Quelle bfq-cgroup.c Sprache: C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* cgroups support for the BFQ I/O scheduler.
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/cgroup.h>
#include <linux/ktime.h>
#include <linux/rbtree.h>
#include <linux/ioprio.h>
#include <linux/sbitmap.h>
#include <linux/delay.h>

#include "elevator.h"
#include "bfq-iosched.h"

#ifdef CONFIG_BFQ_CGROUP_DEBUG
static int bfq_stat_init(struct bfq_stat *stat, gfp_t gfp)
{
int ret;

ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
if (ret)
  return ret;

atomic64_set(&stat->aux_cnt, 0);
return 0;
}

static void bfq_stat_exit(struct bfq_stat *stat)
{
percpu_counter_destroy(&stat->cpu_cnt);
}

/**
* bfq_stat_add - add a value to a bfq_stat
* @stat: target bfq_stat
* @val: value to add
*
* Add @val to @stat.  The caller must ensure that IRQ on the same CPU
* don't re-enter this function for the same counter.
*/
static inline void bfq_stat_add(struct bfq_stat *stat, uint64_t val)
{
percpu_counter_add_batch(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
}

/**
* bfq_stat_read - read the current value of a bfq_stat
* @stat: bfq_stat to read
*/
static inline uint64_t bfq_stat_read(struct bfq_stat *stat)
{
return percpu_counter_sum_positive(&stat->cpu_cnt);
}

/**
* bfq_stat_reset - reset a bfq_stat
* @stat: bfq_stat to reset
*/
static inline void bfq_stat_reset(struct bfq_stat *stat)
{
percpu_counter_set(&stat->cpu_cnt, 0);
atomic64_set(&stat->aux_cnt, 0);
}

/**
* bfq_stat_add_aux - add a bfq_stat into another's aux count
* @to: the destination bfq_stat
* @from: the source
*
* Add @from's count including the aux one to @to's aux count.
*/
static inline void bfq_stat_add_aux(struct bfq_stat *to,
         struct bfq_stat *from)
{
atomic64_add(bfq_stat_read(from) + atomic64_read(&from->aux_cnt),
       &to->aux_cnt);
}

/**
* blkg_prfill_stat - prfill callback for bfq_stat
* @sf: seq_file to print to
* @pd: policy private data of interest
* @off: offset to the bfq_stat in @pd
*
* prfill callback for printing a bfq_stat.
*/
static u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd,
  int off)
{
return __blkg_prfill_u64(sf, pd, bfq_stat_read((void *)pd + off));
}

/* 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 scheduler lock held. */
static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
{
u64 now;

if (!bfqg_stats_waiting(stats))
  return;

now = blk_time_get_ns();
if (now > stats->start_group_wait_time)
  bfq_stat_add(&stats->group_wait_time,
         now - stats->start_group_wait_time);
bfqg_stats_clear_waiting(stats);
}

/* This should be called with the scheduler 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 = blk_time_get_ns();
bfqg_stats_mark_waiting(stats);
}

/* This should be called with the scheduler lock held. */
static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
{
u64 now;

if (!bfqg_stats_empty(stats))
  return;

now = blk_time_get_ns();
if (now > stats->start_empty_time)
  bfq_stat_add(&stats->empty_time,
         now - stats->start_empty_time);
bfqg_stats_clear_empty(stats);
}

void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
{
bfq_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 = blk_time_get_ns();
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)) {
  u64 now = blk_time_get_ns();

  if (now > stats->start_idle_time)
   bfq_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 = blk_time_get_ns();
bfqg_stats_mark_idling(stats);
}

void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
{
struct bfqg_stats *stats = &bfqg->stats;

bfq_stat_add(&stats->avg_queue_size_sum,
        blkg_rwstat_total(&stats->queued));
bfq_stat_add(&stats->avg_queue_size_samples, 1);
bfqg_stats_update_group_wait_time(stats);
}

void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
         blk_opf_t opf)
{
blkg_rwstat_add(&bfqg->stats.queued, opf, 1);
bfqg_stats_end_empty_time(&bfqg->stats);
if (!(bfqq == 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, blk_opf_t opf)
{
blkg_rwstat_add(&bfqg->stats.queued, opf, -1);
}

void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf)
{
blkg_rwstat_add(&bfqg->stats.merged, opf, 1);
}

void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
      u64 io_start_time_ns, blk_opf_t opf)
{
struct bfqg_stats *stats = &bfqg->stats;
u64 now = blk_time_get_ns();

if (now > io_start_time_ns)
  blkg_rwstat_add(&stats->service_time, opf,
    now - io_start_time_ns);
if (io_start_time_ns > start_time_ns)
  blkg_rwstat_add(&stats->wait_time, opf,
    io_start_time_ns - start_time_ns);
}

