ ++ if (time_is_before_jiffies(bfqd->last_ins_in_burst + ++ bfqd->bfq_burst_interval)) { ++ bfqd->large_burst = false; ++ bfq_reset_burst_list(bfqd, bfqq); ++ return; ++ } ++ ++ /* ++ * If we get here, then bfqq is being activated shortly after the ++ * last queue. So, if the current burst is also large, we can mark ++ * bfqq as belonging to this large burst immediately. ++ */ ++ if (bfqd->large_burst) { ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ return; ++ } ++ ++ /* ++ * If we get here, then a large-burst state has not yet been ++ * reached, but bfqq is being activated shortly after the last ++ * queue. Then we add bfqq to the burst. ++ */ ++ bfq_add_to_burst(bfqd, bfqq); ++} ++ ++static void bfq_add_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_data *bfqd = bfqq->bfqd; ++ struct request *next_rq, *prev; ++ unsigned long old_wr_coeff = bfqq->wr_coeff; ++ bool interactive = false; ++ ++ bfq_log_bfqq(bfqd, bfqq, "add_request %d", rq_is_sync(rq)); ++ bfqq->queued[rq_is_sync(rq)]++; ++ bfqd->queued++; ++ ++ elv_rb_add(&bfqq->sort_list, rq); ++ ++ /* ++ * Check if this request is a better next-serve candidate. ++ */ ++ prev = bfqq->next_rq; ++ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position); ++ BUG_ON(next_rq == NULL); ++ bfqq->next_rq = next_rq; ++ ++ /* ++ * Adjust priority tree position, if next_rq changes. ++ */ ++ if (prev != bfqq->next_rq) ++ bfq_rq_pos_tree_add(bfqd, bfqq); ++ ++ if (!bfq_bfqq_busy(bfqq)) { ++ bool soft_rt, ++ idle_for_long_time = time_is_before_jiffies( ++ bfqq->budget_timeout + ++ bfqd->bfq_wr_min_idle_time); ++ ++ if (bfq_bfqq_sync(bfqq)) { ++ bool already_in_burst = ++ !hlist_unhashed(&bfqq->burst_list_node) || ++ bfq_bfqq_in_large_burst(bfqq); ++ bfq_handle_burst(bfqd, bfqq, idle_for_long_time); ++ /* ++ * If bfqq was not already in the current burst, ++ * then, at this point, bfqq either has been ++ * added to the current burst or has caused the ++ * current burst to terminate. In particular, in ++ * the second case, bfqq has become the first ++ * queue in a possible new burst. ++ * In both cases last_ins_in_burst needs to be ++ * moved forward. ++ */ ++ if (!already_in_burst) ++ bfqd->last_ins_in_burst = jiffies; ++ } ++ ++ soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 && ++ !bfq_bfqq_in_large_burst(bfqq) && ++ time_is_before_jiffies(bfqq->soft_rt_next_start); ++ interactive = !bfq_bfqq_in_large_burst(bfqq) && ++ idle_for_long_time; ++ entity->budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)); ++ ++ if (!bfq_bfqq_IO_bound(bfqq)) { ++ if (time_before(jiffies, ++ RQ_BIC(rq)->ttime.last_end_request + ++ bfqd->bfq_slice_idle)) { ++ bfqq->requests_within_timer++; ++ if (bfqq->requests_within_timer >= ++ bfqd->bfq_requests_within_timer) ++ bfq_mark_bfqq_IO_bound(bfqq); ++ } else ++ bfqq->requests_within_timer = 0; ++ } ++ ++ if (!bfqd->low_latency) ++ goto add_bfqq_busy; ++ ++ /* ++ * If the queue is not being boosted and has been idle ++ * for enough time, start a weight-raising period ++ */ ++ if (old_wr_coeff == 1 && (interactive || soft_rt)) { ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ if (interactive) ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ else ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais starting at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } else if (old_wr_coeff > 1) { ++ if (interactive) ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ else if (bfq_bfqq_in_large_burst(bfqq) || ++ (bfqq->wr_cur_max_time == ++ bfqd->bfq_wr_rt_max_time && ++ !soft_rt)) { ++ bfqq->wr_coeff = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais ending at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq-> ++ wr_cur_max_time)); ++ } else if (time_before( ++ bfqq->last_wr_start_finish + ++ bfqq->wr_cur_max_time, ++ jiffies + ++ bfqd->bfq_wr_rt_max_time) && ++ soft_rt) { ++ /* ++ * ++ * The remaining weight-raising time is lower ++ * than bfqd->bfq_wr_rt_max_time, which ++ * means that the application is enjoying ++ * weight raising either because deemed soft- ++ * rt in the near past, or because deemed ++ * interactive a long ago. In both cases, ++ * resetting now the current remaining weight- ++ * raising time for the application to the ++ * weight-raising duration for soft rt ++ * applications would not cause any latency ++ * increase for the application (as the new ++ * duration would be higher than the remaining ++ * time). ++ * ++ * In addition, the application is now meeting ++ * the requirements for being deemed soft rt. ++ * In the end we can correctly and safely ++ * (re)charge the weight-raising duration for ++ * the application with the weight-raising ++ * duration for soft rt applications. ++ * ++ * In particular, doing this recharge now, i.e., ++ * before the weight-raising period for the ++ * application finishes, reduces the probability ++ * of the following negative scenario: ++ * 1) the weight of a soft rt application is ++ * raised at startup (as for any newly ++ * created application), ++ * 2) since the application is not interactive, ++ * at a certain time weight-raising is ++ * stopped for the application, ++ * 3) at that time the application happens to ++ * still have pending requests, and hence ++ * is destined to not have a chance to be ++ * deemed soft rt before these requests are ++ * completed (see the comments to the ++ * function bfq_bfqq_softrt_next_start() ++ * for details on soft rt detection), ++ * 4) these pending requests experience a high ++ * latency because the application is not ++ * weight-raised while they are pending. ++ */ ++ bfqq->last_wr_start_finish = jiffies; ++ bfqq->wr_cur_max_time = ++ bfqd->bfq_wr_rt_max_time; ++ } ++ } ++ if (old_wr_coeff != bfqq->wr_coeff) ++ entity->ioprio_changed = 1; ++add_bfqq_busy: ++ bfqq->last_idle_bklogged = jiffies; ++ bfqq->service_from_backlogged = 0; ++ bfq_clear_bfqq_softrt_update(bfqq); ++ bfq_add_bfqq_busy(bfqd, bfqq); ++ } else { ++ if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) && ++ time_is_before_jiffies( ++ bfqq->last_wr_start_finish + ++ bfqd->bfq_wr_min_inter_arr_async)) { ++ bfqq->wr_coeff = bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); ++ ++ bfqd->wr_busy_queues++; ++ entity->ioprio_changed = 1; ++ bfq_log_bfqq(bfqd, bfqq, ++ "non-idle wrais starting at %lu, rais_max_time %u", ++ jiffies, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ if (prev != bfqq->next_rq) ++ bfq_updated_next_req(bfqd, bfqq); ++ } ++ ++ if (bfqd->low_latency && ++ (old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive)) ++ bfqq->last_wr_start_finish = jiffies; ++} ++ ++static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd, ++ struct bio *bio) ++{ ++ struct task_struct *tsk = current; ++ struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq; ++ ++ bic = bfq_bic_lookup(bfqd, tsk->io_context); ++ if (bic == NULL) ++ return NULL; ++ ++ bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio)); ++ if (bfqq != NULL) ++ return elv_rb_find(&bfqq->sort_list, bio_end_sector(bio)); ++ ++ return NULL; ++} ++ ++static void bfq_activate_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ ++ bfqd->rq_in_driver++; ++ bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); ++ bfq_log(bfqd, "activate_request: new bfqd->last_position %llu", ++ (long long unsigned)bfqd->last_position); ++} ++ ++static inline void bfq_deactivate_request(struct request_queue *q, ++ struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ ++ BUG_ON(bfqd->rq_in_driver == 0); ++ bfqd->rq_in_driver--; ++} ++ ++static void bfq_remove_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ const int sync = rq_is_sync(rq); ++ ++ if (bfqq->next_rq == rq) { ++ bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq); ++ bfq_updated_next_req(bfqd, bfqq); ++ } ++ ++ list_del_init(&rq->queuelist); ++ BUG_ON(bfqq->queued[sync] == 0); ++ bfqq->queued[sync]--; ++ bfqd->queued--; ++ elv_rb_del(&bfqq->sort_list, rq); ++ ++ if (RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue) ++ bfq_del_bfqq_busy(bfqd, bfqq, 1); ++ /* ++ * Remove queue from request-position tree as it is empty. ++ */ ++ if (bfqq->pos_root != NULL) { ++ rb_erase(&bfqq->pos_node, bfqq->pos_root); ++ bfqq->pos_root = NULL; ++ } ++ } ++ ++ if (rq->cmd_flags & REQ_META) { ++ BUG_ON(bfqq->meta_pending == 0); ++ bfqq->meta_pending--; ++ } ++} ++ ++static int bfq_merge(struct request_queue *q, struct request **req, ++ struct bio *bio) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct request *__rq; ++ ++ __rq = bfq_find_rq_fmerge(bfqd, bio); ++ if (__rq != NULL && elv_rq_merge_ok(__rq, bio)) { ++ *req = __rq; ++ return ELEVATOR_FRONT_MERGE; ++ } ++ ++ return ELEVATOR_NO_MERGE; ++} ++ ++static void bfq_merged_request(struct request_queue *q, struct request *req, ++ int type) ++{ ++ if (type == ELEVATOR_FRONT_MERGE && ++ rb_prev(&req->rb_node) && ++ blk_rq_pos(req) < ++ blk_rq_pos(container_of(rb_prev(&req->rb_node), ++ struct request, rb_node))) { ++ struct bfq_queue *bfqq = RQ_BFQQ(req); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ struct request *prev, *next_rq; ++ ++ /* Reposition request in its sort_list */ ++ elv_rb_del(&bfqq->sort_list, req); ++ elv_rb_add(&bfqq->sort_list, req); ++ /* Choose next request to be served for bfqq */ ++ prev = bfqq->next_rq; ++ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req, ++ bfqd->last_position); ++ BUG_ON(next_rq == NULL); ++ bfqq->next_rq = next_rq; ++ /* ++ * If next_rq changes, update both the queue's budget to ++ * fit the new request and the queue's position in its ++ * rq_pos_tree. ++ */ ++ if (prev != bfqq->next_rq) { ++ bfq_updated_next_req(bfqd, bfqq); ++ bfq_rq_pos_tree_add(bfqd, bfqq); ++ } ++ } ++} ++ ++static void bfq_merged_requests(struct request_queue *q, struct request *rq, ++ struct request *next) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ /* ++ * Reposition in fifo if next is older than rq. ++ */ ++ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && ++ time_before(next->fifo_time, rq->fifo_time)) { ++ list_move(&rq->queuelist, &next->queuelist); ++ rq->fifo_time = next->fifo_time; ++ } ++ ++ if (bfqq->next_rq == next) ++ bfqq->next_rq = rq; ++ ++ bfq_remove_request(next); ++} ++ ++/* Must be called with bfqq != NULL */ ++static inline void bfq_bfqq_end_wr(struct bfq_queue *bfqq) ++{ ++ BUG_ON(bfqq == NULL); ++ if (bfq_bfqq_busy(bfqq)) ++ bfqq->bfqd->wr_busy_queues--; ++ bfqq->wr_coeff = 1; ++ bfqq->wr_cur_max_time = 0; ++ /* Trigger a weight change on the next activation of the queue */ ++ bfqq->entity.ioprio_changed = 1; ++} ++ ++static void bfq_end_wr_async_queues(struct bfq_data *bfqd, ++ struct bfq_group *bfqg) ++{ ++ int i, j; ++ ++ for (i = 0; i < 2; i++) ++ for (j = 0; j < IOPRIO_BE_NR; j++) ++ if (bfqg->async_bfqq[i][j] != NULL) ++ bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]); ++ if (bfqg->async_idle_bfqq != NULL) ++ bfq_bfqq_end_wr(bfqg->async_idle_bfqq); ++} ++ ++static void bfq_end_wr(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq; ++ ++ spin_lock_irq(bfqd->queue->queue_lock); ++ ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) ++ bfq_bfqq_end_wr(bfqq); ++ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) ++ bfq_bfqq_end_wr(bfqq); ++ bfq_end_wr_async(bfqd); ++ ++ spin_unlock_irq(bfqd->queue->queue_lock); ++} ++ ++static int bfq_allow_merge(struct request_queue *q, struct request *rq, ++ struct bio *bio) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq; ++ ++ /* ++ * Disallow merge of a sync bio into an async request. ++ */ ++ if (bfq_bio_sync(bio) && !rq_is_sync(rq)) ++ return 0; ++ ++ /* ++ * Lookup the bfqq that this bio will be queued with. Allow ++ * merge only if rq is queued there. ++ * Queue lock is held here. ++ */ ++ bic = bfq_bic_lookup(bfqd, current->io_context); ++ if (bic == NULL) ++ return 0; ++ ++ bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio)); ++ return bfqq == RQ_BFQQ(rq); ++} ++ ++static void __bfq_set_in_service_queue(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ if (bfqq != NULL) { ++ bfq_mark_bfqq_must_alloc(bfqq); ++ bfq_mark_bfqq_budget_new(bfqq); ++ bfq_clear_bfqq_fifo_expire(bfqq); ++ ++ bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8; ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "set_in_service_queue, cur-budget = %lu", ++ bfqq->entity.budget); ++ } ++ ++ bfqd->in_service_queue = bfqq; ++} ++ ++/* ++ * Get and set a new queue for service. ++ */ ++static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ if (!bfqq) ++ bfqq = bfq_get_next_queue(bfqd); ++ else ++ bfq_get_next_queue_forced(bfqd, bfqq); ++ ++ __bfq_set_in_service_queue(bfqd, bfqq); ++ return bfqq; ++} ++ ++static inline sector_t bfq_dist_from_last(struct bfq_data *bfqd, ++ struct request *rq) ++{ ++ if (blk_rq_pos(rq) >= bfqd->last_position) ++ return blk_rq_pos(rq) - bfqd->last_position; ++ else ++ return bfqd->last_position - blk_rq_pos(rq); ++} ++ ++/* ++ * Return true if bfqq has no request pending and rq is close enough to ++ * bfqd->last_position, or if rq is closer to bfqd->last_position than ++ * bfqq->next_rq ++ */ ++static inline int bfq_rq_close(struct bfq_data *bfqd, struct request *rq) ++{ ++ return bfq_dist_from_last(bfqd, rq) <= BFQQ_SEEK_THR; ++} ++ ++static struct bfq_queue *bfqq_close(struct bfq_data *bfqd) ++{ ++ struct rb_root *root = &bfqd->rq_pos_tree; ++ struct rb_node *parent, *node; ++ struct bfq_queue *__bfqq; ++ sector_t sector = bfqd->last_position; ++ ++ if (RB_EMPTY_ROOT(root)) ++ return NULL; ++ ++ /* ++ * First, if we find a request starting at the end of the last ++ * request, choose it. ++ */ ++ __bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL); ++ if (__bfqq != NULL) ++ return __bfqq; ++ ++ /* ++ * If the exact sector wasn't found, the parent of the NULL leaf ++ * will contain the closest sector (rq_pos_tree sorted by ++ * next_request position). ++ */ ++ __bfqq = rb_entry(parent, struct bfq_queue, pos_node); ++ if (bfq_rq_close(bfqd, __bfqq->next_rq)) ++ return __bfqq; ++ ++ if (blk_rq_pos(__bfqq->next_rq) < sector) ++ node = rb_next(&__bfqq->pos_node); ++ else ++ node = rb_prev(&__bfqq->pos_node); ++ if (node == NULL) ++ return NULL; ++ ++ __bfqq = rb_entry(node, struct bfq_queue, pos_node); ++ if (bfq_rq_close(bfqd, __bfqq->next_rq)) ++ return __bfqq; ++ ++ return NULL; ++} ++ ++/* ++ * bfqd - obvious ++ * cur_bfqq - passed in so that we don't decide that the current queue ++ * is closely cooperating with itself. ++ * ++ * We are assuming that cur_bfqq has dispatched at least one request, ++ * and that bfqd->last_position reflects a position on the disk associated ++ * with the I/O issued by cur_bfqq. ++ */ ++static struct bfq_queue *bfq_close_cooperator(struct bfq_data *bfqd, ++ struct bfq_queue *cur_bfqq) ++{ ++ struct bfq_queue *bfqq; ++ ++ if (bfq_class_idle(cur_bfqq)) ++ return NULL; ++ if (!bfq_bfqq_sync(cur_bfqq)) ++ return NULL; ++ if (BFQQ_SEEKY(cur_bfqq)) ++ return NULL; ++ ++ /* If device has only one backlogged bfq_queue, don't search. */ ++ if (bfqd->busy_queues == 1) ++ return NULL; ++ ++ /* ++ * We should notice if some of the queues are cooperating, e.g. ++ * working closely on the same area of the disk. In that case, ++ * we can group them together and don't waste time idling. ++ */ ++ bfqq = bfqq_close(bfqd); ++ if (bfqq == NULL || bfqq == cur_bfqq) ++ return NULL; ++ ++ /* ++ * Do not merge queues from different bfq_groups. ++ */ ++ if (bfqq->entity.parent != cur_bfqq->entity.parent) ++ return NULL; ++ ++ /* ++ * It only makes sense to merge sync queues. ++ */ ++ if (!bfq_bfqq_sync(bfqq)) ++ return NULL; ++ if (BFQQ_SEEKY(bfqq)) ++ return NULL; ++ ++ /* ++ * Do not merge queues of different priority classes. ++ */ ++ if (bfq_class_rt(bfqq) != bfq_class_rt(cur_bfqq)) ++ return NULL; ++ ++ return bfqq; ++} ++ ++/* ++ * If enough samples have been computed, return the current max budget ++ * stored in bfqd, which is dynamically updated according to the ++ * estimated disk peak rate; otherwise return the default max budget ++ */ ++static inline unsigned long bfq_max_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < 194) ++ return bfq_default_max_budget; ++ else ++ return bfqd->bfq_max_budget; ++} ++ ++/* ++ * Return min budget, which is a fraction of the current or default ++ * max budget (trying with 1/32) ++ */ ++static inline unsigned long bfq_min_budget(struct bfq_data *bfqd) ++{ ++ if (bfqd->budgets_assigned < 194) ++ return bfq_default_max_budget / 32; ++ else ++ return bfqd->bfq_max_budget / 32; ++} ++ ++static void bfq_arm_slice_timer(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfqd->in_service_queue; ++ struct bfq_io_cq *bic; ++ unsigned long sl; ++ ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ /* Processes have exited, don't wait. */ ++ bic = bfqd->in_service_bic; ++ if (bic == NULL || atomic_read(&bic->icq.ioc->active_ref) == 0) ++ return; ++ ++ bfq_mark_bfqq_wait_request(bfqq); ++ ++ /* ++ * We don't want to idle for seeks, but we do want to allow ++ * fair distribution of slice time for a process doing back-to-back ++ * seeks. So allow a little bit of time for him to submit a new rq. ++ * ++ * To prevent processes with (partly) seeky workloads from ++ * being too ill-treated, grant them a small fraction of the ++ * assigned budget before reducing the waiting time to ++ * BFQ_MIN_TT. This happened to help reduce latency. ++ */ ++ sl = bfqd->bfq_slice_idle; ++ /* ++ * Unless the queue is being weight-raised, grant only minimum idle ++ * time if the queue either has been seeky for long enough or has ++ * already proved to be constantly seeky. ++ */ ++ if (bfq_sample_valid(bfqq->seek_samples) && ++ ((BFQQ_SEEKY(bfqq) && bfqq->entity.service > ++ bfq_max_budget(bfqq->bfqd) / 8) || ++ bfq_bfqq_constantly_seeky(bfqq)) && bfqq->wr_coeff == 1) ++ sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT)); ++ else if (bfqq->wr_coeff > 1) ++ sl = sl * 3; ++ bfqd->last_idling_start = ktime_get(); ++ mod_timer(&bfqd->idle_slice_timer, jiffies + sl); ++ bfq_log(bfqd, "arm idle: %u/%u ms", ++ jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle)); ++} ++ ++/* ++ * Set the maximum time for the in-service queue to consume its ++ * budget. This prevents seeky processes from lowering the disk ++ * throughput (always guaranteed with a time slice scheme as in CFQ). ++ */ ++static void bfq_set_budget_timeout(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfqd->in_service_queue; ++ unsigned int timeout_coeff; ++ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time) ++ timeout_coeff = 1; ++ else ++ timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight; ++ ++ bfqd->last_budget_start = ktime_get(); ++ ++ bfq_clear_bfqq_budget_new(bfqq); ++ bfqq->budget_timeout = jiffies + ++ bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * timeout_coeff; ++ ++ bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u", ++ jiffies_to_msecs(bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * ++ timeout_coeff)); ++} ++ ++/* ++ * Move request from internal lists to the request queue dispatch list. ++ */ ++static void bfq_dispatch_insert(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ /* ++ * For consistency, the next instruction should have been executed ++ * after removing the request from the queue and dispatching it. ++ * We execute instead this instruction before bfq_remove_request() ++ * (and hence introduce a temporary inconsistency), for efficiency. ++ * In fact, in a forced_dispatch, this prevents two counters related ++ * to bfqq->dispatched to risk to be uselessly decremented if bfqq ++ * is not in service, and then to be incremented again after ++ * incrementing bfqq->dispatched. ++ */ ++ bfqq->dispatched++; ++ bfq_remove_request(rq); ++ elv_dispatch_sort(q, rq); ++ ++ if (bfq_bfqq_sync(bfqq)) ++ bfqd->sync_flight++; ++} ++ ++/* ++ * Return expired entry, or NULL to just start from scratch in rbtree. ++ */ ++static struct request *bfq_check_fifo(struct bfq_queue *bfqq) ++{ ++ struct request *rq = NULL; ++ ++ if (bfq_bfqq_fifo_expire(bfqq)) ++ return NULL; ++ ++ bfq_mark_bfqq_fifo_expire(bfqq); ++ ++ if (list_empty(&bfqq->fifo)) ++ return NULL; ++ ++ rq = rq_entry_fifo(bfqq->fifo.next); ++ ++ if (time_before(jiffies, rq->fifo_time)) ++ return NULL; ++ ++ return rq; ++} ++ ++/* Must be called with the queue_lock held. */ ++static int bfqq_process_refs(struct bfq_queue *bfqq) ++{ ++ int process_refs, io_refs; ++ ++ io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE]; ++ process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st; ++ BUG_ON(process_refs < 0); ++ return process_refs; ++} ++ ++static void bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) ++{ ++ int process_refs, new_process_refs; ++ struct bfq_queue *__bfqq; ++ ++ /* ++ * If there are no process references on the new_bfqq, then it is ++ * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain ++ * may have dropped their last reference (not just their last process ++ * reference). ++ */ ++ if (!bfqq_process_refs(new_bfqq)) ++ return; ++ ++ /* Avoid a circular list and skip interim queue merges. */ ++ while ((__bfqq = new_bfqq->new_bfqq)) { ++ if (__bfqq == bfqq) ++ return; ++ new_bfqq = __bfqq; ++ } ++ ++ process_refs = bfqq_process_refs(bfqq); ++ new_process_refs = bfqq_process_refs(new_bfqq); ++ /* ++ * If the process for the bfqq has gone away, there is no ++ * sense in merging the queues. ++ */ ++ if (process_refs == 0 || new_process_refs == 0) ++ return; ++ ++ /* ++ * Merge in the direction of the lesser amount of work. ++ */ ++ if (new_process_refs >= process_refs) { ++ bfqq->new_bfqq = new_bfqq; ++ atomic_add(process_refs, &new_bfqq->ref); ++ } else { ++ new_bfqq->new_bfqq = bfqq; ++ atomic_add(new_process_refs, &bfqq->ref); ++ } ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d", ++ new_bfqq->pid); ++} ++ ++static inline unsigned long bfq_bfqq_budget_left(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ return entity->budget - entity->service; ++} ++ ++static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ __bfq_bfqd_reset_in_service(bfqd); ++ ++ /* ++ * If this bfqq is shared between multiple processes, check ++ * to make sure that those processes are still issuing I/Os ++ * within the mean seek distance. If not, it may be time to ++ * break the queues apart again. ++ */ ++ if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq)) ++ bfq_mark_bfqq_split_coop(bfqq); ++ ++ if (RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ /* ++ * Overloading budget_timeout field to store the time ++ * at which the queue remains with no backlog; used by ++ * the weight-raising mechanism. ++ */ ++ bfqq->budget_timeout = jiffies; ++ bfq_del_bfqq_busy(bfqd, bfqq, 1); ++ } else { ++ bfq_activate_bfqq(bfqd, bfqq); ++ /* ++ * Resort priority tree of potential close cooperators. ++ */ ++ bfq_rq_pos_tree_add(bfqd, bfqq); ++ } ++} ++ ++/** ++ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior. ++ * @bfqd: device data. ++ * @bfqq: queue to update. ++ * @reason: reason for expiration. ++ * ++ * Handle the feedback on @bfqq budget. See the body for detailed ++ * comments. ++ */ ++static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ enum bfqq_expiration reason) ++{ ++ struct request *next_rq; ++ unsigned long budget, min_budget; ++ ++ budget = bfqq->max_budget; ++ min_budget = bfq_min_budget(bfqd); ++ ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %lu, budg left %lu", ++ bfqq->entity.budget, bfq_bfqq_budget_left(bfqq)); ++ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %lu, min budg %lu", ++ budget, bfq_min_budget(bfqd)); ++ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d", ++ bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue)); ++ ++ if (bfq_bfqq_sync(bfqq)) { ++ switch (reason) { ++ /* ++ * Caveat: in all the following cases we trade latency ++ * for throughput. ++ */ ++ case BFQ_BFQQ_TOO_IDLE: ++ /* ++ * This is the only case where we may reduce ++ * the budget: if there is no request of the ++ * process still waiting for completion, then ++ * we assume (tentatively) that the timer has ++ * expired because the batch of requests of ++ * the process could have been served with a ++ * smaller budget. Hence, betting that ++ * process will behave in the same way when it ++ * becomes backlogged again, we reduce its ++ * next budget. As long as we guess right, ++ * this budget cut reduces the latency ++ * experienced by the process. ++ * ++ * However, if there are still outstanding ++ * requests, then the process may have not yet ++ * issued its next request just because it is ++ * still waiting for the completion of some of ++ * the still outstanding ones. So in this ++ * subcase we do not reduce its budget, on the ++ * contrary we increase it to possibly boost ++ * the throughput, as discussed in the ++ * comments to the BUDGET_TIMEOUT case. ++ */ ++ if (bfqq->dispatched > 0) /* still outstanding reqs */ ++ budget = min(budget * 2, bfqd->bfq_max_budget); ++ else { ++ if (budget > 5 * min_budget) ++ budget -= 4 * min_budget; ++ else ++ budget = min_budget; ++ } ++ break; ++ case BFQ_BFQQ_BUDGET_TIMEOUT: ++ /* ++ * We double the budget here because: 1) it ++ * gives the chance to boost the throughput if ++ * this is not a seeky process (which may have ++ * bumped into this timeout because of, e.g., ++ * ZBR), 2) together