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Commit 5fe224d2 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 1cd9e039

block/blk-cgroup.c

+6 −20
Original line number Diff line number Diff line
@@ -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);

block/blk-cgroup.h

+3 −3
Original line number Diff line number Diff line
@@ -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

};