#else /* CONFIG_BFQ_CGROUP_DEBUG */

void bfqg_stats_update_io_remove(struct bfq_group *bfqg, blk_opf_t opf) { }
void bfqg_stats_update_io_merged(struct bfq_group *bfqg, blk_opf_t opf) { }
void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
      u64 io_start_time_ns, blk_opf_t opf) { }
void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }

#endif /* CONFIG_BFQ_CGROUP_DEBUG */

#ifdef CONFIG_BFQ_GROUP_IOSCHED

/*
* 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)
{
refcount_inc(&bfqg->ref);
}

static void bfqg_put(struct bfq_group *bfqg)
{
if (refcount_dec_and_test(&bfqg->ref))
  kfree(bfqg);
}

static void bfqg_and_blkg_get(struct bfq_group *bfqg)
{
/* see comments in bfq_bic_update_cgroup for why refcounting bfqg */
bfqg_get(bfqg);

blkg_get(bfqg_to_blkg(bfqg));
}

void bfqg_and_blkg_put(struct bfq_group *bfqg)
{
blkg_put(bfqg_to_blkg(bfqg));

bfqg_put(bfqg);
}

void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq)
{
struct bfq_group *bfqg = blkg_to_bfqg(rq->bio->bi_blkg);

if (!bfqg)
  return;

blkg_rwstat_add(&bfqg->stats.bytes, rq->cmd_flags, blk_rq_bytes(rq));
blkg_rwstat_add(&bfqg->stats.ios, rq->cmd_flags, 1);
}

/* @stats = 0 */
static void bfqg_stats_reset(struct bfqg_stats *stats)
{
#ifdef CONFIG_BFQ_CGROUP_DEBUG
/* queued stats shouldn't be cleared */
blkg_rwstat_reset(&stats->merged);
blkg_rwstat_reset(&stats->service_time);
blkg_rwstat_reset(&stats->wait_time);
bfq_stat_reset(&stats->time);
bfq_stat_reset(&stats->avg_queue_size_sum);
bfq_stat_reset(&stats->avg_queue_size_samples);
bfq_stat_reset(&stats->dequeue);
bfq_stat_reset(&stats->group_wait_time);
bfq_stat_reset(&stats->idle_time);
bfq_stat_reset(&stats->empty_time);
#endif
}

/* @to += @from */
static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
{
if (!to || !from)
  return;

#ifdef CONFIG_BFQ_CGROUP_DEBUG
/* 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);
bfq_stat_add_aux(&from->time, &from->time);
bfq_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
bfq_stat_add_aux(&to->avg_queue_size_samples,
     &from->avg_queue_size_samples);
bfq_stat_add_aux(&to->dequeue, &from->dequeue);
bfq_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
bfq_stat_add_aux(&to->idle_time, &from->idle_time);
bfq_stat_add_aux(&to->empty_time, &from->empty_time);
#endif
}

/*
* 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;
  /*
* Make sure that bfqg and its associated blkg do not
* disappear before entity.
*/
  bfqg_and_blkg_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->bytes);
blkg_rwstat_exit(&stats->ios);
#ifdef CONFIG_BFQ_CGROUP_DEBUG
blkg_rwstat_exit(&stats->merged);
blkg_rwstat_exit(&stats->service_time);
blkg_rwstat_exit(&stats->wait_time);
blkg_rwstat_exit(&stats->queued);
bfq_stat_exit(&stats->time);
bfq_stat_exit(&stats->avg_queue_size_sum);
bfq_stat_exit(&stats->avg_queue_size_samples);
bfq_stat_exit(&stats->dequeue);
bfq_stat_exit(&stats->group_wait_time);
bfq_stat_exit(&stats->idle_time);
bfq_stat_exit(&stats->empty_time);
#endif
}

static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
{
if (blkg_rwstat_init(&stats->bytes, gfp) ||
     blkg_rwstat_init(&stats->ios, gfp))
  goto error;