with charge_full_budget ++ * it helps give seeky processes higher ++ * timestamps, and hence be served less ++ * frequently. ++ */ ++ budget = min(budget * 2, bfqd->bfq_max_budget); ++ break; ++ case BFQ_BFQQ_BUDGET_EXHAUSTED: ++ /* ++ * The process still has backlog, and did not ++ * let either the budget timeout or the disk ++ * idling timeout expire. Hence it is not ++ * seeky, has a short thinktime and may be ++ * happy with a higher budget too. So ++ * definitely increase the budget of this good ++ * candidate to boost the disk throughput. ++ */ ++ budget = min(budget * 4, bfqd->bfq_max_budget); ++ break; ++ case BFQ_BFQQ_NO_MORE_REQUESTS: ++ /* ++ * Leave the budget unchanged. ++ */ ++ default: ++ return; ++ } ++ } else /* async queue */ ++ /* async queues get always the maximum possible budget ++ * (their ability to dispatch is limited by ++ * @bfqd->bfq_max_budget_async_rq). ++ */ ++ budget = bfqd->bfq_max_budget; ++ ++ bfqq->max_budget = budget; ++ ++ if (bfqd->budgets_assigned >= 194 && bfqd->bfq_user_max_budget == 0 && ++ bfqq->max_budget > bfqd->bfq_max_budget) ++ bfqq->max_budget = bfqd->bfq_max_budget; ++ ++ /* ++ * Make sure that we have enough budget for the next request. ++ * Since the finish time of the bfqq must be kept in sync with ++ * the budget, be sure to call __bfq_bfqq_expire() after the ++ * update. ++ */ ++ next_rq = bfqq->next_rq; ++ if (next_rq != NULL) ++ bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget, ++ bfq_serv_to_charge(next_rq, bfqq)); ++ else ++ bfqq->entity.budget = bfqq->max_budget; ++ ++ bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %lu", ++ next_rq != NULL ? blk_rq_sectors(next_rq) : 0, ++ bfqq->entity.budget); ++} ++ ++static unsigned long bfq_calc_max_budget(u64 peak_rate, u64 timeout) ++{ ++ unsigned long max_budget; ++ ++ /* ++ * The max_budget calculated when autotuning is equal to the ++ * amount of sectors transfered in timeout_sync at the ++ * estimated peak rate. ++ */ ++ max_budget = (unsigned long)(peak_rate * 1000 * ++ timeout >> BFQ_RATE_SHIFT); ++ ++ return max_budget; ++} ++ ++/* ++ * In addition to updating the peak rate, checks whether the process ++ * is "slow", and returns 1 if so. This slow flag is used, in addition ++ * to the budget timeout, to reduce the amount of service provided to ++ * seeky processes, and hence reduce their chances to lower the ++ * throughput. See the code for more details. ++ */ ++static int bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ int compensate, enum bfqq_expiration reason) ++{ ++ u64 bw, usecs, expected, timeout; ++ ktime_t delta; ++ int update = 0; ++ ++ if (!bfq_bfqq_sync(bfqq) || bfq_bfqq_budget_new(bfqq)) ++ return 0; ++ ++ if (compensate) ++ delta = bfqd->last_idling_start; ++ else ++ delta = ktime_get(); ++ delta = ktime_sub(delta, bfqd->last_budget_start); ++ usecs = ktime_to_us(delta); ++ ++ /* Don't trust short/unrealistic values. */ ++ if (usecs < 100 || usecs >= LONG_MAX) ++ return 0; ++ ++ /* ++ * Calculate the bandwidth for the last slice. We use a 64 bit ++ * value to store the peak rate, in sectors per usec in fixed ++ * point math. We do so to have enough precision in the estimate ++ * and to avoid overflows. ++ */ ++ bw = (u64)bfqq->entity.service << BFQ_RATE_SHIFT; ++ do_div(bw, (unsigned long)usecs); ++ ++ timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]); ++ ++ /* ++ * Use only long (> 20ms) intervals to filter out spikes for ++ * the peak rate estimation. ++ */ ++ if (usecs > 20000) { ++ if (bw > bfqd->peak_rate || ++ (!BFQQ_SEEKY(bfqq) && ++ reason == BFQ_BFQQ_BUDGET_TIMEOUT)) { ++ bfq_log(bfqd, "measured bw =%llu", bw); ++ /* ++ * To smooth oscillations use a low-pass filter with ++ * alpha=7/8, i.e., ++ * new_rate = (7/8) * old_rate + (1/8) * bw ++ */ ++ do_div(bw, 8); ++ if (bw == 0) ++ return 0; ++ bfqd->peak_rate *= 7; ++ do_div(bfqd->peak_rate, 8); ++ bfqd->peak_rate += bw; ++ update = 1; ++ bfq_log(bfqd, "new peak_rate=%llu", bfqd->peak_rate); ++ } ++ ++ update |= bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES - 1; ++ ++ if (bfqd->peak_rate_samples < BFQ_PEAK_RATE_SAMPLES) ++ bfqd->peak_rate_samples++; ++ ++ if (bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES && ++ update) { ++ int dev_type = blk_queue_nonrot(bfqd->queue); ++ if (bfqd->bfq_user_max_budget == 0) { ++ bfqd->bfq_max_budget = ++ bfq_calc_max_budget(bfqd->peak_rate, ++ timeout); ++ bfq_log(bfqd, "new max_budget=%lu", ++ bfqd->bfq_max_budget); ++ } ++ if (bfqd->device_speed == BFQ_BFQD_FAST && ++ bfqd->peak_rate < device_speed_thresh[dev_type]) { ++ bfqd->device_speed = BFQ_BFQD_SLOW; ++ bfqd->RT_prod = R_slow[dev_type] * ++ T_slow[dev_type]; ++ } else if (bfqd->device_speed == BFQ_BFQD_SLOW && ++ bfqd->peak_rate > device_speed_thresh[dev_type]) { ++ bfqd->device_speed = BFQ_BFQD_FAST; ++ bfqd->RT_prod = R_fast[dev_type] * ++ T_fast[dev_type]; ++ } ++ } ++ } ++ ++ /* ++ * If the process has been served for a too short time ++ * interval to let its possible sequential accesses prevail on ++ * the initial seek time needed to move the disk head on the ++ * first sector it requested, then give the process a chance ++ * and for the moment return false. ++ */ ++ if (bfqq->entity.budget <= bfq_max_budget(bfqd) / 8) ++ return 0; ++ ++ /* ++ * A process is considered ``slow'' (i.e., seeky, so that we ++ * cannot treat it fairly in the service domain, as it would ++ * slow down too much the other processes) if, when a slice ++ * ends for whatever reason, it has received service at a ++ * rate that would not be high enough to complete the budget ++ * before the budget timeout expiration. ++ */ ++ expected = bw * 1000 * timeout >> BFQ_RATE_SHIFT; ++ ++ /* ++ * Caveat: processes doing IO in the slower disk zones will ++ * tend to be slow(er) even if not seeky. And the estimated ++ * peak rate will actually be an average over the disk ++ * surface. Hence, to not be too harsh with unlucky processes, ++ * we keep a budget/3 margin of safety before declaring a ++ * process slow. ++ */ ++ return expected > (4 * bfqq->entity.budget) / 3; ++} ++ ++/* ++ * To be deemed as soft real-time, an application must meet two ++ * requirements. First, the application must not require an average ++ * bandwidth higher than the approximate bandwidth required to playback or ++ * record a compressed high-definition video. ++ * The next function is invoked on the completion of the last request of a ++ * batch, to compute the next-start time instant, soft_rt_next_start, such ++ * that, if the next request of the application does not arrive before ++ * soft_rt_next_start, then the above requirement on the bandwidth is met. ++ * ++ * The second requirement is that the request pattern of the application is ++ * isochronous, i.e., that, after issuing a request or a batch of requests, ++ * the application stops issuing new requests until all its pending requests ++ * have been completed. After that, the application may issue a new batch, ++ * and so on. ++ * For this reason the next function is invoked to compute ++ * soft_rt_next_start only for applications that meet this requirement, ++ * whereas soft_rt_next_start is set to infinity for applications that do ++ * not. ++ * ++ * Unfortunately, even a greedy application may happen to behave in an ++ * isochronous way if the CPU load is high. In fact, the application may ++ * stop issuing requests while the CPUs are busy serving other processes, ++ * then restart, then stop again for a while, and so on. In addition, if ++ * the disk achieves a low enough throughput with the request pattern ++ * issued by the application (e.g., because the request pattern is random ++ * and/or the device is slow), then the application may meet the above ++ * bandwidth requirement too. To prevent such a greedy application to be ++ * deemed as soft real-time, a further rule is used in the computation of ++ * soft_rt_next_start: soft_rt_next_start must be higher than the current ++ * time plus the maximum time for which the arrival of a request is waited ++ * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle. ++ * This filters out greedy applications, as the latter issue instead their ++ * next request as soon as possible after the last one has been completed ++ * (in contrast, when a batch of requests is completed, a soft real-time ++ * application spends some time processing data). ++ * ++ * Unfortunately, the last filter may easily generate false positives if ++ * only bfqd->bfq_slice_idle is used as a reference time interval and one ++ * or both the following cases occur: ++ * 1) HZ is so low that the duration of a jiffy is comparable to or higher ++ * than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with ++ * HZ=100. ++ * 2) jiffies, instead of increasing at a constant rate, may stop increasing ++ * for a while, then suddenly 'jump' by several units to recover the lost ++ * increments. This seems to happen, e.g., inside virtual machines. ++ * To address this issue, we do not use as a reference time interval just ++ * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In ++ * particular we add the minimum number of jiffies for which the filter ++ * seems to be quite precise also in embedded systems and KVM/QEMU virtual ++ * machines. ++ */ ++static inline unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ return max(bfqq->last_idle_bklogged + ++ HZ * bfqq->service_from_backlogged / ++ bfqd->bfq_wr_max_softrt_rate, ++ jiffies + bfqq->bfqd->bfq_slice_idle + 4); ++} ++ ++/* ++ * Return the largest-possible time instant such that, for as long as possible, ++ * the current time will be lower than this time instant according to the macro ++ * time_is_before_jiffies(). ++ */ ++static inline unsigned long bfq_infinity_from_now(unsigned long now) ++{ ++ return now + ULONG_MAX / 2; ++} ++ ++/** ++ * bfq_bfqq_expire - expire a queue. ++ * @bfqd: device owning the queue. ++ * @bfqq: the queue to expire. ++ * @compensate: if true, compensate for the time spent idling. ++ * @reason: the reason causing the expiration. ++ * ++ * ++ * If the process associated to the queue is slow (i.e., seeky), or in ++ * case of budget timeout, or, finally, if it is async, we ++ * artificially charge it an entire budget (independently of the ++ * actual service it received). As a consequence, the queue will get ++ * higher timestamps than the correct ones upon reactivation, and ++ * hence it will be rescheduled as if it had received more service ++ * than what it actually received. In the end, this class of processes ++ * will receive less service in proportion to how slowly they consume ++ * their budgets (and hence how seriously they tend to lower the ++ * throughput). ++ * ++ * In contrast, when a queue expires because it has been idling for ++ * too much or because it exhausted its budget, we do not touch the ++ * amount of service it has received. Hence when the queue will be ++ * reactivated and its timestamps updated, the latter will be in sync ++ * with the actual service received by the queue until expiration. ++ * ++ * Charging a full budget to the first type of queues and the exact ++ * service to the others has the effect of using the WF2Q+ policy to ++ * schedule the former on a timeslice basis, without violating the ++ * service domain guarantees of the latter. ++ */ ++static void bfq_bfqq_expire(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ int compensate, ++ enum bfqq_expiration reason) ++{ ++ int slow; ++ BUG_ON(bfqq != bfqd->in_service_queue); ++ ++ /* Update disk peak rate for autotuning and check whether the ++ * process is slow (see bfq_update_peak_rate). ++ */ ++ slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason); ++ ++ /* ++ * As above explained, 'punish' slow (i.e., seeky), timed-out ++ * and async queues, to favor sequential sync workloads. ++ * ++ * Processes doing I/O in the slower disk zones will tend to be ++ * slow(er) even if not seeky. Hence, since the estimated peak ++ * rate is actually an average over the disk surface, these ++ * processes may timeout just for bad luck. To avoid punishing ++ * them we do not charge a full budget to a process that ++ * succeeded in consuming at least 2/3 of its budget. ++ */ ++ if (slow || (reason == BFQ_BFQQ_BUDGET_TIMEOUT && ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3)) ++ bfq_bfqq_charge_full_budget(bfqq); ++ ++ bfqq->service_from_backlogged += bfqq->entity.service; ++ ++ if (BFQQ_SEEKY(bfqq) && reason == BFQ_BFQQ_BUDGET_TIMEOUT && ++ !bfq_bfqq_constantly_seeky(bfqq)) { ++ bfq_mark_bfqq_constantly_seeky(bfqq); ++ if (!blk_queue_nonrot(bfqd->queue)) ++ bfqd->const_seeky_busy_in_flight_queues++; ++ } ++ ++ if (reason == BFQ_BFQQ_TOO_IDLE && ++ bfqq->entity.service <= 2 * bfqq->entity.budget / 10 ) ++ bfq_clear_bfqq_IO_bound(bfqq); ++ ++ if (bfqd->low_latency && bfqq->wr_coeff == 1) ++ bfqq->last_wr_start_finish = jiffies; ++ ++ if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 && ++ RB_EMPTY_ROOT(&bfqq->sort_list)) { ++ /* ++ * If we get here, and there are no outstanding requests, ++ * then the request pattern is isochronous (see the comments ++ * to the function bfq_bfqq_softrt_next_start()). Hence we ++ * can compute soft_rt_next_start. If, instead, the queue ++ * still has outstanding requests, then we have to wait ++ * for the completion of all the outstanding requests to ++ * discover whether the request pattern is actually ++ * isochronous. ++ */ ++ if (bfqq->dispatched == 0) ++ bfqq->soft_rt_next_start = ++ bfq_bfqq_softrt_next_start(bfqd, bfqq); ++ else { ++ /* ++ * The application is still waiting for the ++ * completion of one or more requests: ++ * prevent it from possibly being incorrectly ++ * deemed as soft real-time by setting its ++ * soft_rt_next_start to infinity. In fact, ++ * without this assignment, the application ++ * would be incorrectly deemed as soft ++ * real-time if: ++ * 1) it issued a new request before the ++ * completion of all its in-flight ++ * requests, and ++ * 2) at that time, its soft_rt_next_start ++ * happened to be in the past. ++ */ ++ bfqq->soft_rt_next_start = ++ bfq_infinity_from_now(jiffies); ++ /* ++ * Schedule an update of soft_rt_next_start to when ++ * the task may be discovered to be isochronous. ++ */ ++ bfq_mark_bfqq_softrt_update(bfqq); ++ } ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "expire (%d, slow %d, num_disp %d, idle_win %d)", reason, ++ slow, bfqq->dispatched, bfq_bfqq_idle_window(bfqq)); ++ ++ /* ++ * Increase, decrease or leave budget unchanged according to ++ * reason. ++ */ ++ __bfq_bfqq_recalc_budget(bfqd, bfqq, reason); ++ __bfq_bfqq_expire(bfqd, bfqq); ++} ++ ++/* ++ * Budget timeout is not implemented through a dedicated timer, but ++ * just checked on request arrivals and completions, as well as on ++ * idle timer expirations. ++ */ ++static int bfq_bfqq_budget_timeout(struct bfq_queue *bfqq) ++{ ++ if (bfq_bfqq_budget_new(bfqq) || ++ time_before(jiffies, bfqq->budget_timeout)) ++ return 0; ++ return 1; ++} ++ ++/* ++ * If we expire a queue that is waiting for the arrival of a new ++ * request, we may prevent the fictitious timestamp back-shifting that ++ * allows the guarantees of the queue to be preserved (see [1] for ++ * this tricky aspect). Hence we return true only if this condition ++ * does not hold, or if the queue is slow enough to deserve only to be ++ * kicked off for preserving a high throughput. ++*/ ++static inline int bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "may_budget_timeout: wait_request %d left %d timeout %d", ++ bfq_bfqq_wait_request(bfqq), ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3, ++ bfq_bfqq_budget_timeout(bfqq)); ++ ++ return (!bfq_bfqq_wait_request(bfqq) || ++ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3) ++ && ++ bfq_bfqq_budget_timeout(bfqq); ++} ++ ++/* ++ * Device idling is allowed only for the queues for which this function ++ * returns true. For this reason, the return value of this function plays a ++ * critical role for both throughput boosting and service guarantees. The ++ * return value is computed through a logical expression. In this rather ++ * long comment, we try to briefly describe all the details and motivations ++ * behind the components of this logical expression. ++ * ++ * First, the expression is false if bfqq is not sync, or if: bfqq happened ++ * to become active during a large burst of queue activations, and the ++ * pattern of requests bfqq contains boosts the throughput if bfqq is ++ * expired. In fact, queues that became active during a large burst benefit ++ * only from throughput, as discussed in the comments to bfq_handle_burst. ++ * In this respect, expiring bfqq certainly boosts the throughput on NCQ- ++ * capable flash-based devices, whereas, on rotational devices, it boosts ++ * the throughput only if bfqq contains random requests. ++ * ++ * On the opposite end, if (a) bfqq is sync, (b) the above burst-related ++ * condition does not hold, and (c) bfqq is being weight-raised, then the ++ * expression always evaluates to true, as device idling is instrumental ++ * for preserving low-latency guarantees (see [1]). If, instead, conditions ++ * (a) and (b) do hold, but (c) does not, then the expression evaluates to ++ * true only if: (1) bfqq is I/O-bound and has a non-null idle window, and ++ * (2) at least one of the following two conditions holds. ++ * The first condition is that the device is not performing NCQ, because ++ * idling the device most certainly boosts the throughput if this condition ++ * holds and bfqq is I/O-bound and has been granted a non-null idle window. ++ * The second compound condition is made of the logical AND of two components. ++ * ++ * The first component is true only if there is no weight-raised busy ++ * queue. This guarantees that the device is not idled for a sync non- ++ * weight-raised queue when there are busy weight-raised queues. The former ++ * is then expired immediately if empty. Combined with the timestamping ++ * rules of BFQ (see [1] for details), this causes sync non-weight-raised ++ * queues to get a lower number of requests served, and hence to ask for a ++ * lower number of requests from the request pool, before the busy weight- ++ * raised queues get served again. ++ * ++ * This is beneficial for the processes associated with weight-raised ++ * queues, when the request pool is saturated (e.g., in the presence of ++ * write hogs). In fact, if the processes associated with the other queues ++ * ask for requests at a lower rate, then weight-raised processes have a ++ * higher probability to get a request from the pool immediately (or at ++ * least soon) when they need one. Hence they have a higher probability to ++ * actually get a fraction of the disk throughput proportional to their ++ * high weight. This is especially true with NCQ-capable drives, which ++ * enqueue several requests in advance and further reorder internally- ++ * queued requests. ++ * ++ * In the end, mistreating non-weight-raised queues when there are busy ++ * weight-raised queues seems to mitigate starvation problems in the ++ * presence of heavy write workloads and NCQ, and hence to guarantee a ++ * higher application and system responsiveness in these hostile scenarios. ++ * ++ * If the first component of the compound condition is instead true, i.e., ++ * there is no weight-raised busy queue, then the second component of the ++ * compound condition takes into account service-guarantee and throughput ++ * issues related to NCQ (recall that the compound condition is evaluated ++ * only if the device is detected as supporting NCQ). ++ * ++ * As for service guarantees, allowing the drive to enqueue more than one ++ * request at a time, and hence delegating de facto final scheduling ++ * decisions to the drive's internal scheduler, causes loss of control on ++ * the actual request service order. In this respect, when the drive is ++ * allowed to enqueue more than one request at a time, the service ++ * distribution enforced by the drive's internal scheduler is likely to ++ * coincide with the desired device-throughput distribution only in the ++ * following, perfectly symmetric, scenario: ++ * 1) all active queues have the same weight, ++ * 2) all active groups at the same level in the groups tree have the same ++ * weight, ++ * 3) all active groups at the same level in the groups tree have the same ++ * number of children. ++ * ++ * Even in such a scenario, sequential I/O may still receive a preferential ++ * treatment, but this is not likely to be a big issue with flash-based ++ * devices, because of their non-dramatic loss of throughput with random ++ * I/O. Things do differ with HDDs, for which additional care is taken, as ++ * explained after completing the discussion for flash-based devices. ++ * ++ * Unfortunately, keeping the necessary state for evaluating exactly the ++ * above symmetry conditions would be quite complex and time-consuming. ++ * Therefore BFQ evaluates instead the following stronger sub-conditions, ++ * for which it is much easier to maintain the needed state: ++ * 1) all active queues have the same weight, ++ * 2) all active groups have the same weight, ++ * 3) all active groups have at most one active child each. ++ * In particular, the last two conditions are always true if hierarchical ++ * support and the cgroups interface are not enabled, hence no state needs ++ * to be maintained in this case. ++ * ++ * According to the above considerations, the second component of the ++ * compound condition evaluates to true if any of the above symmetry ++ * sub-condition does not hold, or the device is not flash-based. Therefore, ++ * if also the first component is true, then idling is allowed for a sync ++ * queue. These are the only sub-conditions considered if the device is ++ * flash-based, as, for such a device, it is sensible to force idling only ++ * for service-guarantee issues. In fact, as for throughput, idling ++ * NCQ-capable flash-based devices would not boost the throughput even ++ * with sequential I/O; rather it would lower the throughput in proportion ++ * to how fast the device is. In the end, (only) if all the three ++ * sub-conditions hold and the device is flash-based, the compound ++ * condition evaluates to false and therefore no idling is performed. ++ * ++ * As already said, things change with a rotational device, where idling ++ * boosts the throughput with sequential I/O (even with NCQ). Hence, for ++ * such a device the second component of the compound condition evaluates ++ * to true also if the following additional sub-condition does not hold: ++ * the queue is constantly seeky. Unfortunately, this different behavior ++ * with respect to flash-based devices causes an additional asymmetry: if ++ * some sync queues enjoy idling and some other sync queues do not, then ++ * the latter get a low share of the device throughput, simply because the ++ * former get many requests served after being set as in service, whereas ++ * the latter do not. As a consequence, to guarantee the desired throughput ++ * distribution, on HDDs the compound expression evaluates to true (and ++ * hence device idling is performed) also if the following last symmetry ++ * condition does not hold: no other queue is benefiting from idling. Also ++ * this last condition is actually replaced with a simpler-to-maintain and ++ * stronger condition: there is no busy queue which is not constantly seeky ++ * (and hence may also benefit from idling). ++ * ++ * To sum up, when all the required symmetry and throughput-boosting ++ * sub-conditions hold, the second component of the compound condition ++ * evaluates to false, and hence no idling is performed. This helps to ++ * keep the drives' internal queues full on NCQ-capable devices, and hence ++ * to boost the throughput, without causing 'almost' any loss of service ++ * guarantees. The 'almost' follows from the fact that, if the internal ++ * queue of one such device is filled while all the sub-conditions hold, ++ * but at some point in time some sub-condition stops to hold, then it may ++ * become impossible to let requests be served in the new desired order ++ * until all the requests already queued in the device have been served. ++ */ ++static inline bool bfq_bfqq_must_not_expire(struct bfq_queue *bfqq) ++{ ++ struct bfq_data *bfqd = bfqq->bfqd; ++#ifdef CONFIG_CGROUP_BFQIO ++#define symmetric_scenario (!bfqd->active_numerous_groups && \ ++ !bfq_differentiated_weights(bfqd)) ++#else ++#define symmetric_scenario (!bfq_differentiated_weights(bfqd)) ++#endif ++#define cond_for_seeky_on_ncq_hdd (bfq_bfqq_constantly_seeky(bfqq) && \ ++ bfqd->busy_in_flight_queues == \ ++ bfqd->const_seeky_busy_in_flight_queues) ++ ++#define cond_for_expiring_in_burst (bfq_bfqq_in_large_burst(bfqq) && \ ++ bfqd->hw_tag && \ ++ (blk_queue_nonrot(bfqd->queue) || \ ++ bfq_bfqq_constantly_seeky(bfqq))) ++ ++/* ++ * Condition for expiring a non-weight-raised queue (and hence not idling ++ * the device). ++ */ ++#define cond_for_expiring_non_wr (bfqd->hw_tag && \ ++ (bfqd->wr_busy_queues > 0 || \ ++ (symmetric_scenario && \ ++ (blk_queue_nonrot(bfqd->queue) || \ ++ cond_for_seeky_on_ncq_hdd)))) ++ ++ return bfq_bfqq_sync(bfqq) && ++ !cond_for_expiring_in_burst && ++ (bfqq->wr_coeff > 