Messages in this thread Patch in this message | | | From | Chad Talbott <> | Subject | [PATCH 3/3] cfq-iosched: Fair cross-group preemption (stats) | Date | Mon, 21 Mar 2011 18:10:45 -0700 |
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Add three counters to monitor the cross-group preemption behavior.
preempt_count: counts the number of times this group preempted another
preempt_active: counts the number of times this group issued an IO but was already the active group
preempt_throttle: number of times this group would have preempted another if it hadn't already used up its assigned weight
Signed-off-by: Chad Talbott <ctalbott@google.com> --- block/blk-cgroup.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ block/blk-cgroup.h | 18 ++++++++++++++++++ block/cfq-iosched.c | 20 +++++++++++++++++--- 3 files changed, 81 insertions(+), 3 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index f2c553e..41ee61c 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -347,6 +347,25 @@ void blkiocg_set_start_empty_time(struct blkio_group *blkg) } EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time); +void blkiocg_update_preempt_stats(struct blkio_group *blkg, + enum stat_type which, bool direction, bool sync) +{ + unsigned long flags; + + spin_lock_irqsave(&blkg->stats_lock, flags); + switch (which) { + case BLKIO_STAT_PREEMPT_COUNT: + case BLKIO_STAT_PREEMPT_ACTIVE: + case BLKIO_STAT_PREEMPT_THROTTLE: + blkio_add_stat(blkg->stats.stat_arr[which], 1, direction, sync); + break; + default: + BUG(); + } + spin_unlock_irqrestore(&blkg->stats_lock, flags); +} +EXPORT_SYMBOL_GPL(blkiocg_update_preempt_stats); + void blkiocg_update_dequeue_stats(struct blkio_group *blkg, unsigned long dequeue) { @@ -1193,6 +1212,15 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft, case BLKIO_PROP_empty_time: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_EMPTY_TIME, 0); + case BLKIO_PROP_preempt_count: + return blkio_read_blkg_stats(blkcg, cft, cb, + BLKIO_STAT_PREEMPT_COUNT, 0); + case BLKIO_PROP_preempt_active: + return blkio_read_blkg_stats(blkcg, cft, cb, + BLKIO_STAT_PREEMPT_ACTIVE, 0); + case BLKIO_PROP_preempt_throttle: + return blkio_read_blkg_stats(blkcg, cft, cb, + BLKIO_STAT_PREEMPT_THROTTLE, 0); #endif default: BUG(); @@ -1443,6 +1471,24 @@ struct cftype blkio_files[] = { BLKIO_PROP_dequeue), .read_map = blkiocg_file_read_map, }, + { + .name = "preempt_count", + .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, + BLKIO_PROP_preempt_count), + .read_map = blkiocg_file_read_map, + }, + { + .name = "preempt_active", + .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, + BLKIO_PROP_preempt_active), + .read_map = blkiocg_file_read_map, + }, + { + .name = "preempt_throttle", + .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP, + BLKIO_PROP_preempt_throttle), + .read_map = blkiocg_file_read_map, + }, #endif }; diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 0e9cd32..d2cbdcd 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -44,6 +44,14 @@ enum stat_type { BLKIO_STAT_WAIT_TIME, /* Number of IOs merged */ BLKIO_STAT_MERGED, +#ifdef CONFIG_DEBUG_BLK_CGROUP + /* Number of IOs Added to active group */ + BLKIO_STAT_PREEMPT_ACTIVE, + /* Number of cross-group preemptions */ + BLKIO_STAT_PREEMPT_COUNT, + /* Number of cross-group preemptions disallowed by weight */ + BLKIO_STAT_PREEMPT_THROTTLE, +#endif /* Number of IOs queued up */ BLKIO_STAT_QUEUED, /* All the single valued stats go below this */ @@ -98,6 +106,9 @@ enum blkcg_file_name_prop { BLKIO_PROP_idle_time, BLKIO_PROP_empty_time, BLKIO_PROP_dequeue, + BLKIO_PROP_preempt_count, + BLKIO_PROP_preempt_active, + BLKIO_PROP_preempt_throttle, }; /* cgroup files owned by throttle policy */ @@ -271,6 +282,10 @@ void blkiocg_update_dequeue_stats(struct blkio_group *blkg, void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg); void blkiocg_update_idle_time_stats(struct blkio_group *blkg); void blkiocg_set_start_empty_time(struct blkio_group *blkg); +void blkiocg_update_preempt_stats(struct blkio_group *blkg, + enum stat_type which, + bool direction, + bool sync); #define BLKG_FLAG_FNS(name) \ static inline void blkio_mark_blkg_##name( \ @@ -301,6 +316,9 @@ static inline void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg) {} static inline void blkiocg_update_idle_time_stats(struct blkio_group *blkg) {} static inline void blkiocg_set_start_empty_time(struct blkio_group *blkg) {} +static inline void blkiocg_update_preempt_stats( + struct blkio_group *blkg, enum stat_type which, bool direction, + bool sync) {} #endif #if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index dfcce80..0d55be3 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1171,16 +1171,30 @@ cfq_group_should_preempt(struct cfq_queue *new_cfqq, struct cfq_queue *cfqq, u64 grace_period; /* in-group preemption is handled elsewhere */ - if (new_cfqg == cfqg) + if (new_cfqg == cfqg) { + blkiocg_update_preempt_stats(&new_cfqg->blkg, + BLKIO_STAT_PREEMPT_ACTIVE, + rq_data_dir(rq), rq_is_sync(rq)); return false; + } if (!(new_cfqg->class == BLKIO_RT_CLASS && cfqg->class == BLKIO_BE_CLASS)) return false; grace_period = cfq_scale_slice(cfqq->allocated_slice, cfqg); - return time_before64(new_cfqg->vdisktime, - cfqg->vdisktime + grace_period); + if (time_before64(new_cfqg->vdisktime, + cfqg->vdisktime + grace_period)) { + blkiocg_update_preempt_stats(&new_cfqg->blkg, + BLKIO_STAT_PREEMPT_COUNT, + rq_data_dir(rq), rq_is_sync(rq)); + return true; + } + + blkiocg_update_preempt_stats(&new_cfqg->blkg, + BLKIO_STAT_PREEMPT_THROTTLE, + rq_data_dir(rq), rq_is_sync(rq)); + return false; } #else /* GROUP_IOSCHED */ -- 1.7.3.1
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