#ifdef CONFIG_BFQ_CGROUP_DEBUG
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) ||
     bfq_stat_init(&stats->time, gfp) ||
     bfq_stat_init(&stats->avg_queue_size_sum, gfp) ||
     bfq_stat_init(&stats->avg_queue_size_samples, gfp) ||
     bfq_stat_init(&stats->dequeue, gfp) ||
     bfq_stat_init(&stats->group_wait_time, gfp) ||
     bfq_stat_init(&stats->idle_time, gfp) ||
     bfq_stat_init(&stats->empty_time, gfp))
  goto error;
#endif

return 0;

error:
bfqg_stats_exit(stats);
return -ENOMEM;
}

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;

bgd->weight = CGROUP_WEIGHT_DFL;
return &bgd->pd;
}

static void bfq_cpd_free(struct blkcg_policy_data *cpd)
{
kfree(cpd_to_bfqgd(cpd));
}

static struct blkg_policy_data *bfq_pd_alloc(struct gendisk *disk,
  struct blkcg *blkcg, gfp_t gfp)
{
struct bfq_group *bfqg;

bfqg = kzalloc_node(sizeof(*bfqg), gfp, disk->node_id);
if (!bfqg)
  return NULL;

if (bfqg_stats_init(&bfqg->stats, gfp)) {
  kfree(bfqg);
  return NULL;
}

/* see comments in bfq_bic_update_cgroup for why refcounting */
refcount_set(&bfqg->ref, 1);
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;
entity->last_bfqq_created = NULL;

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->num_queues_with_pending_reqs = 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);
bfqg_put(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 void bfq_link_bfqg(struct bfq_data *bfqd, struct bfq_group *bfqg)
{
struct bfq_group *parent;
struct bfq_entity *entity;

/*
* 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) {
  struct bfq_group *curr_bfqg = container_of(entity,
      struct bfq_group, entity);
  if (curr_bfqg != bfqd->root_group) {
   parent = bfqg_parent(curr_bfqg);
   if (!parent)
    parent = bfqd->root_group;
   bfq_group_set_parent(curr_bfqg, parent);
  }
}
}

struct bfq_group *bfq_bio_bfqg(struct bfq_data *bfqd, struct bio *bio)
{
struct blkcg_gq *blkg = bio->bi_blkg;
struct bfq_group *bfqg;

while (blkg) {
  if (!blkg->online) {
   blkg = blkg->parent;
   continue;
  }
  bfqg = blkg_to_bfqg(blkg);
  if (bfqg->pd.online) {
   bio_associate_blkg_from_css(bio, &blkg->blkcg->css);
   return bfqg;
  }
  blkg = blkg->parent;
}
bio_associate_blkg_from_css(bio,
    &bfqg_to_blkg(bfqd->root_group)->blkcg->css);
return bfqd->root_group;
}

/**
* 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 scheduler lock, to make sure that the blkg
* owning @bfqg does not disappear (see comments in
* bfq_bic_update_cgroup on guaranteeing the consistency of blkg
* objects).
*/
void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
     struct bfq_group *bfqg)
{
struct bfq_entity *entity = &bfqq->entity;
struct bfq_group *old_parent = bfqq_group(bfqq);
bool has_pending_reqs = false;

/*
* No point to move bfqq to the same group, which can happen when
* root group is offlined
*/
if (old_parent == bfqg)
  return;

/*
* oom_bfqq is not allowed to move, oom_bfqq will hold ref to root_group
* until elevator exit.
*/
if (bfqq == &bfqd->oom_bfqq)
  return;
/*
* Get extra reference to prevent bfqq from being freed in
* next possible expire or deactivate.
*/
bfqq->ref++;

if (entity->in_groups_with_pending_reqs) {
  has_pending_reqs = true;
  bfq_del_bfqq_in_groups_with_pending_reqs(bfqq);
}