1 || ++ (bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_idle_window(bfqq) && ++ !cond_for_expiring_non_wr) ++ ); ++} ++ ++/* ++ * If the in-service queue is empty but sync, and the function ++ * bfq_bfqq_must_not_expire returns true, then: ++ * 1) the queue must remain in service and cannot be expired, and ++ * 2) the disk must be idled to wait for the possible arrival of a new ++ * request for the queue. ++ * See the comments to the function bfq_bfqq_must_not_expire for the reasons ++ * why performing device idling is the best choice to boost the throughput ++ * and preserve service guarantees when bfq_bfqq_must_not_expire itself ++ * returns true. ++ */ ++static inline bool bfq_bfqq_must_idle(struct bfq_queue *bfqq) ++{ ++ struct bfq_data *bfqd = bfqq->bfqd; ++ ++ return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 && ++ bfq_bfqq_must_not_expire(bfqq); ++} ++ ++/* ++ * Select a queue for service. If we have a current queue in service, ++ * check whether to continue servicing it, or retrieve and set a new one. ++ */ ++static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq, *new_bfqq = NULL; ++ struct request *next_rq; ++ enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT; ++ ++ bfqq = bfqd->in_service_queue; ++ if (bfqq == NULL) ++ goto new_queue; ++ ++ bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue"); ++ ++ /* ++ * If another queue has a request waiting within our mean seek ++ * distance, let it run. The expire code will check for close ++ * cooperators and put the close queue at the front of the ++ * service tree. If possible, merge the expiring queue with the ++ * new bfqq. ++ */ ++ new_bfqq = bfq_close_cooperator(bfqd, bfqq); ++ if (new_bfqq != NULL && bfqq->new_bfqq == NULL) ++ bfq_setup_merge(bfqq, new_bfqq); ++ ++ if (bfq_may_expire_for_budg_timeout(bfqq) && ++ !timer_pending(&bfqd->idle_slice_timer) && ++ !bfq_bfqq_must_idle(bfqq)) ++ goto expire; ++ ++ next_rq = bfqq->next_rq; ++ /* ++ * If bfqq has requests queued and it has enough budget left to ++ * serve them, keep the queue, otherwise expire it. ++ */ ++ if (next_rq != NULL) { ++ if (bfq_serv_to_charge(next_rq, bfqq) > ++ bfq_bfqq_budget_left(bfqq)) { ++ reason = BFQ_BFQQ_BUDGET_EXHAUSTED; ++ goto expire; ++ } else { ++ /* ++ * The idle timer may be pending because we may ++ * not disable disk idling even when a new request ++ * arrives. ++ */ ++ if (timer_pending(&bfqd->idle_slice_timer)) { ++ /* ++ * If we get here: 1) at least a new request ++ * has arrived but we have not disabled the ++ * timer because the request was too small, ++ * 2) then the block layer has unplugged ++ * the device, causing the dispatch to be ++ * invoked. ++ * ++ * Since the device is unplugged, now the ++ * requests are probably large enough to ++ * provide a reasonable throughput. ++ * So we disable idling. ++ */ ++ bfq_clear_bfqq_wait_request(bfqq); ++ del_timer(&bfqd->idle_slice_timer); ++ } ++ if (new_bfqq == NULL) ++ goto keep_queue; ++ else ++ goto expire; ++ } ++ } ++ ++ /* ++ * No requests pending. If the in-service queue still has requests ++ * in flight (possibly waiting for a completion) or is idling for a ++ * new request, then keep it. ++ */ ++ if (new_bfqq == NULL && (timer_pending(&bfqd->idle_slice_timer) || ++ (bfqq->dispatched != 0 && bfq_bfqq_must_not_expire(bfqq)))) { ++ bfqq = NULL; ++ goto keep_queue; ++ } else if (new_bfqq != NULL && timer_pending(&bfqd->idle_slice_timer)) { ++ /* ++ * Expiring the queue because there is a close cooperator, ++ * cancel timer. ++ */ ++ bfq_clear_bfqq_wait_request(bfqq); ++ del_timer(&bfqd->idle_slice_timer); ++ } ++ ++ reason = BFQ_BFQQ_NO_MORE_REQUESTS; ++expire: ++ bfq_bfqq_expire(bfqd, bfqq, 0, reason); ++new_queue: ++ bfqq = bfq_set_in_service_queue(bfqd, new_bfqq); ++ bfq_log(bfqd, "select_queue: new queue %d returned", ++ bfqq != NULL ? bfqq->pid : 0); ++keep_queue: ++ return bfqq; ++} ++ ++static void bfq_update_wr_data(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ if (bfqq->wr_coeff > 1) { /* queue is being boosted */ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "raising period dur %u/%u msec, old coeff %u, w %d(%d)", ++ jiffies_to_msecs(jiffies - ++ bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time), ++ bfqq->wr_coeff, ++ bfqq->entity.weight, bfqq->entity.orig_weight); ++ ++ BUG_ON(bfqq != bfqd->in_service_queue && entity->weight != ++ entity->orig_weight * bfqq->wr_coeff); ++ if (entity->ioprio_changed) ++ bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change"); ++ /* ++ * If the queue was activated in a burst, or ++ * too much time has elapsed from the beginning ++ * of this weight-raising, then end weight raising. ++ */ ++ if (bfq_bfqq_in_large_burst(bfqq) || ++ time_is_before_jiffies(bfqq->last_wr_start_finish + ++ bfqq->wr_cur_max_time)) { ++ bfqq->last_wr_start_finish = jiffies; ++ bfq_log_bfqq(bfqd, bfqq, ++ "wrais ending at %lu, rais_max_time %u", ++ bfqq->last_wr_start_finish, ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ bfq_bfqq_end_wr(bfqq); ++ __bfq_entity_update_weight_prio( ++ bfq_entity_service_tree(entity), ++ entity); ++ } ++ } ++} ++ ++/* ++ * Dispatch one request from bfqq, moving it to the request queue ++ * dispatch list. ++ */ ++static int bfq_dispatch_request(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ int dispatched = 0; ++ struct request *rq; ++ unsigned long service_to_charge; ++ ++ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ /* Follow expired path, else get first next available. */ ++ rq = bfq_check_fifo(bfqq); ++ if (rq == NULL) ++ rq = bfqq->next_rq; ++ service_to_charge = bfq_serv_to_charge(rq, bfqq); ++ ++ if (service_to_charge > bfq_bfqq_budget_left(bfqq)) { ++ /* ++ * This may happen if the next rq is chosen in fifo order ++ * instead of sector order. The budget is properly ++ * dimensioned to be always sufficient to serve the next ++ * request only if it is chosen in sector order. The reason ++ * is that it would be quite inefficient and little useful ++ * to always make sure that the budget is large enough to ++ * serve even the possible next rq in fifo order. ++ * In fact, requests are seldom served in fifo order. ++ * ++ * Expire the queue for budget exhaustion, and make sure ++ * that the next act_budget is enough to serve the next ++ * request, even if it comes from the fifo expired path. ++ */ ++ bfqq->next_rq = rq; ++ /* ++ * Since this dispatch is failed, make sure that ++ * a new one will be performed ++ */ ++ if (!bfqd->rq_in_driver) ++ bfq_schedule_dispatch(bfqd); ++ goto expire; ++ } ++ ++ /* Finally, insert request into driver dispatch list. */ ++ bfq_bfqq_served(bfqq, service_to_charge); ++ bfq_dispatch_insert(bfqd->queue, rq); ++ ++ bfq_update_wr_data(bfqd, bfqq); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "dispatched %u sec req (%llu), budg left %lu", ++ blk_rq_sectors(rq), ++ (long long unsigned)blk_rq_pos(rq), ++ bfq_bfqq_budget_left(bfqq)); ++ ++ dispatched++; ++ ++ if (bfqd->in_service_bic == NULL) { ++ atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount); ++ bfqd->in_service_bic = RQ_BIC(rq); ++ } ++ ++ if (bfqd->busy_queues > 1 && ((!bfq_bfqq_sync(bfqq) && ++ dispatched >= bfqd->bfq_max_budget_async_rq) || ++ bfq_class_idle(bfqq))) ++ goto expire; ++ ++ return dispatched; ++ ++expire: ++ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_EXHAUSTED); ++ return dispatched; ++} ++ ++static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq) ++{ ++ int dispatched = 0; ++ ++ while (bfqq->next_rq != NULL) { ++ bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq); ++ dispatched++; ++ } ++ ++ BUG_ON(!list_empty(&bfqq->fifo)); ++ return dispatched; ++} ++ ++/* ++ * Drain our current requests. ++ * Used for barriers and when switching io schedulers on-the-fly. ++ */ ++static int bfq_forced_dispatch(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq, *n; ++ struct bfq_service_tree *st; ++ int dispatched = 0; ++ ++ bfqq = bfqd->in_service_queue; ++ if (bfqq != NULL) ++ __bfq_bfqq_expire(bfqd, bfqq); ++ ++ /* ++ * Loop through classes, and be careful to leave the scheduler ++ * in a consistent state, as feedback mechanisms and vtime ++ * updates cannot be disabled during the process. ++ */ ++ list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) { ++ st = bfq_entity_service_tree(&bfqq->entity); ++ ++ dispatched += __bfq_forced_dispatch_bfqq(bfqq); ++ bfqq->max_budget = bfq_max_budget(bfqd); ++ ++ bfq_forget_idle(st); ++ } ++ ++ BUG_ON(bfqd->busy_queues != 0); ++ ++ return dispatched; ++} ++ ++static int bfq_dispatch_requests(struct request_queue *q, int force) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_queue *bfqq; ++ int max_dispatch; ++ ++ bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues); ++ if (bfqd->busy_queues == 0) ++ return 0; ++ ++ if (unlikely(force)) ++ return bfq_forced_dispatch(bfqd); ++ ++ bfqq = bfq_select_queue(bfqd); ++ if (bfqq == NULL) ++ return 0; ++ ++ max_dispatch = bfqd->bfq_quantum; ++ if (bfq_class_idle(bfqq)) ++ max_dispatch = 1; ++ ++ if (!bfq_bfqq_sync(bfqq)) ++ max_dispatch = bfqd->bfq_max_budget_async_rq; ++ ++ if (bfqq->dispatched >= max_dispatch) { ++ if (bfqd->busy_queues > 1) ++ return 0; ++ if (bfqq->dispatched >= 4 * max_dispatch) ++ return 0; ++ } ++ ++ if (bfqd->sync_flight != 0 && !bfq_bfqq_sync(bfqq)) ++ return 0; ++ ++ bfq_clear_bfqq_wait_request(bfqq); ++ BUG_ON(timer_pending(&bfqd->idle_slice_timer)); ++ ++ if (!bfq_dispatch_request(bfqd, bfqq)) ++ return 0; ++ ++ bfq_log_bfqq(bfqd, bfqq, "dispatched one request of %d (max_disp %d)", ++ bfqq->pid, max_dispatch); ++ ++ return 1; ++} ++ ++/* ++ * Task holds one reference to the queue, dropped when task exits. Each rq ++ * in-flight on this queue also holds a reference, dropped when rq is freed. ++ * ++ * Queue lock must be held here. ++ */ ++static void bfq_put_queue(struct bfq_queue *bfqq) ++{ ++ struct bfq_data *bfqd = bfqq->bfqd; ++ ++ BUG_ON(atomic_read(&bfqq->ref) <= 0); ++ ++ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq, ++ atomic_read(&bfqq->ref)); ++ if (!atomic_dec_and_test(&bfqq->ref)) ++ return; ++ ++ BUG_ON(rb_first(&bfqq->sort_list) != NULL); ++ BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0); ++ BUG_ON(bfqq->entity.tree != NULL); ++ BUG_ON(bfq_bfqq_busy(bfqq)); ++ BUG_ON(bfqd->in_service_queue == bfqq); ++ ++ if (bfq_bfqq_sync(bfqq)) ++ /* ++ * The fact that this queue is being destroyed does not ++ * invalidate the fact that this queue may have been ++ * activated during the current burst. As a consequence, ++ * although the queue does not exist anymore, and hence ++ * needs to be removed from the burst list if there, ++ * the burst size has not to be decremented. ++ */ ++ hlist_del_init(&bfqq->burst_list_node); ++ ++ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p freed", bfqq); ++ ++ kmem_cache_free(bfq_pool, bfqq); ++} ++ ++static void bfq_put_cooperator(struct bfq_queue *bfqq) ++{ ++ struct bfq_queue *__bfqq, *next; ++ ++ /* ++ * If this queue was scheduled to merge with another queue, be ++ * sure to drop the reference taken on that queue (and others in ++ * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs. ++ */ ++ __bfqq = bfqq->new_bfqq; ++ while (__bfqq) { ++ if (__bfqq == bfqq) ++ break; ++ next = __bfqq->new_bfqq; ++ bfq_put_queue(__bfqq); ++ __bfqq = next; ++ } ++} ++ ++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ if (bfqq == bfqd->in_service_queue) { ++ __bfq_bfqq_expire(bfqd, bfqq); ++ bfq_schedule_dispatch(bfqd); ++ } ++ ++ bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq, ++ atomic_read(&bfqq->ref)); ++ ++ bfq_put_cooperator(bfqq); ++ ++ bfq_put_queue(bfqq); ++} ++ ++static inline void bfq_init_icq(struct io_cq *icq) ++{ ++ struct bfq_io_cq *bic = icq_to_bic(icq); ++ ++ bic->ttime.last_end_request = jiffies; ++} ++ ++static void bfq_exit_icq(struct io_cq *icq) ++{ ++ struct bfq_io_cq *bic = icq_to_bic(icq); ++ struct bfq_data *bfqd = bic_to_bfqd(bic); ++ ++ if (bic->bfqq[BLK_RW_ASYNC]) { ++ bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_ASYNC]); ++ bic->bfqq[BLK_RW_ASYNC] = NULL; ++ } ++ ++ if (bic->bfqq[BLK_RW_SYNC]) { ++ bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_SYNC]); ++ bic->bfqq[BLK_RW_SYNC] = NULL; ++ } ++} ++ ++/* ++ * Update the entity prio values; note that the new values will not ++ * be used until the next (re)activation. ++ */ ++static void bfq_init_prio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic) ++{ ++ struct task_struct *tsk = current; ++ int ioprio_class; ++ ++ if (!bfq_bfqq_prio_changed(bfqq)) ++ return; ++ ++ ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); ++ switch (ioprio_class) { ++ default: ++ dev_err(bfqq->bfqd->queue->backing_dev_info.dev, ++ "bfq: bad prio class %d\n", ioprio_class); ++ case IOPRIO_CLASS_NONE: ++ /* ++ * No prio set, inherit CPU scheduling settings. ++ */ ++ bfqq->entity.new_ioprio = task_nice_ioprio(tsk); ++ bfqq->entity.new_ioprio_class = task_nice_ioclass(tsk); ++ break; ++ case IOPRIO_CLASS_RT: ++ bfqq->entity.new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_RT; ++ break; ++ case IOPRIO_CLASS_BE: ++ bfqq->entity.new_ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_BE; ++ break; ++ case IOPRIO_CLASS_IDLE: ++ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_IDLE; ++ bfqq->entity.new_ioprio = 7; ++ bfq_clear_bfqq_idle_window(bfqq); ++ break; ++ } ++ ++ if (bfqq->entity.new_ioprio < 0 || ++ bfqq->entity.new_ioprio >= IOPRIO_BE_NR) { ++ printk(KERN_CRIT "bfq_init_prio_data: new_ioprio %d\n", ++ bfqq->entity.new_ioprio); ++ BUG(); ++ } ++ ++ bfqq->entity.ioprio_changed = 1; ++ ++ bfq_clear_bfqq_prio_changed(bfqq); ++} ++ ++static void bfq_changed_ioprio(struct bfq_io_cq *bic) ++{ ++ struct bfq_data *bfqd; ++ struct bfq_queue *bfqq, *new_bfqq; ++ struct bfq_group *bfqg; ++ unsigned long uninitialized_var(flags); ++ int ioprio = bic->icq.ioc->ioprio; ++ ++ bfqd = bfq_get_bfqd_locked(&(bic->icq.q->elevator->elevator_data), ++ &flags); ++ /* ++ * This condition may trigger on a newly created bic, be sure to ++ * drop the lock before returning. ++ */ ++ if (unlikely(bfqd == NULL) || likely(bic->ioprio == ioprio)) ++ goto out; ++ ++ bfqq = bic->bfqq[BLK_RW_ASYNC]; ++ if (bfqq != NULL) { ++ bfqg = container_of(bfqq->entity.sched_data, struct bfq_group, ++ sched_data); ++ new_bfqq = bfq_get_queue(bfqd, bfqg, BLK_RW_ASYNC, bic, ++ GFP_ATOMIC); ++ if (new_bfqq != NULL) { ++ bic->bfqq[BLK_RW_ASYNC] = new_bfqq; ++ bfq_log_bfqq(bfqd, bfqq, ++ "changed_ioprio: bfqq %p %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ bfq_put_queue(bfqq); ++ } ++ } ++ ++ bfqq = bic->bfqq[BLK_RW_SYNC]; ++ if (bfqq != NULL) ++ bfq_mark_bfqq_prio_changed(bfqq); ++ ++ bic->ioprio = ioprio; ++ ++out: ++ bfq_put_bfqd_unlock(bfqd, &flags); ++} ++ ++static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ pid_t pid, int is_sync) ++{ ++ RB_CLEAR_NODE(&bfqq->entity.rb_node); ++ INIT_LIST_HEAD(&bfqq->fifo); ++ INIT_HLIST_NODE(&bfqq->burst_list_node); ++ ++ atomic_set(&bfqq->ref, 0); ++ bfqq->bfqd = bfqd; ++ ++ bfq_mark_bfqq_prio_changed(bfqq); ++ ++ if (is_sync) { ++ if (!bfq_class_idle(bfqq)) ++ bfq_mark_bfqq_idle_window(bfqq); ++ bfq_mark_bfqq_sync(bfqq); ++ } ++ bfq_mark_bfqq_IO_bound(bfqq); ++ ++ /* Tentative initial value to trade off between thr and lat */ ++ bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3; ++ bfqq->pid = pid; ++ ++ bfqq->wr_coeff = 1; ++ bfqq->last_wr_start_finish = 0; ++ /* ++ * Set to the value for which bfqq will not be deemed as ++ * soft rt when it becomes backlogged. ++ */ ++ bfqq->soft_rt_next_start = bfq_infinity_from_now(jiffies); ++} ++ ++static struct bfq_queue *bfq_find_alloc_queue(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, ++ int is_sync, ++ struct bfq_io_cq *bic, ++ gfp_t gfp_mask) ++{ ++ struct bfq_queue *bfqq, *new_bfqq = NULL; ++ ++retry: ++ /* bic always exists here */ ++ bfqq = bic_to_bfqq(bic, is_sync); ++ ++ /* ++ * Always try a new alloc if we fall back to the OOM bfqq ++ * originally, since it should just be a temporary situation. ++ */ ++ if (bfqq == NULL || bfqq == &bfqd->oom_bfqq) { ++ bfqq = NULL; ++ if (new_bfqq != NULL) { ++ bfqq = new_bfqq; ++ new_bfqq = NULL; ++ } else if (gfp_mask & __GFP_WAIT) { ++ spin_unlock_irq(bfqd->queue->queue_lock); ++ new_bfqq = kmem_cache_alloc_node(bfq_pool, ++ gfp_mask | __GFP_ZERO, ++ bfqd->queue->node); ++ spin_lock_irq(bfqd->queue->queue_lock); ++ if (new_bfqq != NULL) ++ goto retry; ++ } else { ++ bfqq = kmem_cache_alloc_node(bfq_pool, ++ gfp_mask | __GFP_ZERO, ++ bfqd->queue->node); ++ } ++ ++ if (bfqq != NULL) { ++ bfq_init_bfqq(bfqd, bfqq, current->pid, is_sync); ++ bfq_init_prio_data(bfqq, bic); ++ bfq_init_entity(&bfqq->entity, bfqg); ++ bfq_log_bfqq(bfqd, bfqq, "allocated"); ++ } else { ++ bfqq = &bfqd->oom_bfqq; ++ bfq_log_bfqq(bfqd, bfqq, "using oom bfqq"); ++ } ++ } ++ ++ if (new_bfqq != NULL) ++ kmem_cache_free(bfq_pool, new_bfqq); ++ ++ return bfqq; ++} ++ ++static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, ++ int ioprio_class, int ioprio) ++{ ++ switch (ioprio_class) { ++ case IOPRIO_CLASS_RT: ++ return &bfqg->async_bfqq[0][ioprio]; ++ case IOPRIO_CLASS_NONE: ++ ioprio = IOPRIO_NORM; ++ /* fall through */ ++ case IOPRIO_CLASS_BE: ++ return &bfqg->async_bfqq[1][ioprio]; ++ case IOPRIO_CLASS_IDLE: ++ return &bfqg->async_idle_bfqq; ++ default: ++ BUG(); ++ } ++} ++ ++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, int is_sync, ++ struct bfq_io_cq *bic, gfp_t gfp_mask) ++{ ++ const int ioprio = IOPRIO_PRIO_DATA(bic->ioprio); ++ const int ioprio_class = IOPRIO_PRIO_CLASS(bic->ioprio); ++ struct bfq_queue **async_bfqq = NULL; ++ struct bfq_queue *bfqq = NULL; ++ ++ if (!is_sync) { ++ async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class, ++ ioprio); ++ bfqq = *async_bfqq; ++ } ++ ++ if (bfqq == NULL) ++ bfqq = bfq_find_alloc_queue(bfqd, bfqg, is_sync, bic, gfp_mask); ++ ++ /* ++ * Pin the queue now that it's allocated, scheduler exit will ++ * prune it. ++ */ ++ if (!is_sync && *async_bfqq == NULL) { ++ atomic_inc(&bfqq->ref); ++ bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ *async_bfqq = bfqq; ++ } ++ ++ atomic_inc(&bfqq->ref); ++ bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq, ++ atomic_read(&bfqq->ref)); ++ return bfqq; ++} ++ ++static void bfq_update_io_thinktime(struct bfq_data *bfqd, ++ struct bfq_io_cq *bic) ++{ ++ unsigned long elapsed = jiffies - bic->ttime.last_end_request; ++ unsigned long ttime = min(elapsed, 2UL * bfqd->bfq_slice_idle); ++ ++ bic->ttime.ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8; ++ bic->ttime.ttime_total = (7*bic->ttime.ttime_total + 256*ttime) / 8; ++ bic->ttime.ttime_mean = (bic->ttime.ttime_total + 128) / ++ bic->ttime.ttime_samples; ++} ++ ++static void bfq_update_io_seektime(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct request *rq) ++{ ++ sector_t sdist; ++ u64 total; ++ ++ if (bfqq->last_request_pos < blk_rq_pos(rq)) ++ sdist = blk_rq_pos(rq) - bfqq->last_request_pos; ++ else ++ sdist = bfqq->last_request_pos - blk_rq_pos(rq); ++ ++ /* ++ * Don't allow the seek distance to get too large from the ++ * odd fragment, pagein, etc. ++ */ ++ if (bfqq->seek_samples == 0) /* first request, not really a seek */ ++ sdist = 0; ++ else if (bfqq->seek_samples <= 60) /* second & third seek */ ++ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*1024); ++ else ++ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*64); ++ ++ bfqq->seek_samples = (7*bfqq->seek_samples + 256) / 8; ++ bfqq->seek_total = (7*bfqq->seek_total + (u64)256*sdist) / 8; ++ total = bfqq->seek_total + (bfqq->seek_samples/2); ++ do_div(total, bfqq->seek_samples); ++ bfqq->seek_mean = (sector_t)total; ++ ++ bfq_log_bfqq(bfqd, bfqq, "dist=%llu mean=%llu", (u64)sdist, ++ (u64)bfqq->seek_mean); ++} ++ ++/* ++ * Disable idle window if the process thinks too long or seeks so much that ++ * it doesn't matter. ++ */ ++static void bfq_update_idle_window(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq, ++ struct bfq_io_cq *bic) ++{ ++ int enable_idle; ++ ++ /* Don't idle for async or idle io prio class. */ ++ if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq)) ++ return; ++ ++ enable_idle = bfq_bfqq_idle_window(bfqq); ++ ++ if (atomic_read(&bic->icq.ioc->active_ref) == 0 || ++ bfqd->bfq_slice_idle == 0 || ++ (bfqd->hw_tag && BFQQ_SEEKY(bfqq) && ++ bfqq->wr_coeff == 1)) ++ enable_idle = 0; ++ else if (bfq_sample_valid(bic->ttime.ttime_samples)) { ++ if (bic->ttime.ttime_mean > bfqd->bfq_slice_idle && ++ bfqq->wr_coeff == 1) ++ enable_idle = 0; ++ else ++ enable_idle = 1; ++ } ++ bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d", ++ enable_idle); ++ ++ if (enable_idle) ++ bfq_mark_bfqq_idle_window(bfqq); ++ else ++ bfq_clear_bfqq_idle_window(bfqq); ++} ++ ++/* ++ * Called when a new fs request (rq) is added to bfqq. Check if there's ++ * something we should do about it. ++ */ ++static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ struct request *rq) ++{ ++ struct bfq_io_cq *bic = RQ_BIC(rq); ++ ++ if (rq->cmd_flags & REQ_META) ++ bfqq->meta_pending++; ++ ++ bfq_update_io_thinktime(bfqd, bic); ++ bfq_update_io_seektime(bfqd, bfqq, rq); ++ if (!BFQQ_SEEKY(bfqq) && bfq_bfqq_constantly_seeky(bfqq)) { ++ bfq_clear_bfqq_constantly_seeky(bfqq); ++ if (!blk_queue_nonrot(bfqd->queue)) { ++ BUG_ON(!bfqd->const_seeky_busy_in_flight_queues); ++ bfqd->const_seeky_busy_in_flight_queues--; ++ } ++ } ++ if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 || ++ !BFQQ_SEEKY(bfqq)) ++ bfq_update_idle_window(bfqd, bfqq, bic); ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "rq_enqueued: idle_window=%d (seeky %d, mean %llu)", ++ bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq), ++ (long long unsigned)bfqq->seek_mean); ++ ++ bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); ++ ++ if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) { ++ int small_req = bfqq->queued[rq_is_sync(rq)] == 1 && ++ blk_rq_sectors(rq) < 32; ++ int budget_timeout = bfq_bfqq_budget_timeout(bfqq); ++ ++ /* ++ * There is just this request queued: if the request ++ * is small and the queue is not to be expired, then ++ * just exit. ++ * ++ * In this way, if the disk is being idled to wait for ++ * a new request from the in-service queue, we avoid ++ * unplugging the device and committing the disk to serve ++ * just a small request. On the contrary, we wait for ++ * the block layer to decide when to unplug the device: ++ * hopefully, new requests will be merged to this one ++ * quickly, then the device will be unplugged and ++ * larger requests will be dispatched. ++ */ ++ if (small_req && !budget_timeout) ++ return; ++ ++ /* ++ * A large enough request arrived, or the queue is to ++ * be expired: in both cases disk idling is to be ++ * stopped, so clear wait_request flag and reset ++ * timer. ++ */ ++ bfq_clear_bfqq_wait_request(bfqq); ++ del_timer(&bfqd->idle_slice_timer); ++ ++ /* ++ * The queue is not empty, because a new request just ++ * arrived. Hence we can safely expire the queue, in ++ * case of budget timeout, without risking that the ++ * timestamps of the queue are not updated correctly. ++ * See [1] for more details. ++ */ ++ if (budget_timeout) ++ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_TIMEOUT); ++ ++ /* ++ * Let the request rip immediately, or let a new queue be ++ * selected if bfqq has just been expired. ++ */ ++ __blk_run_queue(bfqd->queue); ++ } ++} ++ ++static void bfq_insert_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ assert_spin_locked(bfqd->queue->queue_lock); ++ bfq_init_prio_data(bfqq, RQ_BIC(rq)); ++ ++ bfq_add_request(rq); ++ ++ rq->fifo_time = jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)]; ++ list_add_tail(&rq->queuelist, &bfqq->fifo); ++ ++ bfq_rq_enqueued(bfqd, bfqq, rq); ++} ++ ++static void bfq_update_hw_tag(struct bfq_data *bfqd) ++{ ++ bfqd->max_rq_in_driver = max(bfqd->max_rq_in_driver, ++ bfqd->rq_in_driver); ++ ++ if (bfqd->hw_tag == 1) ++ return; ++ ++ /* ++ * This sample is valid if the number of outstanding requests ++ * is large enough to allow a queueing behavior. Note that the ++ * sum is not exact, as it's not taking into account deactivated ++ * requests. ++ */ ++ if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD) ++ return; ++ ++ if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES) ++ return; ++ ++ bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD; ++ bfqd->max_rq_in_driver = 0; ++ bfqd->hw_tag_samples = 0; ++} ++ ++static void bfq_completed_request(struct request_queue *q, struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_data *bfqd = bfqq->bfqd; ++ bool sync = bfq_bfqq_sync(bfqq); ++ ++ bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left (%d)", ++ blk_rq_sectors(rq), sync); ++ ++ bfq_update_hw_tag(bfqd); ++ ++ BUG_ON(!bfqd->rq_in_driver); ++ BUG_ON(!bfqq->dispatched); ++ bfqd->rq_in_driver--; ++ bfqq->dispatched--; ++ ++ if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) { ++ bfq_weights_tree_remove(bfqd, &bfqq->entity, ++ &bfqd->queue_weights_tree); ++ if (!blk_queue_nonrot(bfqd->queue)) { ++ BUG_ON(!bfqd->busy_in_flight_queues); ++ bfqd->busy_in_flight_queues--; ++ if (bfq_bfqq_constantly_seeky(bfqq)) { ++ BUG_ON(!bfqd-> ++ const_seeky_busy_in_flight_queues); ++ bfqd->const_seeky_busy_in_flight_queues--; ++ } ++ } ++ } ++ ++ if (sync) { ++ bfqd->sync_flight--; ++ RQ_BIC(rq)->ttime.last_end_request = jiffies; ++ } ++ ++ /* ++ * If we are waiting to discover whether the request pattern of the ++ * task associated with the queue is actually isochronous, and ++ * both requisites for this condition to hold are satisfied, then ++ * compute soft_rt_next_start (see the comments to the function ++ * bfq_bfqq_softrt_next_start()). ++ */ ++ if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 && ++ RB_EMPTY_ROOT(&bfqq->sort_list)) ++ bfqq->soft_rt_next_start = ++ bfq_bfqq_softrt_next_start(bfqd, bfqq); ++ ++ /* ++ * If this is the in-service queue, check if it needs to be expired, ++ * or if we want to idle in case it has no pending requests. ++ */ ++ if (bfqd->in_service_queue == bfqq) { ++ if (bfq_bfqq_budget_new(bfqq)) ++ bfq_set_budget_timeout(bfqd); ++ ++ if (bfq_bfqq_must_idle(bfqq)) { ++ bfq_arm_slice_timer(bfqd); ++ goto out; ++ } else if (bfq_may_expire_for_budg_timeout(bfqq)) ++ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_TIMEOUT); ++ else if (RB_EMPTY_ROOT(&bfqq->sort_list) && ++ (bfqq->dispatched == 0 || ++ !bfq_bfqq_must_not_expire(bfqq))) ++ bfq_bfqq_expire(bfqd, bfqq, 0, ++ BFQ_BFQQ_NO_MORE_REQUESTS); ++ } ++ ++ if (!bfqd->rq_in_driver) ++ bfq_schedule_dispatch(bfqd); ++ ++out: ++ return; ++} ++ ++static inline int __bfq_may_queue(struct bfq_queue *bfqq) ++{ ++ if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) { ++ bfq_clear_bfqq_must_alloc(bfqq); ++ return ELV_MQUEUE_MUST; ++ } ++ ++ return ELV_MQUEUE_MAY; ++} ++ ++static int bfq_may_queue(struct request_queue *q, int rw) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct task_struct *tsk = current; ++ struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq; ++ ++ /* ++ * Don't force setup of a queue from here, as a call to may_queue ++ * does not necessarily imply that a request actually will be ++ * queued. So just lookup a possibly existing queue, or return ++ * 'may queue' if that fails. ++ */ ++ bic = bfq_bic_lookup(bfqd, tsk->io_context); ++ if (bic == NULL) ++ return ELV_MQUEUE_MAY; ++ ++ bfqq = bic_to_bfqq(bic, rw_is_sync(rw)); ++ if (bfqq != NULL) { ++ bfq_init_prio_data(bfqq, bic); ++ ++ return __bfq_may_queue(bfqq); ++ } ++ ++ return ELV_MQUEUE_MAY; ++} ++ ++/* ++ * Queue lock held here. ++ */ ++static void bfq_put_request(struct request *rq) ++{ ++ struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ ++ if (bfqq != NULL) { ++ const int rw = rq_data_dir(rq); ++ ++ BUG_ON(!bfqq->allocated[rw]); ++ bfqq->allocated[rw]--; ++ ++ rq->elv.priv[0] = NULL; ++ rq->elv.priv[1] = NULL; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ bfq_put_queue(bfqq); ++ } ++} ++ ++static struct bfq_queue * ++bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, ++ struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu", ++ (long unsigned)bfqq->new_bfqq->pid); ++ bic_set_bfqq(bic, bfqq->new_bfqq, 1); ++ bfq_mark_bfqq_coop(bfqq->new_bfqq); ++ bfq_put_queue(bfqq); ++ return bic_to_bfqq(bic, 1); ++} ++ ++/* ++ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this ++ * was the last process referring to said bfqq. ++ */ ++static struct bfq_queue * ++bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq) ++{ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue"); ++ if (bfqq_process_refs(bfqq) == 1) { ++ bfqq->pid = current->pid; ++ bfq_clear_bfqq_coop(bfqq); ++ bfq_clear_bfqq_split_coop(bfqq); ++ return bfqq; ++ } ++ ++ bic_set_bfqq(bic, NULL, 1); ++ ++ bfq_put_cooperator(bfqq); ++ ++ bfq_put_queue(bfqq); ++ return NULL; ++} ++ ++/* ++ * Allocate bfq data structures associated with this request. ++ */ ++static int bfq_set_request(struct request_queue *q, struct request *rq, ++ struct bio *bio, gfp_t gfp_mask) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq); ++ const int rw = rq_data_dir(rq); ++ const int is_sync = rq_is_sync(rq); ++ struct bfq_queue *bfqq; ++ struct bfq_group *bfqg; ++ unsigned long flags; ++ ++ might_sleep_if(gfp_mask & __GFP_WAIT); ++ ++ bfq_changed_ioprio(bic); ++ ++ spin_lock_irqsave(q->queue_lock, flags); ++ ++ if (bic == NULL) ++ goto queue_fail; ++ ++ bfqg = bfq_bic_update_cgroup(bic); ++ ++new_queue: ++ bfqq = bic_to_bfqq(bic, is_sync); ++ if (bfqq == NULL || bfqq == &bfqd->oom_bfqq) { ++ bfqq = bfq_get_queue(bfqd, bfqg, is_sync, bic, gfp_mask); ++ bic_set_bfqq(bic, bfqq, is_sync); ++ } else { ++ /* ++ * If the queue was seeky for too long, break it apart. ++ */ ++ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) { ++ bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq"); ++ bfqq = bfq_split_bfqq(bic, bfqq); ++ if (!bfqq) ++ goto new_queue; ++ } ++ ++ /* ++ * Check to see if this queue is scheduled to merge with ++ * another closely cooperating queue. The merging of queues ++ * happens here as it must be done in process context. ++ * The reference on new_bfqq was taken in merge_bfqqs. ++ */ ++ if (bfqq->new_bfqq != NULL) ++ bfqq = bfq_merge_bfqqs(bfqd, bic, bfqq); ++ } ++ ++ bfqq->allocated[rw]++; ++ atomic_inc(&bfqq->ref); ++ bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq, ++ atomic_read(&bfqq->ref)); ++ ++ rq->elv.priv[0] = bic; ++ rq->elv.priv[1] = bfqq; ++ ++ spin_unlock_irqrestore(q->queue_lock, flags); ++ ++ return 0; ++ ++queue_fail: ++ bfq_schedule_dispatch(bfqd); ++ spin_unlock_irqrestore(q->queue_lock, flags); ++ ++ return 1; ++} ++ ++static void bfq_kick_queue(struct work_struct *work) ++{ ++ struct bfq_data *bfqd = ++ container_of(work, struct bfq_data, unplug_work); ++ struct request_queue *q = bfqd->queue; ++ ++ spin_lock_irq(q->queue_lock); ++ __blk_run_queue(q); ++ spin_unlock_irq(q->queue_lock); ++} ++ ++/* ++ * Handler of the expiration of the timer running if the in-service queue ++ * is idling inside its time slice. ++ */ ++static void bfq_idle_slice_timer(unsigned long data) ++{ ++ struct bfq_data *bfqd = (struct bfq_data *)data; ++ struct bfq_queue *bfqq; ++ unsigned long flags; ++ enum bfqq_expiration reason; ++ ++ spin_lock_irqsave(bfqd->queue->queue_lock, flags); ++ ++ bfqq = bfqd->in_service_queue; ++ /* ++ * Theoretical race here: the in-service queue can be NULL or ++ * different from the queue that was idling if the timer handler ++ * spins on the queue_lock and a new request arrives for the ++ * current queue and there is a full dispatch cycle that changes ++ * the in-service queue. This can hardly happen, but in the worst ++ * case we just expire a queue too early. ++ */ ++ if (bfqq != NULL) { ++ bfq_log_bfqq(bfqd, bfqq, "slice_timer expired"); ++ if (bfq_bfqq_budget_timeout(bfqq)) ++ /* ++ * Also here the queue can be safely expired ++ * for budget timeout without wasting ++ * guarantees ++ */ ++ reason = BFQ_BFQQ_BUDGET_TIMEOUT; ++ else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0) ++ /* ++ * The queue may not be empty upon timer expiration, ++ * because we may not disable the timer when the ++ * first request of the in-service queue arrives ++ * during disk idling. ++ */ ++ reason = BFQ_BFQQ_TOO_IDLE; ++ else ++ goto schedule_dispatch; ++ ++ bfq_bfqq_expire(bfqd, bfqq, 1, reason); ++ } ++ ++schedule_dispatch: ++ bfq_schedule_dispatch(bfqd); ++ ++ spin_unlock_irqrestore(bfqd->queue->queue_lock, flags); ++} ++ ++static void bfq_shutdown_timer_wq(struct bfq_data *bfqd) ++{ ++ del_timer_sync(&bfqd->idle_slice_timer); ++ cancel_work_sync(&bfqd->unplug_work); ++} ++ ++static inline void __bfq_put_async_bfqq(struct bfq_data *bfqd, ++ struct bfq_queue **bfqq_ptr) ++{ ++ struct bfq_group *root_group = bfqd->root_group; ++ struct bfq_queue *bfqq = *bfqq_ptr; ++ ++ bfq_log(bfqd, "put_async_bfqq: %p", bfqq); ++ if (bfqq != NULL) { ++ bfq_bfqq_move(bfqd, bfqq, &bfqq->entity, root_group); ++ bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ bfq_put_queue(bfqq); ++ *bfqq_ptr = NULL; ++ } ++} ++ ++/* ++ * Release all the bfqg references to its async queues. If we are ++ * deallocating the group these queues may still contain requests, so ++ * we reparent them to the root cgroup (i.e., the only one that will ++ * exist for sure until all the requests on a device are gone). ++ */ ++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg) ++{ ++ int i, j; ++ ++ for (i = 0; i < 2; i++) ++ for (j = 0; j < IOPRIO_BE_NR; j++) ++ __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]); ++ ++ __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq); ++} ++ ++static void bfq_exit_queue(struct elevator_queue *e) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ struct request_queue *q = bfqd->queue; ++ struct bfq_queue *bfqq, *n; ++ ++ bfq_shutdown_timer_wq(bfqd); ++ ++ spin_lock_irq(q->queue_lock); ++ ++ BUG_ON(bfqd->in_service_queue != NULL); ++ list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list) ++ bfq_deactivate_bfqq(bfqd, bfqq, 0); ++ ++ bfq_disconnect_groups(bfqd); ++ spin_unlock_irq(q->queue_lock); ++ ++ bfq_shutdown_timer_wq(bfqd); ++ ++ synchronize_rcu(); ++ ++ BUG_ON(timer_pending(&bfqd->idle_slice_timer)); ++ ++ bfq_free_root_group(bfqd); ++ kfree(bfqd); ++} ++ ++static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) ++{ ++ struct bfq_group *bfqg; ++ struct bfq_data *bfqd; ++ struct elevator_queue *eq; ++ ++ eq = elevator_alloc(q, e); ++ if (eq == NULL) ++ return -ENOMEM; ++ ++ bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node); ++ if (bfqd == NULL) { ++ kobject_put(&eq->kobj); ++ return -ENOMEM; ++ } ++ eq->elevator_data = bfqd; ++ ++ /* ++ * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues. ++ * Grab a permanent reference to it, so that the normal code flow ++ * will not attempt to free it. ++ */ ++ bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, 1, 0); ++ atomic_inc(&bfqd->oom_bfqq.ref); ++ bfqd->oom_bfqq.entity.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO; ++ bfqd->oom_bfqq.entity.new_ioprio_class = IOPRIO_CLASS_BE; ++ /* ++ * Trigger weight initialization, according to ioprio, at the ++ * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio ++ * class won't be changed any more. ++ */ ++ bfqd->oom_bfqq.entity.ioprio_changed = 1; ++ ++ bfqd->queue = q; ++ ++ spin_lock_irq(q->queue_lock); ++ q->elevator = eq; ++ spin_unlock_irq(q->queue_lock); ++ ++ bfqg = bfq_alloc_root_group(bfqd, q->node); ++ if (bfqg == NULL) { ++ kfree(bfqd); ++ kobject_put(&eq->kobj); ++ return -ENOMEM; ++ } ++ ++ bfqd->root_group = bfqg; ++ bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group); ++#ifdef CONFIG_CGROUP_BFQIO ++ bfqd->active_numerous_groups = 0; ++#endif ++ ++ init_timer(&bfqd->idle_slice_timer); ++ bfqd->idle_slice_timer.function = bfq_idle_slice_timer; ++ bfqd->idle_slice_timer.data = (unsigned long)bfqd; ++ ++ bfqd->rq_pos_tree = RB_ROOT; ++ bfqd->queue_weights_tree = RB_ROOT; ++ bfqd->group_weights_tree = RB_ROOT; ++ ++ INIT_WORK(&bfqd->unplug_work, bfq_kick_queue); ++ ++ INIT_LIST_HEAD(&bfqd->active_list); ++ INIT_LIST_HEAD(&bfqd->idle_list); ++ INIT_HLIST_HEAD(&bfqd->burst_list); ++ ++ bfqd->hw_tag = -1; ++ ++ bfqd->bfq_max_budget = bfq_default_max_budget; ++ ++ bfqd->bfq_quantum = bfq_quantum; ++ bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0]; ++ bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1]; ++ bfqd->bfq_back_max = bfq_back_max; ++ bfqd->bfq_back_penalty = bfq_back_penalty; ++ bfqd->bfq_slice_idle = bfq_slice_idle; ++ bfqd->bfq_class_idle_last_service = 0; ++ bfqd->bfq_max_budget_async_rq = bfq_max_budget_async_rq; ++ bfqd->bfq_timeout[BLK_RW_ASYNC] = bfq_timeout_async; ++ bfqd->bfq_timeout[BLK_RW_SYNC] = bfq_timeout_sync; ++ ++ bfqd->bfq_coop_thresh = 2; ++ bfqd->bfq_failed_cooperations = 7000; ++ bfqd->bfq_requests_within_timer = 120; ++ ++ bfqd->bfq_large_burst_thresh = 11; ++ bfqd->bfq_burst_interval = msecs_to_jiffies(500); ++ ++ bfqd->low_latency = true; ++ ++ bfqd->bfq_wr_coeff = 20; ++ bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300); ++ bfqd->bfq_wr_max_time = 0; ++ bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000); ++ bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500); ++ bfqd->bfq_wr_max_softrt_rate = 7000; /* ++ * Approximate rate required ++ * to playback or record a ++ * high-definition compressed ++ * video. ++ */ ++ bfqd->wr_busy_queues = 0; ++ bfqd->busy_in_flight_queues = 0; ++ bfqd->const_seeky_busy_in_flight_queues = 0; ++ ++ /* ++ * Begin by assuming, optimistically, that the device peak rate is ++ * equal to the highest reference rate. ++ */ ++ bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] * ++ T_fast[blk_queue_nonrot(bfqd->queue)]; ++ bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)]; ++ bfqd->device_speed = BFQ_BFQD_FAST; ++ ++ return 0; ++} ++ ++static void bfq_slab_kill(void) ++{ ++ if (bfq_pool != NULL) ++ kmem_cache_destroy(bfq_pool); ++} ++ ++static int __init bfq_slab_setup(void) ++{ ++ bfq_pool = KMEM_CACHE(bfq_queue, 0); ++ if (bfq_pool == NULL) ++ return -ENOMEM; ++ return 0; ++} ++ ++static ssize_t bfq_var_show(unsigned int var, char *page) ++{ ++ return sprintf(page, "%d\n", var); ++} ++ ++static ssize_t bfq_var_store(unsigned long *var, const char *page, ++ size_t count) ++{ ++ unsigned long new_val; ++ int ret = kstrtoul(page, 10, &new_val); ++ ++ if (ret == 0) ++ *var = new_val; ++ ++ return count; ++} ++ ++static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ? ++ jiffies_to_msecs(bfqd->bfq_wr_max_time) : ++ jiffies_to_msecs(bfq_wr_duration(bfqd))); ++} ++ ++static ssize_t bfq_weights_show(struct elevator_queue *e, char *page) ++{ ++ struct bfq_queue *bfqq; ++ struct bfq_data *bfqd = e->elevator_data; ++ ssize_t num_char = 0; ++ ++ num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n", ++ bfqd->queued); ++ ++ spin_lock_irq(bfqd->queue->queue_lock); ++ ++ num_char += sprintf(page + num_char, "Active:\n"); ++ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) { ++ num_char += sprintf(page + num_char, ++ "pid%d: weight %hu, nr_queued %d %d, dur %d/%u\n", ++ bfqq->pid, ++ bfqq->entity.weight, ++ bfqq->queued[0], ++ bfqq->queued[1], ++ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ num_char += sprintf(page + num_char, "Idle:\n"); ++ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) { ++ num_char += sprintf(page + num_char, ++ "pid%d: weight %hu, dur %d/%u\n", ++ bfqq->pid, ++ bfqq->entity.weight, ++ jiffies_to_msecs(jiffies - ++ bfqq->last_wr_start_finish), ++ jiffies_to_msecs(bfqq->wr_cur_max_time)); ++ } ++ ++ spin_unlock_irq(bfqd->queue->queue_lock); ++ ++ return num_char; ++} ++ ++#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \ ++static ssize_t __FUNC(struct elevator_queue *e, char *page) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ unsigned int __data = __VAR; \ ++ if (__CONV) \ ++ __data = jiffies_to_msecs(__data); \ ++ return bfq_var_show(__data, (page)); \ ++} ++SHOW_FUNCTION(bfq_quantum_show, bfqd->bfq_quantum, 0); ++SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 1); ++SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 1); ++SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0); ++SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0); ++SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 1); ++SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0); ++SHOW_FUNCTION(bfq_max_budget_async_rq_show, ++ bfqd->bfq_max_budget_async_rq, 0); ++SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout[BLK_RW_SYNC], 1); ++SHOW_FUNCTION(bfq_timeout_async_show, bfqd->bfq_timeout[BLK_RW_ASYNC], 1); ++SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0); ++SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0); ++SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1); ++SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1); ++SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async, ++ 1); ++SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0); ++#undef SHOW_FUNCTION ++ ++#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \ ++static ssize_t \ ++__FUNC(struct elevator_queue *e, const char *page, size_t count) \ ++{ \ ++ struct bfq_data *bfqd = e->elevator_data; \ ++ unsigned long uninitialized_var(__data); \ ++ int ret = bfq_var_store(&__data, (page), count); \ ++ if (__data < (MIN)) \ ++ __data = (MIN); \ ++ else if (__data > (MAX)) \ ++ __data = (MAX); \ ++ if (__CONV) \ ++ *(__PTR) = msecs_to_jiffies(__data); \ ++ else \ ++ *(__PTR) = __data; \ ++ return ret; \ ++} ++STORE_FUNCTION(bfq_quantum_store, &bfqd->bfq_quantum, 1, INT_MAX, 0); ++STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0); ++STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1, ++ INT_MAX, 0); ++STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_max_budget_async_rq_store, &bfqd->bfq_max_budget_async_rq, ++ 1, INT_MAX, 0); ++STORE_FUNCTION(bfq_timeout_async_store, &bfqd->bfq_timeout[BLK_RW_ASYNC], 0, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0); ++STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX, ++ 1); ++STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0, ++ INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_min_inter_arr_async_store, ++ &bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1); ++STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0, ++ INT_MAX, 0); ++#undef STORE_FUNCTION ++ ++/* do nothing for the moment */ ++static ssize_t bfq_weights_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ return count; ++} ++ ++static inline unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd) ++{ ++ u64 timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]); ++ ++ if (bfqd->peak_rate_samples >= BFQ_PEAK_RATE_SAMPLES) ++ return bfq_calc_max_budget(bfqd->peak_rate, timeout); ++ else ++ return bfq_default_max_budget; ++} ++ ++static ssize_t bfq_max_budget_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data == 0) ++ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd); ++ else { ++ if (__data > INT_MAX) ++ __data = INT_MAX; ++ bfqd->bfq_max_budget = __data; ++ } ++ ++ bfqd->bfq_user_max_budget = __data; ++ ++ return ret; ++} ++ ++static ssize_t bfq_timeout_sync_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data < 1) ++ __data = 1; ++ else if (__data > INT_MAX) ++ __data = INT_MAX; ++ ++ bfqd->bfq_timeout[BLK_RW_SYNC] = msecs_to_jiffies(__data); ++ if (bfqd->bfq_user_max_budget == 0) ++ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd); ++ ++ return ret; ++} ++ ++static ssize_t bfq_low_latency_store(struct elevator_queue *e, ++ const char *page, size_t count) ++{ ++ struct bfq_data *bfqd = e->elevator_data; ++ unsigned long uninitialized_var(__data); ++ int ret = bfq_var_store(&__data, (page), count); ++ ++ if (__data > 1) ++ __data = 1; ++ if (__data == 0 && bfqd->low_latency != 0) ++ bfq_end_wr(bfqd); ++ bfqd->low_latency = __data; ++ ++ return ret; ++} ++ ++#define BFQ_ATTR(name) \ ++ __ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store) ++ ++static struct elv_fs_entry bfq_attrs[] = { ++ BFQ_ATTR(quantum), ++ BFQ_ATTR(fifo_expire_sync), ++ BFQ_ATTR(fifo_expire_async), ++ BFQ_ATTR(back_seek_max), ++ BFQ_ATTR(back_seek_penalty), ++ BFQ_ATTR(slice_idle), ++ BFQ_ATTR(max_budget), ++ BFQ_ATTR(max_budget_async_rq), ++ BFQ_ATTR(timeout_sync), ++ BFQ_ATTR(timeout_async), ++ BFQ_ATTR(low_latency), ++ BFQ_ATTR(wr_coeff), ++ BFQ_ATTR(wr_max_time), ++ BFQ_ATTR(wr_rt_max_time), ++ BFQ_ATTR(wr_min_idle_time), ++ BFQ_ATTR(wr_min_inter_arr_async), ++ BFQ_ATTR(wr_max_softrt_rate), ++ BFQ_ATTR(weights), ++ __ATTR_NULL ++}; ++ ++static struct elevator_type iosched_bfq = { ++ .ops = { ++ .elevator_merge_fn = bfq_merge, ++ .elevator_merged_fn = bfq_merged_request, ++ .elevator_merge_req_fn = bfq_merged_requests, ++ .elevator_allow_merge_fn = bfq_allow_merge, ++ .elevator_dispatch_fn = bfq_dispatch_requests, ++ .elevator_add_req_fn = bfq_insert_request, ++ .elevator_activate_req_fn = bfq_activate_request, ++ .elevator_deactivate_req_fn = bfq_deactivate_request, ++ .elevator_completed_req_fn = bfq_completed_request, ++ .elevator_former_req_fn = elv_rb_former_request, ++ .elevator_latter_req_fn = elv_rb_latter_request, ++ .elevator_init_icq_fn = bfq_init_icq, ++ .elevator_exit_icq_fn = bfq_exit_icq, ++ .elevator_set_req_fn = bfq_set_request, ++ .elevator_put_req_fn = bfq_put_request, ++ .elevator_may_queue_fn = bfq_may_queue, ++ .elevator_init_fn = bfq_init_queue, ++ .elevator_exit_fn = bfq_exit_queue, ++ }, ++ .icq_size = sizeof(struct bfq_io_cq), ++ .icq_align = __alignof__(struct bfq_io_cq), ++ .elevator_attrs = bfq_attrs, ++ .elevator_name = "bfq", ++ .elevator_owner = THIS_MODULE, ++}; ++ ++static int __init bfq_init(void) ++{ ++ /* ++ * Can be 0 on HZ < 1000 setups. ++ */ ++ if (bfq_slice_idle == 0) ++ bfq_slice_idle = 1; ++ ++ if (bfq_timeout_async == 0) ++ bfq_timeout_async = 1; ++ ++ if (bfq_slab_setup()) ++ return -ENOMEM; ++ ++ /* ++ * Times to load large popular applications for the typical systems ++ * installed on the reference devices (see the comments before the ++ * definitions of the two arrays). ++ */ ++ T_slow[0] = msecs_to_jiffies(2600); ++ T_slow[1] = msecs_to_jiffies(1000); ++ T_fast[0] = msecs_to_jiffies(5500); ++ T_fast[1] = msecs_to_jiffies(2000); ++ ++ /* ++ * Thresholds that determine the switch between speed classes (see ++ * the comments before the definition of the array). ++ */ ++ device_speed_thresh[0] = (R_fast[0] + R_slow[0]) / 2; ++ device_speed_thresh[1] = (R_fast[1] + R_slow[1]) / 2; ++ ++ elv_register(&iosched_bfq); ++ pr_info("BFQ I/O-scheduler version: v7r7"); ++ ++ return 0; ++} ++ ++static void __exit bfq_exit(void) ++{ ++ elv_unregister(&iosched_bfq); ++ bfq_slab_kill(); ++} ++ ++module_init(bfq_init); ++module_exit(bfq_exit); ++ ++MODULE_AUTHOR("Fabio Checconi, Paolo Valente"); ++MODULE_LICENSE("GPL"); +diff --git a/block/bfq-sched.c b/block/bfq-sched.c +new file mode 100644 +index 0000000..2931563 +--- /dev/null ++++ b/block/bfq-sched.c +@@ -0,0 +1,1214 @@ ++/* ++ * BFQ: Hierarchical B-WF2Q+ scheduler. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ */ ++ ++#ifdef CONFIG_CGROUP_BFQIO ++#define for_each_entity(entity) \ ++ for (; entity != NULL; entity = entity->parent) ++ ++#define for_each_entity_safe(entity, parent) \ ++ for (; entity && ({ parent = entity->parent; 1; }); entity = parent) ++ ++static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, ++ int extract, ++ struct bfq_data *bfqd); ++ ++static inline void bfq_update_budget(struct bfq_entity *next_in_service) ++{ ++ struct bfq_entity *bfqg_entity; ++ struct bfq_group *bfqg; ++ struct bfq_sched_data *group_sd; ++ ++ BUG_ON(next_in_service == NULL); ++ ++ group_sd = next_in_service->sched_data; ++ ++ bfqg = container_of(group_sd, struct bfq_group, sched_data); ++ /* ++ * bfq_group's my_entity field is not NULL only if the group ++ * is not the root group. We must not touch the root entity ++ * as it must never become an in-service entity. ++ */ ++ bfqg_entity = bfqg->my_entity; ++ if (bfqg_entity != NULL) ++ bfqg_entity->budget = next_in_service->budget; ++} ++ ++static int bfq_update_next_in_service(struct bfq_sched_data *sd) ++{ ++ struct bfq_entity *next_in_service; ++ ++ if (sd->in_service_entity != NULL) ++ /* will update/requeue at the end of service */ ++ return 0; ++ ++ /* ++ * NOTE: this can be improved in many ways, such as returning ++ * 1 (and thus propagating upwards the update) only when the ++ * budget changes, or caching the bfqq that will be scheduled ++ * next from this subtree. By now we worry more about ++ * correctness than about performance... ++ */ ++ next_in_service = bfq_lookup_next_entity(sd, 0, NULL); ++ sd->next_in_service = next_in_service; ++ ++ if (next_in_service != NULL) ++ bfq_update_budget(next_in_service); ++ ++ return 1; ++} ++ ++static inline void bfq_check_next_in_service(struct bfq_sched_data *sd, ++ struct bfq_entity *entity) ++{ ++ BUG_ON(sd->next_in_service != entity); ++} ++#else ++#define for_each_entity(entity) \ ++ for (; entity != NULL; entity = NULL) ++ ++#define for_each_entity_safe(entity, parent) \ ++ for (parent = NULL; entity != NULL; entity = parent) ++ ++static inline int bfq_update_next_in_service(struct bfq_sched_data *sd) ++{ ++ return 0; ++} ++ ++static inline void bfq_check_next_in_service(struct bfq_sched_data *sd, ++ struct bfq_entity *entity) ++{ ++} ++ ++static inline void bfq_update_budget(struct bfq_entity *next_in_service) ++{ ++} ++#endif ++ ++/* ++ * Shift for timestamp calculations. This actually limits the maximum ++ * service allowed in one timestamp delta (small shift values increase it), ++ * the maximum total weight that can be used for the queues in the system ++ * (big shift values increase it), and the period of virtual time ++ * wraparounds. ++ */ ++#define WFQ_SERVICE_SHIFT 22 ++ ++/** ++ * bfq_gt - compare two timestamps. ++ * @a: first ts. ++ * @b: second ts. ++ * ++ * Return @a > @b, dealing with wrapping correctly. ++ */ ++static inline int bfq_gt(u64 a, u64 b) ++{ ++ return (s64)(a - b) > 0; ++} ++ ++static inline struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = NULL; ++ ++ BUG_ON(entity == NULL); ++ ++ if (entity->my_sched_data == NULL) ++ bfqq = container_of(entity, struct bfq_queue, entity); ++ ++ return bfqq; ++} ++ ++ ++/** ++ * bfq_delta - map service into the virtual time domain. ++ * @service: amount of service. ++ * @weight: scale factor (weight of an entity or weight sum). ++ */ ++static inline u64 bfq_delta(unsigned long service, ++ unsigned long weight) ++{ ++ u64 d = (u64)service << WFQ_SERVICE_SHIFT; ++ ++ do_div(d, weight); ++ return d; ++} ++ ++/** ++ * bfq_calc_finish - assign the finish time to an entity. ++ * @entity: the entity to act upon. ++ * @service: the service to be charged to the entity. ++ */ ++static inline void bfq_calc_finish(struct bfq_entity *entity, ++ unsigned long service) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ BUG_ON(entity->weight == 0); ++ ++ entity->finish = entity->start + ++ bfq_delta(service, entity->weight); ++ ++ if (bfqq != NULL) { ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "calc_finish: serv %lu, w %d", ++ service, entity->weight); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, ++ "calc_finish: start %llu, finish %llu, delta %llu", ++ entity->start, entity->finish, ++ bfq_delta(service, entity->weight)); ++ } ++} ++ ++/** ++ * bfq_entity_of - get an entity from a node. ++ * @node: the node field of the entity. ++ * ++ * Convert a node pointer to the relative entity. This is used only ++ * to simplify the logic of some functions and not as the generic ++ * conversion mechanism because, e.g., in the tree walking functions, ++ * the check for a %NULL value would be redundant. ++ */ ++static inline struct bfq_entity *bfq_entity_of(struct rb_node *node) ++{ ++ struct bfq_entity *entity = NULL; ++ ++ if (node != NULL) ++ entity = rb_entry(node, struct bfq_entity, rb_node); ++ ++ return entity; ++} ++ ++/** ++ * bfq_extract - remove an entity from a tree. ++ * @root: the tree root. ++ * @entity: the entity to remove. ++ */ ++static inline void bfq_extract(struct rb_root *root, ++ struct bfq_entity *entity) ++{ ++ BUG_ON(entity->tree != root); ++ ++ entity->tree = NULL; ++ rb_erase(&entity->rb_node, root); ++} ++ ++/** ++ * bfq_idle_extract - extract an entity from the idle tree. ++ * @st: the service tree of the owning @entity. ++ * @entity: the entity being removed. ++ */ ++static void bfq_idle_extract(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct rb_node *next; ++ ++ BUG_ON(entity->tree != &st->idle); ++ ++ if (entity == st->first_idle) { ++ next = rb_next(&entity->rb_node); ++ st->first_idle = bfq_entity_of(next); ++ } ++ ++ if (entity == st->last_idle) { ++ next = rb_prev(&entity->rb_node); ++ st->last_idle = bfq_entity_of(next); ++ } ++ ++ bfq_extract(&st->idle, entity); ++ ++ if (bfqq != NULL) ++ list_del(&bfqq->bfqq_list); ++} ++ ++/** ++ * bfq_insert - generic tree insertion. ++ * @root: tree root. ++ * @entity: entity to insert. ++ * ++ * This is used for the idle and the active tree, since they are both ++ * ordered by finish time. ++ */ ++static void bfq_insert(struct rb_root *root, struct bfq_entity *entity) ++{ ++ struct bfq_entity *entry; ++ struct rb_node **node = &root->rb_node; ++ struct rb_node *parent = NULL; ++ ++ BUG_ON(entity->tree != NULL); ++ ++ while (*node != NULL) { ++ parent = *node; ++ entry = rb_entry(parent, struct bfq_entity, rb_node); ++ ++ if (bfq_gt(entry->finish, entity->finish)) ++ node = &parent->rb_left; ++ else ++ node = &parent->rb_right; ++ } ++ ++ rb_link_node(&entity->rb_node, parent, node); ++ rb_insert_color(&entity->rb_node, root); ++ ++ entity->tree = root; ++} ++ ++/** ++ * bfq_update_min - update the min_start field of a entity. ++ * @entity: the entity to update. ++ * @node: one of its children. ++ * ++ * This function is called when @entity may store an invalid value for ++ * min_start due to updates to the active tree. The function assumes ++ * that the subtree rooted at @node (which may be its left or its right ++ * child) has a valid min_start value. ++ */ ++static inline void bfq_update_min(struct bfq_entity *entity, ++ struct rb_node *node) ++{ ++ struct bfq_entity *child; ++ ++ if (node != NULL) { ++ child = rb_entry(node, struct bfq_entity, rb_node); ++ if (bfq_gt(entity->min_start, child->min_start)) ++ entity->min_start = child->min_start; ++ } ++} ++ ++/** ++ * bfq_update_active_node - recalculate min_start. ++ * @node: the node to update. ++ * ++ * @node may have changed position or one of its children may have moved, ++ * this function updates its min_start value. The left and right subtrees ++ * are assumed to hold a correct min_start value. ++ */ ++static inline void bfq_update_active_node(struct rb_node *node) ++{ ++ struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node); ++ ++ entity->min_start = entity->start; ++ bfq_update_min(entity, node->rb_right); ++ bfq_update_min(entity, node->rb_left); ++} ++ ++/** ++ * bfq_update_active_tree - update min_start for the whole active tree. ++ * @node: the starting node. ++ * ++ * @node must be the deepest modified node after an update. This function ++ * updates its min_start using the values held by its children, assuming ++ * that they did not change, and then updates all the nodes that may have ++ * changed in the path to the root. The only nodes that may have changed ++ * are the ones in the path or their siblings. ++ */ ++static void bfq_update_active_tree(struct rb_node *node) ++{ ++ struct rb_node *parent; ++ ++up: ++ bfq_update_active_node(node); ++ ++ parent = rb_parent(node); ++ if (parent == NULL) ++ return; ++ ++ if (node == parent->rb_left && parent->rb_right != NULL) ++ bfq_update_active_node(parent->rb_right); ++ else if (parent->rb_left != NULL) ++ bfq_update_active_node(parent->rb_left); ++ ++ node = parent; ++ goto up; ++} ++ ++static void bfq_weights_tree_add(struct bfq_data *bfqd, ++ struct bfq_entity *entity, ++ struct rb_root *root); ++ ++static void bfq_weights_tree_remove(struct bfq_data *bfqd, ++ struct bfq_entity *entity, ++ struct rb_root *root); ++ ++ ++/** ++ * bfq_active_insert - insert an entity in the active tree of its ++ * group/device. ++ * @st: the service tree of the entity. ++ * @entity: the entity being inserted. ++ * ++ * The active tree is ordered by finish time, but an extra key is kept ++ * per each node, containing the minimum value for the start times of ++ * its children (and the node itself), so it's possible to search for ++ * the eligible node with the lowest finish time in logarithmic time. ++ */ ++static void bfq_active_insert(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct rb_node *node = &entity->rb_node; ++#ifdef CONFIG_CGROUP_BFQIO ++ struct bfq_sched_data *sd = NULL; ++ struct bfq_group *bfqg = NULL; ++ struct bfq_data *bfqd = NULL; ++#endif ++ ++ bfq_insert(&st->active, entity); ++ ++ if (node->rb_left != NULL) ++ node = node->rb_left; ++ else if (node->rb_right != NULL) ++ node = node->rb_right; ++ ++ bfq_update_active_tree(node); ++ ++#ifdef CONFIG_CGROUP_BFQIO ++ sd = entity->sched_data; ++ bfqg = container_of(sd, struct bfq_group, sched_data); ++ BUG_ON(!bfqg); ++ bfqd = (struct bfq_data *)bfqg->bfqd; ++#endif ++ if (bfqq != NULL) ++ list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list); ++#ifdef CONFIG_CGROUP_BFQIO ++ else { /* bfq_group */ ++ BUG_ON(!bfqd); ++ bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree); ++ } ++ if (bfqg != bfqd->root_group) { ++ BUG_ON(!bfqg); ++ BUG_ON(!bfqd); ++ bfqg->active_entities++; ++ if (bfqg->active_entities == 2) ++ bfqd->active_numerous_groups++; ++ } ++#endif ++} ++ ++/** ++ * bfq_ioprio_to_weight - calc a weight from an ioprio. ++ * @ioprio: the ioprio value to convert. ++ */ ++static inline unsigned short bfq_ioprio_to_weight(int ioprio) ++{ ++ BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR); ++ return IOPRIO_BE_NR - ioprio; ++} ++ ++/** ++ * bfq_weight_to_ioprio - calc an ioprio from a weight. ++ * @weight: the weight value to convert. ++ * ++ * To preserve as mush as possible the old only-ioprio user interface, ++ * 0 is used as an escape ioprio value for weights (numerically) equal or ++ * larger than IOPRIO_BE_NR ++ */ ++static inline unsigned short bfq_weight_to_ioprio(int weight) ++{ ++ BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT); ++ return IOPRIO_BE_NR - weight < 0 ? 0 : IOPRIO_BE_NR - weight; ++} ++ ++static inline void bfq_get_entity(struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ ++ if (bfqq != NULL) { ++ atomic_inc(&bfqq->ref); ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ } ++} ++ ++/** ++ * bfq_find_deepest - find the deepest node that an extraction can modify. ++ * @node: the node being removed. ++ * ++ * Do the first step of an extraction in an rb tree, looking for the ++ * node that will replace @node, and returning the deepest node that ++ * the following modifications to the tree can touch. If @node is the ++ * last node in the tree return %NULL. ++ */ ++static struct rb_node *bfq_find_deepest(struct rb_node *node) ++{ ++ struct rb_node *deepest; ++ ++ if (node->rb_right == NULL && node->rb_left == NULL) ++ deepest = rb_parent(node); ++ else if (node->rb_right == NULL) ++ deepest = node->rb_left; ++ else if (node->rb_left == NULL) ++ deepest = node->rb_right; ++ else { ++ deepest = rb_next(node); ++ if (deepest->rb_right != NULL) ++ deepest = deepest->rb_right; ++ else if (rb_parent(deepest) != node) ++ deepest = rb_parent(deepest); ++ } ++ ++ return deepest; ++} ++ ++/** ++ * bfq_active_extract - remove an entity from the active tree. ++ * @st: the service_tree containing the tree. ++ * @entity: the entity being removed. ++ */ ++static void bfq_active_extract(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct rb_node *node; ++#ifdef CONFIG_CGROUP_BFQIO ++ struct bfq_sched_data *sd = NULL; ++ struct bfq_group *bfqg = NULL; ++ struct bfq_data *bfqd = NULL; ++#endif ++ ++ node = bfq_find_deepest(&entity->rb_node); ++ bfq_extract(&st->active, entity); ++ ++ if (node != NULL) ++ bfq_update_active_tree(node); ++ ++#ifdef CONFIG_CGROUP_BFQIO ++ sd = entity->sched_data; ++ bfqg = container_of(sd, struct bfq_group, sched_data); ++ BUG_ON(!bfqg); ++ bfqd = (struct bfq_data *)bfqg->bfqd; ++#endif ++ if (bfqq != NULL) ++ list_del(&bfqq->bfqq_list); ++#ifdef CONFIG_CGROUP_BFQIO ++ else { /* bfq_group */ ++ BUG_ON(!bfqd); ++ bfq_weights_tree_remove(bfqd, entity, ++ &bfqd->group_weights_tree); ++ } ++ if (bfqg != bfqd->root_group) { ++ BUG_ON(!bfqg); ++ BUG_ON(!bfqd); ++ BUG_ON(!bfqg->active_entities); ++ bfqg->active_entities--; ++ if (bfqg->active_entities == 1) { ++ BUG_ON(!bfqd->active_numerous_groups); ++ bfqd->active_numerous_groups--; ++ } ++ } ++#endif ++} ++ ++/** ++ * bfq_idle_insert - insert an entity into the idle tree. ++ * @st: the service tree containing the tree. ++ * @entity: the entity to insert. ++ */ ++static void bfq_idle_insert(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct bfq_entity *first_idle = st->first_idle; ++ struct bfq_entity *last_idle = st->last_idle; ++ ++ if (first_idle == NULL || bfq_gt(first_idle->finish, entity->finish)) ++ st->first_idle = entity; ++ if (last_idle == NULL || bfq_gt(entity->finish, last_idle->finish)) ++ st->last_idle = entity; ++ ++ bfq_insert(&st->idle, entity); ++ ++ if (bfqq != NULL) ++ list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list); ++} ++ ++/** ++ * bfq_forget_entity - remove an entity from the wfq trees. ++ * @st: the service tree. ++ * @entity: the entity being removed. ++ * ++ * Update the device status and forget everything about @entity, putting ++ * the device reference to it, if it is a queue. Entities belonging to ++ * groups are not refcounted. ++ */ ++static void bfq_forget_entity(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ struct bfq_sched_data *sd; ++ ++ BUG_ON(!entity->on_st); ++ ++ entity->on_st = 0; ++ st->wsum -= entity->weight; ++ if (bfqq != NULL) { ++ sd = entity->sched_data; ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity: %p %d", ++ bfqq, atomic_read(&bfqq->ref)); ++ bfq_put_queue(bfqq); ++ } ++} ++ ++/** ++ * bfq_put_idle_entity - release the idle tree ref of an entity. ++ * @st: service tree for the entity. ++ * @entity: the entity being released. ++ */ ++static void bfq_put_idle_entity(struct bfq_service_tree *st, ++ struct bfq_entity *entity) ++{ ++ bfq_idle_extract(st, entity); ++ bfq_forget_entity(st, entity); ++} ++ ++/** ++ * bfq_forget_idle - update the idle tree if necessary. ++ * @st: the service tree to act upon. ++ * ++ * To preserve the global O(log N) complexity we only remove one entry here; ++ * as the idle tree will not grow indefinitely this can be done safely. ++ */ ++static void bfq_forget_idle(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *first_idle = st->first_idle; ++ struct bfq_entity *last_idle = st->last_idle; ++ ++ if (RB_EMPTY_ROOT(&st->active) && last_idle != NULL && ++ !bfq_gt(last_idle->finish, st->vtime)) { ++ /* ++ * Forget the whole idle tree, increasing the vtime past ++ * the last finish time of idle entities. ++ */ ++ st->vtime = last_idle->finish; ++ } ++ ++ if (first_idle != NULL && !bfq_gt(first_idle->finish, st->vtime)) ++ bfq_put_idle_entity(st, first_idle); ++} ++ ++static struct bfq_service_tree * ++__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, ++ struct bfq_entity *entity) ++{ ++ struct bfq_service_tree *new_st = old_st; ++ ++ if (entity->ioprio_changed) { ++ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); ++ unsigned short prev_weight, new_weight; ++ struct bfq_data *bfqd = NULL; ++ struct rb_root *root; ++#ifdef CONFIG_CGROUP_BFQIO ++ struct bfq_sched_data *sd; ++ struct bfq_group *bfqg; ++#endif ++ ++ if (bfqq != NULL) ++ bfqd = bfqq->bfqd; ++#ifdef CONFIG_CGROUP_BFQIO ++ else { ++ sd = entity->my_sched_data; ++ bfqg = container_of(sd, struct bfq_group, sched_data); ++ BUG_ON(!bfqg); ++ bfqd = (struct bfq_data *)bfqg->bfqd; ++ BUG_ON(!bfqd); ++ } ++#endif ++ ++ BUG_ON(old_st->wsum < entity->weight); ++ old_st->wsum -= entity->weight; ++ ++ if (entity->new_weight != entity->orig_weight) { ++ if (entity->new_weight < BFQ_MIN_WEIGHT || ++ entity->new_weight > BFQ_MAX_WEIGHT) { ++ printk(KERN_CRIT "update_weight_prio: " ++ "new_weight %d\n", ++ entity->new_weight); ++ BUG(); ++ } ++ entity->orig_weight = entity->new_weight; ++ entity->ioprio = ++ bfq_weight_to_ioprio(entity->orig_weight); ++ } else if (entity->new_ioprio != entity->ioprio) { ++ entity->ioprio = entity->new_ioprio; ++ entity->orig_weight = ++ bfq_ioprio_to_weight(entity->ioprio); ++ } else ++ entity->new_weight = entity->orig_weight = ++ bfq_ioprio_to_weight(entity->ioprio); ++ ++ entity->ioprio_class = entity->new_ioprio_class; ++ entity->ioprio_changed = 0; ++ ++ /* ++ * NOTE: here we may be changing the weight too early, ++ * this will cause unfairness. The correct approach ++ * would have required additional complexity to defer ++ * weight changes to the proper time instants (i.e., ++ * when entity->finish <= old_st->vtime). ++ */ ++ new_st = bfq_entity_service_tree(entity); ++ ++ prev_weight = entity->weight; ++ new_weight = entity->orig_weight * ++ (bfqq != NULL ? bfqq->wr_coeff : 1); ++ /* ++ * If the weight of the entity changes, remove the entity ++ * from its old weight counter (if there is a counter ++ * associated with the entity), and add it to the counter ++ * associated with its new weight. ++ */ ++ if (prev_weight != new_weight) { ++ root = bfqq ? &bfqd->queue_weights_tree : ++ &bfqd->group_weights_tree; ++ bfq_weights_tree_remove(bfqd, entity, root); ++ } ++ entity->weight = new_weight; ++ /* ++ * Add the entity to its weights tree only if it is ++ * not associated with a weight-raised queue. ++ */ ++ if (prev_weight != new_weight && ++ (bfqq ? bfqq->wr_coeff == 1 : 1)) ++ /* If we get here, root has been initialized. */ ++ bfq_weights_tree_add(bfqd, entity, root); ++ ++ new_st->wsum += entity->weight; ++ ++ if (new_st != old_st) ++ entity->start = new_st->vtime; ++ } ++ ++ return new_st; ++} ++ ++/** ++ * bfq_bfqq_served - update the scheduler status after selection for ++ * service. ++ * @bfqq: the queue being served. ++ * @served: bytes to transfer. ++ * ++ * NOTE: this can be optimized, as the timestamps of upper level entities ++ * are synchronized every time a new bfqq is selected for service. By now, ++ * we keep it to better check consistency. ++ */ ++static void bfq_bfqq_served(struct bfq_queue *bfqq, unsigned long served) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ struct bfq_service_tree *st; ++ ++ for_each_entity(entity) { ++ st = bfq_entity_service_tree(entity); ++ ++ entity->service += served; ++ BUG_ON(entity->service > entity->budget); ++ BUG_ON(st->wsum == 0); ++ ++ st->vtime += bfq_delta(served, st->wsum); ++ bfq_forget_idle(st); ++ } ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %lu secs", served); ++} ++ ++/** ++ * bfq_bfqq_charge_full_budget - set the service to the entity budget. ++ * @bfqq: the queue that needs a service update. ++ * ++ * When it's not possible to be fair in the service domain, because ++ * a queue is not consuming its budget fast enough (the meaning of ++ * fast depends on the timeout parameter), we charge it a full ++ * budget. In this way we should obtain a sort of time-domain ++ * fairness among all the seeky/slow queues. ++ */ ++static inline void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "charge_full_budget"); ++ ++ bfq_bfqq_served(bfqq, entity->budget - entity->service); ++} ++ ++/** ++ * __bfq_activate_entity - activate an entity. ++ * @entity: the entity being activated. ++ * ++ * Called whenever an entity is activated, i.e., it is not active and one ++ * of its children receives a new request, or has to be reactivated due to ++ * budget exhaustion. It uses the current budget of the entity (and the ++ * service received if @entity is active) of the queue to calculate its ++ * timestamps. ++ */ ++static void __bfq_activate_entity(struct bfq_entity *entity) ++{ ++ struct bfq_sched_data *sd = entity->sched_data; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ ++ if (entity == sd->in_service_entity) { ++ BUG_ON(entity->tree != NULL); ++ /* ++ * If we are requeueing the current entity we have ++ * to take care of not charging to it service it has ++ * not received. ++ */ ++ bfq_calc_finish(entity, entity->service); ++ entity->start = entity->finish; ++ sd->in_service_entity = NULL; ++ } else if (entity->tree == &st->active) { ++ /* ++ * Requeueing an entity due to a change of some ++ * next_in_service entity below it. We reuse the ++ * old start time. ++ */ ++ bfq_active_extract(st, entity); ++ } else if (entity->tree == &st->idle) { ++ /* ++ * Must be on the idle tree, bfq_idle_extract() will ++ * check for that. ++ */ ++ bfq_idle_extract(st, entity); ++ entity->start = bfq_gt(st->vtime, entity->finish) ? ++ st->vtime : entity->finish; ++ } else { ++ /* ++ * The finish time of the entity may be invalid, and ++ * it is in the past for sure, otherwise the queue ++ * would have been on the idle tree. ++ */ ++ entity->start = st->vtime; ++ st->wsum += entity->weight; ++ bfq_get_entity(entity); ++ ++ BUG_ON(entity->on_st); ++ entity->on_st = 1; ++ } ++ ++ st = __bfq_entity_update_weight_prio(st, entity); ++ bfq_calc_finish(entity, entity->budget); ++ bfq_active_insert(st, entity); ++} ++ ++/** ++ * bfq_activate_entity - activate an entity and its ancestors if necessary. ++ * @entity: the entity to activate. ++ * ++ * Activate @entity and all the entities on the path from it to the root. ++ */ ++static void bfq_activate_entity(struct bfq_entity *entity) ++{ ++ struct bfq_sched_data *sd; ++ ++ for_each_entity(entity) { ++ __bfq_activate_entity(entity); ++ ++ sd = entity->sched_data; ++ if (!bfq_update_next_in_service(sd)) ++ /* ++ * No need to propagate the activation to the ++ * upper entities, as they will be updated when ++ * the in-service entity is rescheduled. ++ */ ++ break; ++ } ++} ++ ++/** ++ * __bfq_deactivate_entity - deactivate an entity from its service tree. ++ * @entity: the entity to deactivate. ++ * @requeue: if false, the entity will not be put into the idle tree. ++ * ++ * Deactivate an entity, independently from its previous state. If the ++ * entity was not on a service tree just return, otherwise if it is on ++ * any scheduler tree, extract it from that tree, and if necessary ++ * and if the caller did not specify @requeue, put it on the idle tree. ++ * ++ * Return %1 if the caller should update the entity hierarchy, i.e., ++ * if the entity was in service or if it was the next_in_service for ++ * its sched_data; return %0 otherwise. ++ */ ++static int __bfq_deactivate_entity(struct bfq_entity *entity, int requeue) ++{ ++ struct bfq_sched_data *sd = entity->sched_data; ++ struct bfq_service_tree *st = bfq_entity_service_tree(entity); ++ int was_in_service = entity == sd->in_service_entity; ++ int ret = 0; ++ ++ if (!entity->on_st) ++ return 0; ++ ++ BUG_ON(was_in_service && entity->tree != NULL); ++ ++ if (was_in_service) { ++ bfq_calc_finish(entity, entity->service); ++ sd->in_service_entity = NULL; ++ } else if (entity->tree == &st->active) ++ bfq_active_extract(st, entity); ++ else if (entity->tree == &st->idle) ++ bfq_idle_extract(st, entity); ++ else if (entity->tree != NULL) ++ BUG(); ++ ++ if (was_in_service || sd->next_in_service == entity) ++ ret = bfq_update_next_in_service(sd); ++ ++ if (!requeue || !bfq_gt(entity->finish, st->vtime)) ++ bfq_forget_entity(st, entity); ++ else ++ bfq_idle_insert(st, entity); ++ ++ BUG_ON(sd->in_service_entity == entity); ++ BUG_ON(sd->next_in_service == entity); ++ ++ return ret; ++} ++ ++/** ++ * bfq_deactivate_entity - deactivate an entity. ++ * @entity: the entity to deactivate. ++ * @requeue: true if the entity can be put on the idle tree ++ */ ++static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue) ++{ ++ struct bfq_sched_data *sd; ++ struct bfq_entity *parent; ++ ++ for_each_entity_safe(entity, parent) { ++ sd = entity->sched_data; ++ ++ if (!