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blkcg: remove blkio_group->stats_lock
With recent plug merge updates, all non-percpu stat updates happen under queue_lock making stats_lock unnecessary to synchronize stat updates. The only synchronization necessary is stat reading, which can be done using u64_stats_sync instead. This patch removes blkio_group->stats_lock and adds blkio_group_stats->syncp for reader synchronization. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
parent
c4c76a0538
commit
edf1b879e3
@ -156,7 +156,7 @@ static inline void blkio_update_group_iops(struct blkio_group *blkg,
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/*
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* Add to the appropriate stat variable depending on the request type.
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* This should be called with the blkg->stats_lock held.
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* This should be called with queue_lock held.
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*/
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static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
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bool sync)
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@ -174,7 +174,7 @@ static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
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/*
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* Decrements the appropriate stat variable if non-zero depending on the
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* request type. Panics on value being zero.
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* This should be called with the blkg->stats_lock held.
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* This should be called with the queue_lock held.
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*/
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static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
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{
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@ -195,7 +195,7 @@ static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
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}
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#ifdef CONFIG_DEBUG_BLK_CGROUP
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/* This should be called with the blkg->stats_lock held. */
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/* This should be called with the queue_lock held. */
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static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
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struct blkio_policy_type *pol,
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struct blkio_group *curr_blkg)
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@ -210,7 +210,7 @@ static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
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blkio_mark_blkg_waiting(&pd->stats);
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}
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/* This should be called with the blkg->stats_lock held. */
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/* This should be called with the queue_lock held. */
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static void blkio_update_group_wait_time(struct blkio_group_stats *stats)
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{
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unsigned long long now;
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@ -224,7 +224,7 @@ static void blkio_update_group_wait_time(struct blkio_group_stats *stats)
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blkio_clear_blkg_waiting(stats);
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}
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/* This should be called with the blkg->stats_lock held. */
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/* This should be called with the queue_lock held. */
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static void blkio_end_empty_time(struct blkio_group_stats *stats)
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{
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unsigned long long now;
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@ -241,84 +241,74 @@ static void blkio_end_empty_time(struct blkio_group_stats *stats)
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void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg,
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struct blkio_policy_type *pol)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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unsigned long flags;
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struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
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spin_lock_irqsave(&blkg->stats_lock, flags);
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BUG_ON(blkio_blkg_idling(&pd->stats));
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pd->stats.start_idle_time = sched_clock();
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blkio_mark_blkg_idling(&pd->stats);
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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lockdep_assert_held(blkg->q->queue_lock);
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BUG_ON(blkio_blkg_idling(stats));
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stats->start_idle_time = sched_clock();
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blkio_mark_blkg_idling(stats);
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats);
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void blkiocg_update_idle_time_stats(struct blkio_group *blkg,
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struct blkio_policy_type *pol)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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unsigned long flags;
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unsigned long long now;
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struct blkio_group_stats *stats;
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struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
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lockdep_assert_held(blkg->q->queue_lock);
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spin_lock_irqsave(&blkg->stats_lock, flags);
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stats = &pd->stats;
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if (blkio_blkg_idling(stats)) {
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now = sched_clock();
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if (time_after64(now, stats->start_idle_time))
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unsigned long long now = sched_clock();
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if (time_after64(now, stats->start_idle_time)) {
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u64_stats_update_begin(&stats->syncp);
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stats->idle_time += now - stats->start_idle_time;
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u64_stats_update_end(&stats->syncp);
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}
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blkio_clear_blkg_idling(stats);
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}
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats);
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void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg,
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struct blkio_policy_type *pol)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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unsigned long flags;
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struct blkio_group_stats *stats;
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struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
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spin_lock_irqsave(&blkg->stats_lock, flags);
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stats = &pd->stats;
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lockdep_assert_held(blkg->q->queue_lock);
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u64_stats_update_begin(&stats->syncp);
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stats->avg_queue_size_sum +=
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stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
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stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
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stats->avg_queue_size_samples++;
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blkio_update_group_wait_time(stats);
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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u64_stats_update_end(&stats->syncp);
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);
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void blkiocg_set_start_empty_time(struct blkio_group *blkg,
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struct blkio_policy_type *pol)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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unsigned long flags;
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struct blkio_group_stats *stats;
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struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
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spin_lock_irqsave(&blkg->stats_lock, flags);
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stats = &pd->stats;
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lockdep_assert_held(blkg->q->queue_lock);
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if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] ||
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stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]) {
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE])
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return;
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}
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/*
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* group is already marked empty. This can happen if cfqq got new
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* request in parent group and moved to this group while being added
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* to service tree. Just ignore the event and move on.