/* 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_or_in_serv)
  bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
bfqg_and_blkg_put(old_parent);

bfq_reassign_last_bfqq(bfqq, NULL);
entity->parent = bfqg->my_entity;
entity->sched_data = &bfqg->sched_data;
/* pin down bfqg and its associated blkg  */
bfqg_and_blkg_get(bfqg);

if (has_pending_reqs)
  bfq_add_bfqq_in_groups_with_pending_reqs(bfqq);

if (bfq_bfqq_busy(bfqq)) {
  if (unlikely(!bfqd->nonrot_with_queueing))
   bfq_pos_tree_add_move(bfqd, bfqq);
  bfq_activate_bfqq(bfqd, bfqq);
}

if (!bfqd->in_service_queue && !bfqd->tot_rq_in_driver)
  bfq_schedule_dispatch(bfqd);
/* release extra ref taken above, bfqq may happen to be freed now */
bfq_put_queue(bfqq);
}

static void bfq_sync_bfqq_move(struct bfq_data *bfqd,
          struct bfq_queue *sync_bfqq,
          struct bfq_io_cq *bic,
          struct bfq_group *bfqg,
          unsigned int act_idx)
{
struct bfq_queue *bfqq;

if (!sync_bfqq->new_bfqq && !bfq_bfqq_coop(sync_bfqq)) {
  /* We are the only user of this bfqq, just move it */
  if (sync_bfqq->entity.sched_data != &bfqg->sched_data)
   bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
  return;
}

/*
* The queue was merged to a different queue. Check
* that the merge chain still belongs to the same
* cgroup.
*/
for (bfqq = sync_bfqq; bfqq; bfqq = bfqq->new_bfqq)
  if (bfqq->entity.sched_data != &bfqg->sched_data)
   break;
if (bfqq) {
  /*
* Some queue changed cgroup so the merge is not valid
* anymore. We cannot easily just cancel the merge (by
* clearing new_bfqq) as there may be other processes
* using this queue and holding refs to all queues
* below sync_bfqq->new_bfqq. Similarly if the merge
* already happened, we need to detach from bfqq now
* so that we cannot merge bio to a request from the
* old cgroup.
*/
  bfq_put_cooperator(sync_bfqq);
  bic_set_bfqq(bic, NULL, true, act_idx);
  bfq_release_process_ref(bfqd, sync_bfqq);
}
}

/**
* __bfq_bic_change_cgroup - move @bic to @bfqg.
* @bfqd: the queue descriptor.
* @bic: the bic to move.
* @bfqg: the group to move to.
*
* Move bic to blkcg, assuming that bfqd->lock is held; which makes
* sure that the reference to cgroup is valid across the call (see
* comments in bfq_bic_update_cgroup on this issue)
*/
static void __bfq_bic_change_cgroup(struct bfq_data *bfqd,
        struct bfq_io_cq *bic,
        struct bfq_group *bfqg)
{
unsigned int act_idx;

for (act_idx = 0; act_idx < bfqd->num_actuators; act_idx++) {
  struct bfq_queue *async_bfqq = bic_to_bfqq(bic, false, act_idx);
  struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, true, act_idx);

  if (async_bfqq &&
      async_bfqq->entity.sched_data != &bfqg->sched_data) {
   bic_set_bfqq(bic, NULL, false, act_idx);
   bfq_release_process_ref(bfqd, async_bfqq);
  }

  if (sync_bfqq)
   bfq_sync_bfqq_move(bfqd, sync_bfqq, bic, bfqg, act_idx);
}
}

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 = bfq_bio_bfqg(bfqd, bio);
uint64_t serial_nr;

serial_nr = bfqg_to_blkg(bfqg)->blkcg->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))
  return;

/*
* New cgroup for this process. Make sure it is linked to bfq internal
* cgroup hierarchy.
*/
bfq_link_bfqg(bfqd, bfqg);
__bfq_bic_change_cgroup(bfqd, bic, bfqg);
bic->blkcg_serial_nr = serial_nr;
}

