diff options
| -rw-r--r-- | block/Makefile | 3 | ||||
| -rw-r--r-- | block/bfq-cgroup.c | 1139 | ||||
| -rw-r--r-- | block/bfq-iosched.c | 3663 | ||||
| -rw-r--r-- | block/bfq-iosched.h | 942 | ||||
| -rw-r--r-- | block/bfq-wf2q.c | 1616 |
5 files changed, 3738 insertions, 3625 deletions
diff --git a/block/Makefile b/block/Makefile index 4c1d68cb49dd..2b281cf258a0 100644 --- a/block/Makefile +++ b/block/Makefile @@ -21,7 +21,8 @@ obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o obj-$(CONFIG_MQ_IOSCHED_DEADLINE) += mq-deadline.o obj-$(CONFIG_MQ_IOSCHED_KYBER) += kyber-iosched.o -obj-$(CONFIG_IOSCHED_BFQ) += bfq-iosched.o +bfq-y := bfq-iosched.o bfq-wf2q.o bfq-cgroup.o +obj-$(CONFIG_IOSCHED_BFQ) += bfq.o obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o obj-$(CONFIG_BLK_CMDLINE_PARSER) += cmdline-parser.o diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c new file mode 100644 index 000000000000..c8a32fb345cf --- /dev/null +++ b/block/bfq-cgroup.c @@ -0,0 +1,1139 @@ +/* + * cgroups support for the BFQ I/O scheduler. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/blkdev.h> +#include <linux/cgroup.h> +#include <linux/elevator.h> +#include <linux/ktime.h> +#include <linux/rbtree.h> +#include <linux/ioprio.h> +#include <linux/sbitmap.h> +#include <linux/delay.h> + +#include "bfq-iosched.h" + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + +/* bfqg stats flags */ +enum bfqg_stats_flags { + BFQG_stats_waiting = 0, + BFQG_stats_idling, + BFQG_stats_empty, +}; + +#define BFQG_FLAG_FNS(name) \ +static void bfqg_stats_mark_##name(struct bfqg_stats *stats) \ +{ \ + stats->flags |= (1 << BFQG_stats_##name); \ +} \ +static void bfqg_stats_clear_##name(struct bfqg_stats *stats) \ +{ \ + stats->flags &= ~(1 << BFQG_stats_##name); \ +} \ +static int bfqg_stats_##name(struct bfqg_stats *stats) \ +{ \ + return (stats->flags & (1 << BFQG_stats_##name)) != 0; \ +} \ + +BFQG_FLAG_FNS(waiting) +BFQG_FLAG_FNS(idling) +BFQG_FLAG_FNS(empty) +#undef BFQG_FLAG_FNS + +/* This should be called with the queue_lock held. */ +static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats) +{ + unsigned long long now; + + if (!bfqg_stats_waiting(stats)) + return; + + now = sched_clock(); + if (time_after64(now, stats->start_group_wait_time)) + blkg_stat_add(&stats->group_wait_time, + now - stats->start_group_wait_time); + bfqg_stats_clear_waiting(stats); +} + +/* This should be called with the queue_lock held. */ +static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, + struct bfq_group *curr_bfqg) +{ + struct bfqg_stats *stats = &bfqg->stats; + + if (bfqg_stats_waiting(stats)) + return; + if (bfqg == curr_bfqg) + return; + stats->start_group_wait_time = sched_clock(); + bfqg_stats_mark_waiting(stats); +} + +/* This should be called with the queue_lock held. */ +static void bfqg_stats_end_empty_time(struct bfqg_stats *stats) +{ + unsigned long long now; + + if (!bfqg_stats_empty(stats)) + return; + + now = sched_clock(); + if (time_after64(now, stats->start_empty_time)) + blkg_stat_add(&stats->empty_time, + now - stats->start_empty_time); + bfqg_stats_clear_empty(stats); +} + +void bfqg_stats_update_dequeue(struct bfq_group *bfqg) +{ + blkg_stat_add(&bfqg->stats.dequeue, 1); +} + +void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) +{ + struct bfqg_stats *stats = &bfqg->stats; + + if (blkg_rwstat_total(&stats->queued)) + return; + + /* + * group is already marked empty. This can happen if bfqq got new + * request in parent group and moved to this group while being added + * to service tree. Just ignore the event and move on. + */ + if (bfqg_stats_empty(stats)) + return; + + stats->start_empty_time = sched_clock(); + bfqg_stats_mark_empty(stats); +} + +void bfqg_stats_update_idle_time(struct bfq_group *bfqg) +{ + struct bfqg_stats *stats = &bfqg->stats; + + if (bfqg_stats_idling(stats)) { + unsigned long long now = sched_clock(); + + if (time_after64(now, stats->start_idle_time)) + blkg_stat_add(&stats->idle_time, + now - stats->start_idle_time); + bfqg_stats_clear_idling(stats); + } +} + +void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) +{ + struct bfqg_stats *stats = &bfqg->stats; + + stats->start_idle_time = sched_clock(); + bfqg_stats_mark_idling(stats); +} + +void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) +{ + struct bfqg_stats *stats = &bfqg->stats; + + blkg_stat_add(&stats->avg_queue_size_sum, + blkg_rwstat_total(&stats->queued)); + blkg_stat_add(&stats->avg_queue_size_samples, 1); + bfqg_stats_update_group_wait_time(stats); +} + +/* + * blk-cgroup policy-related handlers + * The following functions help in converting between blk-cgroup + * internal structures and BFQ-specific structures. + */ + +static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd) +{ + return pd ? container_of(pd, struct bfq_group, pd) : NULL; +} + +struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg) +{ + return pd_to_blkg(&bfqg->pd); +} + +static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg) +{ + return pd_to_bfqg(blkg_to_pd(blkg, &blkcg_policy_bfq)); +} + +/* + * bfq_group handlers + * The following functions help in navigating the bfq_group hierarchy + * by allowing to find the parent of a bfq_group or the bfq_group + * associated to a bfq_queue. + */ + +static struct bfq_group *bfqg_parent(struct bfq_group *bfqg) +{ + struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent; + + return pblkg ? blkg_to_bfqg(pblkg) : NULL; +} + +struct bfq_group *bfqq_group(struct bfq_queue *bfqq) +{ + struct bfq_entity *group_entity = bfqq->entity.parent; + + return group_entity ? container_of(group_entity, struct bfq_group, + entity) : + bfqq->bfqd->root_group; +} + +/* + * The following two functions handle get and put of a bfq_group by + * wrapping the related blk-cgroup hooks. + */ + +static void bfqg_get(struct bfq_group *bfqg) +{ + return blkg_get(bfqg_to_blkg(bfqg)); +} + +void bfqg_put(struct bfq_group *bfqg) +{ + return blkg_put(bfqg_to_blkg(bfqg)); +} + +void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq, + unsigned int op) +{ + blkg_rwstat_add(&bfqg->stats.queued, op, 1); + bfqg_stats_end_empty_time(&bfqg->stats); + if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue)) + bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq)); +} + +void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) +{ + blkg_rwstat_add(&bfqg->stats.queued, op, -1); +} + +void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) +{ + blkg_rwstat_add(&bfqg->stats.merged, op, 1); +} + +void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time, + uint64_t io_start_time, unsigned int op) +{ + struct bfqg_stats *stats = &bfqg->stats; + unsigned long long now = sched_clock(); + + if (time_after64(now, io_start_time)) + blkg_rwstat_add(&stats->service_time, op, + now - io_start_time); + if (time_after64(io_start_time, start_time)) + blkg_rwstat_add(&stats->wait_time, op, + io_start_time - start_time); +} + +/* @stats = 0 */ +static void bfqg_stats_reset(struct bfqg_stats *stats) +{ + /* queued stats shouldn't be cleared */ + blkg_rwstat_reset(&stats->merged); + blkg_rwstat_reset(&stats->service_time); + blkg_rwstat_reset(&stats->wait_time); + blkg_stat_reset(&stats->time); + blkg_stat_reset(&stats->avg_queue_size_sum); + blkg_stat_reset(&stats->avg_queue_size_samples); + blkg_stat_reset(&stats->dequeue); + blkg_stat_reset(&stats->group_wait_time); + blkg_stat_reset(&stats->idle_time); + blkg_stat_reset(&stats->empty_time); +} + +/* @to += @from */ +static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from) +{ + if (!to || !from) + return; + + /* queued stats shouldn't be cleared */ + blkg_rwstat_add_aux(&to->merged, &from->merged); + blkg_rwstat_add_aux(&to->service_time, &from->service_time); + blkg_rwstat_add_aux(&to->wait_time, &from->wait_time); + blkg_stat_add_aux(&from->time, &from->time); + blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum); + blkg_stat_add_aux(&to->avg_queue_size_samples, + &from->avg_queue_size_samples); + blkg_stat_add_aux(&to->dequeue, &from->dequeue); + blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time); + blkg_stat_add_aux(&to->idle_time, &from->idle_time); + blkg_stat_add_aux(&to->empty_time, &from->empty_time); +} + +/* + * Transfer @bfqg's stats to its parent's aux counts so that the ancestors' + * recursive stats can still account for the amount used by this bfqg after + * it's gone. + */ +static void bfqg_stats_xfer_dead(struct bfq_group *bfqg) +{ + struct bfq_group *parent; + + if (!bfqg) /* root_group */ + return; + + parent = bfqg_parent(bfqg); + + lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock); + + if (unlikely(!parent)) + return; + + bfqg_stats_add_aux(&parent->stats, &bfqg->stats); + bfqg_stats_reset(&bfqg->stats); +} + +void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + entity->weight = entity->new_weight; + entity->orig_weight = entity->new_weight; + if (bfqq) { + bfqq->ioprio = bfqq->new_ioprio; + bfqq->ioprio_class = bfqq->new_ioprio_class; + bfqg_get(bfqg); + } + entity->parent = bfqg->my_entity; /* NULL for root group */ + entity->sched_data = &bfqg->sched_data; +} + +static void bfqg_stats_exit(struct bfqg_stats *stats) +{ + blkg_rwstat_exit(&stats->merged); + blkg_rwstat_exit(&stats->service_time); + blkg_rwstat_exit(&stats->wait_time); + blkg_rwstat_exit(&stats->queued); + blkg_stat_exit(&stats->time); + blkg_stat_exit(&stats->avg_queue_size_sum); + blkg_stat_exit(&stats->avg_queue_size_samples); + blkg_stat_exit(&stats->dequeue); + blkg_stat_exit(&stats->group_wait_time); + blkg_stat_exit(&stats->idle_time); + blkg_stat_exit(&stats->empty_time); +} + +static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) +{ + if (blkg_rwstat_init(&stats->merged, gfp) || + blkg_rwstat_init(&stats->service_time, gfp) || + blkg_rwstat_init(&stats->wait_time, gfp) || + blkg_rwstat_init(&stats->queued, gfp) || + blkg_stat_init(&stats->time, gfp) || + blkg_stat_init(&stats->avg_queue_size_sum, gfp) || + blkg_stat_init(&stats->avg_queue_size_samples, gfp) || + blkg_stat_init(&stats->dequeue, gfp) || + blkg_stat_init(&stats->group_wait_time, gfp) || + blkg_stat_init(&stats->idle_time, gfp) || + blkg_stat_init(&stats->empty_time, gfp)) { + bfqg_stats_exit(stats); + return -ENOMEM; + } + + return 0; +} + +static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd) +{ + return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL; +} + +static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg) +{ + return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq)); +} + +struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp) +{ + struct bfq_group_data *bgd; + + bgd = kzalloc(sizeof(*bgd), gfp); + if (!bgd) + return NULL; + return &bgd->pd; +} + +void bfq_cpd_init(struct blkcg_policy_data *cpd) +{ + struct bfq_group_data *d = cpd_to_bfqgd(cpd); + + d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ? + CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL; +} + +void bfq_cpd_free(struct blkcg_policy_data *cpd) +{ + kfree(cpd_to_bfqgd(cpd)); +} + +struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node) +{ + struct bfq_group *bfqg; + + bfqg = kzalloc_node(sizeof(*bfqg), gfp, node); + if (!bfqg) + return NULL; + + if (bfqg_stats_init(&bfqg->stats, gfp)) { + kfree(bfqg); + return NULL; + } + + return &bfqg->pd; +} + +void bfq_pd_init(struct blkg_policy_data *pd) +{ + struct blkcg_gq *blkg = pd_to_blkg(pd); + struct bfq_group *bfqg = blkg_to_bfqg(blkg); + struct bfq_data *bfqd = blkg->q->elevator->elevator_data; + struct bfq_entity *entity = &bfqg->entity; + struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg); + + entity->orig_weight = entity->weight = entity->new_weight = d->weight; + entity->my_sched_data = &bfqg->sched_data; + bfqg->my_entity = entity; /* + * the root_group's will be set to NULL + * in bfq_init_queue() + */ + bfqg->bfqd = bfqd; + bfqg->active_entities = 0; + bfqg->rq_pos_tree = RB_ROOT; +} + +void bfq_pd_free(struct blkg_policy_data *pd) +{ + struct bfq_group *bfqg = pd_to_bfqg(pd); + + bfqg_stats_exit(&bfqg->stats); + return kfree(bfqg); +} + +void bfq_pd_reset_stats(struct blkg_policy_data *pd) +{ + struct bfq_group *bfqg = pd_to_bfqg(pd); + + bfqg_stats_reset(&bfqg->stats); +} + +static void bfq_group_set_parent(struct bfq_group *bfqg, + struct bfq_group *parent) +{ + struct bfq_entity *entity; + + entity = &bfqg->entity; + entity->parent = parent->my_entity; + entity->sched_data = &parent->sched_data; +} + +static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd, + struct blkcg *blkcg) +{ + struct blkcg_gq *blkg; + + blkg = blkg_lookup(blkcg, bfqd->queue); + if (likely(blkg)) + return blkg_to_bfqg(blkg); + return NULL; +} + +struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, + struct blkcg *blkcg) +{ + struct bfq_group *bfqg, *parent; + struct bfq_entity *entity; + + bfqg = bfq_lookup_bfqg(bfqd, blkcg); + + if (unlikely(!bfqg)) + return NULL; + + /* + * Update chain of bfq_groups as we might be handling a leaf group + * which, along with some of its relatives, has not been hooked yet + * to the private hierarchy of BFQ. + */ + entity = &bfqg->entity; + for_each_entity(entity) { + bfqg = container_of(entity, struct bfq_group, entity); + if (bfqg != bfqd->root_group) { + parent = bfqg_parent(bfqg); + if (!parent) + parent = bfqd->root_group; + bfq_group_set_parent(bfqg, parent); + } + } + + return bfqg; +} + +/** + * bfq_bfqq_move - migrate @bfqq to @bfqg. + * @bfqd: queue descriptor. + * @bfqq: the queue to move. + * @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()). + */ +void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, + struct bfq_group *bfqg) +{ + struct bfq_entity *entity = &bfqq->entity; + + /* If bfqq is empty, then bfq_bfqq_expire also invokes + * bfq_del_bfqq_busy, thereby removing bfqq and its entity + * from data structures related to current group. Otherwise we + * need to remove bfqq explicitly with bfq_deactivate_bfqq, as + * we do below. + */ + if (bfqq == bfqd->in_service_queue) + bfq_bfqq_expire(bfqd, bfqd->in_service_queue, + false, BFQQE_PREEMPTED); + + if (bfq_bfqq_busy(bfqq)) + bfq_deactivate_bfqq(bfqd, bfqq, false, false); + else if (entity->on_st) + bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); + bfqg_put(bfqq_group(bfqq)); + + /* + * 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; + bfqg_get(bfqg); + + if (bfq_bfqq_busy(bfqq)) { + bfq_pos_tree_add_move(bfqd, bfqq); + bfq_activate_bfqq(bfqd, bfqq); + } + + if (!bfqd->in_service_queue && !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. + * @blkcg: the blk-cgroup to move to. + * + * Move bic to blkcg, 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 blkcg *blkcg) +{ + struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0); + struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1); + struct bfq_group *bfqg; + struct bfq_entity *entity; + + bfqg = bfq_find_set_group(bfqd, blkcg); + + if (unlikely(!bfqg)) + bfqg = bfqd->root_group; + + if (async_bfqq) { + 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, async_bfqq->ref); + bfq_put_queue(async_bfqq); + } + } + + if (sync_bfqq) { + entity = &sync_bfqq->entity; + if (entity->sched_data != &bfqg->sched_data) + bfq_bfqq_move(bfqd, sync_bfqq, bfqg); + } + + return bfqg; +} + +void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) +{ + struct bfq_data *bfqd = bic_to_bfqd(bic); + struct bfq_group *bfqg = NULL; + uint64_t serial_nr; + + rcu_read_lock(); + serial_nr = bio_blkcg(bio)->css.serial_nr; + + /* + * Check whether blkcg has changed. The condition may trigger + * spuriously on a newly created cic but there's no harm. + */ + if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr)) + goto out; + + bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio)); + bic->blkcg_serial_nr = serial_nr; +out: + rcu_read_unlock(); +} + +/** + * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st. + * @st: the service tree being flushed. + */ +static void bfq_flush_idle_tree(struct bfq_service_tree *st) +{ + struct bfq_entity *entity = st->first_idle; + + for (; entity ; entity = st->first_idle) + __bfq_deactivate_entity(entity, false); +} + +/** + * 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 void bfq_reparent_leaf_entity(struct bfq_data *bfqd, + struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + bfq_bfqq_move(bfqd, bfqq, bfqd->root_group); +} + +/** + * 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 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 ; entity = bfq_entity_of(rb_first(active))) + bfq_reparent_leaf_entity(bfqd, entity); + + if (bfqg->sched_data.in_service_entity) + bfq_reparent_leaf_entity(bfqd, + bfqg->sched_data.in_service_entity); +} + +/** + * bfq_pd_offline - deactivate the entity associated with @pd, + * and reparent its children entities. + * @pd: descriptor of the policy going offline. + * + * blkio already grabs the queue_lock for us, so no need to use + * RCU-based magic + */ +void bfq_pd_offline(struct blkg_policy_data *pd) +{ + struct bfq_service_tree *st; + struct bfq_group *bfqg = pd_to_bfqg(pd); + struct bfq_data *bfqd = bfqg->bfqd; + struct bfq_entity *entity = bfqg->my_entity; + unsigned long flags; + int i; + + if (!entity) /* root group */ + return; + + spin_lock_irqsave(&bfqd->lock, flags); + /* + * 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. + */ + bfq_reparent_active_entities(bfqd, bfqg, st); + } + + __bfq_deactivate_entity(entity, false); + bfq_put_async_queues(bfqd, bfqg); + + spin_unlock_irqrestore(&bfqd->lock, flags); + /* + * @blkg is going offline and will be ignored by + * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so + * that they don't get lost. If IOs complete after this point, the + * stats for them will be lost. Oh well... + */ + bfqg_stats_xfer_dead(bfqg); +} + +void bfq_end_wr_async(struct bfq_data *bfqd) +{ + struct blkcg_gq *blkg; + + list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) { + struct bfq_group *bfqg = blkg_to_bfqg(blkg); + + bfq_end_wr_async_queues(bfqd, bfqg); + } + bfq_end_wr_async_queues(bfqd, bfqd->root_group); +} + +static int bfq_io_show_weight(struct seq_file *sf, void *v) +{ + struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); + struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); + unsigned int val = 0; + + if (bfqgd) + val = bfqgd->weight; + + seq_printf(sf, "%u\n", val); + + return 0; +} + +static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, + struct cftype *cftype, + u64 val) +{ + struct blkcg *blkcg = css_to_blkcg(css); + struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); + struct blkcg_gq *blkg; + int ret = -ERANGE; + + if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) + return ret; + + ret = 0; + spin_lock_irq(&blkcg->lock); + bfqgd->weight = (unsigned short)val; + hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { + struct bfq_group *bfqg = blkg_to_bfqg(blkg); + + if (!bfqg) + continue; + /* + * Setting the prio_changed flag of the entity + * to 1 with new_weight == weight 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_weight) { + bfqg->entity.new_weight = (unsigned short)val; + /* + * Make sure that the above new value has been + * stored in bfqg->entity.new_weight before + * setting the prio_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_weight (in + * __bfq_entity_update_weight_prio). + * This barrier makes sure that the new value + * of bfqg->entity.new_weight is correctly + * seen in that code. + */ + smp_wmb(); + bfqg->entity.prio_changed = 1; + } + } + spin_unlock_irq(&blkcg->lock); + + return ret; +} + +static ssize_t bfq_io_set_weight(struct kernfs_open_file *of, + char *buf, size_t nbytes, + loff_t off) +{ + u64 weight; + /* First unsigned long found in the file is used */ + int ret = kstrtoull(strim(buf), 0, &weight); + + if (ret) + return ret; + + return bfq_io_set_weight_legacy(of_css(of), NULL, weight); +} + +static int bfqg_print_stat(struct seq_file *sf, void *v) +{ + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat, + &blkcg_policy_bfq, seq_cft(sf)->private, false); + return 0; +} + +static int bfqg_print_rwstat(struct seq_file *sf, void *v) +{ + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat, + &blkcg_policy_bfq, seq_cft(sf)->private, true); + return 0; +} + +static u64 bfqg_prfill_stat_recursive(struct seq_file *sf, + struct blkg_policy_data *pd, int off) +{ + u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd), + &blkcg_policy_bfq, off); + return __blkg_prfill_u64(sf, pd, sum); +} + +static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf, + struct blkg_policy_data *pd, int off) +{ + struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd), + &blkcg_policy_bfq, + off); + return __blkg_prfill_rwstat(sf, pd, &sum); +} + +static int bfqg_print_stat_recursive(struct seq_file *sf, void *v) +{ + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + bfqg_prfill_stat_recursive, &blkcg_policy_bfq, + seq_cft(sf)->private, false); + return 0; +} + +static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v) +{ + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq, + seq_cft(sf)->private, true); + return 0; +} + +static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd, + int off) +{ + u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes); + + return __blkg_prfill_u64(sf, pd, sum >> 9); +} + +static int bfqg_print_stat_sectors(struct seq_file *sf, void *v) +{ + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false); + return 0; +} + +static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf, + struct blkg_policy_data *pd, int off) +{ + struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL, + offsetof(struct blkcg_gq, stat_bytes)); + u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) + + atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]); + + return __blkg_prfill_u64(sf, pd, sum >> 9); +} + +static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v) +{ + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0, + false); + return 0; +} + +static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf, + struct blkg_policy_data *pd, int off) +{ + struct bfq_group *bfqg = pd_to_bfqg(pd); + u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples); + u64 v = 0; + + if (samples) { + v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum); + v = div64_u64(v, samples); + } + __blkg_prfill_u64(sf, pd, v); + return 0; +} + +/* print avg_queue_size */ +static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v) +{ + blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), + bfqg_prfill_avg_queue_size, &blkcg_policy_bfq, + 0, false); + return 0; +} + +struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) +{ + int ret; + + ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq); + if (ret) + return NULL; + + return blkg_to_bfqg(bfqd->queue->root_blkg); +} + +struct blkcg_policy blkcg_policy_bfq = { + .dfl_cftypes = bfq_blkg_files, + .legacy_cftypes = bfq_blkcg_legacy_files, + + .cpd_alloc_fn = bfq_cpd_alloc, + .cpd_init_fn = bfq_cpd_init, + .cpd_bind_fn = bfq_cpd_init, + .cpd_free_fn = bfq_cpd_free, + + .pd_alloc_fn = bfq_pd_alloc, + .pd_init_fn = bfq_pd_init, + .pd_offline_fn = bfq_pd_offline, + .pd_free_fn = bfq_pd_free, + .pd_reset_stats_fn = bfq_pd_reset_stats, +}; + +struct cftype bfq_blkcg_legacy_files[] = { + { + .name = "bfq.weight", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = bfq_io_show_weight, + .write_u64 = bfq_io_set_weight_legacy, + }, + + /* statistics, covers only the tasks in the bfqg */ + { + .name = "bfq.time", + .private = offsetof(struct bfq_group, stats.time), + .seq_show = bfqg_print_stat, + }, + { + .name = "bfq.sectors", + .seq_show = bfqg_print_stat_sectors, + }, + { + .name = "bfq.io_service_bytes", + .private = (unsigned long)&blkcg_policy_bfq, + .seq_show = blkg_print_stat_bytes, + }, + { + .name = "bfq.io_serviced", + .private = (unsigned long)&blkcg_policy_bfq, + .seq_show = blkg_print_stat_ios, + }, + { + .name = "bfq.io_service_time", + .private = offsetof(struct bfq_group, stats.service_time), + .seq_show = bfqg_print_rwstat, + }, + { + .name = "bfq.io_wait_time", + .private = offsetof(struct bfq_group, stats.wait_time), + .seq_show = bfqg_print_rwstat, + }, + { + .name = "bfq.io_merged", + .private = offsetof(struct bfq_group, stats.merged), + .seq_show = bfqg_print_rwstat, + }, + { + .name = "bfq.io_queued", + .private = offsetof(struct bfq_group, stats.queued), + .seq_show = bfqg_print_rwstat, + }, + + /* the same statictics which cover the bfqg and its descendants */ + { + .name = "bfq.time_recursive", + .private = offsetof(struct bfq_group, stats.time), + .seq_show = bfqg_print_stat_recursive, + }, + { + .name = "bfq.sectors_recursive", + .seq_show = bfqg_print_stat_sectors_recursive, + }, + { + .name = "bfq.io_service_bytes_recursive", + .private = (unsigned long)&blkcg_policy_bfq, + .seq_show = blkg_print_stat_bytes_recursive, + }, + { + .name = "bfq.io_serviced_recursive", + .private = (unsigned long)&blkcg_policy_bfq, + .seq_show = blkg_print_stat_ios_recursive, + }, + { + .name = "bfq.io_service_time_recursive", + .private = offsetof(struct bfq_group, stats.service_time), + .seq_show = bfqg_print_rwstat_recursive, + }, + { + .name = "bfq.io_wait_time_recursive", + .private = offsetof(struct bfq_group, stats.wait_time), + .seq_show = bfqg_print_rwstat_recursive, + }, + { + .name = "bfq.io_merged_recursive", + .private = offsetof(struct bfq_group, stats.merged), + .seq_show = bfqg_print_rwstat_recursive, + }, + { + .name = "bfq.io_queued_recursive", + .private = offsetof(struct bfq_group, stats.queued), + .seq_show = bfqg_print_rwstat_recursive, + }, + { + .name = "bfq.avg_queue_size", + .seq_show = bfqg_print_avg_queue_size, + }, + { + .name = "bfq.group_wait_time", + .private = offsetof(struct bfq_group, stats.group_wait_time), + .seq_show = bfqg_print_stat, + }, + { + .name = "bfq.idle_time", + .private = offsetof(struct bfq_group, stats.idle_time), + .seq_show = bfqg_print_stat, + }, + { + .name = "bfq.empty_time", + .private = offsetof(struct bfq_group, stats.empty_time), + .seq_show = bfqg_print_stat, + }, + { + .name = "bfq.dequeue", + .private = offsetof(struct bfq_group, stats.dequeue), + .seq_show = bfqg_print_stat, + }, + { } /* terminate */ +}; + +struct cftype bfq_blkg_files[] = { + { + .name = "bfq.weight", + .flags = CFTYPE_NOT_ON_ROOT, + .seq_show = bfq_io_show_weight, + .write = bfq_io_set_weight, + }, + {} /* terminate */ +}; + +#else /* CONFIG_BFQ_GROUP_IOSCHED */ + +void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq, + unsigned int op) { } +void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { } +void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { } +void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time, + uint64_t io_start_time, unsigned int op) { } +void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { } +void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { } +void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { } +void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { } +void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { } + +void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, + struct bfq_group *bfqg) {} + +void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + entity->weight = entity->new_weight; + entity->orig_weight = entity->new_weight; + if (bfqq) { + bfqq->ioprio = bfqq->new_ioprio; + bfqq->ioprio_class = bfqq->new_ioprio_class; + } + entity->sched_data = &bfqg->sched_data; +} + +void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {} + +void bfq_end_wr_async(struct bfq_data *bfqd) +{ + bfq_end_wr_async_queues(bfqd, bfqd->root_group); +} + +struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, struct blkcg *blkcg) +{ + return bfqd->root_group; +} + +struct bfq_group *bfqq_group(struct bfq_queue *bfqq) +{ + return bfqq->bfqd->root_group; +} + +struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) +{ + struct bfq_group *bfqg; + int i; + + bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node); + if (!bfqg) + return NULL; + + for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) + bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; + + return bfqg; +} +#endif /* CONFIG_BFQ_GROUP_IOSCHED */ diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 30bb8f905733..6d14f18c0d45 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -102,646 +102,18 @@ #include "blk-mq.h" #include "blk-mq-tag.h" #include "blk-mq-sched.h" -#include <linux/blktrace_api.h> -#include <linux/hrtimer.h> -#include <linux/blk-cgroup.h> - -#define BFQ_IOPRIO_CLASSES 3 -#define BFQ_CL_IDLE_TIMEOUT (HZ/5) - -#define BFQ_MIN_WEIGHT 1 -#define BFQ_MAX_WEIGHT 1000 -#define BFQ_WEIGHT_CONVERSION_COEFF 10 - -#define BFQ_DEFAULT_QUEUE_IOPRIO 4 - -#define BFQ_WEIGHT_LEGACY_DFL 100 -#define BFQ_DEFAULT_GRP_IOPRIO 0 -#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE - -/* - * Soft real-time applications are extremely more latency sensitive - * than interactive ones. Over-raise the weight of the former to - * privilege them against the latter. - */ -#define BFQ_SOFTRT_WEIGHT_FACTOR 100 - -struct bfq_entity; - -/** - * struct bfq_service_tree - per ioprio_class service tree. - * - * 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 { - /* tree for active entities (i.e., those backlogged) */ - struct rb_root active; - /* tree for idle entities (i.e., not backlogged, with V <= F_i)*/ - struct rb_root idle; - - /* idle entity with minimum F_i */ - struct bfq_entity *first_idle; - /* idle entity with maximum F_i */ - struct bfq_entity *last_idle; - - /* scheduler virtual time */ - u64 vtime; - /* scheduler weight sum; active and idle entities contribute to it */ - unsigned long wsum; -}; - -/** - * struct bfq_sched_data - multi-class scheduler. - * - * 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. It is used to reduce the number of steps - * needed for each hierarchical-schedule update. - * - * 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 { - /* entity in service */ - struct bfq_entity *in_service_entity; - /* head-of-line entity (see comments above) */ - struct bfq_entity *next_in_service; - /* array of service trees, one per ioprio_class */ - struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; - /* last time CLASS_IDLE was served */ - unsigned long bfq_class_idle_last_service; - -}; - -/** - * struct bfq_weight_counter - counter of the number of all active entities - * with a given weight. - */ -struct bfq_weight_counter { - unsigned int weight; /* weight of the entities this counter refers to */ - unsigned int num_active; /* nr of active entities with this weight */ - /* - * Weights tree member (see bfq_data's @queue_weights_tree and - * @group_weights_tree) - */ - struct rb_node weights_node; -}; - -/** - * struct bfq_entity - schedulable entity. - * - * 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 @prio_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 { - /* service_tree member */ - struct rb_node rb_node; - /* pointer to the weight counter associated with this entity */ - struct bfq_weight_counter *weight_counter; - - /* - * Flag, true if the entity is on a tree (either the active or - * the idle one of its service_tree) or is in service. - */ - bool on_st; - - /* B-WF2Q+ start and finish timestamps [sectors/weight] */ - u64 start, finish; - - /* tree the entity is enqueued into; %NULL if not on a tree */ - struct rb_root *tree; - - /* - * minimum start time of the (active) subtree rooted at this - * entity; used for O(log N) lookups into active trees - */ - u64 min_start; - - /* amount of service received during the last service slot */ - int service; - - /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */ - int budget; - - /* weight of the queue */ - int weight; - /* next weight if a change is in progress */ - int new_weight; - - /* original weight, used to implement weight boosting */ - int orig_weight; - - /* parent entity, for hierarchical scheduling */ - struct bfq_entity *parent; - - /* - * For non-leaf nodes in the hierarchy, the associated - * scheduler queue, %NULL on leaf nodes. - */ - struct bfq_sched_data *my_sched_data; - /* the scheduler queue this entity belongs to */ - struct bfq_sched_data *sched_data; - - /* flag, set to request a weight, ioprio or ioprio_class change */ - int prio_changed; -}; - -struct bfq_group; - -/** - * struct bfq_ttime - per process thinktime stats. - */ -struct bfq_ttime { - /* completion time of the last request */ - u64 last_end_request; - - /* total process thinktime */ - u64 ttime_total; - /* number of thinktime samples */ - unsigned long ttime_samples; - /* average process thinktime */ - u64 ttime_mean; -}; - -/** - * struct bfq_queue - leaf schedulable entity. - * - * 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 { - /* reference counter */ - int ref; - /* parent bfq_data */ - struct bfq_data *bfqd; - - /* current ioprio and ioprio class */ - unsigned short ioprio, ioprio_class; - /* next ioprio and ioprio class if a change is in progress */ - unsigned short new_ioprio, new_ioprio_class; - - /* - * Shared bfq_queue if queue is cooperating with one or more - * other queues. - */ - struct bfq_queue *new_bfqq; - /* request-position tree member (see bfq_group's @rq_pos_tree) */ - struct rb_node pos_node; - /* request-position tree root (see bfq_group's @rq_pos_tree) */ - struct rb_root *pos_root; - - /* sorted list of pending requests */ - struct rb_root sort_list; - /* if fifo isn't expired, next request to serve */ - struct request *next_rq; - /* number of sync and async requests queued */ - int queued[2]; - /* number of requests currently allocated */ - int allocated; - /* number of pending metadata requests */ - int meta_pending; - /* fifo list of requests in sort_list */ - struct list_head fifo; - - /* entity representing this queue in the scheduler */ - struct bfq_entity entity; - - /* maximum budget allowed from the feedback mechanism */ - int max_budget; - /* budget expiration (in jiffies) */ - unsigned long budget_timeout; - - /* number of requests on the dispatch list or inside driver */ - int dispatched; - - /* status flags */ - unsigned long flags; - - /* node for active/idle bfqq list inside parent bfqd */ - struct list_head bfqq_list; - - /* associated @bfq_ttime struct */ - struct bfq_ttime ttime; - - /* bit vector: a 1 for each seeky requests in history */ - u32 seek_history; - - /* node for the device's burst list */ - struct hlist_node burst_list_node; - - /* position of the last request enqueued */ - sector_t last_request_pos; - - /* 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 flag has been - * cleared. - */ - unsigned int requests_within_timer; - - /* pid of the process owning the queue, used for logging purposes */ - pid_t pid; - - /* - * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL - * if the queue is shared. - */ - struct bfq_io_cq *bic; - - /* current maximum weight-raising time for this queue */ - unsigned long wr_cur_max_time; - /* - * 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 on - * the function bfq_bfqq_softrt_next_start()) - */ - unsigned long soft_rt_next_start; - /* - * 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. - */ - unsigned long last_wr_start_finish; - /* factor by which the weight of this queue is multiplied */ - unsigned int wr_coeff; - /* - * Time of the last transition of the @bfq_queue from idle to - * backlogged. - */ - unsigned long last_idle_bklogged; - /* - * Cumulative service received from the @bfq_queue since the - * last transition from idle to backlogged. - */ - unsigned long service_from_backlogged; - - /* - * Value of wr start time when switching to soft rt - */ - unsigned long wr_start_at_switch_to_srt; - - unsigned long split_time; /* time of last split */ -}; - -/** - * struct bfq_io_cq - per (request_queue, io_context) structure. - */ -struct bfq_io_cq { - /* associated io_cq structure */ - struct io_cq icq; /* must be the first member */ - /* array of two process queues, the sync and the async */ - struct bfq_queue *bfqq[2]; - /* per (request_queue, blkcg) ioprio */ - int ioprio; -#ifdef CONFIG_BFQ_GROUP_IOSCHED - uint64_t blkcg_serial_nr; /* the current blkcg serial */ -#endif - /* - * Snapshot of the idle window before merging; taken to - * remember this value while the queue is merged, so as to be - * able to restore it in case of split. - */ - bool saved_idle_window; - /* - * Same purpose as the previous two fields for the I/O bound - * classification of a queue. - */ - bool saved_IO_bound; - - /* - * Same purpose as the previous fields for the value of the - * field keeping the queue's belonging to a large burst - */ - bool saved_in_large_burst; - /* - * True if the queue belonged to a burst list before its merge - * with another cooperating queue. - */ - bool was_in_burst_list; - - /* - * Similar to previous fields: save wr information. - */ - unsigned long saved_wr_coeff; - unsigned long saved_last_wr_start_finish; - unsigned long saved_wr_start_at_switch_to_srt; - unsigned int saved_wr_cur_max_time; - struct bfq_ttime saved_ttime; -}; - -enum bfq_device_speed { - BFQ_BFQD_FAST, - BFQ_BFQD_SLOW, -}; - -/** - * struct bfq_data - per-device data structure. - * - * All the fields are protected by @lock. - */ -struct bfq_data { - /* device request queue */ - struct request_queue *queue; - /* dispatch queue */ - struct list_head dispatch; - - /* root bfq_group for the device */ - struct bfq_group *root_group; - - /* - * 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). - */ - struct rb_root queue_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). - */ - struct rb_root group_weights_tree; - - /* - * Number of bfq_queues containing requests (including the - * queue in service, even if it is idling). - */ - int busy_queues; - /* number of weight-raised busy @bfq_queues */ - int wr_busy_queues; - /* number of queued requests */ - int queued; - /* number of requests dispatched and waiting for completion */ - int rq_in_driver; - - /* - * Maximum number of requests in driver in the last - * @hw_tag_samples completed requests. - */ - int max_rq_in_driver; - /* number of samples used to calculate hw_tag */ - int hw_tag_samples; - /* flag set to one if the driver is showing a queueing behavior */ - int hw_tag; - - /* number of budgets assigned */ - int budgets_assigned; - - /* - * Timer set when idling (waiting) for the next request from - * the queue in service. - */ - struct hrtimer idle_slice_timer; - - /* bfq_queue in service */ - struct bfq_queue *in_service_queue; - - /* on-disk position of the last served request */ - sector_t last_position; - - /* time of last request completion (ns) */ - u64 last_completion; - - /* time of first rq dispatch in current observation interval (ns) */ - u64 first_dispatch; - /* time of last rq dispatch in current observation interval (ns) */ - u64 last_dispatch; - - /* beginning of the last budget */ - ktime_t last_budget_start; - /* beginning of the last idle slice */ - ktime_t last_idling_start; - - /* number of samples in current observation interval */ - int peak_rate_samples; - /* num of samples of seq dispatches in current observation interval */ - u32 sequential_samples; - /* total num of sectors transferred in current observation interval */ - u64 tot_sectors_dispatched; - /* max rq size seen during current observation interval (sectors) */ - u32 last_rq_max_size; - /* time elapsed from first dispatch in current observ. interval (us) */ - u64 delta_from_first; - /* - * Current estimate of the device peak rate, measured in - * [BFQ_RATE_SHIFT * sectors/usec]. The left-shift by - * BFQ_RATE_SHIFT is performed to increase precision in - * fixed-point calculations. - */ - u32 peak_rate; - - /* maximum budget allotted to a bfq_queue before rescheduling */ - int bfq_max_budget; - - /* list of all the bfq_queues active on the device */ - struct list_head active_list; - /* list of all the bfq_queues idle on the device */ - struct list_head idle_list; - - /* - * Timeout for async/sync requests; when it fires, requests - * are served in fifo order. - */ - u64 bfq_fifo_expire[2]; - /* weight of backward seeks wrt forward ones */ - unsigned int bfq_back_penalty; - /* maximum allowed backward seek */ - unsigned int bfq_back_max; - /* maximum idling time */ - u32 bfq_slice_idle; - - /* user-configured max budget value (0 for auto-tuning) */ - int bfq_user_max_budget; - /* - * Timeout for bfq_queues to consume their budget; used to - * prevent seeky queues from imposing long latencies to - * sequential or quasi-sequential ones (this also implies that - * seeky queues cannot receive guarantees in the service - * domain; after a timeout they are charged for the time they - * have been in service, to preserve fairness among them, but - * without service-domain guarantees). - */ - unsigned int bfq_timeout; - - /* - * 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). - */ - unsigned int bfq_requests_within_timer; - - /* - * Force device idling whenever needed to provide accurate - * service guarantees, without caring about throughput - * issues. CAVEAT: this may even increase latencies, in case - * of useless idling for processes that did stop doing I/O. - */ - bool strict_guarantees; - - /* - * 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 on the function - * bfq_handle_burst. - */ - unsigned long last_ins_in_burst; - /* - * Reference time interval used to decide whether a queue has - * been activated shortly after @last_ins_in_burst. - */ - unsigned long bfq_burst_interval; - /* number of queues in the current burst of queue activations */ - int burst_size; - - /* common parent entity for the queues in the burst */ - struct bfq_entity *burst_parent_entity; - /* Maximum burst size above which the current queue-activation - * burst is deemed as 'large'. - */ - unsigned long bfq_large_burst_thresh; - /* true if a large queue-activation burst is in progress */ - bool large_burst; - /* - * Head of the burst list (as for the above fields, more - * details in the comments on the function bfq_handle_burst). - */ - struct hlist_head burst_list; - - /* if set to true, low-latency heuristics are enabled */ - bool low_latency; - /* - * Maximum factor by which the weight of a weight-raised queue - * is multiplied. - */ - unsigned int bfq_wr_coeff; - /* maximum duration of a weight-raising period (jiffies) */ - unsigned int bfq_wr_max_time; - - /* Maximum weight-raising duration for soft real-time processes */ - unsigned int bfq_wr_rt_max_time; - /* - * Minimum idle period after which weight-raising may be - * reactivated for a queue (in jiffies). - */ - unsigned int bfq_wr_min_idle_time; - /* - * Minimum period between request arrivals after which - * weight-raising may be reactivated for an already busy async - * queue (in jiffies). - */ - unsigned long bfq_wr_min_inter_arr_async; - - /* Max service-rate for a soft real-time queue, in sectors/sec */ - unsigned int bfq_wr_max_softrt_rate; - /* - * Cached value of the product R*T, used for computing the - * maximum duration of weight raising automatically. - */ - u64 RT_prod; - /* device-speed class for the low-latency heuristic */ - enum bfq_device_speed device_speed; - - /* fallback dummy bfqq for extreme OOM conditions */ - struct bfq_queue oom_bfqq; - - spinlock_t lock; - - /* - * bic associated with the task issuing current bio for - * merging. This and the next field are used as a support to - * be able to perform the bic lookup, needed by bio-merge - * functions, before the scheduler lock is taken, and thus - * avoid taking the request-queue lock while the scheduler - * lock is being held. - */ - struct bfq_io_cq *bio_bic; - /* bfqq associated with the task issuing current bio for merging */ - struct bfq_queue *bio_bfqq; -}; - -enum bfqq_state_flags { - BFQQF_just_created = 0, /* queue just allocated */ - BFQQF_busy, /* has requests or is in service */ - BFQQF_wait_request, /* waiting for a request */ - BFQQF_non_blocking_wait_rq, /* - * waiting for a request - * without idling the device - */ - BFQQF_fifo_expire, /* FIFO checked in this slice */ - BFQQF_idle_window, /* slice idling enabled */ - BFQQF_sync, /* synchronous queue */ - BFQQF_IO_bound, /* - * bfqq has timed-out at least once - * having consumed at most 2/10 of - * its budget - */ - BFQQF_in_large_burst, /* - * bfqq activated in a large burst, - * see comments to bfq_handle_burst. - */ - BFQQF_softrt_update, /* - * may need softrt-next-start - * update - */ - BFQQF_coop, /* bfqq is shared */ - BFQQF_split_coop /* shared bfqq will be split */ -}; +#include "bfq-iosched.h" #define BFQ_BFQQ_FNS(name) \ -static void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \ +void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \ { \ __set_bit(BFQQF_##name, &(bfqq)->flags); \ } \ -static void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \ +void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \ { \ __clear_bit(BFQQF_##name, &(bfqq)->flags); \ } \ -static int bfq_bfqq_##name(const struct bfq_queue *bfqq) \ +int bfq_bfqq_##name(const struct bfq_queue *bfqq) \ { \ return test_bit(BFQQF_##name, &(bfqq)->flags); \ } @@ -758,230 +130,7 @@ BFQ_BFQQ_FNS(in_large_burst); BFQ_BFQQ_FNS(coop); BFQ_BFQQ_FNS(split_coop); BFQ_BFQQ_FNS(softrt_update); -#undef BFQ_BFQQ_FNS - -/* Logging facilities. */ -#ifdef CONFIG_BFQ_GROUP_IOSCHED -static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); -static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); - -#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ - char __pbuf[128]; \ - \ - blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \ - blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, (bfqq)->pid, \ - bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ - __pbuf, ##args); \ -} while (0) - -#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ - char __pbuf[128]; \ - \ - blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf)); \ - blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args); \ -} while (0) - -#else /* CONFIG_BFQ_GROUP_IOSCHED */ - -#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ - blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid, \ - bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ - ##args) -#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) - -#endif /* CONFIG_BFQ_GROUP_IOSCHED */ - -#define bfq_log(bfqd, fmt, args...) \ - blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) - -/* Expiration reasons. */ -enum bfqq_expiration { - BFQQE_TOO_IDLE = 0, /* - * queue has been idling for - * too long - */ - BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */ - BFQQE_BUDGET_EXHAUSTED, /* budget consumed */ - BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */ - BFQQE_PREEMPTED /* preemption in progress */ -}; - -struct bfqg_stats { -#ifdef CONFIG_BFQ_GROUP_IOSCHED - /* number of ios merged */ - struct blkg_rwstat merged; - /* total time spent on device in ns, may not be accurate w/ queueing */ - struct blkg_rwstat service_time; - /* total time spent waiting in scheduler queue in ns */ - struct blkg_rwstat wait_time; - /* number of IOs queued up */ - struct blkg_rwstat queued; - /* total disk time and nr sectors dispatched by this group */ - struct blkg_stat time; - /* sum of number of ios queued across all samples */ - struct blkg_stat avg_queue_size_sum; - /* count of samples taken for average */ - struct blkg_stat avg_queue_size_samples; - /* how many times this group has been removed from service tree */ - struct blkg_stat dequeue; - /* total time spent waiting for it to be assigned a timeslice. */ - struct blkg_stat group_wait_time; - /* time spent idling for this blkcg_gq */ - struct blkg_stat idle_time; - /* total time with empty current active q with other requests queued */ - struct blkg_stat empty_time; - /* fields after this shouldn't be cleared on stat reset */ - uint64_t start_group_wait_time; - uint64_t start_idle_time; - uint64_t start_empty_time; - uint16_t flags; -#endif /* CONFIG_BFQ_GROUP_IOSCHED */ -}; - -#ifdef CONFIG_BFQ_GROUP_IOSCHED - -/* - * struct bfq_group_data - per-blkcg storage for the blkio subsystem. - * - * @ps: @blkcg_policy_storage that this structure inherits - * @weight: weight of the bfq_group - */ -struct bfq_group_data { - /* must be the first member */ - struct blkcg_policy_data pd; - - unsigned int weight; -}; - -/** - * 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). - * @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. - * @stats: stats for this bfqg. - * @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_may_idle()). - * @rq_pos_tree: rbtree sorted by next_request position, used when - * determining if two or more queues have interleaving - * requests (see bfq_find_close_cooperator()). - * - * 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 @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 { - /* must be the first member */ - struct blkg_policy_data pd; - - struct bfq_entity entity; - struct bfq_sched_data sched_data; - - 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 rb_root rq_pos_tree; - - struct bfqg_stats stats; -}; - -#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; - - struct rb_root rq_pos_tree; -}; -#endif - -static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); - -static unsigned int bfq_class_idx(struct bfq_entity *entity) -{ - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - - return bfqq ? bfqq->ioprio_class - 1 : - BFQ_DEFAULT_GRP_CLASS - 1; -} - -static struct bfq_service_tree * -bfq_entity_service_tree(struct bfq_entity *entity) -{ - struct bfq_sched_data *sched_data = entity->sched_data; - unsigned int idx = bfq_class_idx(entity); - - return sched_data->service_tree + idx; -} - -static struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync) -{ - return bic->bfqq[is_sync]; -} - -static void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, - bool is_sync) -{ - bic->bfqq[is_sync] = bfqq; -} - -static struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic) -{ - return bic->icq.q->elevator->elevator_data; -} - -#ifdef CONFIG_BFQ_GROUP_IOSCHED - -static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) -{ - struct bfq_entity *group_entity = bfqq->entity.parent; - - if (!group_entity) - group_entity = &bfqq->bfqd->root_group->entity; - - return container_of(group_entity, struct bfq_group, entity); -} - -#else - -static struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) -{ - return bfqq->bfqd->root_group; -} - -#endif - -static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio); -static void bfq_put_queue(struct bfq_queue *bfqq); -static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, - struct bio *bio, bool is_sync, - struct bfq_io_cq *bic); -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); +#undef BFQ_BFQQ_FNS \ /* Expiration time of sync (0) and async (1) requests, in ns. */ static const u64 bfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 }; @@ -1009,7 +158,7 @@ static const int bfq_default_max_budget = 16 * 1024; static const int bfq_async_charge_factor = 10; /* Default timeout values, in jiffies, approximating CFQ defaults. */ -static const int bfq_timeout = HZ / 8; +const int bfq_timeout = HZ / 8; static struct kmem_cache *bfq_pool; @@ -1085,12 +234,24 @@ 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]) +struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync) +{ + return bic->bfqq[is_sync]; +} + +void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync) +{ + bic->bfqq[is_sync] = bfqq; +} + +struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic) +{ + return bic->icq.q->elevator->elevator_data; +} + /** * icq_to_bic - convert iocontext queue structure to bfq_io_cq. * @icq: the iocontext queue. @@ -1129,7 +290,7 @@ static struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd, * Scheduler run of queue, if there are requests pending and no one in the * driver that will restart queueing. */ -static void bfq_schedule_dispatch(struct bfq_data *bfqd) +void bfq_schedule_dispatch(struct bfq_data *bfqd) { if (bfqd->queued != 0) { bfq_log(bfqd, "schedule dispatch"); @@ -1137,2731 +298,6 @@ static void bfq_schedule_dispatch(struct bfq_data *bfqd) } } -/** - * bfq_gt - compare two timestamps. - * @a: first ts. - * @b: second ts. - * - * Return @a > @b, dealing with wrapping correctly. - */ -static int bfq_gt(u64 a, u64 b) -{ - return (s64)(a - b) > 0; -} - -static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree) -{ - struct rb_node *node = tree->rb_node; - - return rb_entry(node, struct bfq_entity, rb_node); -} - -static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd); - -static bool bfq_update_parent_budget(struct bfq_entity *next_in_service); - -/** - * bfq_update_next_in_service - update sd->next_in_service - * @sd: sched_data for which to perform the update. - * @new_entity: if not NULL, pointer to the entity whose activation, - * requeueing or repositionig triggered the invocation of - * this function. - * - * This function is called to update sd->next_in_service, which, in - * its turn, may change as a consequence of the insertion or - * extraction of an entity into/from one of the active trees of - * sd. These insertions/extractions occur as a consequence of - * activations/deactivations of entities, with some activations being - * 'true' activations, and other activations being requeueings (i.e., - * implementing the second, requeueing phase of the mechanism used to - * reposition an entity in its active tree; see comments on - * __bfq_activate_entity and __bfq_requeue_entity for details). In - * both the last two activation sub-cases, new_entity points to the - * just activated or requeued entity. - * - * Returns true if sd->next_in_service changes in such a way that - * entity->parent may become the next_in_service for its parent - * entity. - */ -static bool bfq_update_next_in_service(struct bfq_sched_data *sd, - struct bfq_entity *new_entity) -{ - struct bfq_entity *next_in_service = sd->next_in_service; - bool parent_sched_may_change = false; - - /* - * If this update is triggered by the activation, requeueing - * or repositiong of an entity that does not coincide with - * sd->next_in_service, then a full lookup in the active tree - * can be avoided. In fact, it is enough to check whether the - * just-modified entity has a higher priority than - * sd->next_in_service, or, even if it has the same priority - * as sd->next_in_service, is eligible and has a lower virtual - * finish time than sd->next_in_service. If this compound - * condition holds, then the new entity becomes the new - * next_in_service. Otherwise no change is needed. - */ - if (new_entity && new_entity != sd->next_in_service) { - /* - * Flag used to decide whether to replace - * sd->next_in_service with new_entity. Tentatively - * set to true, and left as true if - * sd->next_in_service is NULL. - */ - bool replace_next = true; - - /* - * If there is already a next_in_service candidate - * entity, then compare class priorities or timestamps - * to decide whether to replace sd->service_tree with - * new_entity. - */ - if (next_in_service) { - unsigned int new_entity_class_idx = - bfq_class_idx(new_entity); - struct bfq_service_tree *st = - sd->service_tree + new_entity_class_idx; - - /* - * For efficiency, evaluate the most likely - * sub-condition first. - */ - replace_next = - (new_entity_class_idx == - bfq_class_idx(next_in_service) - && - !bfq_gt(new_entity->start, st->vtime) - && - bfq_gt(next_in_service->finish, - new_entity->finish)) - || - new_entity_class_idx < - bfq_class_idx(next_in_service); - } - - if (replace_next) - next_in_service = new_entity; - } else /* invoked because of a deactivation: lookup needed */ - next_in_service = bfq_lookup_next_entity(sd); - - if (next_in_service) { - parent_sched_may_change = !sd->next_in_service || - bfq_update_parent_budget(next_in_service); - } - - sd->next_in_service = next_in_service; - - if (!next_in_service) - return parent_sched_may_change; - - return parent_sched_may_change; -} - -#ifdef CONFIG_BFQ_GROUP_IOSCHED -/* both next loops stop at one of the child entities of the root group */ -#define for_each_entity(entity) \ - for (; entity ; entity = entity->parent) - -/* - * For each iteration, compute parent in advance, so as to be safe if - * entity is deallocated during the iteration. Such a deallocation may - * happen as a consequence of a bfq_put_queue that frees the bfq_queue - * containing entity. - */ -#define for_each_entity_safe(entity, parent) \ - for (; entity && ({ parent = entity->parent; 1; }); entity = parent) - -/* - * Returns true if this budget changes may let next_in_service->parent - * become the next_in_service entity for its parent entity. - */ -static bool bfq_update_parent_budget(struct bfq_entity *next_in_service) -{ - struct bfq_entity *bfqg_entity; - struct bfq_group *bfqg; - struct bfq_sched_data *group_sd; - bool ret = false; - - 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) { - if (bfqg_entity->budget > next_in_service->budget) - ret = true; - bfqg_entity->budget = next_in_service->budget; - } - - return ret; -} - -/* - * This function tells whether entity stops being a candidate for next - * service, according to the following logic. - * - * This function is invoked for an entity that is about to be set in - * service. If such an entity is a queue, then the entity is no longer - * a candidate for next service (i.e, a candidate entity to serve - * after the in-service entity is expired). The function then returns - * true. - * - * In contrast, the entity could stil be a candidate for next service - * if it is not a queue, and has more than one child. In fact, even if - * one of its children is about to be set in service, other children - * may still be the next to serve. As a consequence, a non-queue - * entity is not a candidate for next-service only if it has only one - * child. And only if this condition holds, then the function returns - * true for a non-queue entity. - */ -static bool bfq_no_longer_next_in_service(struct bfq_entity *entity) -{ - struct bfq_group *bfqg; - - if (bfq_entity_to_bfqq(entity)) - return true; - - bfqg = container_of(entity, struct bfq_group, entity); - - if (bfqg->active_entities == 1) - return true; - - return false; -} - -#else /* CONFIG_BFQ_GROUP_IOSCHED */ -/* - * Next two macros are fake loops when cgroups support is not - * enabled. I fact, in such a case, there is only one level to go up - * (to reach the root group). - */ -#define for_each_entity(entity) \ - for (; entity ; entity = NULL) - -#define for_each_entity_safe(entity, parent) \ - for (parent = NULL; entity ; entity = parent) - -static bool bfq_update_parent_budget(struct bfq_entity *next_in_service) -{ - return false; -} - -static bool bfq_no_longer_next_in_service(struct bfq_entity *entity) -{ - return true; -} - -#endif /* CONFIG_BFQ_GROUP_IOSCHED */ - -/* - * 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 - -static struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity) -{ - struct bfq_queue *bfqq = NULL; - - if (!entity->my_sched_data) - 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 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 void bfq_calc_finish(struct bfq_entity *entity, unsigned long service) -{ - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - - entity->finish = entity->start + - bfq_delta(service, entity->weight); - - if (bfqq) { - 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 struct bfq_entity *bfq_entity_of(struct rb_node *node) -{ - struct bfq_entity *entity = NULL; - - if (node) - 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 void bfq_extract(struct rb_root *root, struct bfq_entity *entity) -{ - 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; - - 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) - 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; - - while (*node) { - 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 void bfq_update_min(struct bfq_entity *entity, struct rb_node *node) -{ - struct bfq_entity *child; - - if (node) { - 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 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) - return; - - if (node == parent->rb_left && parent->rb_right) - bfq_update_active_node(parent->rb_right); - else if (parent->rb_left) - 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_BFQ_GROUP_IOSCHED - 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) - node = node->rb_left; - else if (node->rb_right) - node = node->rb_right; - - bfq_update_active_tree(node); - -#ifdef CONFIG_BFQ_GROUP_IOSCHED - sd = entity->sched_data; - bfqg = container_of(sd, struct bfq_group, sched_data); - bfqd = (struct bfq_data *)bfqg->bfqd; -#endif - if (bfqq) - list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list); -#ifdef CONFIG_BFQ_GROUP_IOSCHED - else /* bfq_group */ - bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree); - - if (bfqg != bfqd->root_group) - bfqg->active_entities++; -#endif -} - -/** - * bfq_ioprio_to_weight - calc a weight from an ioprio. - * @ioprio: the ioprio value to convert. - */ -static unsigned short bfq_ioprio_to_weight(int ioprio) -{ - return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF; -} - -/** - * bfq_weight_to_ioprio - calc an ioprio from a weight. - * @weight: the weight value to convert. - * - * To preserve as much 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 * BFQ_WEIGHT_CONVERSION_COEFF. - */ -static unsigned short bfq_weight_to_ioprio(int weight) -{ - return max_t(int, 0, - IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight); -} - -static void bfq_get_entity(struct bfq_entity *entity) -{ - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - - if (bfqq) { - bfqq->ref++; - bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", - bfqq, 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 && !node->rb_left) - deepest = rb_parent(node); - else if (!node->rb_right) - deepest = node->rb_left; - else if (!node->rb_left) - deepest = node->rb_right; - else { - deepest = rb_next(node); - if (deepest->rb_right) - 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_BFQ_GROUP_IOSCHED - 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) - bfq_update_active_tree(node); - -#ifdef CONFIG_BFQ_GROUP_IOSCHED - sd = entity->sched_data; - bfqg = container_of(sd, struct bfq_group, sched_data); - bfqd = (struct bfq_data *)bfqg->bfqd; -#endif - if (bfqq) - list_del(&bfqq->bfqq_list); -#ifdef CONFIG_BFQ_GROUP_IOSCHED - else /* bfq_group */ - bfq_weights_tree_remove(bfqd, entity, - &bfqd->group_weights_tree); - - if (bfqg != bfqd->root_group) - bfqg->active_entities--; -#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 || bfq_gt(first_idle->finish, entity->finish)) - st->first_idle = entity; - if (!last_idle || bfq_gt(entity->finish, last_idle->finish)) - st->last_idle = entity; - - bfq_insert(&st->idle, entity); - - if (bfqq) - list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list); -} - -/** - * bfq_forget_entity - do not consider entity any longer for scheduling - * @st: the service tree. - * @entity: the entity being removed. - * @is_in_service: true if entity is currently the in-service entity. - * - * Forget everything about @entity. In addition, if entity represents - * a queue, and the latter is not in service, then release the service - * reference to the queue (the one taken through bfq_get_entity). In - * fact, in this case, there is really no more service reference to - * the queue, as the latter is also outside any service tree. If, - * instead, the queue is in service, then __bfq_bfqd_reset_in_service - * will take care of putting the reference when the queue finally - * stops being served. - */ -static void bfq_forget_entity(struct bfq_service_tree *st, - struct bfq_entity *entity, - bool is_in_service) -{ - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - - entity->on_st = false; - st->wsum -= entity->weight; - if (bfqq && !is_in_service) - 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, - entity == entity->sched_data->in_service_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 && - !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 && !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->prio_changed) { - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - unsigned int prev_weight, new_weight; - struct bfq_data *bfqd = NULL; - struct rb_root *root; -#ifdef CONFIG_BFQ_GROUP_IOSCHED - struct bfq_sched_data *sd; - struct bfq_group *bfqg; -#endif - - if (bfqq) - bfqd = bfqq->bfqd; -#ifdef CONFIG_BFQ_GROUP_IOSCHED - else { - sd = entity->my_sched_data; - bfqg = container_of(sd, struct bfq_group, sched_data); - bfqd = (struct bfq_data *)bfqg->bfqd; - } -#endif - - 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) { - pr_crit("update_weight_prio: new_weight %d\n", - entity->new_weight); - if (entity->new_weight < BFQ_MIN_WEIGHT) - entity->new_weight = BFQ_MIN_WEIGHT; - else - entity->new_weight = BFQ_MAX_WEIGHT; - } - entity->orig_weight = entity->new_weight; - if (bfqq) - bfqq->ioprio = - bfq_weight_to_ioprio(entity->orig_weight); - } - - if (bfqq) - bfqq->ioprio_class = bfqq->new_ioprio_class; - entity->prio_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 ? 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; -} - -static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg); -static struct bfq_group *bfqq_group(struct bfq_queue *bfqq); - -/** - * 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, int 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; - - st->vtime += bfq_delta(served, st->wsum); - bfq_forget_idle(st); - } - bfqg_stats_set_start_empty_time(bfqq_group(bfqq)); - bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served); -} - -/** - * bfq_bfqq_charge_time - charge an amount of service equivalent to the length - * of the time interval during which bfqq has been in - * service. - * @bfqd: the device - * @bfqq: the queue that needs a service update. - * @time_ms: the amount of time during which the queue has received service - * - * If a queue does not consume its budget fast enough, then providing - * the queue with service fairness may impair throughput, more or less - * severely. For this reason, queues that consume their budget slowly - * are provided with time fairness instead of service fairness. This - * goal is achieved through the BFQ scheduling engine, even if such an - * engine works in the service, and not in the time domain. The trick - * is charging these queues with an inflated amount of service, equal - * to the amount of service that they would have received during their - * service slot if they had been fast, i.e., if their requests had - * been dispatched at a rate equal to the estimated peak rate. - * - * It is worth noting that time fairness can cause important - * distortions in terms of bandwidth distribution, on devices with - * internal queueing. The reason is that I/O requests dispatched - * during the service slot of a queue may be served after that service - * slot is finished, and may have a total processing time loosely - * correlated with the duration of the service slot. This is - * especially true for short service slots. - */ -static void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq, - unsigned long time_ms) -{ - struct bfq_entity *entity = &bfqq->entity; - int tot_serv_to_charge = entity->service; - unsigned int timeout_ms = jiffies_to_msecs(bfq_timeout); - - if (time_ms > 0 && time_ms < timeout_ms) - tot_serv_to_charge = - (bfqd->bfq_max_budget * time_ms) / timeout_ms; - - if (tot_serv_to_charge < entity->service) - tot_serv_to_charge = entity->service; - - /* Increase budget to avoid inconsistencies */ - if (tot_serv_to_charge > entity->budget) - entity->budget = tot_serv_to_charge; - - bfq_bfqq_served(bfqq, - max_t(int, 0, tot_serv_to_charge - entity->service)); -} - -static void bfq_update_fin_time_enqueue(struct bfq_entity *entity, - struct bfq_service_tree *st, - bool backshifted) -{ - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - - st = __bfq_entity_update_weight_prio(st, entity); - bfq_calc_finish(entity, entity->budget); - - /* - * If some queues enjoy backshifting for a while, then their - * (virtual) finish timestamps may happen to become lower and - * lower than the system virtual time. In particular, if - * these queues often happen to be idle for short time - * periods, and during such time periods other queues with - * higher timestamps happen to be busy, then the backshifted - * timestamps of the former queues can become much lower than - * the system virtual time. In fact, to serve the queues with - * higher timestamps while the ones with lower timestamps are - * idle, the system virtual time may be pushed-up to much - * higher values than the finish timestamps of the idle - * queues. As a consequence, the finish timestamps of all new - * or newly activated queues may end up being much larger than - * those of lucky queues with backshifted timestamps. The - * latter queues may then monopolize the device for a lot of - * time. This would simply break service guarantees. - * - * To reduce this problem, push up a little bit the - * backshifted timestamps of the queue associated with this - * entity (only a queue can happen to have the backshifted - * flag set): just enough to let the finish timestamp of the - * queue be equal to the current value of the system virtual - * time. This may introduce a little unfairness among queues - * with backshifted timestamps, but it does not break - * worst-case fairness guarantees. - * - * As a special case, if bfqq is weight-raised, push up - * timestamps much less, to keep very low the probability that - * this push up causes the backshifted finish timestamps of - * weight-raised queues to become higher than the backshifted - * finish timestamps of non weight-raised queues. - */ - if (backshifted && bfq_gt(st->vtime, entity->finish)) { - unsigned long delta = st->vtime - entity->finish; - - if (bfqq) - delta /= bfqq->wr_coeff; - - entity->start += delta; - entity->finish += delta; - } - - bfq_active_insert(st, entity); -} - -/** - * __bfq_activate_entity - handle activation of