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*/
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if(blkio_blkg_empty(stats)) {
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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if (blkio_blkg_empty(stats))
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return;
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}
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stats->start_empty_time = sched_clock();
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blkio_mark_blkg_empty(stats);
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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}
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EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time);
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@ -328,6 +318,8 @@ void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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lockdep_assert_held(blkg->q->queue_lock);
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pd->stats.dequeue += dequeue;
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
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@ -343,15 +335,16 @@ void blkiocg_update_io_add_stats(struct blkio_group *blkg,
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struct blkio_group *curr_blkg, bool direction,
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bool sync)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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unsigned long flags;
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struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
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lockdep_assert_held(blkg->q->queue_lock);
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u64_stats_update_begin(&stats->syncp);
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blkio_add_stat(stats->stat_arr[BLKIO_STAT_QUEUED], 1, direction, sync);
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blkio_end_empty_time(stats);
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u64_stats_update_end(&stats->syncp);
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spin_lock_irqsave(&blkg->stats_lock, flags);
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blkio_add_stat(pd->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
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sync);
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blkio_end_empty_time(&pd->stats);
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blkio_set_start_group_wait_time(blkg, pol, curr_blkg);
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
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@ -359,13 +352,14 @@ void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
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struct blkio_policy_type *pol,
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bool direction, bool sync)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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unsigned long flags;
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struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
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spin_lock_irqsave(&blkg->stats_lock, flags);
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blkio_check_and_dec_stat(pd->stats.stat_arr[BLKIO_STAT_QUEUED],
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direction, sync);
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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lockdep_assert_held(blkg->q->queue_lock);
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u64_stats_update_begin(&stats->syncp);
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blkio_check_and_dec_stat(stats->stat_arr[BLKIO_STAT_QUEUED], direction,
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sync);
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u64_stats_update_end(&stats->syncp);
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
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@ -374,15 +368,16 @@ void blkiocg_update_timeslice_used(struct blkio_group *blkg,
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unsigned long time,
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unsigned long unaccounted_time)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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unsigned long flags;
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struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
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spin_lock_irqsave(&blkg->stats_lock, flags);
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pd->stats.time += time;
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lockdep_assert_held(blkg->q->queue_lock);
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u64_stats_update_begin(&stats->syncp);
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stats->time += time;
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#ifdef CONFIG_DEBUG_BLK_CGROUP
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pd->stats.unaccounted_time += unaccounted_time;
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stats->unaccounted_time += unaccounted_time;
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#endif
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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u64_stats_update_end(&stats->syncp);
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
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@ -428,20 +423,19 @@ void blkiocg_update_completion_stats(struct blkio_group *blkg,
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uint64_t io_start_time, bool direction,
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bool sync)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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struct blkio_group_stats *stats;
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unsigned long flags;
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struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
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unsigned long long now = sched_clock();
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spin_lock_irqsave(&blkg->stats_lock, flags);
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stats = &pd->stats;
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lockdep_assert_held(blkg->q->queue_lock);
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u64_stats_update_begin(&stats->syncp);
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if (time_after64(now, io_start_time))
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blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
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now - io_start_time, direction, sync);
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if (time_after64(io_start_time, start_time))
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blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME],
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io_start_time - start_time, direction, sync);
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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u64_stats_update_end(&stats->syncp);
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
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@ -450,14 +444,13 @@ void blkiocg_update_io_merged_stats(struct blkio_group *blkg,
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struct blkio_policy_type *pol,
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bool direction, bool sync)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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struct blkio_group_stats *stats;
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unsigned long flags;
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struct blkio_group_stats *stats = &blkg->pd[pol->plid]->stats;
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spin_lock_irqsave(&blkg->stats_lock, flags);
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stats = &pd->stats;
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lockdep_assert_held(blkg->q->queue_lock);
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u64_stats_update_begin(&stats->syncp);
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blkio_add_stat(stats->stat_arr[BLKIO_STAT_MERGED], 1, direction, sync);
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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u64_stats_update_end(&stats->syncp);
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
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@ -558,7 +551,6 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg,
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if (!blkg)
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return NULL;
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spin_lock_init(&blkg->stats_lock);
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blkg->q = q;
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INIT_LIST_HEAD(&blkg->q_node);