/**
* 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, if entity is a leaf; or the parent entity
*     of an active leaf entity to move, if entity is not a leaf.
* @ioprio_class: I/O priority class to reparent.
*/
static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
         struct bfq_entity *entity,
         int ioprio_class)
{
struct bfq_queue *bfqq;
struct bfq_entity *child_entity = entity;

while (child_entity->my_sched_data) { /* leaf not reached yet */
  struct bfq_sched_data *child_sd = child_entity->my_sched_data;
  struct bfq_service_tree *child_st = child_sd->service_tree +
   ioprio_class;
  struct rb_root *child_active = &child_st->active;

  child_entity = bfq_entity_of(rb_first(child_active));

  if (!child_entity)
   child_entity = child_sd->in_service_entity;
}

bfqq = bfq_entity_to_bfqq(child_entity);
bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
}

/**
* bfq_reparent_active_queues - move to the root group all active queues.
* @bfqd: the device data structure with the root group.
* @bfqg: the group to move from.
* @st: the service tree to start the search from.
* @ioprio_class: I/O priority class to reparent.
*/
static void bfq_reparent_active_queues(struct bfq_data *bfqd,
           struct bfq_group *bfqg,
           struct bfq_service_tree *st,
           int ioprio_class)
{
struct rb_root *active = &st->active;
struct bfq_entity *entity;

while ((entity = bfq_entity_of(rb_first(active))))
  bfq_reparent_leaf_entity(bfqd, entity, ioprio_class);

if (bfqg->sched_data.in_service_entity)
  bfq_reparent_leaf_entity(bfqd,
      bfqg->sched_data.in_service_entity,
      ioprio_class);
}

/**
* 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;

spin_lock_irqsave(&bfqd->lock, flags);

if (!entity) /* root group */
  goto put_async_queues;

/*
* 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;

  /*
* 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_queues(bfqd, bfqg, st, 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. In addition, even
* bfq_reparent_active_queues() may happen to add some
* entities to the idle tree. It happens if, in some
* of the calls to bfq_bfqq_move() performed by
* bfq_reparent_active_queues(), the queue to move is
* empty and gets expired.
*/
  bfq_flush_idle_tree(st);
}

__bfq_deactivate_entity(entity, false);

put_async_queues:
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_legacy(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 u64 bfqg_prfill_weight_device(struct seq_file *sf,
         struct blkg_policy_data *pd, int off)
{
struct bfq_group *bfqg = pd_to_bfqg(pd);

if (!bfqg->entity.dev_weight)
  return 0;
return __blkg_prfill_u64(sf, pd, bfqg->entity.dev_weight);
}

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);

seq_printf(sf, "default %u\n", bfqgd->weight);
blkcg_print_blkgs(sf, blkcg, bfqg_prfill_weight_device,
     &blkcg_policy_bfq, 0, false);
return 0;
}

static void bfq_group_set_weight(struct bfq_group *bfqg, u64 weight, u64 dev_weight)
{
weight = dev_weight ?: weight;

bfqg->entity.dev_weight = dev_weight;
/*
* 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)weight != bfqg->entity.new_weight) {
  bfqg->entity.new_weight = (unsigned short)weight;
  /*
* 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;
}
}

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)
   bfq_group_set_weight(bfqg, val, 0);
}
spin_unlock_irq(&blkcg->lock);

return ret;
}

static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
     char *buf, size_t nbytes,
     loff_t off)
{
int ret;
struct blkg_conf_ctx ctx;
struct blkcg *blkcg = css_to_blkcg(of_css(of));
struct bfq_group *bfqg;
u64 v;

blkg_conf_init(&ctx, buf);

ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, &ctx);
if (ret)
  goto out;

if (sscanf(ctx.body, "%llu", &v) == 1) {
  /* require "default" on dfl */
  ret = -ERANGE;
  if (!v)
   goto out;
} else if (!strcmp(strim(ctx.body), "default")) {
  v = 0;
} else {
  ret = -EINVAL;
  goto out;
}

bfqg = blkg_to_bfqg(ctx.blkg);

ret = -ERANGE;
if (!v || (v >= BFQ_MIN_WEIGHT && v <= BFQ_MAX_WEIGHT)) {
  bfq_group_set_weight(bfqg, bfqg->entity.weight, v);
  ret = 0;
}
out:
blkg_conf_exit(&ctx);
return ret ?: nbytes;
}

static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
     char *buf, size_t nbytes,
     loff_t off)
{
char *endp;
int ret;
u64 v;

buf = strim(buf);