entity. - * @entity: the entity being activated. - * @non_blocking_wait_rq: true if entity was waiting for a request - * - * Called for a 'true' activation, i.e., if entity is not active and - * one of its children receives a new request. - * - * Basically, this function updates the timestamps of entity and - * inserts entity into its active tree, ater possible extracting it - * from its idle tree. - */ -static void __bfq_activate_entity(struct bfq_entity *entity, - bool non_blocking_wait_rq) -{ - struct bfq_service_tree *st = bfq_entity_service_tree(entity); - bool backshifted = false; - unsigned long long min_vstart; - - /* See comments on bfq_fqq_update_budg_for_activation */ - if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) { - backshifted = true; - min_vstart = entity->finish; - } else - min_vstart = st->vtime; - - 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(min_vstart, entity->finish) ? - min_vstart : 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 = min_vstart; - st->wsum += entity->weight; - /* - * entity is about to be inserted into a service tree, - * and then set in service: get a reference to make - * sure entity does not disappear until it is no - * longer in service or scheduled for service. - */ - bfq_get_entity(entity); - - entity->on_st = true; - } - - bfq_update_fin_time_enqueue(entity, st, backshifted); -} - -/** - * __bfq_requeue_entity - handle requeueing or repositioning of an entity. - * @entity: the entity being requeued or repositioned. - * - * Requeueing is needed if this entity stops being served, which - * happens if a leaf descendant entity has expired. On the other hand, - * repositioning is needed if the next_inservice_entity for the child - * entity has changed. See the comments inside the function for - * details. - * - * Basically, this function: 1) removes entity from its active tree if - * present there, 2) updates the timestamps of entity and 3) inserts - * entity back into its active tree (in the new, right position for - * the new values of the timestamps). - */ -static void __bfq_requeue_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) { - /* - * We are requeueing the current in-service entity, - * which may have to be done for one of the following - * reasons: - * - entity represents the in-service queue, and the - * in-service queue is being requeued after an - * expiration; - * - entity represents a group, and its budget has - * changed because one of its child entities has - * just been either activated or requeued for some - * reason; the timestamps of the entity need then to - * be updated, and the entity needs to be enqueued - * or repositioned accordingly. - * - * In particular, before requeueing, the start time of - * the entity must be moved forward to account for the - * service that the entity has received while in - * service. This is done by the next instructions. The - * finish time will then be updated according to this - * new value of the start time, and to the budget of - * the entity. - */ - bfq_calc_finish(entity, entity->service); - entity->start = entity->finish; - /* - * In addition, if the entity had more than one child - * when set in service, then was not extracted from - * the active tree. This implies that the position of - * the entity in the active tree may need to be - * changed now, because we have just updated the start - * time of the entity, and we will update its finish - * time in a moment (the requeueing is then, more - * precisely, a repositioning in this case). To - * implement this repositioning, we: 1) dequeue the - * entity here, 2) update the finish time and - * requeue the entity according to the new - * timestamps below. - */ - if (entity->tree) - bfq_active_extract(st, entity); - } else { /* The entity is already active, and not in service */ - /* - * In this case, this function gets called only if the - * next_in_service entity below this entity has - * changed, and this change has caused the budget of - * this entity to change, which, finally implies that - * the finish time of this entity must be - * updated. Such an update may cause the scheduling, - * i.e., the position in the active tree, of this - * entity to change. We handle this change by: 1) - * dequeueing the entity here, 2) updating the finish - * time and requeueing the entity according to the new - * timestamps below. This is the same approach as the - * non-extracted-entity sub-case above. - */ - bfq_active_extract(st, entity); - } - - bfq_update_fin_time_enqueue(entity, st, false); -} - -static void __bfq_activate_requeue_entity(struct bfq_entity *entity, - struct bfq_sched_data *sd, - bool non_blocking_wait_rq) -{ - struct bfq_service_tree *st = bfq_entity_service_tree(entity); - - if (sd->in_service_entity == entity || entity->tree == &st->active) - /* - * in service or already queued on the active tree, - * requeue or reposition - */ - __bfq_requeue_entity(entity); - else - /* - * Not in service and not queued on its active tree: - * the activity is idle and this is a true activation. - */ - __bfq_activate_entity(entity, non_blocking_wait_rq); -} - - -/** - * bfq_activate_entity - activate or requeue an entity representing a bfq_queue, - * and activate, requeue or reposition all ancestors - * for which such an update becomes necessary. - * @entity: the entity to activate. - * @non_blocking_wait_rq: true if this entity was waiting for a request - * @requeue: true if this is a requeue, which implies that bfqq is - * being expired; thus ALL its ancestors stop being served and must - * therefore be requeued - */ -static void bfq_activate_requeue_entity(struct bfq_entity *entity, - bool non_blocking_wait_rq, - bool requeue) -{ - struct bfq_sched_data *sd; - - for_each_entity(entity) { - sd = entity->sched_data; - __bfq_activate_requeue_entity(entity, sd, non_blocking_wait_rq); - - if (!bfq_update_next_in_service(sd, entity) && !requeue) - break; - } -} - -/** - * __bfq_deactivate_entity - deactivate an entity from its service tree. - * @entity: the entity to deactivate. - * @ins_into_idle_tree: if false, the entity will not be put into the - * idle tree. - * - * Deactivates an entity, independently from its previous state. Must - * be invoked only if entity is on a service tree. Extracts the entity - * from that tree, and if necessary and allowed, puts it on the idle - * tree. - */ -static bool __bfq_deactivate_entity(struct bfq_entity *entity, - bool ins_into_idle_tree) -{ - struct bfq_sched_data *sd = entity->sched_data; - struct bfq_service_tree *st = bfq_entity_service_tree(entity); - int is_in_service = entity == sd->in_service_entity; - - if (!entity->on_st) /* entity never activated, or already inactive */ - return false; - - if (is_in_service) - bfq_calc_finish(entity, entity->service); - - if (entity->tree == &st->active) - bfq_active_extract(st, entity); - else if (!is_in_service && entity->tree == &st->idle) - bfq_idle_extract(st, entity); - - if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime)) - bfq_forget_entity(st, entity, is_in_service); - else - bfq_idle_insert(st, entity); - - return true; -} - -/** - * bfq_deactivate_entity - deactivate an entity representing a bfq_queue. - * @entity: the entity to deactivate. - * @ins_into_idle_tree: true if the entity can be put on the idle tree - */ -static void bfq_deactivate_entity(struct bfq_entity *entity, - bool ins_into_idle_tree, - bool expiration) -{ - struct bfq_sched_data *sd; - struct bfq_entity *parent = NULL; - - for_each_entity_safe(entity, parent) { - sd = entity->sched_data; - - if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) { - /* - * entity is not in any tree any more, so - * this deactivation is a no-op, and there is - * nothing to change for upper-level entities - * (in case of expiration, this can never - * happen). - */ - return; - } - - if (sd->next_in_service == entity) - /* - * entity was the next_in_service entity, - * then, since entity has just been - * deactivated, a new one must be found. - */ - bfq_update_next_in_service(sd, NULL); - - if (sd->next_in_service) - /* - * The parent entity is still backlogged, - * because next_in_service is not NULL. So, no - * further upwards deactivation must be - * performed. Yet, next_in_service has - * changed. Then the schedule does need to be - * updated upwards. - */ - break; - - /* - * If we get here, then the parent is no more - * backlogged and we need to propagate the - * deactivation upwards. Thus let the loop go on. - */ - - /* - * Also let parent be queued into the idle tree on - * deactivation, to preserve service guarantees, and - * assuming that who invoked this function does not - * need parent entities too to be removed completely. - */ - ins_into_idle_tree = true; - } - - /* - * If the deactivation loop is fully executed, then there are - * no more entities to touch and next loop is not executed at - * all. Otherwise, requeue remaining entities if they are - * about to stop receiving service, or reposition them if this - * is not the case. - */ - entity = parent; - for_each_entity(entity) { - /* - * Invoke __bfq_requeue_entity on entity, even if - * already active, to requeue/reposition it in the - * active tree (because sd->next_in_service has - * changed) - */ - __bfq_requeue_entity(entity); - - sd = entity->sched_data; - if (!bfq_update_next_in_service(sd, entity) && - !expiration) - /* - * next_in_service unchanged or not causing - * any change in entity->parent->sd, and no - * requeueing needed for expiration: stop - * here. - */ - break; - } -} - -/** - * bfq_calc_vtime_jump - compute the value to which the vtime should jump, - * if needed, to have at least one entity eligible. - * @st: the service tree to act upon. - * - * Assumes that st is not empty. - */ -static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st) -{ - struct bfq_entity *root_entity = bfq_root_active_entity(&st->active); - - if (bfq_gt(root_entity->min_start, st->vtime)) - return root_entity->min_start; - - return st->vtime; -} - -static void bfq_update_vtime(struct bfq_service_tree *st, u64 new_value) -{ - if (new_value > st->vtime) { - st->vtime = new_value; - bfq_forget_idle(st); - } -} - -/** - * bfq_first_active_entity - find the eligible entity with - * the smallest finish time - * @st: the service tree to select from. - * @vtime: the system virtual to use as a reference for eligibility - * - * 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, - u64 vtime) -{ - struct bfq_entity *entry, *first = NULL; - struct rb_node *node = st->active.rb_node; - - while (node) { - entry = rb_entry(node, struct bfq_entity, rb_node); -left: - if (!bfq_gt(entry->start, vtime)) - first = entry; - - if (node->rb_left) { - entry = rb_entry(node->rb_left, - struct bfq_entity, rb_node); - if (!bfq_gt(entry->min_start, vtime)) { - node = node->rb_left; - goto left; - } - } - if (first) - break; - node = node->rb_right; - } - - return first; -} - -/** - * __bfq_lookup_next_entity - return the first eligible entity in @st. - * @st: the service tree. - * - * If there is no in-service entity for the sched_data st belongs to, - * then return the entity that will be set in service if: - * 1) the parent entity this st belongs to is set in service; - * 2) no entity belonging to such parent entity undergoes a state change - * that would influence the timestamps of the entity (e.g., becomes idle, - * becomes backlogged, changes its budget, ...). - * - * In this first case, update the virtual time in @st too (see the - * comments on this update inside the function). - * - * In constrast, if there is an in-service entity, then return the - * entity that would be set in service if not only the above - * conditions, but also the next one held true: the currently - * in-service entity, on expiration, - * 1) gets a finish time equal to the current one, or - * 2) is not eligible any more, or - * 3) is idle. - */ -static struct bfq_entity * -__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service) -{ - struct bfq_entity *entity; - u64 new_vtime; - - if (RB_EMPTY_ROOT(&st->active)) - return NULL; - - /* - * Get the value of the system virtual time for which at - * least one entity is eligible. - */ - new_vtime = bfq_calc_vtime_jump(st); - - /* - * If there is no in-service entity for the sched_data this - * active tree belongs to, then push the system virtual time - * up to the value that guarantees that at least one entity is - * eligible. If, instead, there is an in-service entity, then - * do not make any such update, because there is already an - * eligible entity, namely the in-service one (even if the - * entity is not on st, because it was extracted when set in - * service). - */ - if (!in_service) - bfq_update_vtime(st, new_vtime); - - entity = bfq_first_active_entity(st, new_vtime); - - return entity; -} - -/** - * bfq_lookup_next_entity - return the first eligible entity in @sd. - * @sd: the sched_data. - * - * This function is invoked when there has been a change in the trees - * for sd, and we need know what is the new next entity after this - * change. - */ -static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd) -{ - struct bfq_service_tree *st = sd->service_tree; - struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1); - struct bfq_entity *entity = NULL; - int class_idx = 0; - - /* - * Choose from idle class, if needed to guarantee a minimum - * bandwidth to this class (and if there is some active entity - * in idle class). This should also mitigate - * priority-inversion problems in case a low priority task is - * holding file system resources. - */ - if (time_is_before_jiffies(sd->bfq_class_idle_last_service + - BFQ_CL_IDLE_TIMEOUT)) { - if (!RB_EMPTY_ROOT(&idle_class_st->active)) - class_idx = BFQ_IOPRIO_CLASSES - 1; - /* About to be served if backlogged, or not yet backlogged */ - sd->bfq_class_idle_last_service = jiffies; - } - - /* - * Find the next entity to serve for the highest-priority - * class, unless the idle class needs to be served. - */ - for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) { - entity = __bfq_lookup_next_entity(st + class_idx, - sd->in_service_entity); - - if (entity) - break; - } - - if (!entity) - return NULL; - - return entity; -} - -static bool next_queue_may_preempt(struct bfq_data *bfqd) -{ - struct bfq_sched_data *sd = &bfqd->root_group->sched_data; - - return sd->next_in_service != sd->in_service_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; - - if (bfqd->busy_queues == 0) - return NULL; - - /* - * Traverse the path from the root to the leaf entity to - * serve. Set in service all the entities visited along the - * way. - */ - sd = &bfqd->root_group->sched_data; - for (; sd ; sd = entity->my_sched_data) { - /* - * WARNING. We are about to set the in-service entity - * to sd->next_in_service, i.e., to the (cached) value - * returned by bfq_lookup_next_entity(sd) the last - * time it was invoked, i.e., the last time when the - * service order in sd changed as a consequence of the - * activation or deactivation of an entity. In this - * respect, if we execute bfq_lookup_next_entity(sd) - * in this very moment, it may, although with low - * probability, yield a different entity than that - * pointed to by sd->next_in_service. This rare event - * happens in case there was no CLASS_IDLE entity to - * serve for sd when bfq_lookup_next_entity(sd) was - * invoked for the last time, while there is now one - * such entity. - * - * If the above event happens, then the scheduling of - * such entity in CLASS_IDLE is postponed until the - * service of the sd->next_in_service entity - * finishes. In fact, when the latter is expired, - * bfq_lookup_next_entity(sd) gets called again, - * exactly to update sd->next_in_service. - */ - - /* Make next_in_service entity become in_service_entity */ - entity = sd->next_in_service; - sd->in_service_entity = entity; - - /* - * Reset the accumulator of the amount of service that - * the entity is about to receive. - */ - entity->service = 0; - - /* - * If entity is no longer a candidate for next - * service, then we extract it from its active tree, - * for the following reason. To further boost the - * throughput in some special case, BFQ needs to know - * which is the next candidate entity to serve, while - * there is already an entity in service. In this - * respect, to make it easy to compute/update the next - * candidate entity to serve after the current - * candidate has been set in service, there is a case - * where it is necessary to extract the current - * candidate from its service tree. Such a case is - * when the entity just set in service cannot be also - * a candidate for next service. Details about when - * this conditions holds are reported in the comments - * on the function bfq_no_longer_next_in_service() - * invoked below. - */ - if (bfq_no_longer_next_in_service(entity)) - bfq_active_extract(bfq_entity_service_tree(entity), - entity); - - /* - * For the same reason why we may have just extracted - * entity from its active tree, we may need to update - * next_in_service for the sched_data of entity too, - * regardless of whether entity has been extracted. - * In fact, even if entity has not been extracted, a - * descendant entity may get extracted. Such an event - * would cause a change in next_in_service for the - * level of the descendant entity, and thus possibly - * back to upper levels. - * - * We cannot perform the resulting needed update - * before the end of this loop, because, to know which - * is the correct next-to-serve candidate entity for - * each level, we need first to find the leaf entity - * to set in service. In fact, only after we know - * which is the next-to-serve leaf entity, we can - * discover whether the parent entity of the leaf - * entity becomes the next-to-serve, and so on. - */ - - } - - bfqq = bfq_entity_to_bfqq(entity); - - /* - * We can finally update all next-to-serve entities along the - * path from the leaf entity just set in service to the root. - */ - for_each_entity(entity) { - struct bfq_sched_data *sd = entity->sched_data; - - if (!bfq_update_next_in_service(sd, NULL)) - break; - } - - return bfqq; -} - -static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd) -{ - struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue; - struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity; - struct bfq_entity *entity = in_serv_entity; - - bfq_clear_bfqq_wait_request(in_serv_bfqq); - hrtimer_try_to_cancel(&bfqd->idle_slice_timer); - bfqd->in_service_queue = NULL; - - /* - * When this function is called, all in-service entities have - * been properly deactivated or requeued, so we can safely - * execute the final step: reset in_service_entity along the - * path from entity to the root. - */ - for_each_entity(entity) - entity->sched_data->in_service_entity = NULL; - - /* - * in_serv_entity is no longer in service, so, if it is in no - * service tree either, then release the service reference to - * the queue it represents (taken with bfq_get_entity). - */ - if (!in_serv_entity->on_st) - bfq_put_queue(in_serv_bfqq); -} - -static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, - bool ins_into_idle_tree, bool expiration) -{ - struct bfq_entity *entity = &bfqq->entity; - - bfq_deactivate_entity(entity, ins_into_idle_tree, expiration); -} - -static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) -{ - struct bfq_entity *entity = &bfqq->entity; - - bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq), - false); - bfq_clear_bfqq_non_blocking_wait_rq(bfqq); -} - -static void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) -{ - struct bfq_entity *entity = &bfqq->entity; - - bfq_activate_requeue_entity(entity, false, - bfqq == bfqd->in_service_queue); -} - -static void bfqg_stats_update_dequeue(struct bfq_group *bfqg); - -/* - * Called when the bfqq no longer has requests pending, remove it from - * the service tree. As a special case, it can be invoked during an - * expiration. - */ -static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, - bool expiration) -{ - bfq_log_bfqq(bfqd, bfqq, "del from busy"); - - bfq_clear_bfqq_busy(bfqq); - - bfqd->busy_queues--; - - if (!bfqq->dispatched) - bfq_weights_tree_remove(bfqd, &bfqq->entity, - &bfqd->queue_weights_tree); - - if (bfqq->wr_coeff > 1) - bfqd->wr_busy_queues--; - - bfqg_stats_update_dequeue(bfqq_group(bfqq)); - - bfq_deactivate_bfqq(bfqd, bfqq, true, expiration); -} - -/* - * Called when an inactive queue receives a new request. - */ -static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq) -{ - 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 (bfqq->wr_coeff > 1) - bfqd->wr_busy_queues++; -} - -#ifdef CONFIG_BFQ_GROUP_IOSCHED - -/* bfqg stats flags */ -enum bfqg_stats_flags { - BFQG_stats_waiting = 0, - BFQG_stats_idling, - BFQG_stats_empty, -}; - -#define BFQG_FLAG_FNS(name) \ -static void bfqg_stats_mark_##name(struct bfqg_stats *stats) \ -{ \ - stats->flags |= (1 << BFQG_stats_##name); \ -} \ -static void bfqg_stats_clear_##name(struct bfqg_stats *stats) \ -{ \ - stats->flags &= ~(1 << BFQG_stats_##name); \ -} \ -static int bfqg_stats_##name(struct bfqg_stats *stats) \ -{ \ - return (stats->flags & (1 << BFQG_stats_##name)) != 0; \ -} \ - -BFQG_FLAG_FNS(waiting) -BFQG_FLAG_FNS(idling) -BFQG_FLAG_FNS(empty) -#undef BFQG_FLAG_FNS - -/* This should be called with the queue_lock held. */ -static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats) -{ - unsigned long long now; - - if (!bfqg_stats_waiting(stats)) - return; - - now = sched_clock(); - if (time_after64(now, stats->start_group_wait_time)) - blkg_stat_add(&stats->group_wait_time, - now - stats->start_group_wait_time); - bfqg_stats_clear_waiting(stats); -} - -/* This should be called with the queue_lock held. */ -static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, - struct bfq_group *curr_bfqg) -{ - struct bfqg_stats *stats = &bfqg->stats; - - if (bfqg_stats_waiting(stats)) - return; - if (bfqg == curr_bfqg) - return; - stats->start_group_wait_time = sched_clock(); - bfqg_stats_mark_waiting(stats); -} - -/* This should be called with the queue_lock held. */ -static void bfqg_stats_end_empty_time(struct bfqg_stats *stats) -{ - unsigned long long now; - - if (!bfqg_stats_empty(stats)) - return; - - now = sched_clock(); - if (time_after64(now, stats->start_empty_time)) - blkg_stat_add(&stats->empty_time, - now - stats->start_empty_time); - bfqg_stats_clear_empty(stats); -} - -static void bfqg_stats_update_dequeue(struct bfq_group *bfqg) -{ - blkg_stat_add(&bfqg->stats.dequeue, 1); -} - -static void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) -{ - struct bfqg_stats *stats = &bfqg->stats; - - if (blkg_rwstat_total(&stats->queued)) - return; - - /* - * group is already marked empty. This can happen if bfqq got new - * request in parent group and moved to this group while being added - * to service tree. Just ignore the event and move on. - */ - if (bfqg_stats_empty(stats)) - return; - - stats->start_empty_time = sched_clock(); - bfqg_stats_mark_empty(stats); -} - -static void bfqg_stats_update_idle_time(struct bfq_group *bfqg) -{ - struct bfqg_stats *stats = &bfqg->stats; - - if (bfqg_stats_idling(stats)) { - unsigned long long now = sched_clock(); - - if (time_after64(now, stats->start_idle_time)) - blkg_stat_add(&stats->idle_time, - now - stats->start_idle_time); - bfqg_stats_clear_idling(stats); - } -} - -static