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>
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 622fb41..6eedf3a 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -451,27 +451,13 @@
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 @@
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);