__bfq_deactivate_entity(entity, requeue)) ++ /* ++ * The parent entity is still backlogged, and ++ * we don't need to update it as it is still ++ * in service. ++ */ ++ break; ++ ++ if (sd->next_in_service != NULL) ++ /* ++ * The parent entity is still backlogged and ++ * the budgets on the path towards the root ++ * need to be updated. ++ */ ++ goto update; ++ ++ /* ++ * If we reach there the parent is no more backlogged and ++ * we want to propagate the dequeue upwards. ++ */ ++ requeue = 1; ++ } ++ ++ return; ++ ++update: ++ entity = parent; ++ for_each_entity(entity) { ++ __bfq_activate_entity(entity); ++ ++ sd = entity->sched_data; ++ if (!bfq_update_next_in_service(sd)) ++ break; ++ } ++} ++ ++/** ++ * bfq_update_vtime - update vtime if necessary. ++ * @st: the service tree to act upon. ++ * ++ * If necessary update the service tree vtime to have at least one ++ * eligible entity, skipping to its start time. Assumes that the ++ * active tree of the device is not empty. ++ * ++ * NOTE: this hierarchical implementation updates vtimes quite often, ++ * we may end up with reactivated processes getting timestamps after a ++ * vtime skip done because we needed a ->first_active entity on some ++ * intermediate node. ++ */ ++static void bfq_update_vtime(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *entry; ++ struct rb_node *node = st->active.rb_node; ++ ++ entry = rb_entry(node, struct bfq_entity, rb_node); ++ if (bfq_gt(entry->min_start, st->vtime)) { ++ st->vtime = entry->min_start; ++ bfq_forget_idle(st); ++ } ++} ++ ++/** ++ * bfq_first_active_entity - find the eligible entity with ++ * the smallest finish time ++ * @st: the service tree to select from. ++ * ++ * This function searches the first schedulable entity, starting from the ++ * root of the tree and going on the left every time on this side there is ++ * a subtree with at least one eligible (start >= vtime) entity. The path on ++ * the right is followed only if a) the left subtree contains no eligible ++ * entities and b) no eligible entity has been found yet. ++ */ ++static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st) ++{ ++ struct bfq_entity *entry, *first = NULL; ++ struct rb_node *node = st->active.rb_node; ++ ++ while (node != NULL) { ++ entry = rb_entry(node, struct bfq_entity, rb_node); ++left: ++ if (!bfq_gt(entry->start, st->vtime)) ++ first = entry; ++ ++ BUG_ON(bfq_gt(entry->min_start, st->vtime)); ++ ++ if (node->rb_left != NULL) { ++ entry = rb_entry(node->rb_left, ++ struct bfq_entity, rb_node); ++ if (!bfq_gt(entry->min_start, st->vtime)) { ++ node = node->rb_left; ++ goto left; ++ } ++ } ++ if (first != NULL) ++ break; ++ node = node->rb_right; ++ } ++ ++ BUG_ON(first == NULL && !RB_EMPTY_ROOT(&st->active)); ++ return first; ++} ++ ++/** ++ * __bfq_lookup_next_entity - return the first eligible entity in @st. ++ * @st: the service tree. ++ * ++ * Update the virtual time in @st and return the first eligible entity ++ * it contains. ++ */ ++static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st, ++ bool force) ++{ ++ struct bfq_entity *entity, *new_next_in_service = NULL; ++ ++ if (RB_EMPTY_ROOT(&st->active)) ++ return NULL; ++ ++ bfq_update_vtime(st); ++ entity = bfq_first_active_entity(st); ++ BUG_ON(bfq_gt(entity->start, st->vtime)); ++ ++ /* ++ * If the chosen entity does not match with the sched_data's ++ * next_in_service and we are forcedly serving the IDLE priority ++ * class tree, bubble up budget update. ++ */ ++ if (unlikely(force && entity != entity->sched_data->next_in_service)) { ++ new_next_in_service = entity; ++ for_each_entity(new_next_in_service) ++ bfq_update_budget(new_next_in_service); ++ } ++ ++ return entity; ++} ++ ++/** ++ * bfq_lookup_next_entity - return the first eligible entity in @sd. ++ * @sd: the sched_data. ++ * @extract: if true the returned entity will be also extracted from @sd. ++ * ++ * NOTE: since we cache the next_in_service entity at each level of the ++ * hierarchy, the complexity of the lookup can be decreased with ++ * absolutely no effort just returning the cached next_in_service value; ++ * we prefer to do full lookups to test the consistency of * the data ++ * structures. ++ */ ++static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, ++ int extract, ++ struct bfq_data *bfqd) ++{ ++ struct bfq_service_tree *st = sd->service_tree; ++ struct bfq_entity *entity; ++ int i = 0; ++ ++ BUG_ON(sd->in_service_entity != NULL); ++ ++ if (bfqd != NULL && ++ jiffies - bfqd->bfq_class_idle_last_service > BFQ_CL_IDLE_TIMEOUT) { ++ entity = __bfq_lookup_next_entity(st + BFQ_IOPRIO_CLASSES - 1, ++ true); ++ if (entity != NULL) { ++ i = BFQ_IOPRIO_CLASSES - 1; ++ bfqd->bfq_class_idle_last_service = jiffies; ++ sd->next_in_service = entity; ++ } ++ } ++ for (; i < BFQ_IOPRIO_CLASSES; i++) { ++ entity = __bfq_lookup_next_entity(st + i, false); ++ if (entity != NULL) { ++ if (extract) { ++ bfq_check_next_in_service(sd, entity); ++ bfq_active_extract(st + i, entity); ++ sd->in_service_entity = entity; ++ sd->next_in_service = NULL; ++ } ++ break; ++ } ++ } ++ ++ return entity; ++} ++ ++/* ++ * Get next queue for service. ++ */ ++static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_entity *entity = NULL; ++ struct bfq_sched_data *sd; ++ struct bfq_queue *bfqq; ++ ++ BUG_ON(bfqd->in_service_queue != NULL); ++ ++ if (bfqd->busy_queues == 0) ++ return NULL; ++ ++ sd = &bfqd->root_group->sched_data; ++ for (; sd != NULL; sd = entity->my_sched_data) { ++ entity = bfq_lookup_next_entity(sd, 1, bfqd); ++ BUG_ON(entity == NULL); ++ entity->service = 0; ++ } ++ ++ bfqq = bfq_entity_to_bfqq(entity); ++ BUG_ON(bfqq == NULL); ++ ++ return bfqq; ++} ++ ++/* ++ * Forced extraction of the given queue. ++ */ ++static void bfq_get_next_queue_forced(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity; ++ struct bfq_sched_data *sd; ++ ++ BUG_ON(bfqd->in_service_queue != NULL); ++ ++ entity = &bfqq->entity; ++ /* ++ * Bubble up extraction/update from the leaf to the root. ++ */ ++ for_each_entity(entity) { ++ sd = entity->sched_data; ++ bfq_update_budget(entity); ++ bfq_update_vtime(bfq_entity_service_tree(entity)); ++ bfq_active_extract(bfq_entity_service_tree(entity), entity); ++ sd->in_service_entity = entity; ++ sd->next_in_service = NULL; ++ entity->service = 0; ++ } ++ ++ return; ++} ++ ++static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd) ++{ ++ if (bfqd->in_service_bic != NULL) { ++ put_io_context(bfqd->in_service_bic->icq.ioc); ++ bfqd->in_service_bic = NULL; ++ } ++ ++ bfqd->in_service_queue = NULL; ++ del_timer(&bfqd->idle_slice_timer); ++} ++ ++static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ int requeue) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ if (bfqq == bfqd->in_service_queue) ++ __bfq_bfqd_reset_in_service(bfqd); ++ ++ bfq_deactivate_entity(entity, requeue); ++} ++ ++static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ struct bfq_entity *entity = &bfqq->entity; ++ ++ bfq_activate_entity(entity); ++} ++ ++/* ++ * Called when the bfqq no longer has requests pending, remove it from ++ * the service tree. ++ */ ++static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ int requeue) ++{ ++ BUG_ON(!bfq_bfqq_busy(bfqq)); ++ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list)); ++ ++ bfq_log_bfqq(bfqd, bfqq, "del from busy"); ++ ++ bfq_clear_bfqq_busy(bfqq); ++ ++ BUG_ON(bfqd->busy_queues == 0); ++ bfqd->busy_queues--; ++ ++ if (!bfqq->dispatched) { ++ bfq_weights_tree_remove(bfqd, &bfqq->entity, ++ &bfqd->queue_weights_tree); ++ if (!blk_queue_nonrot(bfqd->queue)) { ++ BUG_ON(!bfqd->busy_in_flight_queues); ++ bfqd->busy_in_flight_queues--; ++ if (bfq_bfqq_constantly_seeky(bfqq)) { ++ BUG_ON(!bfqd-> ++ const_seeky_busy_in_flight_queues); ++ bfqd->const_seeky_busy_in_flight_queues--; ++ } ++ } ++ } ++ if (bfqq->wr_coeff > 1) ++ bfqd->wr_busy_queues--; ++ ++ bfq_deactivate_bfqq(bfqd, bfqq, requeue); ++} ++ ++/* ++ * Called when an inactive queue receives a new request. ++ */ ++static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq) ++{ ++ BUG_ON(bfq_bfqq_busy(bfqq)); ++ BUG_ON(bfqq == bfqd->in_service_queue); ++ ++ bfq_log_bfqq(bfqd, bfqq, "add to busy"); ++ ++ bfq_activate_bfqq(bfqd, bfqq); ++ ++ bfq_mark_bfqq_busy(bfqq); ++ bfqd->busy_queues++; ++ ++ if (!bfqq->dispatched) { ++ if (bfqq->wr_coeff == 1) ++ bfq_weights_tree_add(bfqd, &bfqq->entity, ++ &bfqd->queue_weights_tree); ++ if (!blk_queue_nonrot(bfqd->queue)) { ++ bfqd->busy_in_flight_queues++; ++ if (bfq_bfqq_constantly_seeky(bfqq)) ++ bfqd->const_seeky_busy_in_flight_queues++; ++ } ++ } ++ if (bfqq->wr_coeff > 1) ++ bfqd->wr_busy_queues++; ++} +diff --git a/block/bfq.h b/block/bfq.h +new file mode 100644 +index 0000000..518f2ac +--- /dev/null ++++ b/block/bfq.h +@@ -0,0 +1,775 @@ ++/* ++ * BFQ-v7r7 for 4.0.0: data structures and common functions prototypes. ++ * ++ * Based on ideas and code from CFQ: ++ * Copyright (C) 2003 Jens Axboe ++ * ++ * Copyright (C) 2008 Fabio Checconi ++ * Paolo Valente ++ * ++ * Copyright (C) 2010 Paolo Valente ++ */ ++ ++#ifndef _BFQ_H ++#define _BFQ_H ++ ++#include ++#include ++#include ++#include ++ ++#define BFQ_IOPRIO_CLASSES 3 ++#define BFQ_CL_IDLE_TIMEOUT (HZ/5) ++ ++#define BFQ_MIN_WEIGHT 1 ++#define BFQ_MAX_WEIGHT 1000 ++ ++#define BFQ_DEFAULT_QUEUE_IOPRIO 4 ++ ++#define BFQ_DEFAULT_GRP_WEIGHT 10 ++#define BFQ_DEFAULT_GRP_IOPRIO 0 ++#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE ++ ++struct bfq_entity; ++ ++/** ++ * struct bfq_service_tree - per ioprio_class service tree. ++ * @active: tree for active entities (i.e., those backlogged). ++ * @idle: tree for idle entities (i.e., those not backlogged, with V <= F_i). ++ * @first_idle: idle entity with minimum F_i. ++ * @last_idle: idle entity with maximum F_i. ++ * @vtime: scheduler virtual time. ++ * @wsum: scheduler weight sum; active and idle entities contribute to it. ++ * ++ * Each service tree represents a B-WF2Q+ scheduler on its own. Each ++ * ioprio_class has its own independent scheduler, and so its own ++ * bfq_service_tree. All the fields are protected by the queue lock ++ * of the containing bfqd. ++ */ ++struct bfq_service_tree { ++ struct rb_root active; ++ struct rb_root idle; ++ ++ struct bfq_entity *first_idle; ++ struct bfq_entity *last_idle; ++ ++ u64 vtime; ++ unsigned long wsum; ++}; ++ ++/** ++ * struct bfq_sched_data - multi-class scheduler. ++ * @in_service_entity: entity in service. ++ * @next_in_service: head-of-the-line entity in the scheduler. ++ * @service_tree: array of service trees, one per ioprio_class. ++ * ++ * bfq_sched_data is the basic scheduler queue. It supports three ++ * ioprio_classes, and can be used either as a toplevel queue or as ++ * an intermediate queue on a hierarchical setup. ++ * @next_in_service points to the active entity of the sched_data ++ * service trees that will be scheduled next. ++ * ++ * The supported ioprio_classes are the same as in CFQ, in descending ++ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE. ++ * Requests from higher priority queues are served before all the ++ * requests from lower priority queues; among requests of the same ++ * queue requests are served according to B-WF2Q+. ++ * All the fields are protected by the queue lock of the containing bfqd. ++ */ ++struct bfq_sched_data { ++ struct bfq_entity *in_service_entity; ++ struct bfq_entity *next_in_service; ++ struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; ++}; ++ ++/** ++ * struct bfq_weight_counter - counter of the number of all active entities ++ * with a given weight. ++ * @weight: weight of the entities that this counter refers to. ++ * @num_active: number of active entities with this weight. ++ * @weights_node: weights tree member (see bfq_data's @queue_weights_tree ++ * and @group_weights_tree). ++ */ ++struct bfq_weight_counter { ++ short int weight; ++ unsigned int num_active; ++ struct rb_node weights_node; ++}; ++ ++/** ++ * struct bfq_entity - schedulable entity. ++ * @rb_node: service_tree member. ++ * @weight_counter: pointer to the weight counter associated with this entity. ++ * @on_st: flag, true if the entity is on a tree (either the active or ++ * the idle one of its service_tree). ++ * @finish: B-WF2Q+ finish timestamp (aka F_i). ++ * @start: B-WF2Q+ start timestamp (aka S_i). ++ * @tree: tree the entity is enqueued into; %NULL if not on a tree. ++ * @min_start: minimum start time of the (active) subtree rooted at ++ * this entity; used for O(log N) lookups into active trees. ++ * @service: service received during the last round of service. ++ * @budget: budget used to calculate F_i; F_i = S_i + @budget / @weight. ++ * @weight: weight of the queue ++ * @parent: parent entity, for hierarchical scheduling. ++ * @my_sched_data: for non-leaf nodes in the cgroup hierarchy, the ++ * associated scheduler queue, %NULL on leaf nodes. ++ * @sched_data: the scheduler queue this entity belongs to. ++ * @ioprio: the ioprio in use. ++ * @new_weight: when a weight change is requested, the new weight value. ++ * @orig_weight: original weight, used to implement weight boosting ++ * @new_ioprio: when an ioprio change is requested, the new ioprio value. ++ * @ioprio_class: the ioprio_class in use. ++ * @new_ioprio_class: when an ioprio_class change is requested, the new ++ * ioprio_class value. ++ * @ioprio_changed: flag, true when the user requested a weight, ioprio or ++ * ioprio_class change. ++ * ++ * A bfq_entity is used to represent either a bfq_queue (leaf node in the ++ * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each ++ * entity belongs to the sched_data of the parent group in the cgroup ++ * hierarchy. Non-leaf entities have also their own sched_data, stored ++ * in @my_sched_data. ++ * ++ * Each entity stores independently its priority values; this would ++ * allow different weights on different devices, but this ++ * functionality is not exported to userspace by now. Priorities and ++ * weights are updated lazily, first storing the new values into the ++ * new_* fields, then setting the @ioprio_changed flag. As soon as ++ * there is a transition in the entity state that allows the priority ++ * update to take place the effective and the requested priority ++ * values are synchronized. ++ * ++ * Unless cgroups are used, the weight value is calculated from the ++ * ioprio to export the same interface as CFQ. When dealing with ++ * ``well-behaved'' queues (i.e., queues that do not spend too much ++ * time to consume their budget and have true sequential behavior, and ++ * when there are no external factors breaking anticipation) the ++ * relative weights at each level of the cgroups hierarchy should be ++ * guaranteed. All the fields are protected by the queue lock of the ++ * containing bfqd. ++ */ ++struct bfq_entity { ++ struct rb_node rb_node; ++ struct bfq_weight_counter *weight_counter; ++ ++ int on_st; ++ ++ u64 finish; ++ u64 start; ++ ++ struct rb_root *tree; ++ ++ u64 min_start; ++ ++ unsigned long service, budget; ++ unsigned short weight, new_weight; ++ unsigned short orig_weight; ++ ++ struct bfq_entity *parent; ++ ++ struct bfq_sched_data *my_sched_data; ++ struct bfq_sched_data *sched_data; ++ ++ unsigned short ioprio, new_ioprio; ++ unsigned short ioprio_class, new_ioprio_class; ++ ++ int ioprio_changed; ++}; ++ ++struct bfq_group; ++ ++/** ++ * struct bfq_queue - leaf schedulable entity. ++ * @ref: reference counter. ++ * @bfqd: parent bfq_data. ++ * @new_bfqq: shared bfq_queue if queue is cooperating with ++ * one or more other queues. ++ * @pos_node: request-position tree member (see bfq_data's @rq_pos_tree). ++ * @pos_root: request-position tree root (see bfq_data's @rq_pos_tree). ++ * @sort_list: sorted list of pending requests. ++ * @next_rq: if fifo isn't expired, next request to serve. ++ * @queued: nr of requests queued in @sort_list. ++ * @allocated: currently allocated requests. ++ * @meta_pending: pending metadata requests. ++ * @fifo: fifo list of requests in sort_list. ++ * @entity: entity representing this queue in the scheduler. ++ * @max_budget: maximum budget allowed from the feedback mechanism. ++ * @budget_timeout: budget expiration (in jiffies). ++ * @dispatched: number of requests on the dispatch list or inside driver. ++ * @flags: status flags. ++ * @bfqq_list: node for active/idle bfqq list inside our bfqd. ++ * @burst_list_node: node for the device's burst list. ++ * @seek_samples: number of seeks sampled ++ * @seek_total: sum of the distances of the seeks sampled ++ * @seek_mean: mean seek distance ++ * @last_request_pos: position of the last request enqueued ++ * @requests_within_timer: number of consecutive pairs of request completion ++ * and arrival, such that the queue becomes idle ++ * after the completion, but the next request arrives ++ * within an idle time slice; used only if the queue's ++ * IO_bound has been cleared. ++ * @pid: pid of the process owning the queue, used for logging purposes. ++ * @last_wr_start_finish: start time of the current weight-raising period if ++ * the @bfq-queue is being weight-raised, otherwise ++ * finish time of the last weight-raising period ++ * @wr_cur_max_time: current max raising time for this queue ++ * @soft_rt_next_start: minimum time instant such that, only if a new ++ * request is enqueued after this time instant in an ++ * idle @bfq_queue with no outstanding requests, then ++ * the task associated with the queue it is deemed as ++ * soft real-time (see the comments to the function ++ * bfq_bfqq_softrt_next_start()). ++ * @last_idle_bklogged: time of the last transition of the @bfq_queue from ++ * idle to backlogged ++ * @service_from_backlogged: cumulative service received from the @bfq_queue ++ * since the last transition from idle to ++ * backlogged ++ * ++ * A bfq_queue is a leaf request queue; it can be associated with an io_context ++ * or more, if it is async or shared between cooperating processes. @cgroup ++ * holds a reference to the cgroup, to be sure that it does not disappear while ++ * a bfqq still references it (mostly to avoid races between request issuing and ++ * task migration followed by cgroup destruction). ++ * All the fields are protected by the queue lock of the containing bfqd. ++ */ ++struct bfq_queue { ++ atomic_t ref; ++ struct bfq_data *bfqd; ++ ++ /* fields for cooperating queues handling */ ++ struct bfq_queue *new_bfqq; ++ struct rb_node pos_node; ++ struct rb_root *pos_root; ++ ++ struct rb_root sort_list; ++ struct request *next_rq; ++ int queued[2]; ++ int allocated[2]; ++ int meta_pending; ++ struct list_head fifo; ++ ++ struct bfq_entity entity; ++ ++ unsigned long max_budget; ++ unsigned long budget_timeout; ++ ++ int dispatched; ++ ++ unsigned int flags; ++ ++ struct list_head bfqq_list; ++ ++ struct hlist_node burst_list_node; ++ ++ unsigned int seek_samples; ++ u64 seek_total; ++ sector_t seek_mean; ++ sector_t last_request_pos; ++ ++ unsigned int requests_within_timer; ++ ++ pid_t pid; ++ ++ /* weight-raising fields */ ++ unsigned long wr_cur_max_time; ++ unsigned long soft_rt_next_start; ++ unsigned long last_wr_start_finish; ++ unsigned int wr_coeff; ++ unsigned long last_idle_bklogged; ++ unsigned long service_from_backlogged; ++}; ++ ++/** ++ * struct bfq_ttime - per process thinktime stats. ++ * @ttime_total: total process thinktime ++ * @ttime_samples: number of thinktime samples ++ * @ttime_mean: average process thinktime ++ */ ++struct bfq_ttime { ++ unsigned long last_end_request; ++ ++ unsigned long ttime_total; ++ unsigned long ttime_samples; ++ unsigned long ttime_mean; ++}; ++ ++/** ++ * struct bfq_io_cq - per (request_queue, io_context) structure. ++ * @icq: associated io_cq structure ++ * @bfqq: array of two process queues, the sync and the async ++ * @ttime: associated @bfq_ttime struct ++ */ ++struct bfq_io_cq { ++ struct io_cq icq; /* must be the first member */ ++ struct bfq_queue *bfqq[2]; ++ struct bfq_ttime ttime; ++ int ioprio; ++}; ++ ++enum bfq_device_speed { ++ BFQ_BFQD_FAST, ++ BFQ_BFQD_SLOW, ++}; ++ ++/** ++ * struct bfq_data - per device data structure. ++ * @queue: request queue for the managed device. ++ * @root_group: root bfq_group for the device. ++ * @rq_pos_tree: rbtree sorted by next_request position, used when ++ * determining if two or more queues have interleaving ++ * requests (see bfq_close_cooperator()). ++ * @active_numerous_groups: number of bfq_groups containing more than one ++ * active @bfq_entity. ++ * @queue_weights_tree: rbtree of weight counters of @bfq_queues, sorted by ++ * weight. Used to keep track of whether all @bfq_queues ++ * have the same weight. The tree contains one counter ++ * for each distinct weight associated to some active ++ * and not weight-raised @bfq_queue (see the comments to ++ * the functions bfq_weights_tree_[add|remove] for ++ * further details). ++ * @group_weights_tree: rbtree of non-queue @bfq_entity weight counters, sorted ++ * by weight. Used to keep track of whether all ++ * @bfq_groups have the same weight. The tree contains ++ * one counter for each distinct weight associated to ++ * some active @bfq_group (see the comments to the ++ * functions bfq_weights_tree_[add|remove] for further ++ * details). ++ * @busy_queues: number of bfq_queues containing requests (including the ++ * queue in service, even if it is idling). ++ * @busy_in_flight_queues: number of @bfq_queues containing pending or ++ * in-flight requests, plus the @bfq_queue in ++ * service, even if idle but waiting for the ++ * possible arrival of its next sync request. This ++ * field is updated only if the device is rotational, ++ * but used only if the device is also NCQ-capable. ++ * The reason why the field is updated also for non- ++ * NCQ-capable rotational devices is related to the ++ * fact that the value of @hw_tag may be set also ++ * later than when busy_in_flight_queues may need to ++ * be incremented for the first time(s). Taking also ++ * this possibility into account, to avoid unbalanced ++ * increments/decrements, would imply more overhead ++ * than just updating busy_in_flight_queues ++ * regardless of the value of @hw_tag. ++ * @const_seeky_busy_in_flight_queues: number of constantly-seeky @bfq_queues ++ * (that is, seeky queues that expired ++ * for budget timeout at least once) ++ * containing pending or in-flight ++ * requests, including the in-service ++ * @bfq_queue if constantly seeky. This ++ * field is updated only if the device ++ * is rotational, but used only if the ++ * device is also NCQ-capable (see the ++ * comments to @busy_in_flight_queues). ++ * @wr_busy_queues: number of weight-raised busy @bfq_queues. ++ * @queued: number of queued requests. ++ * @rq_in_driver: number of requests dispatched and waiting for completion. ++ * @sync_flight: number of sync requests in the driver. ++ * @max_rq_in_driver: max number of reqs in driver in the last ++ * @hw_tag_samples completed requests. ++ * @hw_tag_samples: nr of samples used to calculate hw_tag. ++ * @hw_tag: flag set to one if the driver is showing a queueing behavior. ++ * @budgets_assigned: number of budgets assigned. ++ * @idle_slice_timer: timer set when idling for the next sequential request ++ * from the queue in service. ++ * @unplug_work: delayed work to restart dispatching on the request queue. ++ * @in_service_queue: bfq_queue in service. ++ * @in_service_bic: bfq_io_cq (bic) associated with the @in_service_queue. ++ * @last_position: on-disk position of the last served request. ++ * @last_budget_start: beginning of the last budget. ++ * @last_idling_start: beginning of the last idle slice. ++ * @peak_rate: peak transfer rate observed for a budget. ++ * @peak_rate_samples: number of samples used to calculate @peak_rate. ++ * @bfq_max_budget: maximum budget allotted to a bfq_queue before ++ * rescheduling. ++ * @group_list: list of all the bfq_groups active on the device. ++ * @active_list: list of all the bfq_queues active on the device. ++ * @idle_list: list of all the bfq_queues idle on the device. ++ * @bfq_quantum: max number of requests dispatched per dispatch round. ++ * @bfq_fifo_expire: timeout for async/sync requests; when it expires ++ * requests are served in fifo order. ++ * @bfq_back_penalty: weight of backward seeks wrt forward ones. ++ * @bfq_back_max: maximum allowed backward seek. ++ * @bfq_slice_idle: maximum idling time. ++ * @bfq_user_max_budget: user-configured max budget value ++ * (0 for auto-tuning). ++ * @bfq_max_budget_async_rq: maximum budget (in nr of requests) allotted to ++ * async queues. ++ * @bfq_timeout: timeout for bfq_queues to consume their budget; used to ++ * to prevent seeky queues to impose long latencies to well ++ * behaved ones (this also implies that seeky queues cannot ++ * receive guarantees in the service domain; after a timeout ++ * they are charged for the whole allocated budget, to try ++ * to preserve a behavior reasonably fair among them, but ++ * without service-domain guarantees). ++ * @bfq_coop_thresh: number of queue merges after which a @bfq_queue is ++ * no more granted any weight-raising. ++ * @bfq_failed_cooperations: number of consecutive failed cooperation ++ * chances after which weight-raising is restored ++ * to a queue subject to more than bfq_coop_thresh ++ * queue merges. ++ * @bfq_requests_within_timer: number of consecutive requests that must be ++ * issued within the idle time slice to set ++ * again idling to a queue which was marked as ++ * non-I/O-bound (see the definition of the ++ * IO_bound flag for further details). ++ * @last_ins_in_burst: last time at which a queue entered the current ++ * burst of queues being activated shortly after ++ * each other; for more details about this and the ++ * following parameters related to a burst of ++ * activations, see the comments to the function ++ * @bfq_handle_burst. ++ * @bfq_burst_interval: reference time interval used to decide whether a ++ * queue has been activated shortly after ++ * @last_ins_in_burst. ++ * @burst_size: number of queues in the current burst of queue activations. ++ * @bfq_large_burst_thresh: maximum burst size above which the current ++ * queue-activation burst is deemed as 'large'. ++ * @large_burst: true if a large queue-activation burst is in progress. ++ * @burst_list: head of the burst list (as for the above fields, more details ++ * in the comments to the function bfq_handle_burst). ++ * @low_latency: if set to true, low-latency heuristics are enabled. ++ * @bfq_wr_coeff: maximum factor by which the weight of a weight-raised ++ * queue is multiplied. ++ * @bfq_wr_max_time: maximum duration of a weight-raising period (jiffies). ++ * @bfq_wr_rt_max_time: maximum duration for soft real-time processes. ++ * @bfq_wr_min_idle_time: minimum idle period after which weight-raising ++ * may be reactivated for a queue (in jiffies). ++ * @bfq_wr_min_inter_arr_async: minimum period between request arrivals ++ * after which weight-raising may be ++ * reactivated for an already busy queue ++ * (in jiffies). ++ * @bfq_wr_max_softrt_rate: max service-rate for a soft real-time queue, ++ * sectors per seconds. ++ * @RT_prod: cached value of the product R*T used for computing the maximum ++ * duration of the weight raising automatically. ++ * @device_speed: device-speed class for the low-latency heuristic. ++ * @oom_bfqq: fallback dummy bfqq for extreme OOM conditions. ++ * ++ * All the fields are protected by the @queue lock. ++ */ ++struct bfq_data { ++ struct request_queue *queue; ++ ++ struct bfq_group *root_group; ++ struct rb_root rq_pos_tree; ++ ++#ifdef CONFIG_CGROUP_BFQIO ++ int active_numerous_groups; ++#endif ++ ++ struct rb_root queue_weights_tree; ++ struct rb_root group_weights_tree; ++ ++ int busy_queues; ++ int busy_in_flight_queues; ++ int const_seeky_busy_in_flight_queues; ++ int wr_busy_queues; ++ int queued; ++ int rq_in_driver; ++ int sync_flight; ++ ++ int max_rq_in_driver; ++ int hw_tag_samples; ++ int hw_tag; ++ ++ int budgets_assigned; ++ ++ struct timer_list idle_slice_timer; ++ struct work_struct unplug_work; ++ ++ struct bfq_queue *in_service_queue; ++ struct bfq_io_cq *in_service_bic; ++ ++ sector_t last_position; ++ ++ ktime_t last_budget_start; ++ ktime_t last_idling_start; ++ int peak_rate_samples; ++ u64 peak_rate; ++ unsigned long bfq_max_budget; ++ ++ struct hlist_head group_list; ++ struct list_head active_list; ++ struct list_head idle_list; ++ ++ unsigned int bfq_quantum; ++ unsigned int bfq_fifo_expire[2]; ++ unsigned int bfq_back_penalty; ++ unsigned int bfq_back_max; ++ unsigned int bfq_slice_idle; ++ u64 bfq_class_idle_last_service; ++ ++ unsigned int bfq_user_max_budget; ++ unsigned int bfq_max_budget_async_rq; ++ unsigned int bfq_timeout[2]; ++ ++ unsigned int bfq_coop_thresh; ++ unsigned int bfq_failed_cooperations; ++ unsigned int bfq_requests_within_timer; ++ ++ unsigned long last_ins_in_burst; ++ unsigned long bfq_burst_interval; ++ int burst_size; ++ unsigned long bfq_large_burst_thresh; ++ bool large_burst; ++ struct hlist_head burst_list; ++ ++ bool