void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) -{ - struct bfqg_stats *stats = &bfqg->stats; - - stats->start_idle_time = sched_clock(); - bfqg_stats_mark_idling(stats); -} - -static void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) -{ - struct bfqg_stats *stats = &bfqg->stats; - - blkg_stat_add(&stats->avg_queue_size_sum, - blkg_rwstat_total(&stats->queued)); - blkg_stat_add(&stats->avg_queue_size_samples, 1); - bfqg_stats_update_group_wait_time(stats); -} - -/* - * blk-cgroup policy-related handlers - * The following functions help in converting between blk-cgroup - * internal structures and BFQ-specific structures. - */ - -static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd) -{ - return pd ? container_of(pd, struct bfq_group, pd) : NULL; -} - -static struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg) -{ - return pd_to_blkg(&bfqg->pd); -} - -static struct blkcg_policy blkcg_policy_bfq; - -static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg) -{ - return pd_to_bfqg(blkg_to_pd(blkg, &blkcg_policy_bfq)); -} - -/* - * bfq_group handlers - * The following functions help in navigating the bfq_group hierarchy - * by allowing to find the parent of a bfq_group or the bfq_group - * associated to a bfq_queue. - */ - -static struct bfq_group *bfqg_parent(struct bfq_group *bfqg) -{ - struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent; - - return pblkg ? blkg_to_bfqg(pblkg) : NULL; -} - -static struct bfq_group *bfqq_group(struct bfq_queue *bfqq) -{ - struct bfq_entity *group_entity = bfqq->entity.parent; - - return group_entity ? container_of(group_entity, struct bfq_group, - entity) : - bfqq->bfqd->root_group; -} - -/* - * The following two functions handle get and put of a bfq_group by - * wrapping the related blk-cgroup hooks. - */ - -static void bfqg_get(struct bfq_group *bfqg) -{ - return blkg_get(bfqg_to_blkg(bfqg)); -} - -static void bfqg_put(struct bfq_group *bfqg) -{ - return blkg_put(bfqg_to_blkg(bfqg)); -} - -static void bfqg_stats_update_io_add(struct bfq_group *bfqg, - struct bfq_queue *bfqq, - unsigned int op) -{ - blkg_rwstat_add(&bfqg->stats.queued, op, 1); - bfqg_stats_end_empty_time(&bfqg->stats); - if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue)) - bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq)); -} - -static void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) -{ - blkg_rwstat_add(&bfqg->stats.queued, op, -1); -} - -static void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) -{ - blkg_rwstat_add(&bfqg->stats.merged, op, 1); -} - -static void bfqg_stats_update_completion(struct bfq_group *bfqg, - uint64_t start_time, uint64_t io_start_time, - unsigned int op) -{ - struct bfqg_stats *stats = &bfqg->stats; - unsigned long long now = sched_clock(); - - if (time_after64(now, io_start_time)) - blkg_rwstat_add(&stats->service_time, op, - now - io_start_time); - if (time_after64(io_start_time, start_time)) - blkg_rwstat_add(&stats->wait_time, op, - io_start_time - start_time); -} - -/* @stats = 0 */ -static void bfqg_stats_reset(struct bfqg_stats *stats) -{ - /* queued stats shouldn't be cleared */ - blkg_rwstat_reset(&stats->merged); - blkg_rwstat_reset(&stats->service_time); - blkg_rwstat_reset(&stats->wait_time); - blkg_stat_reset(&stats->time); - blkg_stat_reset(&stats->avg_queue_size_sum); - blkg_stat_reset(&stats->avg_queue_size_samples); - blkg_stat_reset(&stats->dequeue); - blkg_stat_reset(&stats->group_wait_time); - blkg_stat_reset(&stats->idle_time); - blkg_stat_reset(&stats->empty_time); -} - -/* @to += @from */ -static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from) -{ - if (!to || !from) - return; - - /* queued stats shouldn't be cleared */ - blkg_rwstat_add_aux(&to->merged, &from->merged); - blkg_rwstat_add_aux(&to->service_time, &from->service_time); - blkg_rwstat_add_aux(&to->wait_time, &from->wait_time); - blkg_stat_add_aux(&from->time, &from->time); - blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum); - blkg_stat_add_aux(&to->avg_queue_size_samples, - &from->avg_queue_size_samples); - blkg_stat_add_aux(&to->dequeue, &from->dequeue); - blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time); - blkg_stat_add_aux(&to->idle_time, &from->idle_time); - blkg_stat_add_aux(&to->empty_time, &from->empty_time); -} - -/* - * Transfer @bfqg's stats to its parent's aux counts so that the ancestors' - * recursive stats can still account for the amount used by this bfqg after - * it's gone. - */ -static void bfqg_stats_xfer_dead(struct bfq_group *bfqg) -{ - struct bfq_group *parent; - - if (!bfqg) /* root_group */ - return; - - parent = bfqg_parent(bfqg); - - lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock); - - if (unlikely(!parent)) - return; - - bfqg_stats_add_aux(&parent->stats, &bfqg->stats); - bfqg_stats_reset(&bfqg->stats); -} - -static void bfq_init_entity(struct bfq_entity *entity, - struct bfq_group *bfqg) -{ - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - - entity->weight = entity->new_weight; - entity->orig_weight = entity->new_weight; - if (bfqq) { - bfqq->ioprio = bfqq->new_ioprio; - bfqq->ioprio_class = bfqq->new_ioprio_class; - bfqg_get(bfqg); - } - entity->parent = bfqg->my_entity; /* NULL for root group */ - entity->sched_data = &bfqg->sched_data; -} - -static void bfqg_stats_exit(struct bfqg_stats *stats) -{ - blkg_rwstat_exit(&stats->merged); - blkg_rwstat_exit(&stats->service_time); - blkg_rwstat_exit(&stats->wait_time); - blkg_rwstat_exit(&stats->queued); - blkg_stat_exit(&stats->time); - blkg_stat_exit(&stats->avg_queue_size_sum); - blkg_stat_exit(&stats->avg_queue_size_samples); - blkg_stat_exit(&stats->dequeue); - blkg_stat_exit(&stats->group_wait_time); - blkg_stat_exit(&stats->idle_time); - blkg_stat_exit(&stats->empty_time); -} - -static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) -{ - if (blkg_rwstat_init(&stats->merged, gfp) || - blkg_rwstat_init(&stats->service_time, gfp) || - blkg_rwstat_init(&stats->wait_time, gfp) || - blkg_rwstat_init(&stats->queued, gfp) || - blkg_stat_init(&stats->time, gfp) || - blkg_stat_init(&stats->avg_queue_size_sum, gfp) || - blkg_stat_init(&stats->avg_queue_size_samples, gfp) || - blkg_stat_init(&stats->dequeue, gfp) || - blkg_stat_init(&stats->group_wait_time, gfp) || - blkg_stat_init(&stats->idle_time, gfp) || - blkg_stat_init(&stats->empty_time, gfp)) { - bfqg_stats_exit(stats); - return -ENOMEM; - } - - return 0; -} - -static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd) -{ - return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL; -} - -static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg) -{ - return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq)); -} - -static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp) -{ - struct bfq_group_data *bgd; - - bgd = kzalloc(sizeof(*bgd), gfp); - if (!bgd) - return NULL; - return &bgd->pd; -} - -static void bfq_cpd_init(struct blkcg_policy_data *cpd) -{ - struct bfq_group_data *d = cpd_to_bfqgd(cpd); - - d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ? - CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL; -} - -static void bfq_cpd_free(struct blkcg_policy_data *cpd) -{ - kfree(cpd_to_bfqgd(cpd)); -} - -static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node) -{ - struct bfq_group *bfqg; - - bfqg = kzalloc_node(sizeof(*bfqg), gfp, node); - if (!bfqg) - return NULL; - - if (bfqg_stats_init(&bfqg->stats, gfp)) { - kfree(bfqg); - return NULL; - } - - return &bfqg->pd; -} - -static void bfq_pd_init(struct blkg_policy_data *pd) -{ - struct blkcg_gq *blkg = pd_to_blkg(pd); - struct bfq_group *bfqg = blkg_to_bfqg(blkg); - struct bfq_data *bfqd = blkg->q->elevator->elevator_data; - struct bfq_entity *entity = &bfqg->entity; - struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg); - - entity->orig_weight = entity->weight = entity->new_weight = d->weight; - entity->my_sched_data = &bfqg->sched_data; - bfqg->my_entity = entity; /* - * the root_group's will be set to NULL - * in bfq_init_queue() - */ - bfqg->bfqd = bfqd; - bfqg->active_entities = 0; - bfqg->rq_pos_tree = RB_ROOT; -} - -static void bfq_pd_free(struct blkg_policy_data *pd) -{ - struct bfq_group *bfqg = pd_to_bfqg(pd); - - bfqg_stats_exit(&bfqg->stats); - return kfree(bfqg); -} - -static void bfq_pd_reset_stats(struct blkg_policy_data *pd) -{ - struct bfq_group *bfqg = pd_to_bfqg(pd); - - bfqg_stats_reset(&bfqg->stats); -} - -static void bfq_group_set_parent(struct bfq_group *bfqg, - struct bfq_group *parent) -{ - struct bfq_entity *entity; - - entity = &bfqg->entity; - entity->parent = parent->my_entity; - entity->sched_data = &parent->sched_data; -} - -static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd, - struct blkcg *blkcg) -{ - struct blkcg_gq *blkg; - - blkg = blkg_lookup(blkcg, bfqd->queue); - if (likely(blkg)) - return blkg_to_bfqg(blkg); - return NULL; -} - -static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, - struct blkcg *blkcg) -{ - struct bfq_group *bfqg, *parent; - struct bfq_entity *entity; - - bfqg = bfq_lookup_bfqg(bfqd, blkcg); - - if (unlikely(!bfqg)) - return NULL; - - /* - * Update chain of bfq_groups as we might be handling a leaf group - * which, along with some of its relatives, has not been hooked yet - * to the private hierarchy of BFQ. - */ - entity = &bfqg->entity; - for_each_entity(entity) { - bfqg = container_of(entity, struct bfq_group, entity); - if (bfqg != bfqd->root_group) { - parent = bfqg_parent(bfqg); - if (!parent) - parent = bfqd->root_group; - bfq_group_set_parent(bfqg, parent); - } - } - - return bfqg; -} - -static void bfq_pos_tree_add_move(struct bfq_data *bfqd, - struct bfq_queue *bfqq); -static void bfq_bfqq_expire(struct bfq_data *bfqd, - struct bfq_queue *bfqq, - bool compensate, - enum bfqq_expiration reason); - -/** - * bfq_bfqq_move - migrate @bfqq to @bfqg. - * @bfqd: queue descriptor. - * @bfqq: the queue to move. - * @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_group *bfqg) -{ - struct bfq_entity *entity = &bfqq->entity; - - /* If bfqq is empty, then bfq_bfqq_expire also invokes - * bfq_del_bfqq_busy, thereby removing bfqq and its entity - * from data structures related to current group. Otherwise we - * need to remove bfqq explicitly with bfq_deactivate_bfqq, as - * we do below. - */ - if (bfqq == bfqd->in_service_queue) - bfq_bfqq_expire(bfqd, bfqd->in_service_queue, - false, BFQQE_PREEMPTED); - - if (bfq_bfqq_busy(bfqq)) - bfq_deactivate_bfqq(bfqd, bfqq, false, false); - else if (entity->on_st) - bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); - bfqg_put(bfqq_group(bfqq)); - - /* - * 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; - bfqg_get(bfqg); - - if (bfq_bfqq_busy(bfqq)) { - bfq_pos_tree_add_move(bfqd, bfqq); - bfq_activate_bfqq(bfqd, bfqq); - } - - if (!bfqd->in_service_queue && !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. - * @blkcg: the blk-cgroup to move to. - * - * Move bic to blkcg, 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 blkcg *blkcg) -{ - struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0); - struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1); - struct bfq_group *bfqg; - struct bfq_entity *entity; - - bfqg = bfq_find_set_group(bfqd, blkcg); - - if (unlikely(!bfqg)) - bfqg = bfqd->root_group; - - if (async_bfqq) { - 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, async_bfqq->ref); - bfq_put_queue(async_bfqq); - } - } - - if (sync_bfqq) { - entity = &sync_bfqq->entity; - if (entity->sched_data != &bfqg->sched_data) - bfq_bfqq_move(bfqd, sync_bfqq, bfqg); - } - - return bfqg; -} - -static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) -{ - struct bfq_data *bfqd = bic_to_bfqd(bic); - struct bfq_group *bfqg = NULL; - uint64_t serial_nr; - - rcu_read_lock(); - serial_nr = bio_blkcg(bio)->css.serial_nr; - - /* - * Check whether blkcg has changed. The condition may trigger - * spuriously on a newly created cic but there's no harm. - */ - if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr)) - goto out; - - bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio)); - bic->blkcg_serial_nr = serial_nr; -out: - rcu_read_unlock(); -} - -/** - * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st. - * @st: the service tree being flushed. - */ -static void bfq_flush_idle_tree(struct bfq_service_tree *st) -{ - struct bfq_entity *entity = st->first_idle; - - for (; entity ; entity = st->first_idle) - __bfq_deactivate_entity(entity, false); -} - -/** - * 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 void bfq_reparent_leaf_entity(struct bfq_data *bfqd, - struct bfq_entity *entity) -{ - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - - bfq_bfqq_move(bfqd, bfqq, bfqd->root_group); -} - -/** - * 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 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 ; entity = bfq_entity_of(rb_first(active))) - bfq_reparent_leaf_entity(bfqd, entity); - - if (bfqg->sched_data.in_service_entity) - bfq_reparent_leaf_entity(bfqd, - bfqg->sched_data.in_service_entity); -} - -/** - * bfq_pd_offline - deactivate the entity associated with @pd, - * and reparent its children entities. - * @pd: descriptor of the policy going offline. - * - * blkio already grabs the queue_lock for us, so no need to use - * RCU-based magic - */ -static void bfq_pd_offline(struct blkg_policy_data *pd) -{ - struct bfq_service_tree *st; - struct bfq_group *bfqg = pd_to_bfqg(pd); - struct bfq_data *bfqd = bfqg->bfqd; - struct bfq_entity *entity = bfqg->my_entity; - unsigned long flags; - int i; - - if (!entity) /* root group */ - return; - - spin_lock_irqsave(&bfqd->lock, flags); - /* - * 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. - */ - bfq_reparent_active_entities(bfqd, bfqg, st); - } - - __bfq_deactivate_entity(entity, false); - bfq_put_async_queues(bfqd, bfqg); - - spin_unlock_irqrestore(&bfqd->lock, flags); - /* - * @blkg is going offline and will be ignored by - * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so - * that they don't get lost. If IOs complete after this point, the - * stats for them will be lost. Oh well... - */ - bfqg_stats_xfer_dead(bfqg); -} - -static void bfq_end_wr_async(struct bfq_data *bfqd) -{ - struct blkcg_gq *blkg; - - list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) { - struct bfq_group *bfqg = blkg_to_bfqg(blkg); - - bfq_end_wr_async_queues(bfqd, bfqg); - } - bfq_end_wr_async_queues(bfqd, bfqd->root_group); -} - -static int bfq_io_show_weight(struct seq_file *sf, void *v) -{ - struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); - struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); - unsigned int val = 0; - - if (bfqgd) - val = bfqgd->weight; - - seq_printf(sf, "%u\n", val); - - return 0; -} - -static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, - struct cftype *cftype, - u64 val) -{ - struct blkcg *blkcg = css_to_blkcg(css); - struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); - struct blkcg_gq *blkg; - int ret = -ERANGE; - - if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) - return ret; - - ret = 0; - spin_lock_irq(&blkcg->lock); - bfqgd->weight = (unsigned short)val; - hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { - struct bfq_group *bfqg = blkg_to_bfqg(blkg); - - if (!bfqg) - continue; - /* - * Setting the prio_changed flag of the entity - * to 1 with new_weight == weight 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_weight) { - bfqg->entity.new_weight = (unsigned short)val; - /* - * Make sure that the above new value has been - * stored in bfqg->entity.new_weight before - * setting the prio_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_weight (in - * __bfq_entity_update_weight_prio). - * This barrier makes sure that the new value - * of bfqg->entity.new_weight is correctly - * seen in that code. - */ - smp_wmb(); - bfqg->entity.prio_changed = 1; - } - } - spin_unlock_irq(&blkcg->lock); - - return ret; -} - -static ssize_t bfq_io_set_weight(struct kernfs_open_file *of, - char *buf, size_t nbytes, - loff_t off) -{ - u64 weight; - /* First unsigned long found in the file is used */ - int ret = kstrtoull(strim(buf), 0, &weight); - - if (ret) - return ret; - - return bfq_io_set_weight_legacy(of_css(of), NULL, weight); -} - -static int bfqg_print_stat(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat, - &blkcg_policy_bfq, seq_cft(sf)->private, false); - return 0; -} - -static int bfqg_print_rwstat(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat, - &blkcg_policy_bfq, seq_cft(sf)->private, true); - return 0; -} - -static u64 bfqg_prfill_stat_recursive(struct seq_file *sf, - struct blkg_policy_data *pd, int off) -{ - u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd), - &blkcg_policy_bfq, off); - return __blkg_prfill_u64(sf, pd, sum); -} - -static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf, - struct blkg_policy_data *pd, int off) -{ - struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd), - &blkcg_policy_bfq, - off); - return __blkg_prfill_rwstat(sf, pd, &sum); -} - -static int bfqg_print_stat_recursive(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), - bfqg_prfill_stat_recursive, &blkcg_policy_bfq, - seq_cft(sf)->private, false); - return 0; -} - -static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), - bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq, - seq_cft(sf)->private, true); - return 0; -} - -static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd, - int off) -{ - u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes); - - return __blkg_prfill_u64(sf, pd, sum >> 9); -} - -static int bfqg_print_stat_sectors(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), - bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false); - return 0; -} - -static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf, - struct blkg_policy_data *pd, int off) -{ - struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL, - offsetof(struct blkcg_gq, stat_bytes)); - u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) + - atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]); - - return __blkg_prfill_u64(sf, pd, sum >> 9); -} - -static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), - bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0, - false); - return 0; -} - -static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf, - struct blkg_policy_data *pd, int off) -{ - struct bfq_group *bfqg = pd_to_bfqg(pd); - u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples); - u64 v = 0; - - if (samples) { - v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum); - v = div64_u64(v, samples); - } - __blkg_prfill_u64(sf, pd, v); - return 0; -} - -/* print avg_queue_size */ -static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v) -{ - blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), - bfqg_prfill_avg_queue_size, &blkcg_policy_bfq, - 0, false); - return 0; -} - -static struct bfq_group * -bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) -{ - int ret; - - ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq); - if (ret) - return NULL; - - return blkg_to_bfqg(bfqd->queue->root_blkg); -} - -static struct cftype bfq_blkcg_legacy_files[] = { - { - .name = "bfq.weight", - .flags = CFTYPE_NOT_ON_ROOT, - .seq_show = bfq_io_show_weight, - .write_u64 = bfq_io_set_weight_legacy, - }, - - /* statistics, covers only the tasks in the bfqg */ - { - .name = "bfq.time", - .private = offsetof(struct bfq_group, stats.time), - .seq_show = bfqg_print_stat, - }, - { - .name = "bfq.sectors", - .seq_show = bfqg_print_stat_sectors, - }, - { - .name = "bfq.io_service_bytes", - .private = (unsigned long)&blkcg_policy_bfq, - .seq_show = blkg_print_stat_bytes, - }, - { - .name = "bfq.io_serviced", - .private = (unsigned long)&blkcg_policy_bfq, - .seq_show = blkg_print_stat_ios, - }, - { - .name = "bfq.io_service_time", - .private = offsetof(struct bfq_group, stats.service_time), - .seq_show = bfqg_print_rwstat, - }, - { - .name = "bfq.io_wait_time", - .private = offsetof(struct bfq_group, stats.wait_time), - .seq_show = bfqg_print_rwstat, - }, - { - .name = "bfq.io_merged", - .private = offsetof(struct bfq_group, stats.merged), - .seq_show = bfqg_print_rwstat, - }, - { - .name = "bfq.io_queued", - .private = offsetof(struct bfq_group, stats.queued), - .seq_show = bfqg_print_rwstat, - }, - - /* the same statictics which cover the bfqg and its descendants */ - { - .name = "bfq.time_recursive", - .private = offsetof(struct bfq_group, stats.time), - .seq_show = bfqg_print_stat_recursive, - }, - { - .name = "bfq.sectors_recursive", - .seq_show = bfqg_print_stat_sectors_recursive, - }, - { - .name = "bfq.io_service_bytes_recursive", - .private = (unsigned long)&blkcg_policy_bfq, - .seq_show = blkg_print_stat_bytes_recursive, - }, - { - .name = "bfq.io_serviced_recursive", - .private = (unsigned long)&blkcg_policy_bfq, - .seq_show = blkg_print_stat_ios_recursive, - }, - { - .name = "bfq.io_service_time_recursive", - .private = offsetof(struct bfq_group, stats.service_time), - .seq_show = bfqg_print_rwstat_recursive, - }, - { - .name = "bfq.io_wait_time_recursive", - .private = offsetof(struct bfq_group, stats.wait_time), - .seq_show = bfqg_print_rwstat_recursive, - }, - { - .name = "bfq.io_merged_recursive", - .private = offsetof(struct bfq_group, stats.merged), - .seq_show = bfqg_print_rwstat_recursive, - }, - { - .name = "bfq.io_queued_recursive", - .private = offsetof(struct bfq_group, stats.queued), - .seq_show = bfqg_print_rwstat_recursive, - }, - { - .name = "bfq.avg_queue_size", - .seq_show = bfqg_print_avg_queue_size, - }, - { - .name = "bfq.group_wait_time", - .private = offsetof(struct bfq_group, stats.group_wait_time), - .seq_show = bfqg_print_stat, - }, - { - .name = "bfq.idle_time", - .private = offsetof(struct bfq_group, stats.idle_time), - .seq_show = bfqg_print_stat, - }, - { - .name = "bfq.empty_time", - .private = offsetof(struct bfq_group, stats.empty_time), - .seq_show = bfqg_print_stat, - }, - { - .name = "bfq.dequeue", - .private = offsetof(struct bfq_group, stats.dequeue), - .seq_show = bfqg_print_stat, - }, - { } /* terminate */ -}; - -static struct cftype bfq_blkg_files[] = { - { - .name = "bfq.weight", - .flags = CFTYPE_NOT_ON_ROOT, - .seq_show = bfq_io_show_weight, - .write = bfq_io_set_weight, - }, - {} /* terminate */ -}; - -#else /* CONFIG_BFQ_GROUP_IOSCHED */ - -static inline void bfqg_stats_update_io_add(struct bfq_group *bfqg, - struct bfq_queue *bfqq, unsigned int op) { } -static inline void -bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { } -static inline void -bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { } -static inline void bfqg_stats_update_completion(struct bfq_group *bfqg, - uint64_t start_time, uint64_t io_start_time, - unsigned int op) { } -static inline void -bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, - struct bfq_group *curr_bfqg) { } -static inline void bfqg_stats_end_empty_time(struct bfqg_stats *stats) { } -static inline void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { } -static inline void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { } -static inline void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { } -static inline void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { } -static inline void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { } - -static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, - struct bfq_group *bfqg) {} - -static void bfq_init_entity(struct bfq_entity *entity, - struct bfq_group *bfqg) -{ - struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); - - entity->weight = entity->new_weight; - entity->orig_weight = entity->new_weight; - if (bfqq) { - bfqq->ioprio = bfqq->new_ioprio; - bfqq->ioprio_class = bfqq->new_ioprio_class; - } - entity->sched_data = &bfqg->sched_data; -} - -static void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {} - -static void bfq_end_wr_async(struct bfq_data *bfqd) -{ - bfq_end_wr_async_queues(bfqd, bfqd->root_group); -} - -static struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, - struct blkcg *blkcg) -{ - return bfqd->root_group; -} - -static struct bfq_group *bfqq_group(struct bfq_queue *bfqq) -{ - return bfqq->bfqd->root_group; -} - -static struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, - int node) -{ - struct bfq_group *bfqg; - int i; - - bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node); - if (!bfqg) - return NULL; - - for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) - bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; - - return bfqg; -} -#endif /* CONFIG_BFQ_GROUP_IOSCHED */ - #define bfq_class_idle(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_IDLE) #define bfq_class_rt(bfqq) ((bfqq)->ioprio_class == IOPRIO_CLASS_RT) @@ -4002,7 +438,7 @@ bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root, return bfqq; } -static void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) +void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) { struct rb_node **p, *parent; struct bfq_queue *__bfqq; @@ -4091,9 +527,8 @@ static bool bfq_symmetric_scenario(struct bfq_data *bfqd) * 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) +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; @@ -4161,9 +596,8 @@ inc_counter: * 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) +void bfq_weights_tree_remove(struct bfq_data *bfqd, struct bfq_entity *entity, + struct rb_root *root) { if (!entity->weight_counter) return; @@ -4580,11 +1014,6 @@ static int bfq_min_budget(struct bfq_data *bfqd) return bfqd->bfq_max_budget / 32; } -static void bfq_bfqq_expire(struct bfq_data *bfqd, - struct bfq_queue *bfqq, - bool compensate, - enum bfqq_expiration reason); - /* * The next function, invoked after the input queue bfqq switches from * idle to busy, updates the budget of bfqq. The function also tells @@ -5275,8 +1704,8 @@ static void bfq_bfqq_end_wr(struct bfq_queue *bfqq) bfqq->entity.prio_changed = 1; } -static void bfq_end_wr_async_queues(struct bfq_data *bfqd, - struct bfq_group *bfqg) +void bfq_end_wr_async_queues(struct bfq_data *bfqd, + struct bfq_group *bfqg) { int i, j; @@ -6495,10 +2924,10 @@ static unsigned long bfq_smallest_from_now(void) * former on a timeslice basis, without violating service domain * guarantees among the latter. */ -static void bfq_bfqq_expire(struct bfq_data *bfqd, - struct bfq_queue *bfqq, - bool compensate, - enum bfqq_expiration reason) +void bfq_bfqq_expire(struct bfq_data *bfqd, + struct bfq_queue *bfqq, + bool compensate, + enum bfqq_expiration reason) { bool slow; unsigned long delta = 0; @@ -7204,7 +3633,7 @@ static struct request *bfq_dispatch_request(struct blk_mq_hw_ctx *hctx) * Scheduler lock must be held here. Recall not to use bfqq after calling * this function on it. */ -static void bfq_put_queue(struct bfq_queue *bfqq) +void bfq_put_queue(struct bfq_queue *bfqq) { #ifdef CONFIG_BFQ_GROUP_IOSCHED struct bfq_group *bfqg = bfqq_group(bfqq); @@ -7345,6 +3774,10 @@ bfq_set_next_ioprio_data(struct bfq_queue *bfqq, struct bfq_io_cq *bic) bfqq->entity.prio_changed = 1; } +static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd, + struct bio *bio, bool is_sync, + struct bfq_io_cq *bic); + static void bfq_check_ioprio_change(struct bfq_io_cq *bic, struct bio *bio) { struct bfq_data *bfqd = bic_to_bfqd(bic); @@ -8121,7 +4554,7 @@ static void __bfq_put_async_bfqq(struct bfq_data *bfqd, * 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) +void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg) { int i, j; @@ -8537,24 +4970,6 @@ static struct elevator_type iosched_bfq_mq = { .elevator_owner = THIS_MODULE, }; -#ifdef CONFIG_BFQ_GROUP_IOSCHED -static struct blkcg_policy blkcg_policy_bfq = { - .dfl_cftypes = bfq_blkg_files, - .legacy_cftypes = bfq_blkcg_legacy_files, - - .cpd_alloc_fn = bfq_cpd_alloc, - .cpd_init_fn = bfq_cpd_init, - .cpd_bind_fn = bfq_cpd_init, - .cpd_free_fn = bfq_cpd_free, - - .pd_alloc_fn = bfq_pd_alloc, - .pd_init_fn = bfq_pd_init, - .pd_offline_fn = bfq_pd_offline, - .pd_free_fn = bfq_pd_free, - .pd_reset_stats_fn = bfq_pd_reset_stats, -}; -#endif - static int __init bfq_init(void) { int ret; diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h new file mode 100644 index 000000000000..4ce7915e8d84 --- /dev/null +++ b/block/bfq-iosched.h @@ -0,0 +1,942 @@ +/* + * Header file for the BFQ I/O scheduler: data structures and + * prototypes of interface functions among BFQ components. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ +#ifndef _BFQ_H +#define _BFQ_H + +#include <linux/blktrace_api.h> +#include <linux/hrtimer.h> +#include <linux/blk-cgroup.h> + +#define BFQ_IOPRIO_CLASSES 3 +#define BFQ_CL_IDLE_TIMEOUT (HZ/5) + +#define BFQ_MIN_WEIGHT 1 +#define BFQ_MAX_WEIGHT 1000 +#define BFQ_WEIGHT_CONVERSION_COEFF 10 + +#define BFQ_DEFAULT_QUEUE_IOPRIO 4 + +#define BFQ_WEIGHT_LEGACY_DFL 100 +#define BFQ_DEFAULT_GRP_IOPRIO 0 +#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE + +/* + * Soft real-time applications are extremely more latency sensitive + * than interactive ones. Over-raise the weight of the former to + * privilege them against the latter. + */ +#define BFQ_SOFTRT_WEIGHT_FACTOR 100 + +struct bfq_entity; + +/** + * struct bfq_service_tree - per ioprio_class service tree. + * + * 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 { + /* tree for active entities (i.e., those backlogged) */ + struct rb_root active; + /* tree for idle entities (i.e., not backlogged, with V <= F_i)*/ + struct rb_root idle; + + /* idle entity with minimum F_i */ + struct bfq_entity *first_idle; + /* idle entity with maximum F_i */ + struct bfq_entity *last_idle; + + /* scheduler virtual time */ + u64 vtime; + /* scheduler weight sum; active and idle entities contribute to it */ + unsigned long wsum; +}; + +/** + * struct bfq_sched_data - multi-class scheduler. + * + * 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. It is used to reduce the number of steps + * needed for each hierarchical-schedule update. + * + * 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 { + /* entity in service */ + struct bfq_entity *in_service_entity; + /* head-of-line entity (see comments above) */ + struct bfq_entity *next_in_service; + /* array of service trees, one per ioprio_class */ + struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; + /* last time CLASS_IDLE was served */ + unsigned long bfq_class_idle_last_service; + +}; + +/** + * struct bfq_weight_counter - counter of the number of all active entities + * with a given weight. + */ +struct bfq_weight_counter { + unsigned int weight; /* weight of the entities this counter refers to */ + unsigned int num_active; /* nr of active entities with this weight */ + /* + * Weights tree member (see bfq_data's @queue_weights_tree and + * @group_weights_tree) + */ + struct rb_node weights_node; +}; + +/** + * struct bfq_entity - schedulable entity. + * + * 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 @prio_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 { + /* service_tree member */ + struct rb_node rb_node; + /* pointer to the weight counter associated with this entity */ + struct bfq_weight_counter *weight_counter; + + /* + * Flag, true if the entity is on a tree (either the active or + * the idle one of its service_tree) or is in service. + */ + bool on_st; + + /* B-WF2Q+ start and finish timestamps [sectors/weight] */ + u64 start, finish; + + /* tree the entity is enqueued into; %NULL if not on a tree */ + struct rb_root *tree; + + /* + * minimum start time of the (active) subtree rooted at this + * entity; used for O(log N) lookups into active trees + */ + u64 min_start; + + /* amount of service received during the last service slot */ + int service; + + /* budget, used also to calculate F_i: F_i = S_i + @budget / @weight */ + int budget; + + /* weight of the queue */ + int weight; + /* next weight if a change is in progress */ + int new_weight; + + /* original weight, used to implement weight boosting */ + int orig_weight; + + /* parent entity, for hierarchical scheduling */ + struct bfq_entity *parent; + + /* + * For non-leaf nodes in the hierarchy, the associated + * scheduler queue, %NULL on leaf nodes. + */ + struct bfq_sched_data *my_sched_data; + /* the scheduler queue this entity belongs to */ + struct bfq_sched_data *sched_data; + + /* flag, set to request a weight, ioprio or ioprio_class change */ + int prio_changed; +}; + +struct bfq_group; + +/** + * struct bfq_ttime - per process thinktime stats. + */ +struct bfq_ttime { + /* completion time of the last request */ + u64 last_end_request; + + /* total process thinktime */ + u64 ttime_total; + /* number of thinktime samples */ + unsigned long ttime_samples; + /* average process thinktime */ + u64 ttime_mean; +}; + +/** + * struct bfq_queue - leaf schedulable entity. + * + * 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 { + /* reference counter */ + int ref; + /* parent bfq_data */ + struct bfq_data *bfqd; + + /* current ioprio and ioprio class */ + unsigned short ioprio, ioprio_class; + /* next ioprio and ioprio class if a change is in progress */ + unsigned short new_ioprio, new_ioprio_class; + + /* + * Shared bfq_queue if queue is cooperating with one or more + * other queues. + */ + struct bfq_queue *new_bfqq; + /* request-position tree member (see bfq_group's @rq_pos_tree) */ + struct rb_node pos_node; + /* request-position tree root (see bfq_group's @rq_pos_tree) */ + struct rb_root *pos_root; + + /* sorted list of pending requests */ + struct rb_root sort_list; + /* if fifo isn't expired, next request to serve */ + struct request *next_rq; + /* number of sync and async requests queued */ + int queued[2]; + /* number of requests currently allocated */ + int allocated; + /* number of pending metadata requests */ + int meta_pending; + /* fifo list of requests in sort_list */ + struct list_head fifo; + + /* entity representing this queue in the scheduler */ + struct bfq_entity entity; + + /* maximum budget allowed from the feedback mechanism */ + int max_budget; + /* budget expiration (in jiffies) */ + unsigned long budget_timeout; + + /* number of requests on the dispatch list or inside driver */ + int dispatched; + + /* status flags */ + unsigned long flags; + + /* node for active/idle bfqq list inside parent bfqd */ + struct list_head bfqq_list; + + /* associated @bfq_ttime struct */ + struct bfq_ttime ttime; + + /* bit vector: a 1 for each seeky requests in history */ + u32 seek_history; + + /* node for the device's burst list */ + struct hlist_node burst_list_node; + + /* position of the last request enqueued */ + sector_t last_request_pos; + + /* 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 flag has been + * cleared. + */ + unsigned int requests_within_timer; + + /* pid of the process owning the queue, used for logging purposes */ + pid_t pid; + + /* + * Pointer to the bfq_io_cq owning the bfq_queue, set to %NULL + * if the queue is shared. + */ + struct bfq_io_cq *bic; + + /* current maximum weight-raising time for this queue */ + unsigned long wr_cur_max_time; + /* + * 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 on + * the function bfq_bfqq_softrt_next_start()) + */ + unsigned long soft_rt_next_start; + /* + * 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. + */ + unsigned long last_wr_start_finish; + /* factor by which the weight of this queue is multiplied */ + unsigned int wr_coeff; + /* + * Time of the last transition of the @bfq_queue from idle to + * backlogged. + */ + unsigned long last_idle_bklogged; + /* + * Cumulative service received from the @bfq_queue since the + * last transition from idle to backlogged. + */ + unsigned long service_from_backlogged; + + /* + * Value of wr start time when switching to soft rt + */ + unsigned long wr_start_at_switch_to_srt; + + unsigned long split_time; /* time of last split */ +}; + +/** + * struct bfq_io_cq - per (request_queue, io_context) structure. + */ +struct bfq_io_cq { + /* associated io_cq structure */ + struct io_cq icq; /* must be the first member */ + /* array of two process queues, the sync and the async */ + struct bfq_queue *bfqq[2]; + /* per (request_queue, blkcg) ioprio */ + int ioprio; +#ifdef CONFIG_BFQ_GROUP_IOSCHED + uint64_t blkcg_serial_nr; /* the current blkcg serial */ +#endif + /* + * Snapshot of the idle window before merging; taken to + * remember this value while the queue is merged, so as to be + * able to restore it in case of split. + */ + bool saved_idle_window; + /* + * Same purpose as the previous two fields for the I/O bound + * classification of a queue. + */ + bool saved_IO_bound; + + /* + * Same purpose as the previous fields for the value of the + * field keeping the queue's belonging to a large burst + */ + bool saved_in_large_burst; + /* + * True if the queue belonged to a burst list before its merge + * with another cooperating queue. + */ + bool was_in_burst_list; + + /* + * Similar to previous fields: save wr information. + */ + unsigned long saved_wr_coeff; + unsigned long saved_last_wr_start_finish; + unsigned long saved_wr_start_at_switch_to_srt; + unsigned int saved_wr_cur_max_time; + struct bfq_ttime saved_ttime; +}; + +enum bfq_device_speed { + BFQ_BFQD_FAST, + BFQ_BFQD_SLOW, +}; + +/** + * struct bfq_data - per-device data structure. + * + * All the fields are protected by @lock. + */ +struct bfq_data { + /* device request queue */ + struct request_queue *queue; + /* dispatch queue */ + struct list_head dispatch; + + /* root bfq_group for the device */ + struct bfq_group *root_group; + + /* + * 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). + */ + struct rb_root queue_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). + */ + struct rb_root group_weights_tree; + + /* + * Number of bfq_queues containing requests (including the + * queue in service, even if it is idling). + */ + int busy_queues; + /* number of weight-raised busy @bfq_queues */ + int wr_busy_queues; + /* number of queued requests */ + int queued; + /* number of requests dispatched and waiting for completion */ + int rq_in_driver; + + /* + * Maximum number of requests in driver in the last + * @hw_tag_samples completed requests. + */ + int max_rq_in_driver; + /* number of samples used to calculate hw_tag */ + int hw_tag_samples; + /* flag set to one if the driver is showing a queueing behavior */ + int hw_tag; + + /* number of budgets assigned */ + int budgets_assigned; + + /* + * Timer set when idling (waiting) for the next request from + * the queue in service. + */ + struct hrtimer idle_slice_timer; + + /* bfq_queue in service */ + struct bfq_queue *in_service_queue; + + /* on-disk position of the last served request */ + sector_t last_position; + + /* time of last request completion (ns) */ + u64 last_completion; + + /* time of first rq dispatch in current observation interval (ns) */ + u64 first_dispatch; + /* time of last rq dispatch in current observation interval (ns) */ + u64 last_dispatch; + + /* beginning of the last budget */ + ktime_t last_budget_start; + /* beginning of the last idle slice */ + ktime_t last_idling_start; + + /* number of samples in current observation interval */ + int peak_rate_samples; + /* num of samples of seq dispatches in current observation interval */ + u32 sequential_samples; + /* total num of sectors transferred in current observation interval */ + u64 tot_sectors_dispatched; + /* max rq size seen during current observation interval (sectors) */ + u32 last_rq_max_size; + /* time elapsed from first dispatch in current observ. interval (us) */ + u64 delta_from_first; + /* + * Current estimate of the device peak rate, measured in + * [BFQ_RATE_SHIFT * sectors/usec]. The left-shift by + * BFQ_RATE_SHIFT is performed to increase precision in + * fixed-point calculations. + */ + u32 peak_rate; + + /* maximum budget allotted to a bfq_queue before rescheduling */ + int bfq_max_budget; + + /* list of all the bfq_queues active on the device */ + struct list_head active_list; + /* list of all the bfq_queues idle on the device */ + struct list_head idle_list; + + /* + * Timeout for async/sync requests; when it fires, requests + * are served in fifo order. + */ + u64 bfq_fifo_expire[2]; + /* weight of backward seeks wrt forward ones */ + unsigned int bfq_back_penalty; + /* maximum allowed backward seek */ + unsigned int bfq_back_max; + /* maximum idling time */ + u32 bfq_slice_idle; + + /* user-configured max budget value (0 for auto-tuning) */ + int bfq_user_max_budget; + /* + * Timeout for bfq_queues to consume their budget; used to + * prevent seeky queues from imposing long latencies to + * sequential or quasi-sequential ones (this also implies that + * seeky queues cannot receive guarantees in the service + * domain; after a timeout they are charged for the time they + * have been in service, to preserve fairness among them, but + * without service-domain guarantees). + */ + unsigned int bfq_timeout; + + /* + * 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). + */ + unsigned int bfq_requests_within_timer; + + /* + * Force device idling whenever needed to provide accurate + * service guarantees, without caring about throughput + * issues. CAVEAT: this may even increase latencies, in case + * of useless idling for processes that did stop doing I/O. + */ + bool strict_guarantees; + + /* + * 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 on the function + * bfq_handle_burst. + */ + unsigned long last_ins_in_burst; + /* + * Reference time interval used to decide whether a queue has + * been activated shortly after @last_ins_in_burst. + */ + unsigned long bfq_burst_interval; + /* number of queues in the current burst of queue activations */ + int burst_size; + + /* common parent entity for the queues in the burst */ + struct bfq_entity *burst_parent_entity; + /* Maximum burst size above which the current queue-activation + * burst is deemed as 'large'. + */ + unsigned long bfq_large_burst_thresh; + /* true if a large queue-activation burst is in progress */ + bool large_burst; + /* + * Head of the burst list (as for the above fields, more + * details in the comments on the function bfq_handle_burst). + */ + struct hlist_head burst_list; + + /* if set to true, low-latency heuristics are enabled */ + bool low_latency; + /* + * Maximum factor by which the weight of a weight-raised queue + * is multiplied. + */ + unsigned int bfq_wr_coeff; + /* maximum duration of a weight-raising period (jiffies) */ + unsigned int bfq_wr_max_time; + + /* Maximum weight-raising duration for soft real-time processes */ + unsigned int bfq_wr_rt_max_time; + /* + * Minimum idle period after which weight-raising may be + * reactivated for a queue (in jiffies). + */ + unsigned int bfq_wr_min_idle_time; + /* + * Minimum period between request arrivals after which + * weight-raising may be reactivated for an already busy async + * queue (in jiffies). + */ + unsigned long bfq_wr_min_inter_arr_async; + + /* Max service-rate for a soft real-time queue, in sectors/sec */ + unsigned int bfq_wr_max_softrt_rate; + /* + * Cached value of the product R*T, used for computing the + * maximum duration of weight raising automatically. + */ + u64 RT_prod; + /* device-speed class for the low-latency heuristic */ + enum bfq_device_speed device_speed; + + /* fallback dummy bfqq for extreme OOM conditions */ + struct bfq_queue oom_bfqq; + + spinlock_t lock; + + /* + * bic associated with the task issuing current bio for + * merging. This and the next field are used as a support to + * be able to perform the bic lookup, needed by bio-merge + * functions, before the scheduler lock is taken, and thus + * avoid taking the request-queue lock while the scheduler + * lock is being held. + */ + struct bfq_io_cq *bio_bic; + /* bfqq associated with the task issuing current bio for merging */ + struct bfq_queue *bio_bfqq; +}; + +enum bfqq_state_flags { + BFQQF_just_created = 0, /* queue just allocated */ + BFQQF_busy, /* has requests or is in service */ + BFQQF_wait_request, /* waiting for a request */ + BFQQF_non_blocking_wait_rq, /* + * waiting for a request + * without idling the device + */ + BFQQF_fifo_expire, /* FIFO checked in this slice */ + BFQQF_idle_window, /* slice idling enabled */ + BFQQF_sync, /* synchronous queue */ + BFQQF_IO_bound, /* + * bfqq has timed-out at least once + * having consumed at most 2/10 of + * its budget + */ + BFQQF_in_large_burst, /* + * bfqq activated in a large burst, + * see comments to bfq_handle_burst. + */ + BFQQF_softrt_update, /* + * may need softrt-next-start + * update + */ + BFQQF_coop, /* bfqq is shared */ + BFQQF_split_coop /* shared bfqq will be split */ +}; + +#define BFQ_BFQQ_FNS(name) \ +void bfq_mark_bfqq_##name(struct bfq_queue *bfqq); \ +void bfq_clear_bfqq_##name(struct bfq_queue *bfqq); \ +int bfq_bfqq_##name(const struct bfq_queue *bfqq); + +BFQ_BFQQ_FNS(just_created); +BFQ_BFQQ_FNS(busy); +BFQ_BFQQ_FNS(wait_request); +BFQ_BFQQ_FNS(non_blocking_wait_rq); +BFQ_BFQQ_FNS(fifo_expire); +BFQ_BFQQ_FNS(idle_window); +BFQ_BFQQ_FNS(sync); +BFQ_BFQQ_FNS(IO_bound); +BFQ_BFQQ_FNS(in_large_burst); +BFQ_BFQQ_FNS(coop); +BFQ_BFQQ_FNS(split_coop); +BFQ_BFQQ_FNS(softrt_update); +#undef BFQ_BFQQ_FNS + +/* Expiration reasons. */ +enum bfqq_expiration { + BFQQE_TOO_IDLE = 0, /* + * queue has been idling for + * too long + */ + BFQQE_BUDGET_TIMEOUT, /* budget took too long to be used */ + BFQQE_BUDGET_EXHAUSTED, /* budget consumed */ + BFQQE_NO_MORE_REQUESTS, /* the queue has no more requests */ + BFQQE_PREEMPTED /* preemption in progress */ +}; + +struct bfqg_stats { +#ifdef CONFIG_BFQ_GROUP_IOSCHED + /* number of ios merged */ + struct blkg_rwstat merged; + /* total time spent on device in ns, may not be accurate w/ queueing */ + struct blkg_rwstat service_time; + /* total time spent waiting in scheduler queue in ns */ + struct blkg_rwstat wait_time; + /* number of IOs queued up */ + struct blkg_rwstat queued; + /* total disk time and nr sectors dispatched by this group */ + struct blkg_stat time; + /* sum of number of ios queued across all samples */ + struct blkg_stat avg_queue_size_sum; + /* count of samples taken for average */ + struct blkg_stat avg_queue_size_samples; + /* how many times this group has been removed from service tree */ + struct blkg_stat dequeue; + /* total time spent waiting for it to be assigned a timeslice. */ + struct blkg_stat group_wait_time; + /* time spent idling for this blkcg_gq */ + struct blkg_stat idle_time; + /* total time with empty current active q with other requests queued */ + struct blkg_stat empty_time; + /* fields after this shouldn't be cleared on stat reset */ + uint64_t start_group_wait_time; + uint64_t start_idle_time; + uint64_t start_empty_time; + uint16_t