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INIT_LIST_HEAD(&blkg->alloc_node);
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@ -929,7 +921,6 @@ static uint64_t blkio_get_stat_cpu(struct blkio_group *blkg, int plid,
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return disk_total;
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}
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/* This should be called with blkg->stats_lock held */
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static uint64_t blkio_get_stat(struct blkio_group *blkg, int plid,
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struct cgroup_map_cb *cb, const char *dname,
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enum stat_type type)
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@ -937,42 +928,46 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg, int plid,
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struct blkio_group_stats *stats = &blkg->pd[plid]->stats;
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uint64_t v = 0, disk_total = 0;
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char key_str[MAX_KEY_LEN];
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unsigned int sync_start;
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int st;
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if (type >= BLKIO_STAT_ARR_NR) {
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switch (type) {
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case BLKIO_STAT_TIME:
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v = stats->time;
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break;
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do {
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sync_start = u64_stats_fetch_begin(&stats->syncp);
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switch (type) {
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case BLKIO_STAT_TIME:
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v = stats->time;
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break;
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#ifdef CONFIG_DEBUG_BLK_CGROUP
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case BLKIO_STAT_UNACCOUNTED_TIME:
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v = stats->unaccounted_time;
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break;
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case BLKIO_STAT_AVG_QUEUE_SIZE: {
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uint64_t samples = stats->avg_queue_size_samples;
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case BLKIO_STAT_UNACCOUNTED_TIME:
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v = stats->unaccounted_time;
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break;
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case BLKIO_STAT_AVG_QUEUE_SIZE: {
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uint64_t samples = stats->avg_queue_size_samples;
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if (samples) {
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v = stats->avg_queue_size_sum;
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do_div(v, samples);
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if (samples) {
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v = stats->avg_queue_size_sum;
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do_div(v, samples);
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}
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break;
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}
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break;
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}
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case BLKIO_STAT_IDLE_TIME:
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v = stats->idle_time;
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break;
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case BLKIO_STAT_EMPTY_TIME:
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v = stats->empty_time;
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break;
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case BLKIO_STAT_DEQUEUE:
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v = stats->dequeue;
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break;
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case BLKIO_STAT_GROUP_WAIT_TIME:
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v = stats->group_wait_time;
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break;
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case BLKIO_STAT_IDLE_TIME:
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v = stats->idle_time;
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break;
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case BLKIO_STAT_EMPTY_TIME:
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v = stats->empty_time;
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break;
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case BLKIO_STAT_DEQUEUE:
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v = stats->dequeue;
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break;
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case BLKIO_STAT_GROUP_WAIT_TIME:
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v = stats->group_wait_time;
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break;
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#endif
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default:
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WARN_ON_ONCE(1);
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}
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default:
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WARN_ON_ONCE(1);
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}
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} while (u64_stats_fetch_retry(&stats->syncp, sync_start));
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blkio_get_key_name(0, dname, key_str, MAX_KEY_LEN, true);
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cb->fill(cb, key_str, v);
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@ -980,7 +975,10 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg, int plid,
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}
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for (st = BLKIO_STAT_READ; st < BLKIO_STAT_TOTAL; st++) {
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v = stats->stat_arr[type][st];
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do {
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sync_start = u64_stats_fetch_begin(&stats->syncp);
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v = stats->stat_arr[type][st];
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} while (u64_stats_fetch_retry(&stats->syncp, sync_start));
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blkio_get_key_name(st, dname, key_str, MAX_KEY_LEN, false);
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cb->fill(cb, key_str, v);
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@ -1250,15 +1248,12 @@ static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
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if (!dname)
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continue;
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if (pcpu) {
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if (pcpu)
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cgroup_total += blkio_get_stat_cpu(blkg, plid,
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cb, dname, type);
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} else {
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spin_lock(&blkg->stats_lock);
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else
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cgroup_total += blkio_get_stat(blkg, plid,
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cb, dname, type);
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spin_unlock(&blkg->stats_lock);
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}
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}
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if (show_total)
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cb->fill(cb, "Total", cgroup_total);
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@ -119,6 +119,7 @@ struct blkio_cgroup {
|
||||
};
|
||||
|
||||
struct blkio_group_stats {
|
||||
struct u64_stats_sync syncp;
|
||||
/* total disk time and nr sectors dispatched by this group */
|
||||
uint64_t time;
|
||||
uint64_t stat_arr[BLKIO_STAT_ARR_NR][BLKIO_STAT_TOTAL];
|
||||
@ -200,8 +201,6 @@ struct blkio_group {
|
||||
/* reference count */
|
||||
int refcnt;
|
||||
|
||||
/* Need to serialize the stats in the case of reset/update */
|
||||
spinlock_t stats_lock;
|
||||
struct blkg_policy_data *pd[BLKIO_NR_POLICIES];
|
||||
|
||||
/* List of blkg waiting for per cpu stats memory to be allocated */
|
||||
|
Loading…
Reference in New Issue
Block a user