low_latency; ++ ++ /* parameters of the low_latency heuristics */ ++ unsigned int bfq_wr_coeff; ++ unsigned int bfq_wr_max_time; ++ unsigned int bfq_wr_rt_max_time; ++ unsigned int bfq_wr_min_idle_time; ++ unsigned long bfq_wr_min_inter_arr_async; ++ unsigned int bfq_wr_max_softrt_rate; ++ u64 RT_prod; ++ enum bfq_device_speed device_speed; ++ ++ struct bfq_queue oom_bfqq; ++}; ++ ++enum bfqq_state_flags { ++ BFQ_BFQQ_FLAG_busy = 0, /* has requests or is in service */ ++ BFQ_BFQQ_FLAG_wait_request, /* waiting for a request */ ++ BFQ_BFQQ_FLAG_must_alloc, /* must be allowed rq alloc */ ++ BFQ_BFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ ++ BFQ_BFQQ_FLAG_idle_window, /* slice idling enabled */ ++ BFQ_BFQQ_FLAG_prio_changed, /* task priority has changed */ ++ BFQ_BFQQ_FLAG_sync, /* synchronous queue */ ++ BFQ_BFQQ_FLAG_budget_new, /* no completion with this budget */ ++ BFQ_BFQQ_FLAG_IO_bound, /* ++ * bfqq has timed-out at least once ++ * having consumed at most 2/10 of ++ * its budget ++ */ ++ BFQ_BFQQ_FLAG_in_large_burst, /* ++ * bfqq activated in a large burst, ++ * see comments to bfq_handle_burst. ++ */ ++ BFQ_BFQQ_FLAG_constantly_seeky, /* ++ * bfqq has proved to be slow and ++ * seeky until budget timeout ++ */ ++ BFQ_BFQQ_FLAG_softrt_update, /* ++ * may need softrt-next-start ++ * update ++ */ ++ BFQ_BFQQ_FLAG_coop, /* bfqq is shared */ ++ BFQ_BFQQ_FLAG_split_coop, /* shared bfqq will be splitted */ ++}; ++ ++#define BFQ_BFQQ_FNS(name) \ ++static inline void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \ ++{ \ ++ (bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name); \ ++} \ ++static inline void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \ ++{ \ ++ (bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name); \ ++} \ ++static inline int bfq_bfqq_##name(const struct bfq_queue *bfqq) \ ++{ \ ++ return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0; \ ++} ++ ++BFQ_BFQQ_FNS(busy); ++BFQ_BFQQ_FNS(wait_request); ++BFQ_BFQQ_FNS(must_alloc); ++BFQ_BFQQ_FNS(fifo_expire); ++BFQ_BFQQ_FNS(idle_window); ++BFQ_BFQQ_FNS(prio_changed); ++BFQ_BFQQ_FNS(sync); ++BFQ_BFQQ_FNS(budget_new); ++BFQ_BFQQ_FNS(IO_bound); ++BFQ_BFQQ_FNS(in_large_burst); ++BFQ_BFQQ_FNS(constantly_seeky); ++BFQ_BFQQ_FNS(coop); ++BFQ_BFQQ_FNS(split_coop); ++BFQ_BFQQ_FNS(softrt_update); ++#undef BFQ_BFQQ_FNS ++ ++/* Logging facilities. */ ++#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ ++ blk_add_trace_msg((bfqd)->queue, "bfq%d " fmt, (bfqq)->pid, ##args) ++ ++#define bfq_log(bfqd, fmt, args...) \ ++ blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) ++ ++/* Expiration reasons. */ ++enum bfqq_expiration { ++ BFQ_BFQQ_TOO_IDLE = 0, /* ++ * queue has been idling for ++ * too long ++ */ ++ BFQ_BFQQ_BUDGET_TIMEOUT, /* budget took too long to be used */ ++ BFQ_BFQQ_BUDGET_EXHAUSTED, /* budget consumed */ ++ BFQ_BFQQ_NO_MORE_REQUESTS, /* the queue has no more requests */ ++}; ++ ++#ifdef CONFIG_CGROUP_BFQIO ++/** ++ * struct bfq_group - per (device, cgroup) data structure. ++ * @entity: schedulable entity to insert into the parent group sched_data. ++ * @sched_data: own sched_data, to contain child entities (they may be ++ * both bfq_queues and bfq_groups). ++ * @group_node: node to be inserted into the bfqio_cgroup->group_data ++ * list of the containing cgroup's bfqio_cgroup. ++ * @bfqd_node: node to be inserted into the @bfqd->group_list list ++ * of the groups active on the same device; used for cleanup. ++ * @bfqd: the bfq_data for the device this group acts upon. ++ * @async_bfqq: array of async queues for all the tasks belonging to ++ * the group, one queue per ioprio value per ioprio_class, ++ * except for the idle class that has only one queue. ++ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored). ++ * @my_entity: pointer to @entity, %NULL for the toplevel group; used ++ * to avoid too many special cases during group creation/ ++ * migration. ++ * @active_entities: number of active entities belonging to the group; ++ * unused for the root group. Used to know whether there ++ * are groups with more than one active @bfq_entity ++ * (see the comments to the function ++ * bfq_bfqq_must_not_expire()). ++ * ++ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup ++ * there is a set of bfq_groups, each one collecting the lower-level ++ * entities belonging to the group that are acting on the same device. ++ * ++ * Locking works as follows: ++ * o @group_node is protected by the bfqio_cgroup lock, and is accessed ++ * via RCU from its readers. ++ * o @bfqd is protected by the queue lock, RCU is used to access it ++ * from the readers. ++ * o All the other fields are protected by the @bfqd queue lock. ++ */ ++struct bfq_group { ++ struct bfq_entity entity; ++ struct bfq_sched_data sched_data; ++ ++ struct hlist_node group_node; ++ struct hlist_node bfqd_node; ++ ++ void *bfqd; ++ ++ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; ++ struct bfq_queue *async_idle_bfqq; ++ ++ struct bfq_entity *my_entity; ++ ++ int active_entities; ++}; ++ ++/** ++ * struct bfqio_cgroup - bfq cgroup data structure. ++ * @css: subsystem state for bfq in the containing cgroup. ++ * @online: flag marked when the subsystem is inserted. ++ * @weight: cgroup weight. ++ * @ioprio: cgroup ioprio. ++ * @ioprio_class: cgroup ioprio_class. ++ * @lock: spinlock that protects @ioprio, @ioprio_class and @group_data. ++ * @group_data: list containing the bfq_group belonging to this cgroup. ++ * ++ * @group_data is accessed using RCU, with @lock protecting the updates, ++ * @ioprio and @ioprio_class are protected by @lock. ++ */ ++struct bfqio_cgroup { ++ struct cgroup_subsys_state css; ++ bool online; ++ ++ unsigned short weight, ioprio, ioprio_class; ++ ++ spinlock_t lock; ++ struct hlist_head group_data; ++}; ++#else ++struct bfq_group { ++ struct bfq_sched_data sched_data; ++ ++ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR]; ++ struct bfq_queue *async_idle_bfqq; ++}; ++#endif ++ ++static inline struct bfq_service_tree * ++bfq_entity_service_tree(struct bfq_entity *entity) ++{ ++ struct bfq_sched_data *sched_data = entity->sched_data; ++ unsigned int idx = entity->ioprio_class - 1; ++ ++ BUG_ON(idx >= BFQ_IOPRIO_CLASSES); ++ BUG_ON(sched_data == NULL); ++ ++ return sched_data->service_tree + idx; ++} ++ ++static inline struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, ++ bool is_sync) ++{ ++ return bic->bfqq[is_sync]; ++} ++ ++static inline void bic_set_bfqq(struct bfq_io_cq *bic, ++ struct bfq_queue *bfqq, bool is_sync) ++{ ++ bic->bfqq[is_sync] = bfqq; ++} ++ ++static inline struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic) ++{ ++ return bic->icq.q->elevator->elevator_data; ++} ++ ++/** ++ * bfq_get_bfqd_locked - get a lock to a bfqd using a RCU protected pointer. ++ * @ptr: a pointer to a bfqd. ++ * @flags: storage for the flags to be saved. ++ * ++ * This function allows bfqg->bfqd to be protected by the ++ * queue lock of the bfqd they reference; the pointer is dereferenced ++ * under RCU, so the storage for bfqd is assured to be safe as long ++ * as the RCU read side critical section does not end. After the ++ * bfqd->queue->queue_lock is taken the pointer is rechecked, to be ++ * sure that no other writer accessed it. If we raced with a writer, ++ * the function returns NULL, with the queue unlocked, otherwise it ++ * returns the dereferenced pointer, with the queue locked. ++ */ ++static inline struct bfq_data *bfq_get_bfqd_locked(void **ptr, ++ unsigned long *flags) ++{ ++ struct bfq_data *bfqd; ++ ++ rcu_read_lock(); ++ bfqd = rcu_dereference(*(struct bfq_data **)ptr); ++ ++ if (bfqd != NULL) { ++ spin_lock_irqsave(bfqd->queue->queue_lock, *flags); ++ if (*ptr == bfqd) ++ goto out; ++ spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags); ++ } ++ ++ bfqd = NULL; ++out: ++ rcu_read_unlock(); ++ return bfqd; ++} ++ ++static inline void bfq_put_bfqd_unlock(struct bfq_data *bfqd, ++ unsigned long *flags) ++{ ++ spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags); ++} ++ ++static void bfq_changed_ioprio(struct bfq_io_cq *bic); ++static void bfq_put_queue(struct bfq_queue *bfqq); ++static void bfq_dispatch_insert(struct request_queue *q, struct request *rq); ++static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, ++ struct bfq_group *bfqg, int is_sync, ++ struct bfq_io_cq *bic, gfp_t gfp_mask); ++static void bfq_end_wr_async_queues(struct bfq_data *bfqd, ++ struct bfq_group *bfqg); ++static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); ++static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); ++ ++#endif /* _BFQ_H */ +-- +2.1.0 + diff --git a/5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r7-for-4.0.0.patch b/5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r7-for-4.0.0.patch new file mode 100644 index 00000000..53267cdd --- /dev/null +++ b/5003_block-bfq-add-Early-Queue-Merge-EQM-to-BFQ-v7r7-for-4.0.0.patch @@ -0,0 +1,1222 @@ +From d49cf2e7913ec1c4b86a9de657140d9ec5fa8c19 Mon Sep 17 00:00:00 2001 +From: Mauro Andreolini +Date: Thu, 18 Dec 2014 21:32:08 +0100 +Subject: [PATCH 3/3] block, bfq: add Early Queue Merge (EQM) to BFQ-v7r7 for + 4.0.0 + +A set of processes may happen to perform interleaved reads, i.e.,requests +whose union would give rise to a sequential read pattern. There are two +typical cases: in the first case, processes read fixed-size chunks of +data at a fixed distance from each other, while in the second case processes +may read variable-size chunks at variable distances. The latter case occurs +for example with QEMU, which splits the I/O generated by the guest into +multiple chunks, and lets these chunks be served by a pool of cooperating +processes, iteratively assigning the next chunk of I/O to the first +available process. CFQ uses actual queue merging for the first type of +rocesses, whereas it uses preemption to get a sequential read pattern out +of the read requests performed by the second type of processes. In the end +it uses two different mechanisms to achieve the same goal: boosting the +throughput with interleaved I/O. + +This patch introduces Early Queue Merge (EQM), a unified mechanism to get a +sequential read pattern with both types of processes. The main idea is +checking newly arrived requests against the next request of the active queue +both in case of actual request insert and in case of request merge. By doing +so, both the types of processes can be handled by just merging their queues. +EQM is then simpler and more compact than the pair of mechanisms used in +CFQ. + +Finally, EQM also preserves the typical low-latency properties of BFQ, by +properly restoring the weight-raising state of a queue when it gets back to +a non-merged state. + +Signed-off-by: Mauro Andreolini +Signed-off-by: Arianna Avanzini +Signed-off-by: Paolo Valente +--- + block/bfq-iosched.c | 751 +++++++++++++++++++++++++++++++++++++--------------- + block/bfq-sched.c | 28 -- + block/bfq.h | 54 +++- + 3 files changed, 581 insertions(+), 252 deletions(-) + +diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c +index 97ee934..328f33c 100644 +--- a/block/bfq-iosched.c ++++ b/block/bfq-iosched.c +@@ -571,6 +571,57 @@ static inline unsigned int bfq_wr_duration(struct bfq_data *bfqd) + return dur; + } + ++static inline unsigned ++bfq_bfqq_cooperations(struct bfq_queue *bfqq) ++{ ++ return bfqq->bic ? bfqq->bic->cooperations : 0; ++} ++ ++static inline void ++bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic) ++{ ++ if (bic->saved_idle_window) ++ bfq_mark_bfqq_idle_window(bfqq); ++ else ++ bfq_clear_bfqq_idle_window(bfqq); ++ if (bic->saved_IO_bound) ++ bfq_mark_bfqq_IO_bound(bfqq); ++ else ++ bfq_clear_bfqq_IO_bound(bfqq); ++ /* Assuming that the flag in_large_burst is already correctly set */ ++ if (bic->wr_time_left && bfqq->bfqd->low_latency && ++ !bfq_bfqq_in_large_burst(bfqq) && ++ bic->cooperations < bfqq->bfqd->bfq_coop_thresh) { ++ /* ++ * Start a weight raising period with the duration given by ++ * the raising_time_left snapshot. ++ */ ++ if (bfq_bfqq_busy(bfqq)) ++ bfqq->bfqd->wr_busy_queues++; ++ bfqq->wr_coeff = bfqq->bfqd->bfq_wr_coeff; ++ bfqq->wr_cur_max_time = bic->wr_time_left; ++ bfqq->last_wr_start_finish = jiffies; ++ bfqq->entity.ioprio_changed = 1; ++ } ++ /* ++ * Clear wr_time_left to prevent bfq_bfqq_save_state() from ++ * getting confused about the queue's need of a weight-raising ++ * period. ++ */ ++ bic->wr_time_left = 0; ++} ++ ++/* Must be called with the queue_lock held. */ ++static int bfqq_process_refs(struct bfq_queue *bfqq) ++{ ++ int process_refs, io_refs; ++ ++ io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE]; ++ process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st; ++ BUG_ON(process_refs < 0); ++ return process_refs; ++} ++ + /* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */ + static inline void bfq_reset_burst_list(struct bfq_data *bfqd, + struct bfq_queue *bfqq) +@@ -815,7 +866,7 @@ static void bfq_add_request(struct request *rq) + bfq_rq_pos_tree_add(bfqd, bfqq); + + if (!bfq_bfqq_busy(bfqq)) { +- bool soft_rt, ++ bool soft_rt, coop_or_in_burst, + idle_for_long_time = time_is_before_jiffies( + bfqq->budget_timeout + + bfqd->bfq_wr_min_idle_time); +@@ -839,11 +890,12 @@ static void bfq_add_request(struct request *rq) + bfqd->last_ins_in_burst = jiffies; + } + ++ coop_or_in_burst = bfq_bfqq_in_large_burst(bfqq) || ++ bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh; + soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 && +- !bfq_bfqq_in_large_burst(bfqq) && ++ !coop_or_in_burst && + time_is_before_jiffies(bfqq->soft_rt_next_start); +- interactive = !bfq_bfqq_in_large_burst(bfqq) && +- idle_for_long_time; ++ interactive = !coop_or_in_burst && idle_for_long_time; + entity->budget = max_t(unsigned long, bfqq->max_budget, + bfq_serv_to_charge(next_rq, bfqq)); + +@@ -862,11 +914,20 @@ static void bfq_add_request(struct request *rq) + if (!bfqd->low_latency) + goto add_bfqq_busy; + ++ if (bfq_bfqq_just_split(bfqq)) ++ goto set_ioprio_changed; ++ + /* +- * If the queue is not being boosted and has been idle +- * for enough time, start a weight-raising period ++ * If the queue: ++ * - is not being boosted, ++ * - has been idle for enough time, ++ * - is not a sync queue or is linked to a bfq_io_cq (it is ++ * shared "for its nature" or it is not shared and its ++ * requests have not been redirected to a shared queue) ++ * start a weight-raising period. + */ +- if (old_wr_coeff == 1 && (interactive || soft_rt)) { ++ if (old_wr_coeff == 1 && (interactive || soft_rt) && ++ (!bfq_bfqq_sync(bfqq) || bfqq->bic != NULL)) { + bfqq->wr_coeff = bfqd->bfq_wr_coeff; + if (interactive) + bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); +@@ -880,7 +941,7 @@ static void bfq_add_request(struct request *rq) + } else if (old_wr_coeff > 1) { + if (interactive) + bfqq->wr_cur_max_time = bfq_wr_duration(bfqd); +- else if (bfq_bfqq_in_large_burst(bfqq) || ++ else if (coop_or_in_burst || + (bfqq->wr_cur_max_time == + bfqd->bfq_wr_rt_max_time && + !soft_rt)) { +@@ -899,18 +960,18 @@ static void bfq_add_request(struct request *rq) + /* + * + * The remaining weight-raising time is lower +- * than bfqd->bfq_wr_rt_max_time, which +- * means that the application is enjoying +- * weight raising either because deemed soft- +- * rt in the near past, or because deemed +- * interactive a long ago. In both cases, +- * resetting now the current remaining weight- +- * raising time for the application to the +- * weight-raising duration for soft rt +- * applications would not cause any latency +- * increase for the application (as the new +- * duration would be higher than the remaining +- * time). ++ * than bfqd->bfq_wr_rt_max_time, which means ++ * that the application is enjoying weight ++ * raising either because deemed soft-rt in ++ * the near past, or because deemed interactive ++ * a long ago. ++ * In both cases, resetting now the current ++ * remaining weight-raising time for the ++ * application to the weight-raising duration ++ * for soft rt applications would not cause any ++ * latency increase for the application (as the ++ * new duration would be higher than the ++ * remaining time). + * + * In addition, the application is now meeting + * the requirements for being deemed soft rt. +@@ -945,6 +1006,7 @@ static void bfq_add_request(struct request *rq) + bfqd->bfq_wr_rt_max_time; + } + } ++set_ioprio_changed: + if (old_wr_coeff != bfqq->wr_coeff) + entity->ioprio_changed = 1; + add_bfqq_busy: +@@ -1156,90 +1218,35 @@ static void bfq_end_wr(struct bfq_data *bfqd) + spin_unlock_irq(bfqd->queue->queue_lock); + } + +-static int bfq_allow_merge(struct request_queue *q, struct request *rq, +- struct bio *bio) ++static inline sector_t bfq_io_struct_pos(void *io_struct, bool request) + { +- struct bfq_data *bfqd = q->elevator->elevator_data; +- struct bfq_io_cq *bic; +- struct bfq_queue *bfqq; +- +- /* +- * Disallow merge of a sync bio into an async request. +- */ +- if (bfq_bio_sync(bio) && !rq_is_sync(rq)) +- return 0; +- +- /* +- * Lookup the bfqq that this bio will be queued with. Allow +- * merge only if rq is queued there. +- * Queue lock is held here. +- */ +- bic = bfq_bic_lookup(bfqd, current->io_context); +- if (bic == NULL) +- return 0; +- +- bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio)); +- return bfqq == RQ_BFQQ(rq); +-} +- +-static void __bfq_set_in_service_queue(struct bfq_data *bfqd, +- struct bfq_queue *bfqq) +-{ +- if (bfqq != NULL) { +- bfq_mark_bfqq_must_alloc(bfqq); +- bfq_mark_bfqq_budget_new(bfqq); +- bfq_clear_bfqq_fifo_expire(bfqq); +- +- bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8; +- +- bfq_log_bfqq(bfqd, bfqq, +- "set_in_service_queue, cur-budget = %lu", +- bfqq->entity.budget); +- } +- +- bfqd->in_service_queue = bfqq; +-} +- +-/* +- * Get and set a new queue for service. +- */ +-static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd, +- struct bfq_queue *bfqq) +-{ +- if (!bfqq) +- bfqq = bfq_get_next_queue(bfqd); ++ if (request) ++ return blk_rq_pos(io_struct); + else +- bfq_get_next_queue_forced(bfqd, bfqq); +- +- __bfq_set_in_service_queue(bfqd, bfqq); +- return bfqq; ++ return ((struct bio *)io_struct)->bi_iter.bi_sector; + } + +-static inline sector_t bfq_dist_from_last(struct bfq_data *bfqd, +- struct request *rq) ++static inline sector_t bfq_dist_from(sector_t pos1, ++ sector_t pos2) + { +- if (blk_rq_pos(rq) >= bfqd->last_position) +- return blk_rq_pos(rq) - bfqd->last_position; ++ if (pos1 >= pos2) ++ return pos1 - pos2; + else +- return bfqd->last_position - blk_rq_pos(rq); ++ return pos2 - pos1; + } + +-/* +- * Return true if bfqq has no request pending and rq is close enough to +- * bfqd->last_position, or if rq is closer to bfqd->last_position than +- * bfqq->next_rq +- */ +-static inline int bfq_rq_close(struct bfq_data *bfqd, struct request *rq) ++static inline int bfq_rq_close_to_sector(void *io_struct, bool request, ++ sector_t sector) + { +- return bfq_dist_from_last(bfqd, rq) <= BFQQ_SEEK_THR; ++ return bfq_dist_from(bfq_io_struct_pos(io_struct, request), sector) <= ++ BFQQ_SEEK_THR; + } + +-static struct bfq_queue *bfqq_close(struct bfq_data *bfqd) ++static struct bfq_queue *bfqq_close(struct bfq_data *bfqd, sector_t sector) + { + struct rb_root *root = &bfqd->rq_pos_tree; + struct rb_node *parent, *node; + struct bfq_queue *__bfqq; +- sector_t sector = bfqd->last_position; + + if (RB_EMPTY_ROOT(root)) + return NULL; +@@ -1258,7 +1265,7 @@ static struct bfq_queue *bfqq_close(struct bfq_data *bfqd) + * next_request position). + */ + __bfqq = rb_entry(parent, struct bfq_queue, pos_node); +- if (bfq_rq_close(bfqd, __bfqq->next_rq)) ++ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector)) + return __bfqq; + + if (blk_rq_pos(__bfqq->next_rq) < sector) +@@ -1269,7 +1276,7 @@ static struct bfq_queue *bfqq_close(struct bfq_data *bfqd) + return NULL; + + __bfqq = rb_entry(node, struct bfq_queue, pos_node); +- if (bfq_rq_close(bfqd, __bfqq->next_rq)) ++ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector)) + return __bfqq; + + return NULL; +@@ -1278,14 +1285,12 @@ static struct bfq_queue *bfqq_close(struct bfq_data *bfqd) + /* + * bfqd - obvious + * cur_bfqq - passed in so that we don't decide that the current queue +- * is closely cooperating with itself. +- * +- * We are assuming that cur_bfqq has dispatched at least one request, +- * and that bfqd->last_position reflects a position on the disk associated +- * with the I/O issued by cur_bfqq. ++ * is closely cooperating with itself ++ * sector - used as a reference point to search for a close queue + */ + static struct bfq_queue *bfq_close_cooperator(struct bfq_data *bfqd, +- struct bfq_queue *cur_bfqq) ++ struct bfq_queue *cur_bfqq, ++ sector_t sector) + { + struct bfq_queue *bfqq; + +@@ -1305,7 +1310,7 @@ static struct bfq_queue *bfq_close_cooperator(struct bfq_data *bfqd, + * working closely on the same area of the disk. In that case, + * we can group them together and don't waste time idling. + */ +- bfqq = bfqq_close(bfqd); ++ bfqq = bfqq_close(bfqd, sector); + if (bfqq == NULL || bfqq == cur_bfqq) + return NULL; + +@@ -1332,6 +1337,315 @@ static struct bfq_queue *bfq_close_cooperator(struct bfq_data *bfqd, + return bfqq; + } + ++static struct bfq_queue * ++bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) ++{ ++ int process_refs, new_process_refs; ++ struct bfq_queue *__bfqq; ++ ++ /* ++ * If there are no process references on the new_bfqq, then it is ++ * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain ++ * may have dropped their last reference (not just their last process ++ * reference). ++ */ ++ if (!bfqq_process_refs(new_bfqq)) ++ return NULL; ++ ++ /* Avoid a circular list and skip interim queue merges. */ ++ while ((__bfqq = new_bfqq->new_bfqq)) { ++ if (__bfqq == bfqq) ++ return NULL; ++ new_bfqq = __bfqq; ++ } ++ ++ process_refs = bfqq_process_refs(bfqq); ++ new_process_refs = bfqq_process_refs(new_bfqq); ++ /* ++ * If the process for the bfqq has gone away, there is no ++ * sense in merging the queues. ++ */ ++ if (process_refs == 0 || new_process_refs == 0) ++ return NULL; ++ ++ bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d", ++ new_bfqq->pid); ++ ++ /* ++ * Merging is just a redirection: the requests of the process ++ * owning one of the two queues are redirected to the other queue. ++ * The latter queue, in its turn, is set as shared if this is the ++ * first time that the requests of some process are redirected to ++ * it. ++ * ++ * We redirect bfqq to new_bfqq and not the opposite, because we ++ * are in the context of the process owning bfqq, hence we have ++ * the io_cq of this process. So we can immediately configure this ++ * io_cq to redirect the requests of the process to new_bfqq. ++ * ++ * NOTE, even if new_bfqq coincides with the in-service queue, the ++ * io_cq of new_bfqq is not available, because, if the in-service ++ * queue is shared, bfqd->in_service_bic may not point to the ++ * io_cq of the in-service queue. ++ * Redirecting the requests of the process owning bfqq to the ++ * currently in-service queue is in any case the best option, as ++ * we feed the in-service queue with new requests close to the ++ * last request served and, by doing so, hopefully increase the ++ * throughput. ++ */ ++ bfqq->new_bfqq = new_bfqq; ++ atomic_add(process_refs, &new_bfqq->ref); ++ return new_bfqq; ++} ++ ++/* ++ * Attempt to schedule a merge of bfqq with the currently in-service queue ++ * or with a close queue among the scheduled queues. ++ * Return NULL if no merge was scheduled, a pointer to the shared bfq_queue ++ * structure otherwise. ++ * ++ * The OOM queue is not allowed to participate to cooperation: in fact, since ++ * the requests temporarily redirected to the OOM queue could be redirected ++ * again to dedicated queues at any time, the state needed to correctly ++ * handle merging with the OOM queue would be quite complex and expensive ++ * to maintain. Besides, in such a critical condition as an out of memory, ++ * the benefits of queue merging may be little relevant, or even negligible. ++ */ ++static struct bfq_queue * ++bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, ++ void *io_struct, bool request) ++{ ++ struct bfq_queue *in_service_bfqq, *new_bfqq; ++ ++ if (bfqq->new_bfqq) ++ return bfqq->new_bfqq; ++ ++ if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) ++ return NULL; ++ ++ in_service_bfqq = bfqd->in_service_queue; ++ ++ if (in_service_bfqq == NULL || in_service_bfqq == bfqq || ++ !bfqd->in_service_bic || ++ unlikely(in_service_bfqq == &bfqd->oom_bfqq)) ++ goto check_scheduled; ++ ++ if (bfq_class_idle(in_service_bfqq) || bfq_class_idle(bfqq)) ++ goto check_scheduled; ++ ++ if (bfq_class_rt(in_service_bfqq) != bfq_class_rt(bfqq)) ++ goto check_scheduled; ++ ++ if (in_service_bfqq->entity.parent != bfqq->entity.parent) ++ goto check_scheduled; ++ ++ if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) && ++ bfq_bfqq_sync(in_service_bfqq) && bfq_bfqq_sync(bfqq)) { ++ new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq); ++ if (new_bfqq != NULL) ++ return new_bfqq; /* Merge with in-service queue */ ++ } ++ ++ /* ++ * Check whether there is a cooperator among currently scheduled ++ * queues. The only thing we need is that the bio/request is not ++ * NULL, as we need it to establish whether a cooperator exists. ++ */ ++check_scheduled: ++ new_bfqq = bfq_close_cooperator(bfqd, bfqq, ++ bfq_io_struct_pos(io_struct, request)); ++ if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq)) ++ return bfq_setup_merge(bfqq, new_bfqq); ++ ++ return NULL; ++} ++ ++static inline void ++bfq_bfqq_save_state(struct bfq_queue *bfqq) ++{ ++ /* ++ * If bfqq->bic == NULL, the queue is already shared or its requests ++ * have already been redirected to a shared queue; both idle window ++ * and weight raising state have already been saved. Do nothing. ++ */ ++ if (bfqq->bic == NULL) ++ return; ++ if (bfqq->bic->wr_time_left) ++ /* ++ * This is the queue of a just-started process, and would ++ * deserve weight raising: we set wr_time_left to the full ++ * weight-raising duration to trigger weight-raising when ++ * and if the queue is split and the first request of the ++ * queue is enqueued. ++ */ ++ bfqq->bic->wr_time_left = bfq_wr_duration(bfqq->bfqd); ++ else if (bfqq->wr_coeff > 1) { ++ unsigned long wr_duration = ++ jiffies - bfqq->last_wr_start_finish; ++ /* ++ * It may happen that a queue's weight raising period lasts ++ * longer than its wr_cur_max_time, as weight raising is ++ * handled only when a request is enqueued or dispatched (it ++ * does not use any timer). If the weight raising period is ++ * about to end, don't save it. ++ */ ++ if (bfqq->wr_cur_max_time <= wr_duration) ++ bfqq->bic->wr_time_left = 0; ++ else ++ bfqq->bic->wr_time_left = ++ bfqq->wr_cur_max_time - wr_duration; ++ /* ++ * The bfq_queue is becoming shared or the requests of the ++ * process owning the queue are being redirected to a shared ++ * queue. Stop the weight raising period of the queue, as in ++ * both cases it should not be owned by an interactive or ++ * soft real-time application. ++ */ ++ bfq_bfqq_end_wr(bfqq); ++ } else ++ bfqq->bic->wr_time_left = 0; ++ bfqq->bic->saved_idle_window = bfq_bfqq_idle_window(bfqq); ++ bfqq->bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq); ++ bfqq->bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq); ++ bfqq->bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node); ++ bfqq->bic->cooperations++; ++ bfqq->bic->failed_cooperations = 0; ++} ++ ++static inline void ++bfq_get_bic_reference(struct bfq_queue *bfqq) ++{ ++ /* ++ * If bfqq->bic has a non-NULL value, the bic to which it belongs ++ * is about to begin using a shared bfq_queue. ++ */ ++ if (bfqq->bic) ++ atomic_long_inc(&bfqq->bic->icq.ioc->refcount); ++} ++ ++static void ++bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, ++ struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) ++{ ++ bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu", ++ (long unsigned)new_bfqq->pid); ++ /* Save weight raising and idle window of the merged queues */ ++ bfq_bfqq_save_state(bfqq); ++ bfq_bfqq_save_state(new_bfqq); ++ if (bfq_bfqq_IO_bound(bfqq)) ++ bfq_mark_bfqq_IO_bound(new_bfqq); ++ bfq_clear_bfqq_IO_bound(bfqq); ++ /* ++ * Grab a reference to the bic, to prevent it from being destroyed ++ * before being possibly touched by a bfq_split_bfqq(). ++ */ ++ bfq_get_bic_reference(bfqq); ++ bfq_get_bic_reference(new_bfqq); ++ /* ++ * Merge queues (that is, let bic redirect its requests to new_bfqq) ++ */ ++ bic_set_bfqq(bic, new_bfqq, 1); ++ bfq_mark_bfqq_coop(new_bfqq); ++ /* ++ * new_bfqq now belongs to at least two bics (it is a shared queue): ++ * set new_bfqq->bic to NULL. bfqq either: ++ * - does not belong to any bic any more, and hence bfqq->bic must ++ * be set to NULL, or ++ * - is a queue whose owning bics have already been redirected to a ++ * different queue, hence the queue is destined to not belong to ++ * any bic soon and bfqq->bic is already NULL (therefore the next ++ * assignment causes no harm). ++ */ ++ new_bfqq->bic = NULL; ++ bfqq->bic = NULL; ++ bfq_put_queue(bfqq); ++} ++ ++static inline void bfq_bfqq_increase_failed_cooperations(struct bfq_queue *bfqq) ++{ ++ struct bfq_io_cq *bic = bfqq->bic; ++ struct bfq_data *bfqd = bfqq->bfqd; ++ ++ if (bic && bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh) { ++ bic->failed_cooperations++; ++ if (bic->failed_cooperations >= bfqd->bfq_failed_cooperations) ++ bic->cooperations = 0; ++ } ++} ++ ++static int bfq_allow_merge(struct request_queue *q, struct request *rq, ++ struct bio *bio) ++{ ++ struct bfq_data *bfqd = q->elevator->elevator_data; ++ struct bfq_io_cq *bic; ++ struct bfq_queue *bfqq, *new_bfqq; ++ ++ /* ++ * Disallow merge of a sync bio into an async request. ++ */ ++ if (bfq_bio_sync(bio) && !rq_is_sync(rq)) ++ return 0; ++ ++ /* ++ * Lookup the bfqq that this bio will be queued with. Allow ++ * merge only if rq is queued there. ++ * Queue lock is held here. ++ */ ++ bic = bfq_bic_lookup(bfqd, current->io_context); ++ if (bic == NULL) ++ return 0; ++ ++ bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio)); ++ /* ++ * We take advantage of this function to perform an early merge ++ * of the queues of possible cooperating processes. ++ */ ++ if (bfqq != NULL) { ++ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false); ++ if (new_bfqq != NULL) { ++ bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq); ++ /* ++ * If we get here, the bio will be queued in the ++ * shared queue, i.e., new_bfqq, so use new_bfqq ++ * to decide whether bio and rq can be merged. ++ */ ++ bfqq = new_bfqq; ++ } else ++ bfq_bfqq_increase_failed_cooperations(bfqq); ++ } ++ ++ return bfqq == RQ_BFQQ(rq); ++} ++ ++static void __bfq_set_in_service_queue(struct bfq_data *bfqd, ++ struct bfq_queue *bfqq) ++{ ++ if (bfqq != NULL) { ++ bfq_mark_bfqq_must_alloc(bfqq); ++ bfq_mark_bfqq_budget_new(bfqq); ++ bfq_clear_bfqq_fifo_expire(bfqq); ++ ++ bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8; ++ ++ bfq_log_bfqq(bfqd, bfqq, ++ "set_in_service_queue, cur-budget = %lu", ++ bfqq->entity.budget); ++ } ++ ++ bfqd->in_service_queue = bfqq; ++} ++ ++/* ++ * Get and set a new queue for service. ++ */ ++static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd) ++{ ++ struct bfq_queue *bfqq = bfq_get_next_queue(bfqd); ++ ++ __bfq_set_in_service_queue(bfqd, bfqq); ++ return bfqq; ++} ++ + /* + * If enough samples have been computed, return the current max budget + * stored in bfqd, which is dynamically updated according to the +@@ -1475,61 +1789,6 @@ static struct request *bfq_check_fifo(struct bfq_queue *bfqq) + return rq; + } + +-/* Must be called with the queue_lock held. */ +-static int bfqq_process_refs(struct bfq_queue *bfqq) +-{ +- int process_refs, io_refs; +- +- io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE]; +- process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st; +- BUG_ON(process_refs < 0); +- return process_refs; +-} +- +-static void bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) +-{ +- int process_refs, new_process_refs; +- struct bfq_queue *__bfqq; +- +- /* +- * If there are no process references on the new_bfqq, then it is +- * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain +- * may have dropped their last reference (not just their last process +- * reference). +- */ +- if (!bfqq_process_refs(new_bfqq)) +- return; +- +- /* Avoid a circular list and skip interim queue merges. */ +- while ((__bfqq = new_bfqq->new_bfqq)) { +- if (__bfqq == bfqq) +- return; +- new_bfqq = __bfqq; +- } +- +- process_refs = bfqq_process_refs(bfqq); +- new_process_refs = bfqq_process_refs(new_bfqq); +- /* +- * If the process for the bfqq has gone away, there is no +- * sense in merging the queues. +- */ +- if (process_refs == 0 || new_process_refs == 0) +- return; +- +- /* +- * Merge in the direction of the lesser amount of work. +- */ +- if (new_process_refs >= process_refs) { +- bfqq->new_bfqq = new_bfqq; +- atomic_add(process_refs, &new_bfqq->ref); +- } else { +- new_bfqq->new_bfqq = bfqq; +- atomic_add(new_process_refs, &bfqq->ref); +- } +- bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d", +- new_bfqq->pid); +-} +- + static inline unsigned long bfq_bfqq_budget_left(struct bfq_queue *bfqq) + { + struct bfq_entity *entity = &bfqq->entity; +@@ -2263,7 +2522,7 @@ static inline bool bfq_bfqq_must_idle(struct bfq_queue *bfqq) + */ + static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) + { +- struct bfq_queue *bfqq, *new_bfqq = NULL; ++ struct bfq_queue *bfqq; + struct request *next_rq; + enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT; + +@@ -2273,17 +2532,6 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) + + bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue"); + +- /* +- * If another queue has a request waiting within our mean seek +- * distance, let it run. The expire code will check for close +- * cooperators and put the close queue at the front of the +- * service tree. If possible, merge the expiring queue with the +- * new bfqq. +- */ +- new_bfqq = bfq_close_cooperator(bfqd, bfqq); +- if (new_bfqq != NULL && bfqq->new_bfqq == NULL) +- bfq_setup_merge(bfqq, new_bfqq); +- + if (bfq_may_expire_for_budg_timeout(bfqq) && + !timer_pending(&bfqd->idle_slice_timer) && + !bfq_bfqq_must_idle(bfqq)) +@@ -2322,10 +2570,7 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) + bfq_clear_bfqq_wait_request(bfqq); + del_timer(&bfqd->idle_slice_timer); + } +- if (new_bfqq == NULL) +- goto keep_queue; +- else +- goto expire; ++ goto keep_queue; + } + } + +@@ -2334,40 +2579,30 @@ static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd) + * in flight (possibly waiting for a completion) or is idling for a + * new request, then keep it. + */ +- if (new_bfqq == NULL && (timer_pending(&bfqd->idle_slice_timer) || +- (bfqq->dispatched != 0 && bfq_bfqq_must_not_expire(bfqq)))) { ++ if (timer_pending(&bfqd->idle_slice_timer) || ++ (bfqq->dispatched != 0 && bfq_bfqq_must_not_expire(bfqq))) { + bfqq = NULL; + goto keep_queue; +- } else if (new_bfqq != NULL && timer_pending(&bfqd->idle_slice_timer)) { +- /* +- * Expiring the queue because there is a close cooperator, +- * cancel timer. +- */ +- bfq_clear_bfqq_wait_request(bfqq); +- del_timer(&bfqd->idle_slice_timer); + } + + reason = BFQ_BFQQ_NO_MORE_REQUESTS; + expire: + bfq_bfqq_expire(bfqd, bfqq, 0, reason); + new_queue: +- bfqq = bfq_set_in_service_queue(bfqd, new_bfqq); ++ bfqq = bfq_set_in_service_queue(bfqd); + bfq_log(bfqd, "select_queue: new queue %d returned", + bfqq != NULL ? bfqq->pid : 0); + keep_queue: + return bfqq; + } + +-static void bfq_update_wr_data(struct bfq_data *bfqd, +- struct bfq_queue *bfqq) ++static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq) + { +- if (bfqq->wr_coeff > 1) { /* queue is being boosted */ +- struct bfq_entity *entity = &bfqq->entity; +- ++ struct bfq_entity *entity = &bfqq->entity; ++ if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */ + bfq_log_bfqq(bfqd, bfqq, + "raising period dur %u/%u msec, old coeff %u, w %d(%d)", +- jiffies_to_msecs(jiffies - +- bfqq->last_wr_start_finish), ++ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish), + jiffies_to_msecs(bfqq->wr_cur_max_time), + bfqq->wr_coeff, + bfqq->entity.weight, bfqq->entity.orig_weight); +@@ -2376,12 +2611,16 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, + entity->orig_weight * bfqq->wr_coeff); + if (entity->ioprio_changed) + bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change"); ++ + /* + * If the queue was activated in a burst, or + * too much time has elapsed from the beginning +- * of this weight-raising, then end weight raising. ++ * of this weight-raising period, or the queue has ++ * exceeded the acceptable number of cooperations, ++ * then end weight raising. + */ + if (bfq_bfqq_in_large_burst(bfqq) || ++ bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh || + time_is_before_jiffies(bfqq->last_wr_start_finish + + bfqq->wr_cur_max_time)) { + bfqq->last_wr_start_finish = jiffies; +@@ -2390,11 +2629,13 @@ static void bfq_update_wr_data(struct bfq_data *bfqd, + bfqq->last_wr_start_finish, + jiffies_to_msecs(bfqq->wr_cur_max_time)); + bfq_bfqq_end_wr(bfqq); +- __bfq_entity_update_weight_prio( +- bfq_entity_service_tree(entity), +- entity); + } + } ++ /* Update weight both if it must be raised and if it must be lowered */ ++ if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1)) ++ __bfq_entity_update_weight_prio( ++ bfq_entity_service_tree(entity), ++ entity); + } + + /* +@@ -2642,6 +2883,25 @@ static inline void bfq_init_icq(struct io_cq *icq) + struct bfq_io_cq *bic = icq_to_bic(icq); + + bic->ttime.last_end_request = jiffies; ++ /* ++ * A newly created bic indicates that the process has just ++ * started doing I/O, and is probably mapping into memory its ++ * executable and libraries: it definitely needs weight raising. ++ * There is however the possibility that the process performs, ++ * for a while, I/O close to some other process. EQM intercepts ++ * this behavior and may merge the queue corresponding to the ++ * process with some other queue, BEFORE the weight of the queue ++ * is raised. Merged queues are not weight-raised (they are assumed ++ * to belong to processes that benefit only from high throughput). ++ * If the merge is basically the consequence of an accident, then ++ * the queue will be split soon and will get back its old weight. ++ * It is then important to write down somewhere that this queue ++ * does need weight raising, even if it did not make it to get its ++ * weight raised before being merged. To this purpose, we overload ++ * the field raising_time_left and assign 1 to it, to mark the queue ++ * as needing weight raising. ++ */ ++ bic->wr_time_left = 1; + } + + static void bfq_exit_icq(struct io_cq *icq) +@@ -2655,6 +2915,13 @@ static void bfq_exit_icq(struct io_cq *icq) + } + + if (bic->bfqq[BLK_RW_SYNC]) { ++ /* ++ * If the bic is using a shared queue, put the reference ++ * taken on the io_context when the bic started using a ++ * shared bfq_queue. ++ */ ++ if (bfq_bfqq_coop(bic->bfqq[BLK_RW_SYNC])) ++ put_io_context(icq->ioc); + bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_SYNC]); + bic->bfqq[BLK_RW_SYNC] = NULL; + } +@@ -2950,6 +3217,10 @@ static void bfq_update_idle_window(struct bfq_data *bfqd, + if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq)) + return; + ++ /* Idle window just restored, statistics are meaningless. */ ++ if (bfq_bfqq_just_split(bfqq)) ++ return; ++ + enable_idle = bfq_bfqq_idle_window(bfqq); + + if (atomic_read(&bic->icq.ioc->active_ref) == 0 || +@@ -2997,6 +3268,7 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, + if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 || + !BFQQ_SEEKY(bfqq)) + bfq_update_idle_window(bfqd, bfqq, bic); ++ bfq_clear_bfqq_just_split(bfqq); + + bfq_log_bfqq(bfqd, bfqq, + "rq_enqueued: idle_window=%d (seeky %d, mean %llu)", +@@ -3057,13 +3329,49 @@ static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq, + static void bfq_insert_request(struct request_queue *q, struct request *rq) + { + struct bfq_data *bfqd = q->elevator->elevator_data; +- struct bfq_queue *bfqq = RQ_BFQQ(rq); ++ struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq; + + assert_spin_locked(bfqd->queue->queue_lock); ++ ++ /* ++ * An unplug may trigger a requeue of a request from the device ++ * driver: make sure we are in process context while trying to ++ * merge two bfq_queues. ++ */ ++ if (!in_interrupt()) { ++ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true); ++ if (new_bfqq != NULL) { ++ if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq) ++ new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1); ++ /* ++ * Release the request's reference to the old bfqq ++ * and make sure one is taken to the shared queue. ++ */ ++ new_bfqq->allocated[rq_data_dir(rq)]++; ++ bfqq->allocated[rq_data_dir(rq)]--; ++ atomic_inc(&new_bfqq->ref); ++ bfq_put_queue(bfqq); ++ if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq) ++ bfq_merge_bfqqs(bfqd, RQ_BIC(rq), ++ bfqq, new_bfqq); ++ rq->elv.priv[1] = new_bfqq; ++ bfqq = new_bfqq; ++ } else ++ bfq_bfqq_increase_failed_cooperations(bfqq); ++ } ++ + bfq_init_prio_data(bfqq, RQ_BIC(rq)); + + bfq_add_request(rq); + ++ /* ++ * Here a newly-created bfq_queue has already started a weight-raising ++ * period: clear raising_time_left to prevent bfq_bfqq_save_state() ++ * from assigning it a full weight-raising period. See the detailed ++ * comments about this field in bfq_init_icq(). ++ */ ++ if (bfqq->bic != NULL) ++ bfqq->bic->wr_time_left = 0; + rq->fifo_time = jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)]; + list_add_tail(&rq->queuelist, &bfqq->fifo); + +@@ -3228,18 +3536,6 @@ static void bfq_put_request(struct request *rq) + } + } + +-static struct bfq_queue * +-bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic, +- struct bfq_queue *bfqq) +-{ +- bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu", +- (long unsigned)bfqq->new_bfqq->pid); +- bic_set_bfqq(bic, bfqq->new_bfqq, 1); +- bfq_mark_bfqq_coop(bfqq->new_bfqq); +- bfq_put_queue(bfqq); +- return bic_to_bfqq(bic, 1); +-} +- + /* + * Returns NULL if a new bfqq should be allocated, or the old bfqq if this + * was the last process referring to said bfqq. +@@ -3248,6 +3544,9 @@ static struct bfq_queue * + bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq) + { + bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue"); ++ ++ put_io_context(bic->icq.ioc); ++ + if (bfqq_process_refs(bfqq) == 1) { + bfqq->pid = current->pid; + bfq_clear_bfqq_coop(bfqq); +@@ -3276,6 +3575,7 @@ static int bfq_set_request(struct request_queue *q, struct request *rq, + struct bfq_queue *bfqq; + struct bfq_group *bfqg; + unsigned long flags; ++ bool split = false; + + might_sleep_if(gfp_mask & __GFP_WAIT); + +@@ -3293,25 +3593,26 @@ new_queue: + if (bfqq == NULL || bfqq == &bfqd->oom_bfqq) { + bfqq = bfq_get_queue(bfqd, bfqg, is_sync, bic, gfp_mask); + bic_set_bfqq(bic, bfqq, is_sync); ++ if (split && is_sync) { ++ if ((bic->was_in_burst_list && bfqd->large_burst) || ++ bic->saved_in_large_burst) ++ bfq_mark_bfqq_in_large_burst(bfqq); ++ else { ++ bfq_clear_bfqq_in_large_burst(bfqq); ++ if (bic->was_in_burst_list) ++ hlist_add_head(&bfqq->burst_list_node, ++ &bfqd->burst_list); ++ } ++ } + } else { +- /* +- * If the queue was seeky for too long, break it apart. +- */ ++ /* If the queue was seeky for too long, break it apart. */ + if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) { + bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq"); + bfqq = bfq_split_bfqq(bic, bfqq); ++ split = true; + if (!bfqq) + goto new_queue; + } +- +- /* +- * Check to see if this queue is scheduled to merge with +- * another closely cooperating queue. The merging of queues +- * happens here as it must be done in process context. +- * The reference on new_bfqq was taken in merge_bfqqs. +- */ +- if (bfqq->new_bfqq != NULL) +- bfqq = bfq_merge_bfqqs(bfqd, bic, bfqq); + } + + bfqq->allocated[rw]++; +@@ -3322,6 +3623,26 @@ new_queue: + rq->elv.priv[0] = bic; + rq->elv.priv[1] = bfqq; + ++ /* ++ * If a bfq_queue has only one process reference, it is owned ++ * by only one bfq_io_cq: we can set the bic field of the ++ * bfq_queue to the address of that structure. Also, if the ++ * queue has just been split, mark a flag so that the ++ * information is available to the other scheduler hooks. ++ */ ++ if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) { ++ bfqq->bic = bic; ++ if (split) { ++ bfq_mark_bfqq_just_split(bfqq); ++ /* ++ * If the queue has just been split from a shared ++ * queue, restore the idle window and the possible ++ * weight raising period. ++ */ ++ bfq_bfqq_resume_state(bfqq, bic); ++ } ++ } ++ + spin_unlock_irqrestore(q->queue_lock, flags); + + return 0; +diff --git a/block/bfq-sched.c b/block/bfq-sched.c +index 2931563..6764a7e 100644 +--- a/block/bfq-sched.c ++++ b/block/bfq-sched.c +@@ -1091,34 +1091,6 @@ static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd) + return bfqq; + } + +-/* +- * Forced extraction of the given queue. +- */ +-static void bfq_get_next_queue_forced(struct bfq_data *bfqd, +- struct bfq_queue *bfqq) +-{ +- struct bfq_entity *entity; +- struct bfq_sched_data *sd; +- +- BUG_ON(bfqd->in_service_queue != NULL); +- +- entity = &bfqq->entity; +- /* +- * Bubble up extraction/update from the leaf to the root. +- */ +- for_each_entity(entity) { +- sd = entity->sched_data; +- bfq_update_budget(entity); +- bfq_update_vtime(bfq_entity_service_tree(entity)); +- bfq_active_extract(bfq_entity_service_tree(entity), entity); +- sd->in_service_entity = entity; +- sd->next_in_service = NULL; +- entity->service = 0; +- } +- +- return; +-} +- + static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd) + { + if (bfqd->in_service_bic != NULL) { +diff --git a/block/bfq.h b/block/bfq.h +index 518f2ac..4f519ea 100644 +--- a/block/bfq.h ++++ b/block/bfq.h +@@ -218,18 +218,21 @@ struct bfq_group; + * idle @bfq_queue with no outstanding requests, then + * the task associated with the queue it is deemed as + * soft real-time (see the comments to the function +- * bfq_bfqq_softrt_next_start()). ++ * bfq_bfqq_softrt_next_start()) + * @last_idle_bklogged: time of the last transition of the @bfq_queue from + * idle to backlogged + * @service_from_backlogged: cumulative service received from the @bfq_queue + * since the last transition from idle to + * backlogged ++ * @bic: pointer to the bfq_io_cq owning the bfq_queue, set to %NULL if the ++ * queue is shared + * +- * A bfq_queue is a leaf request queue; it can be associated with an io_context +- * or more, if it is async or shared between cooperating processes. @cgroup +- * holds a reference to the cgroup, to be sure that it does not disappear while +- * a bfqq still references it (mostly to avoid races between request issuing and +- * task migration followed by cgroup destruction). ++ * A bfq_queue is a leaf request queue; it can be associated with an ++ * io_context or more, if it is async or shared between cooperating ++ * processes. @cgroup holds a reference to the cgroup, to be sure that it ++ * does not disappear while a bfqq still references it (mostly to avoid ++ * races between request issuing and task migration followed by cgroup ++ * destruction). + * All the fields are protected by the queue lock of the containing bfqd. + */ + struct bfq_queue { +@@ -269,6 +272,7 @@ struct bfq_queue { + unsigned int requests_within_timer; + + pid_t pid; ++ struct bfq_io_cq *bic; + + /* weight-raising fields */ + unsigned long wr_cur_max_time; +@@ -298,12 +302,42 @@ struct bfq_ttime { + * @icq: associated io_cq structure + * @bfqq: array of two process queues, the sync and the async + * @ttime: associated @bfq_ttime struct ++ * @wr_time_left: snapshot of the time left before weight raising ends ++ * for the sync queue associated to this process; this ++ * snapshot is taken to remember this value while the weight ++ * raising is suspended because the queue is merged with a ++ * shared queue, and is used to set @raising_cur_max_time ++ * when the queue is split from the shared queue and its ++ * weight is raised again ++ * @saved_idle_window: same purpose as the previous field for the idle ++ * window ++ * @saved_IO_bound: same purpose as the previous two fields for the I/O ++ * bound classification of a queue ++ * @saved_in_large_burst: same purpose as the previous fields for the ++ * value of the field keeping the queue's belonging ++ * to a large burst ++ * @was_in_burst_list: true if the queue belonged to a burst list ++ * before its merge with another cooperating queue ++ * @cooperations: counter of consecutive successful queue merges underwent ++ * by any of the process' @bfq_queues ++ * @failed_cooperations: counter of consecutive failed queue merges of any ++ * of the process' @bfq_queues + */ + struct bfq_io_cq { + struct io_cq icq; /* must be the first member */ + struct bfq_queue *bfqq[2]; + struct bfq_ttime ttime; + int ioprio; ++ ++ unsigned int wr_time_left; ++ bool saved_idle_window; ++ bool saved_IO_bound; ++ ++ bool saved_in_large_burst; ++ bool was_in_burst_list; ++ ++ unsigned int cooperations; ++ unsigned int failed_cooperations; + }; + + enum bfq_device_speed { +@@ -539,7 +573,7 @@ enum bfqq_state_flags { + BFQ_BFQQ_FLAG_prio_changed, /* task priority has changed */ + BFQ_BFQQ_FLAG_sync, /* synchronous queue */ + BFQ_BFQQ_FLAG_budget_new, /* no completion with this budget */ +- BFQ_BFQQ_FLAG_IO_bound, /* ++ BFQ_BFQQ_FLAG_IO_bound, /* + * bfqq has timed-out at least once + * having consumed at most 2/10 of + * its budget +@@ -552,12 +586,13 @@ enum bfqq_state_flags { + * bfqq has proved to be slow and + * seeky until budget timeout + */ +- BFQ_BFQQ_FLAG_softrt_update, /* ++ BFQ_BFQQ_FLAG_softrt_update, /* + * may need softrt-next-start + * update + */ + BFQ_BFQQ_FLAG_coop, /* bfqq is shared */ +- BFQ_BFQQ_FLAG_split_coop, /* shared bfqq will be splitted */ ++ BFQ_BFQQ_FLAG_split_coop, /* shared bfqq will be split */ ++ BFQ_BFQQ_FLAG_just_split, /* queue has just been split */ + }; + + #define BFQ_BFQQ_FNS(name) \ +@@ -587,6 +622,7 @@ BFQ_BFQQ_FNS(in_large_burst); + BFQ_BFQQ_FNS(constantly_seeky); + BFQ_BFQQ_FNS(coop); + BFQ_BFQQ_FNS(split_coop); ++BFQ_BFQQ_FNS(just_split); + BFQ_BFQQ_FNS(softrt_update); + #undef BFQ_BFQQ_FNS + +-- +2.1.0 + -- cgit v1.2.3-65-gdbad