flags; +#endif /* CONFIG_BFQ_GROUP_IOSCHED */ +}; + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + +/* + * struct bfq_group_data - per-blkcg storage for the blkio subsystem. + * + * @ps: @blkcg_policy_storage that this structure inherits + * @weight: weight of the bfq_group + */ +struct bfq_group_data { + /* must be the first member */ + struct blkcg_policy_data pd; + + unsigned int weight; +}; + +/** + * 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). + * @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. + * @stats: stats for this bfqg. + * @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_may_idle()). + * @rq_pos_tree: rbtree sorted by next_request position, used when + * determining if two or more queues have interleaving + * requests (see bfq_find_close_cooperator()). + * + * 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 @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 { + /* must be the first member */ + struct blkg_policy_data pd; + + struct bfq_entity entity; + struct bfq_sched_data sched_data; + + 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 rb_root rq_pos_tree; + + struct bfqg_stats stats; +}; + +#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; + + struct rb_root rq_pos_tree; +}; +#endif + +struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); + +/* --------------- main algorithm interface ----------------- */ + +#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \ + { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 }) + +extern const int bfq_timeout; + +struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic, bool is_sync); +void bic_set_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq, bool is_sync); +struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic); +void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); +void bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq); +void bfq_weights_tree_add(struct bfq_data *bfqd, struct bfq_entity *entity, + struct rb_root *root); +void bfq_weights_tree_remove(struct bfq_data *bfqd, struct bfq_entity *entity, + struct rb_root *root); +void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq, + bool compensate, enum bfqq_expiration reason); +void bfq_put_queue(struct bfq_queue *bfqq); +void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); +void bfq_schedule_dispatch(struct bfq_data *bfqd); +void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); + +/* ------------ end of main algorithm interface -------------- */ + +/* ---------------- cgroups-support interface ---------------- */ + +extern struct cftype bfq_blkcg_legacy_files[]; +extern struct cftype bfq_blkg_files[]; + +void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq, + unsigned int op); +void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op); +void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op); +void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time, + uint64_t io_start_time, unsigned int op); +void bfqg_stats_update_dequeue(struct bfq_group *bfqg); +void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg); +void bfqg_stats_update_idle_time(struct bfq_group *bfqg); +void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg); +void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg); +void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, + struct bfq_group *bfqg); + +void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg); +void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio); +void bfq_end_wr_async(struct bfq_data *bfqd); +struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, + struct blkcg *blkcg); +struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg); +struct bfq_group *bfqq_group(struct bfq_queue *bfqq); +struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node); +void bfqg_put(struct bfq_group *bfqg); + +#ifdef CONFIG_BFQ_GROUP_IOSCHED +extern struct blkcg_policy blkcg_policy_bfq; +#endif + +/* ------------- end of cgroups-support interface ------------- */ + +/* - interface of the internal hierarchical B-WF2Q+ scheduler - */ + +#ifdef CONFIG_BFQ_GROUP_IOSCHED +/* both next loops stop at one of the child entities of the root group */ +#define for_each_entity(entity) \ + for (; entity ; entity = entity->parent) + +/* + * For each iteration, compute parent in advance, so as to be safe if + * entity is deallocated during the iteration. Such a deallocation may + * happen as a consequence of a bfq_put_queue that frees the bfq_queue + * containing entity. + */ +#define for_each_entity_safe(entity, parent) \ + for (; entity && ({ parent = entity->parent; 1; }); entity = parent) + +#else /* CONFIG_BFQ_GROUP_IOSCHED */ +/* + * Next two macros are fake loops when cgroups support is not + * enabled. I fact, in such a case, there is only one level to go up + * (to reach the root group). + */ +#define for_each_entity(entity) \ + for (; entity ; entity = NULL) + +#define for_each_entity_safe(entity, parent) \ + for (parent = NULL; entity ; entity = parent) +#endif /* CONFIG_BFQ_GROUP_IOSCHED */ + +struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq); +struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity); +struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity); +struct bfq_entity *bfq_entity_of(struct rb_node *node); +unsigned short bfq_ioprio_to_weight(int ioprio); +void bfq_put_idle_entity(struct bfq_service_tree *st, + struct bfq_entity *entity); +struct bfq_service_tree * +__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st, + struct bfq_entity *entity); +void bfq_bfqq_served(struct bfq_queue *bfqq, int served); +void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq, + unsigned long time_ms); +bool __bfq_deactivate_entity(struct bfq_entity *entity, + bool ins_into_idle_tree); +bool next_queue_may_preempt(struct bfq_data *bfqd); +struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd); +void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd); +void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, + bool ins_into_idle_tree, bool expiration); +void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); +void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq); +void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, + bool expiration); +void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq); + +/* --------------- end of interface of B-WF2Q+ ---------------- */ + +/* Logging facilities. */ +#ifdef CONFIG_BFQ_GROUP_IOSCHED +struct bfq_group *bfqq_group(struct bfq_queue *bfqq); + +#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) do { \ + char __pbuf[128]; \ + \ + blkg_path(bfqg_to_blkg(bfqq_group(bfqq)), __pbuf, sizeof(__pbuf)); \ + blk_add_trace_msg((bfqd)->queue, "bfq%d%c %s " fmt, (bfqq)->pid, \ + bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ + __pbuf, ##args); \ +} while (0) + +#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do { \ + char __pbuf[128]; \ + \ + blkg_path(bfqg_to_blkg(bfqg), __pbuf, sizeof(__pbuf)); \ + blk_add_trace_msg((bfqd)->queue, "%s " fmt, __pbuf, ##args); \ +} while (0) + +#else /* CONFIG_BFQ_GROUP_IOSCHED */ + +#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \ + blk_add_trace_msg((bfqd)->queue, "bfq%d%c " fmt, (bfqq)->pid, \ + bfq_bfqq_sync((bfqq)) ? 'S' : 'A', \ + ##args) +#define bfq_log_bfqg(bfqd, bfqg, fmt, args...) do {} while (0) + +#endif /* CONFIG_BFQ_GROUP_IOSCHED */ + +#define bfq_log(bfqd, fmt, args...) \ + blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args) + +#endif /* _BFQ_H */ diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c new file mode 100644 index 000000000000..b4fc3e4260b7 --- /dev/null +++ b/block/bfq-wf2q.c @@ -0,0 +1,1616 @@ +/* + * Hierarchical Budget Worst-case Fair Weighted Fair Queueing + * (B-WF2Q+): hierarchical scheduling algorithm by which the BFQ I/O + * scheduler schedules generic entities. The latter can represent + * either single bfq queues (associated with processes) or groups of + * bfq queues (associated with cgroups). + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ +#include "bfq-iosched.h" + +/** + * bfq_gt - compare two timestamps. + * @a: first ts. + * @b: second ts. + * + * Return @a > @b, dealing with wrapping correctly. + */ +static int bfq_gt(u64 a, u64 b) +{ + return (s64)(a - b) > 0; +} + +static struct bfq_entity *bfq_root_active_entity(struct rb_root *tree) +{ + struct rb_node *node = tree->rb_node; + + return rb_entry(node, struct bfq_entity, rb_node); +} + +static unsigned int bfq_class_idx(struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + return bfqq ? bfqq->ioprio_class - 1 : + BFQ_DEFAULT_GRP_CLASS - 1; +} + +static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd); + +static bool bfq_update_parent_budget(struct bfq_entity *next_in_service); + +/** + * bfq_update_next_in_service - update sd->next_in_service + * @sd: sched_data for which to perform the update. + * @new_entity: if not NULL, pointer to the entity whose activation, + * requeueing or repositionig triggered the invocation of + * this function. + * + * This function is called to update sd->next_in_service, which, in + * its turn, may change as a consequence of the insertion or + * extraction of an entity into/from one of the active trees of + * sd. These insertions/extractions occur as a consequence of + * activations/deactivations of entities, with some activations being + * 'true' activations, and other activations being requeueings (i.e., + * implementing the second, requeueing phase of the mechanism used to + * reposition an entity in its active tree; see comments on + * __bfq_activate_entity and __bfq_requeue_entity for details). In + * both the last two activation sub-cases, new_entity points to the + * just activated or requeued entity. + * + * Returns true if sd->next_in_service changes in such a way that + * entity->parent may become the next_in_service for its parent + * entity. + */ +static bool bfq_update_next_in_service(struct bfq_sched_data *sd, + struct bfq_entity *new_entity) +{ + struct bfq_entity *next_in_service = sd->next_in_service; + bool parent_sched_may_change = false; + + /* + * If this update is triggered by the activation, requeueing + * or repositiong of an entity that does not coincide with + * sd->next_in_service, then a full lookup in the active tree + * can be avoided. In fact, it is enough to check whether the + * just-modified entity has a higher priority than + * sd->next_in_service, or, even if it has the same priority + * as sd->next_in_service, is eligible and has a lower virtual + * finish time than sd->next_in_service. If this compound + * condition holds, then the new entity becomes the new + * next_in_service. Otherwise no change is needed. + */ + if (new_entity && new_entity != sd->next_in_service) { + /* + * Flag used to decide whether to replace + * sd->next_in_service with new_entity. Tentatively + * set to true, and left as true if + * sd->next_in_service is NULL. + */ + bool replace_next = true; + + /* + * If there is already a next_in_service candidate + * entity, then compare class priorities or timestamps + * to decide whether to replace sd->service_tree with + * new_entity. + */ + if (next_in_service) { + unsigned int new_entity_class_idx = + bfq_class_idx(new_entity); + struct bfq_service_tree *st = + sd->service_tree + new_entity_class_idx; + + /* + * For efficiency, evaluate the most likely + * sub-condition first. + */ + replace_next = + (new_entity_class_idx == + bfq_class_idx(next_in_service) + && + !bfq_gt(new_entity->start, st->vtime) + && + bfq_gt(next_in_service->finish, + new_entity->finish)) + || + new_entity_class_idx < + bfq_class_idx(next_in_service); + } + + if (replace_next) + next_in_service = new_entity; + } else /* invoked because of a deactivation: lookup needed */ + next_in_service = bfq_lookup_next_entity(sd); + + if (next_in_service) { + parent_sched_may_change = !sd->next_in_service || + bfq_update_parent_budget(next_in_service); + } + + sd->next_in_service = next_in_service; + + if (!next_in_service) + return parent_sched_may_change; + + return parent_sched_may_change; +} + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + +struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) +{ + struct bfq_entity *group_entity = bfqq->entity.parent; + + if (!group_entity) + group_entity = &bfqq->bfqd->root_group->entity; + + return container_of(group_entity, struct bfq_group, entity); +} + +/* + * Returns true if this budget changes may let next_in_service->parent + * become the next_in_service entity for its parent entity. + */ +static bool bfq_update_parent_budget(struct bfq_entity *next_in_service) +{ + struct bfq_entity *bfqg_entity; + struct bfq_group *bfqg; + struct bfq_sched_data *group_sd; + bool ret = false; + + 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) { + if (bfqg_entity->budget > next_in_service->budget) + ret = true; + bfqg_entity->budget = next_in_service->budget; + } + + return ret; +} + +/* + * This function tells whether entity stops being a candidate for next + * service, according to the following logic. + * + * This function is invoked for an entity that is about to be set in + * service. If such an entity is a queue, then the entity is no longer + * a candidate for next service (i.e, a candidate entity to serve + * after the in-service entity is expired). The function then returns + * true. + * + * In contrast, the entity could stil be a candidate for next service + * if it is not a queue, and has more than one child. In fact, even if + * one of its children is about to be set in service, other children + * may still be the next to serve. As a consequence, a non-queue + * entity is not a candidate for next-service only if it has only one + * child. And only if this condition holds, then the function returns + * true for a non-queue entity. + */ +static bool bfq_no_longer_next_in_service(struct bfq_entity *entity) +{ + struct bfq_group *bfqg; + + if (bfq_entity_to_bfqq(entity)) + return true; + + bfqg = container_of(entity, struct bfq_group, entity); + + if (bfqg->active_entities == 1) + return true; + + return false; +} + +#else /* CONFIG_BFQ_GROUP_IOSCHED */ + +struct bfq_group *bfq_bfqq_to_bfqg(struct bfq_queue *bfqq) +{ + return bfqq->bfqd->root_group; +} + +static bool bfq_update_parent_budget(struct bfq_entity *next_in_service) +{ + return false; +} + +static bool bfq_no_longer_next_in_service(struct bfq_entity *entity) +{ + return true; +} + +#endif /* CONFIG_BFQ_GROUP_IOSCHED */ + +/* + * 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 + +struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = NULL; + + if (!entity->my_sched_data) + 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 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 void bfq_calc_finish(struct bfq_entity *entity, unsigned long service) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + entity->finish = entity->start + + bfq_delta(service, entity->weight); + + if (bfqq) { + 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. + */ +struct bfq_entity *bfq_entity_of(struct rb_node *node) +{ + struct bfq_entity *entity = NULL; + + if (node) + 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 void bfq_extract(struct rb_root *root, struct bfq_entity *entity) +{ + 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; + + 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) + 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; + + while (*node) { + 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 void bfq_update_min(struct bfq_entity *entity, struct rb_node *node) +{ + struct bfq_entity *child; + + if (node) { + 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 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) + return; + + if (node == parent->rb_left && parent->rb_right) + bfq_update_active_node(parent->rb_right); + else if (parent->rb_left) + bfq_update_active_node(parent->rb_left); + + node = parent; + goto up; +} + +/** + * 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_BFQ_GROUP_IOSCHED + 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) + node = node->rb_left; + else if (node->rb_right) + node = node->rb_right; + + bfq_update_active_tree(node); + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + sd = entity->sched_data; + bfqg = container_of(sd, struct bfq_group, sched_data); + bfqd = (struct bfq_data *)bfqg->bfqd; +#endif + if (bfqq) + list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + else /* bfq_group */ + bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree); + + if (bfqg != bfqd->root_group) + bfqg->active_entities++; +#endif +} + +/** + * bfq_ioprio_to_weight - calc a weight from an ioprio. + * @ioprio: the ioprio value to convert. + */ +unsigned short bfq_ioprio_to_weight(int ioprio) +{ + return (IOPRIO_BE_NR - ioprio) * BFQ_WEIGHT_CONVERSION_COEFF; +} + +/** + * bfq_weight_to_ioprio - calc an ioprio from a weight. + * @weight: the weight value to convert. + * + * To preserve as much 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 * BFQ_WEIGHT_CONVERSION_COEFF. + */ +static unsigned short bfq_weight_to_ioprio(int weight) +{ + return max_t(int, 0, + IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight); +} + +static void bfq_get_entity(struct bfq_entity *entity) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + if (bfqq) { + bfqq->ref++; + bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d", + bfqq, 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 && !node->rb_left) + deepest = rb_parent(node); + else if (!node->rb_right) + deepest = node->rb_left; + else if (!node->rb_left) + deepest = node->rb_right; + else { + deepest = rb_next(node); + if (deepest->rb_right) + 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_BFQ_GROUP_IOSCHED + 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) + bfq_update_active_tree(node); + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + sd = entity->sched_data; + bfqg = container_of(sd, struct bfq_group, sched_data); + bfqd = (struct bfq_data *)bfqg->bfqd; +#endif + if (bfqq) + list_del(&bfqq->bfqq_list); +#ifdef CONFIG_BFQ_GROUP_IOSCHED + else /* bfq_group */ + bfq_weights_tree_remove(bfqd, entity, + &bfqd->group_weights_tree); + + if (bfqg != bfqd->root_group) + bfqg->active_entities--; +#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 || bfq_gt(first_idle->finish, entity->finish)) + st->first_idle = entity; + if (!last_idle || bfq_gt(entity->finish, last_idle->finish)) + st->last_idle = entity; + + bfq_insert(&st->idle, entity); + + if (bfqq) + list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list); +} + +/** + * bfq_forget_entity - do not consider entity any longer for scheduling + * @st: the service tree. + * @entity: the entity being removed. + * @is_in_service: true if entity is currently the in-service entity. + * + * Forget everything about @entity. In addition, if entity represents + * a queue, and the latter is not in service, then release the service + * reference to the queue (the one taken through bfq_get_entity). In + * fact, in this case, there is really no more service reference to + * the queue, as the latter is also outside any service tree. If, + * instead, the queue is in service, then __bfq_bfqd_reset_in_service + * will take care of putting the reference when the queue finally + * stops being served. + */ +static void bfq_forget_entity(struct bfq_service_tree *st, + struct bfq_entity *entity, + bool is_in_service) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + entity->on_st = false; + st->wsum -= entity->weight; + if (bfqq && !is_in_service) + 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. + */ +void bfq_put_idle_entity(struct bfq_service_tree *st, struct bfq_entity *entity) +{ + bfq_idle_extract(st, entity); + bfq_forget_entity(st, entity, + entity == entity->sched_data->in_service_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 && + !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 && !bfq_gt(first_idle->finish, st->vtime)) + bfq_put_idle_entity(st, first_idle); +} + +struct bfq_service_tree *bfq_entity_service_tree(struct bfq_entity *entity) +{ + struct bfq_sched_data *sched_data = entity->sched_data; + unsigned int idx = bfq_class_idx(entity); + + return sched_data->service_tree + idx; +} + + +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->prio_changed) { + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + unsigned int prev_weight, new_weight; + struct bfq_data *bfqd = NULL; + struct rb_root *root; +#ifdef CONFIG_BFQ_GROUP_IOSCHED + struct bfq_sched_data *sd; + struct bfq_group *bfqg; +#endif + + if (bfqq) + bfqd = bfqq->bfqd; +#ifdef CONFIG_BFQ_GROUP_IOSCHED + else { + sd = entity->my_sched_data; + bfqg = container_of(sd, struct bfq_group, sched_data); + bfqd = (struct bfq_data *)bfqg->bfqd; + } +#endif + + 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) { + pr_crit("update_weight_prio: new_weight %d\n", + entity->new_weight); + if (entity->new_weight < BFQ_MIN_WEIGHT) + entity->new_weight = BFQ_MIN_WEIGHT; + else + entity->new_weight = BFQ_MAX_WEIGHT; + } + entity->orig_weight = entity->new_weight; + if (bfqq) + bfqq->ioprio = + bfq_weight_to_ioprio(entity->orig_weight); + } + + if (bfqq) + bfqq->ioprio_class = bfqq->new_ioprio_class; + entity->prio_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 ? 