/* "WEIGHT" or "default WEIGHT" sets the default weight */
v = simple_strtoull(buf, &endp, 0);
if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
  ret = bfq_io_set_weight_legacy(of_css(of), NULL, v);
  return ret ?: nbytes;
}

return bfq_io_set_device_weight(of, buf, nbytes, off);
}

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_rwstat_recursive(struct seq_file *sf,
     struct blkg_policy_data *pd, int off)
{
struct blkg_rwstat_sample sum;

blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off, &sum);
return __blkg_prfill_rwstat(sf, pd, &sum);
}

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;
}

#ifdef CONFIG_BFQ_CGROUP_DEBUG
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 u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
          struct blkg_policy_data *pd, int off)
{
struct blkcg_gq *blkg = pd_to_blkg(pd);
struct blkcg_gq *pos_blkg;
struct cgroup_subsys_state *pos_css;
u64 sum = 0;

lockdep_assert_held(&blkg->q->queue_lock);

rcu_read_lock();
blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
  struct bfq_stat *stat;

  if (!pos_blkg->online)
   continue;

  stat = (void *)blkg_to_pd(pos_blkg, &blkcg_policy_bfq) + off;
  sum += bfq_stat_read(stat) + atomic64_read(&stat->aux_cnt);
}
rcu_read_unlock();

return __blkg_prfill_u64(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 u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
          int off)
{
struct bfq_group *bfqg = blkg_to_bfqg(pd->blkg);
u64 sum = blkg_rwstat_total(&bfqg->stats.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_sample tmp;

blkg_rwstat_recursive_sum(pd->blkg, &blkcg_policy_bfq,
   offsetof(struct bfq_group, stats.bytes), &tmp);

return __blkg_prfill_u64(sf, pd,
  (tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE]) >> 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 = bfq_stat_read(&bfqg->stats.avg_queue_size_samples);
u64 v = 0;

if (samples) {
  v = bfq_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;
}
#endif /* CONFIG_BFQ_CGROUP_DEBUG */

struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
{
int ret;

ret = blkcg_activate_policy(bfqd->queue->disk, &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_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_legacy,
  .write_u64 = bfq_io_set_weight_legacy,
},
{
  .name = "bfq.weight_device",
  .flags = CFTYPE_NOT_ON_ROOT,
  .seq_show = bfq_io_show_weight,
  .write = bfq_io_set_weight,
},

/* statistics, covers only the tasks in the bfqg */
{
  .name = "bfq.io_service_bytes",
  .private = offsetof(struct bfq_group, stats.bytes),
  .seq_show = bfqg_print_rwstat,
},
{
  .name = "bfq.io_serviced",
  .private = offsetof(struct bfq_group, stats.ios),
  .seq_show = bfqg_print_rwstat,
},
#ifdef CONFIG_BFQ_CGROUP_DEBUG
{
  .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_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,
},
#endif /* CONFIG_BFQ_CGROUP_DEBUG */

/* the same statistics which cover the bfqg and its descendants */
{
  .name = "bfq.io_service_bytes_recursive",
  .private = offsetof(struct bfq_group, stats.bytes),
  .seq_show = bfqg_print_rwstat_recursive,
},
{
  .name = "bfq.io_serviced_recursive",
  .private = offsetof(struct bfq_group, stats.ios),
  .seq_show = bfqg_print_rwstat_recursive,
},
#ifdef CONFIG_BFQ_CGROUP_DEBUG
{
  .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_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,
},
#endif /* CONFIG_BFQ_CGROUP_DEBUG */
{ } /* 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 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_bio_bfqg(struct bfq_data *bfqd, struct bio *bio)
{
return bfqd->root_group;
}

struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
{
return bfqq->bfqd->root_group;
}

void bfqg_and_blkg_put(struct bfq_group *bfqg) {}

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 */

quality92%

¤ Dauer der Verarbeitung: 0.26 Sekunden ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.