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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 <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2012-03-08 10:53:57 -08:00 committed by Jens Axboe
parent 1cd9e039fc
commit 5fe224d2d5
2 changed files with 9 additions and 23 deletions
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26
block/blk-cgroup.c
View File

@ -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);

6
block/blk-cgroup.h
View File

@ -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
};