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. + */ +void bfq_bfqq_served(struct bfq_queue *bfqq, int 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; + + st->vtime += bfq_delta(served, st->wsum); + bfq_forget_idle(st); + } + bfqg_stats_set_start_empty_time(bfqq_group(bfqq)); + bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %d secs", served); +} + +/** + * bfq_bfqq_charge_time - charge an amount of service equivalent to the length + * of the time interval during which bfqq has been in + * service. + * @bfqd: the device + * @bfqq: the queue that needs a service update. + * @time_ms: the amount of time during which the queue has received service + * + * If a queue does not consume its budget fast enough, then providing + * the queue with service fairness may impair throughput, more or less + * severely. For this reason, queues that consume their budget slowly + * are provided with time fairness instead of service fairness. This + * goal is achieved through the BFQ scheduling engine, even if such an + * engine works in the service, and not in the time domain. The trick + * is charging these queues with an inflated amount of service, equal + * to the amount of service that they would have received during their + * service slot if they had been fast, i.e., if their requests had + * been dispatched at a rate equal to the estimated peak rate. + * + * It is worth noting that time fairness can cause important + * distortions in terms of bandwidth distribution, on devices with + * internal queueing. The reason is that I/O requests dispatched + * during the service slot of a queue may be served after that service + * slot is finished, and may have a total processing time loosely + * correlated with the duration of the service slot. This is + * especially true for short service slots. + */ +void bfq_bfqq_charge_time(struct bfq_data *bfqd, struct bfq_queue *bfqq, + unsigned long time_ms) +{ + struct bfq_entity *entity = &bfqq->entity; + int tot_serv_to_charge = entity->service; + unsigned int timeout_ms = jiffies_to_msecs(bfq_timeout); + + if (time_ms > 0 && time_ms < timeout_ms) + tot_serv_to_charge = + (bfqd->bfq_max_budget * time_ms) / timeout_ms; + + if (tot_serv_to_charge < entity->service) + tot_serv_to_charge = entity->service; + + /* Increase budget to avoid inconsistencies */ + if (tot_serv_to_charge > entity->budget) + entity->budget = tot_serv_to_charge; + + bfq_bfqq_served(bfqq, + max_t(int, 0, tot_serv_to_charge - entity->service)); +} + +static void bfq_update_fin_time_enqueue(struct bfq_entity *entity, + struct bfq_service_tree *st, + bool backshifted) +{ + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); + + st = __bfq_entity_update_weight_prio(st, entity); + bfq_calc_finish(entity, entity->budget); + + /* + * If some queues enjoy backshifting for a while, then their + * (virtual) finish timestamps may happen to become lower and + * lower than the system virtual time. In particular, if + * these queues often happen to be idle for short time + * periods, and during such time periods other queues with + * higher timestamps happen to be busy, then the backshifted + * timestamps of the former queues can become much lower than + * the system virtual time. In fact, to serve the queues with + * higher timestamps while the ones with lower timestamps are + * idle, the system virtual time may be pushed-up to much + * higher values than the finish timestamps of the idle + * queues. As a consequence, the finish timestamps of all new + * or newly activated queues may end up being much larger than + * those of lucky queues with backshifted timestamps. The + * latter queues may then monopolize the device for a lot of + * time. This would simply break service guarantees. + * + * To reduce this problem, push up a little bit the + * backshifted timestamps of the queue associated with this + * entity (only a queue can happen to have the backshifted + * flag set): just enough to let the finish timestamp of the + * queue be equal to the current value of the system virtual + * time. This may introduce a little unfairness among queues + * with backshifted timestamps, but it does not break + * worst-case fairness guarantees. + * + * As a special case, if bfqq is weight-raised, push up + * timestamps much less, to keep very low the probability that + * this push up causes the backshifted finish timestamps of + * weight-raised queues to become higher than the backshifted + * finish timestamps of non weight-raised queues. + */ + if (backshifted && bfq_gt(st->vtime, entity->finish)) { + unsigned long delta = st->vtime - entity->finish; + + if (bfqq) + delta /= bfqq->wr_coeff; + + entity->start += delta; + entity->finish += delta; + } + + bfq_active_insert(st, entity); +} + +/** + * __bfq_activate_entity - handle activation of entity. + * @entity: the entity being activated. + * @non_blocking_wait_rq: true if entity was waiting for a request + * + * Called for a 'true' activation, i.e., if entity is not active and + * one of its children receives a new request. + * + * Basically, this function updates the timestamps of entity and + * inserts entity into its active tree, ater possible extracting it + * from its idle tree. + */ +static void __bfq_activate_entity(struct bfq_entity *entity, + bool non_blocking_wait_rq) +{ + struct bfq_service_tree *st = bfq_entity_service_tree(entity); + bool backshifted = false; + unsigned long long min_vstart; + + /* See comments on bfq_fqq_update_budg_for_activation */ + if (non_blocking_wait_rq && bfq_gt(st->vtime, entity->finish)) { + backshifted = true; + min_vstart = entity->finish; + } else + min_vstart = st->vtime; + + 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(min_vstart, entity->finish) ? + min_vstart : 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 = min_vstart; + st->wsum += entity->weight; + /* + * entity is about to be inserted into a service tree, + * and then set in service: get a reference to make + * sure entity does not disappear until it is no + * longer in service or scheduled for service. + */ + bfq_get_entity(entity); + + entity->on_st = true; + } + + bfq_update_fin_time_enqueue(entity, st, backshifted); +} + +/** + * __bfq_requeue_entity - handle requeueing or repositioning of an entity. + * @entity: the entity being requeued or repositioned. + * + * Requeueing is needed if this entity stops being served, which + * happens if a leaf descendant entity has expired. On the other hand, + * repositioning is needed if the next_inservice_entity for the child + * entity has changed. See the comments inside the function for + * details. + * + * Basically, this function: 1) removes entity from its active tree if + * present there, 2) updates the timestamps of entity and 3) inserts + * entity back into its active tree (in the new, right position for + * the new values of the timestamps). + */ +static void __bfq_requeue_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) { + /* + * We are requeueing the current in-service entity, + * which may have to be done for one of the following + * reasons: + * - entity represents the in-service queue, and the + * in-service queue is being requeued after an + * expiration; + * - entity represents a group, and its budget has + * changed because one of its child entities has + * just been either activated or requeued for some + * reason; the timestamps of the entity need then to + * be updated, and the entity needs to be enqueued + * or repositioned accordingly. + * + * In particular, before requeueing, the start time of + * the entity must be moved forward to account for the + * service that the entity has received while in + * service. This is done by the next instructions. The + * finish time will then be updated according to this + * new value of the start time, and to the budget of + * the entity. + */ + bfq_calc_finish(entity, entity->service); + entity->start = entity->finish; + /* + * In addition, if the entity had more than one child + * when set in service, then was not extracted from + * the active tree. This implies that the position of + * the entity in the active tree may need to be + * changed now, because we have just updated the start + * time of the entity, and we will update its finish + * time in a moment (the requeueing is then, more + * precisely, a repositioning in this case). To + * implement this repositioning, we: 1) dequeue the + * entity here, 2) update the finish time and + * requeue the entity according to the new + * timestamps below. + */ + if (entity->tree) + bfq_active_extract(st, entity); + } else { /* The entity is already active, and not in service */ + /* + * In this case, this function gets called only if the + * next_in_service entity below this entity has + * changed, and this change has caused the budget of + * this entity to change, which, finally implies that + * the finish time of this entity must be + * updated. Such an update may cause the scheduling, + * i.e., the position in the active tree, of this + * entity to change. We handle this change by: 1) + * dequeueing the entity here, 2) updating the finish + * time and requeueing the entity according to the new + * timestamps below. This is the same approach as the + * non-extracted-entity sub-case above. + */ + bfq_active_extract(st, entity); + } + + bfq_update_fin_time_enqueue(entity, st, false); +} + +static void __bfq_activate_requeue_entity(struct bfq_entity *entity, + struct bfq_sched_data *sd, + bool non_blocking_wait_rq) +{ + struct bfq_service_tree *st = bfq_entity_service_tree(entity); + + if (sd->in_service_entity == entity || entity->tree == &st->active) + /* + * in service or already queued on the active tree, + * requeue or reposition + */ + __bfq_requeue_entity(entity); + else + /* + * Not in service and not queued on its active tree: + * the activity is idle and this is a true activation. + */ + __bfq_activate_entity(entity, non_blocking_wait_rq); +} + + +/** + * bfq_activate_entity - activate or requeue an entity representing a bfq_queue, + * and activate, requeue or reposition all ancestors + * for which such an update becomes necessary. + * @entity: the entity to activate. + * @non_blocking_wait_rq: true if this entity was waiting for a request + * @requeue: true if this is a requeue, which implies that bfqq is + * being expired; thus ALL its ancestors stop being served and must + * therefore be requeued + */ +static void bfq_activate_requeue_entity(struct bfq_entity *entity, + bool non_blocking_wait_rq, + bool requeue) +{ + struct bfq_sched_data *sd; + + for_each_entity(entity) { + sd = entity->sched_data; + __bfq_activate_requeue_entity(entity, sd, non_blocking_wait_rq); + + if (!bfq_update_next_in_service(sd, entity) && !requeue) + break; + } +} + +/** + * __bfq_deactivate_entity - deactivate an entity from its service tree. + * @entity: the entity to deactivate. + * @ins_into_idle_tree: if false, the entity will not be put into the + * idle tree. + * + * Deactivates an entity, independently from its previous state. Must + * be invoked only if entity is on a service tree. Extracts the entity + * from that tree, and if necessary and allowed, puts it on the idle + * tree. + */ +bool __bfq_deactivate_entity(struct bfq_entity *entity, bool ins_into_idle_tree) +{ + struct bfq_sched_data *sd = entity->sched_data; + struct bfq_service_tree *st = bfq_entity_service_tree(entity); + int is_in_service = entity == sd->in_service_entity; + + if (!entity->on_st) /* entity never activated, or already inactive */ + return false; + + if (is_in_service) + bfq_calc_finish(entity, entity->service); + + if (entity->tree == &st->active) + bfq_active_extract(st, entity); + else if (!is_in_service && entity->tree == &st->idle) + bfq_idle_extract(st, entity); + + if (!ins_into_idle_tree || !bfq_gt(entity->finish, st->vtime)) + bfq_forget_entity(st, entity, is_in_service); + else + bfq_idle_insert(st, entity); + + return true; +} + +/** + * bfq_deactivate_entity - deactivate an entity representing a bfq_queue. + * @entity: the entity to deactivate. + * @ins_into_idle_tree: true if the entity can be put on the idle tree + */ +static void bfq_deactivate_entity(struct bfq_entity *entity, + bool ins_into_idle_tree, + bool expiration) +{ + struct bfq_sched_data *sd; + struct bfq_entity *parent = NULL; + + for_each_entity_safe(entity, parent) { + sd = entity->sched_data; + + if (!__bfq_deactivate_entity(entity, ins_into_idle_tree)) { + /* + * entity is not in any tree any more, so + * this deactivation is a no-op, and there is + * nothing to change for upper-level entities + * (in case of expiration, this can never + * happen). + */ + return; + } + + if (sd->next_in_service == entity) + /* + * entity was the next_in_service entity, + * then, since entity has just been + * deactivated, a new one must be found. + */ + bfq_update_next_in_service(sd, NULL); + + if (sd->next_in_service) + /* + * The parent entity is still backlogged, + * because next_in_service is not NULL. So, no + * further upwards deactivation must be + * performed. Yet, next_in_service has + * changed. Then the schedule does need to be + * updated upwards. + */ + break; + + /* + * If we get here, then the parent is no more + * backlogged and we need to propagate the + * deactivation upwards. Thus let the loop go on. + */ + + /* + * Also let parent be queued into the idle tree on + * deactivation, to preserve service guarantees, and + * assuming that who invoked this function does not + * need parent entities too to be removed completely. + */ + ins_into_idle_tree = true; + } + + /* + * If the deactivation loop is fully executed, then there are + * no more entities to touch and next loop is not executed at + * all. Otherwise, requeue remaining entities if they are + * about to stop receiving service, or reposition them if this + * is not the case. + */ + entity = parent; + for_each_entity(entity) { + /* + * Invoke __bfq_requeue_entity on entity, even if + * already active, to requeue/reposition it in the + * active tree (because sd->next_in_service has + * changed) + */ + __bfq_requeue_entity(entity); + + sd = entity->sched_data; + if (!bfq_update_next_in_service(sd, entity) && + !expiration) + /* + * next_in_service unchanged or not causing + * any change in entity->parent->sd, and no + * requeueing needed for expiration: stop + * here. + */ + break; + } +} + +/** + * bfq_calc_vtime_jump - compute the value to which the vtime should jump, + * if needed, to have at least one entity eligible. + * @st: the service tree to act upon. + * + * Assumes that st is not empty. + */ +static u64 bfq_calc_vtime_jump(struct bfq_service_tree *st) +{ + struct bfq_entity *root_entity = bfq_root_active_entity(&st->active); + + if (bfq_gt(root_entity->min_start, st->vtime)) + return root_entity->min_start; + + return st->vtime; +} + +static void bfq_update_vtime(struct bfq_service_tree *st, u64 new_value) +{ + if (new_value > st->vtime) { + st->vtime = new_value; + bfq_forget_idle(st); + } +} + +/** + * bfq_first_active_entity - find the eligible entity with + * the smallest finish time + * @st: the service tree to select from. + * @vtime: the system virtual to use as a reference for eligibility + * + * 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, + u64 vtime) +{ + struct bfq_entity *entry, *first = NULL; + struct rb_node *node = st->active.rb_node; + + while (node) { + entry = rb_entry(node, struct bfq_entity, rb_node); +left: + if (!bfq_gt(entry->start, vtime)) + first = entry; + + if (node->rb_left) { + entry = rb_entry(node->rb_left, + struct bfq_entity, rb_node); + if (!bfq_gt(entry->min_start, vtime)) { + node = node->rb_left; + goto left; + } + } + if (first) + break; + node = node->rb_right; + } + + return first; +} + +/** + * __bfq_lookup_next_entity - return the first eligible entity in @st. + * @st: the service tree. + * + * If there is no in-service entity for the sched_data st belongs to, + * then return the entity that will be set in service if: + * 1) the parent entity this st belongs to is set in service; + * 2) no entity belonging to such parent entity undergoes a state change + * that would influence the timestamps of the entity (e.g., becomes idle, + * becomes backlogged, changes its budget, ...). + * + * In this first case, update the virtual time in @st too (see the + * comments on this update inside the function). + * + * In constrast, if there is an in-service entity, then return the + * entity that would be set in service if not only the above + * conditions, but also the next one held true: the currently + * in-service entity, on expiration, + * 1) gets a finish time equal to the current one, or + * 2) is not eligible any more, or + * 3) is idle. + */ +static struct bfq_entity * +__bfq_lookup_next_entity(struct bfq_service_tree *st, bool in_service) +{ + struct bfq_entity *entity; + u64 new_vtime; + + if (RB_EMPTY_ROOT(&st->active)) + return NULL; + + /* + * Get the value of the system virtual time for which at + * least one entity is eligible. + */ + new_vtime = bfq_calc_vtime_jump(st); + + /* + * If there is no in-service entity for the sched_data this + * active tree belongs to, then push the system virtual time + * up to the value that guarantees that at least one entity is + * eligible. If, instead, there is an in-service entity, then + * do not make any such update, because there is already an + * eligible entity, namely the in-service one (even if the + * entity is not on st, because it was extracted when set in + * service). + */ + if (!in_service) + bfq_update_vtime(st, new_vtime); + + entity = bfq_first_active_entity(st, new_vtime); + + return entity; +} + +/** + * bfq_lookup_next_entity - return the first eligible entity in @sd. + * @sd: the sched_data. + * + * This function is invoked when there has been a change in the trees + * for sd, and we need know what is the new next entity after this + * change. + */ +static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd) +{ + struct bfq_service_tree *st = sd->service_tree; + struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1); + struct bfq_entity *entity = NULL; + int class_idx = 0; + + /* + * Choose from idle class, if needed to guarantee a minimum + * bandwidth to this class (and if there is some active entity + * in idle class). This should also mitigate + * priority-inversion problems in case a low priority task is + * holding file system resources. + */ + if (time_is_before_jiffies(sd->bfq_class_idle_last_service + + BFQ_CL_IDLE_TIMEOUT)) { + if (!RB_EMPTY_ROOT(&idle_class_st->active)) + class_idx = BFQ_IOPRIO_CLASSES - 1; + /* About to be served if backlogged, or not yet backlogged */ + sd->bfq_class_idle_last_service = jiffies; + } + + /* + * Find the next entity to serve for the highest-priority + * class, unless the idle class needs to be served. + */ + for (; class_idx < BFQ_IOPRIO_CLASSES; class_idx++) { + entity = __bfq_lookup_next_entity(st + class_idx, + sd->in_service_entity); + + if (entity) + break; + } + + if (!entity) + return NULL; + + return entity; +} + +bool next_queue_may_preempt(struct bfq_data *bfqd) +{ + struct bfq_sched_data *sd = &bfqd->root_group->sched_data; + + return sd->next_in_service != sd->in_service_entity; +} + +/* + * Get next queue for service. + */ +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; + + if (bfqd->busy_queues == 0) + return NULL; + + /* + * Traverse the path from the root to the leaf entity to + * serve. Set in service all the entities visited along the + * way. + */ + sd = &bfqd->root_group->sched_data; + for (; sd ; sd = entity->my_sched_data) { + /* + * WARNING. We are about to set the in-service entity + * to sd->next_in_service, i.e., to the (cached) value + * returned by bfq_lookup_next_entity(sd) the last + * time it was invoked, i.e., the last time when the + * service order in sd changed as a consequence of the + * activation or deactivation of an entity. In this + * respect, if we execute bfq_lookup_next_entity(sd) + * in this very moment, it may, although with low + * probability, yield a different entity than that + * pointed to by sd->next_in_service. This rare event + * happens in case there was no CLASS_IDLE entity to + * serve for sd when bfq_lookup_next_entity(sd) was + * invoked for the last time, while there is now one + * such entity. + * + * If the above event happens, then the scheduling of + * such entity in CLASS_IDLE is postponed until the + * service of the sd->next_in_service entity + * finishes. In fact, when the latter is expired, + * bfq_lookup_next_entity(sd) gets called again, + * exactly to update sd->next_in_service. + */ + + /* Make next_in_service entity become in_service_entity */ + entity = sd->next_in_service; + sd->in_service_entity = entity; + + /* + * Reset the accumulator of the amount of service that + * the entity is about to receive. + */ + entity->service = 0; + + /* + * If entity is no longer a candidate for next + * service, then we extract it from its active tree, + * for the following reason. To further boost the + * throughput in some special case, BFQ needs to know + * which is the next candidate entity to serve, while + * there is already an entity in service. In this + * respect, to make it easy to compute/update the next + * candidate entity to serve after the current + * candidate has been set in service, there is a case + * where it is necessary to extract the current + * candidate from its service tree. Such a case is + * when the entity just set in service cannot be also + * a candidate for next service. Details about when + * this conditions holds are reported in the comments + * on the function bfq_no_longer_next_in_service() + * invoked below. + */ + if (bfq_no_longer_next_in_service(entity)) + bfq_active_extract(bfq_entity_service_tree(entity), + entity); + + /* + * For the same reason why we may have just extracted + * entity from its active tree, we may need to update + * next_in_service for the sched_data of entity too, + * regardless of whether entity has been extracted. + * In fact, even if entity has not been extracted, a + * descendant entity may get extracted. Such an event + * would cause a change in next_in_service for the + * level of the descendant entity, and thus possibly + * back to upper levels. + * + * We cannot perform the resulting needed update + * before the end of this loop, because, to know which + * is the correct next-to-serve candidate entity for + * each level, we need first to find the leaf entity + * to set in service. In fact, only after we know + * which is the next-to-serve leaf entity, we can + * discover whether the parent entity of the leaf + * entity becomes the next-to-serve, and so on. + */ + + } + + bfqq = bfq_entity_to_bfqq(entity); + + /* + * We can finally update all next-to-serve entities along the + * path from the leaf entity just set in service to the root. + */ + for_each_entity(entity) { + struct bfq_sched_data *sd = entity->sched_data; + + if (!bfq_update_next_in_service(sd, NULL)) + break; + } + + return bfqq; +} + +void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd) +{ + struct bfq_queue *in_serv_bfqq = bfqd->in_service_queue; + struct bfq_entity *in_serv_entity = &in_serv_bfqq->entity; + struct bfq_entity *entity = in_serv_entity; + + bfq_clear_bfqq_wait_request(in_serv_bfqq); + hrtimer_try_to_cancel(&bfqd->idle_slice_timer); + bfqd->in_service_queue = NULL; + + /* + * When this function is called, all in-service entities have + * been properly deactivated or requeued, so we can safely + * execute the final step: reset in_service_entity along the + * path from entity to the root. + */ + for_each_entity(entity) + entity->sched_data->in_service_entity = NULL; + + /* + * in_serv_entity is no longer in service, so, if it is in no + * service tree either, then release the service reference to + * the queue it represents (taken with bfq_get_entity). + */ + if (!in_serv_entity->on_st) + bfq_put_queue(in_serv_bfqq); +} + +void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq, + bool ins_into_idle_tree, bool expiration) +{ + struct bfq_entity *entity = &bfqq->entity; + + bfq_deactivate_entity(entity, ins_into_idle_tree, expiration); +} + +void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) +{ + struct bfq_entity *entity = &bfqq->entity; + + bfq_activate_requeue_entity(entity, bfq_bfqq_non_blocking_wait_rq(bfqq), + false); + bfq_clear_bfqq_non_blocking_wait_rq(bfqq); +} + +void bfq_requeue_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq) +{ + struct bfq_entity *entity = &bfqq->entity; + + bfq_activate_requeue_entity(entity, false, + bfqq == bfqd->in_service_queue); +} + +/* + * Called when the bfqq no longer has requests pending, remove it from + * the service tree. As a special case, it can be invoked during an + * expiration. + */ +void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq, + bool expiration) +{ + bfq_log_bfqq(bfqd, bfqq, "del from busy"); + + bfq_clear_bfqq_busy(bfqq); + + bfqd->busy_queues--; + + if (!bfqq->dispatched) + bfq_weights_tree_remove(bfqd, &bfqq->entity, + &bfqd->queue_weights_tree); + + if (bfqq->wr_coeff > 1) + bfqd->wr_busy_queues--; + + bfqg_stats_update_dequeue(bfqq_group(bfqq)); + + bfq_deactivate_bfqq(bfqd, bfqq, true, expiration); +} + +/* + * Called when an inactive queue receives a new request. + */ +void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq) +{ + 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 (bfqq->wr_coeff > 1) + bfqd->wr_busy_queues++; +} |