From 5fe224d2d5fbf8f020b30d0ba69fed7856923752 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 8 Mar 2012 10:53:57 -0800 Subject: [PATCH] blkcg: don't use percpu for merged stats With recent plug merge updates, merged stats are no longer called for plug merges and now only updated while holding queue_lock. As stats_lock is scheduled to be removed, there's no reason to use percpu for merged stats. Don't use percpu for merged stats. Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 26 ++++++-------------------- block/blk-cgroup.h | 6 +++--- 2 files changed, 9 insertions(+), 23 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 622fb4143226..6eedf3afa276 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -451,27 +451,13 @@ void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction, bool sync) { struct blkg_policy_data *pd = blkg->pd[pol->plid]; - struct blkio_group_stats_cpu *stats_cpu; + struct blkio_group_stats *stats; unsigned long flags; - /* If per cpu stats are not allocated yet, don't do any accounting. */ - if (pd->stats_cpu == NULL) - return; - - /* - * Disabling interrupts to provide mutual exclusion between two - * writes on same cpu. It probably is not needed for 64bit. Not - * optimizing that case yet. - */ - local_irq_save(flags); - - stats_cpu = this_cpu_ptr(pd->stats_cpu); - - u64_stats_update_begin(&stats_cpu->syncp); - blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_MERGED], 1, - direction, sync); - u64_stats_update_end(&stats_cpu->syncp); - local_irq_restore(flags); + spin_lock_irqsave(&blkg->stats_lock, flags); + stats = &pd->stats; + blkio_add_stat(stats->stat_arr[BLKIO_STAT_MERGED], 1, direction, sync); + spin_unlock_irqrestore(&blkg->stats_lock, flags); } EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats); @@ -1342,7 +1328,7 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft, BLKIO_STAT_WAIT_TIME, 1, 0); case BLKIO_PROP_io_merged: return blkio_read_blkg_stats(blkcg, cft, cb, - BLKIO_STAT_CPU_MERGED, 1, 1); + BLKIO_STAT_MERGED, 1, 0); case BLKIO_PROP_io_queued: return blkio_read_blkg_stats(blkcg, cft, cb, BLKIO_STAT_QUEUED, 1, 0); diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 1de32fe0e2af..6c8e3e345426 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -29,10 +29,12 @@ enum blkio_policy_id { #ifdef CONFIG_BLK_CGROUP enum stat_type { + /* Number of IOs merged */ + BLKIO_STAT_MERGED, /* Total time spent (in ns) between request dispatch to the driver and * request completion for IOs doen by this cgroup. This may not be * accurate when NCQ is turned on. */ - BLKIO_STAT_SERVICE_TIME = 0, + BLKIO_STAT_SERVICE_TIME, /* Total time spent waiting in scheduler queue in ns */ BLKIO_STAT_WAIT_TIME, /* Number of IOs queued up */ @@ -57,8 +59,6 @@ enum stat_type_cpu { BLKIO_STAT_CPU_SERVICE_BYTES, /* Total IOs serviced, post merge */ BLKIO_STAT_CPU_SERVICED, - /* Number of IOs merged */ - BLKIO_STAT_CPU_MERGED, BLKIO_STAT_CPU_NR };