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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>
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@ -451,27 +451,13 @@ void blkiocg_update_io_merged_stats(struct blkio_group *blkg,
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bool direction, bool sync)
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{
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struct blkg_policy_data *pd = blkg->pd[pol->plid];
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struct blkio_group_stats_cpu *stats_cpu;
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struct blkio_group_stats *stats;
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unsigned long flags;
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/* If per cpu stats are not allocated yet, don't do any accounting. */
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if (pd->stats_cpu == NULL)
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return;
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/*
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* Disabling interrupts to provide mutual exclusion between two
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* writes on same cpu. It probably is not needed for 64bit. Not
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* optimizing that case yet.
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*/
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local_irq_save(flags);
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stats_cpu = this_cpu_ptr(pd->stats_cpu);
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u64_stats_update_begin(&stats_cpu->syncp);
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blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_MERGED], 1,
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direction, sync);
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u64_stats_update_end(&stats_cpu->syncp);
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local_irq_restore(flags);
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spin_lock_irqsave(&blkg->stats_lock, flags);
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stats = &pd->stats;
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blkio_add_stat(stats->stat_arr[BLKIO_STAT_MERGED], 1, direction, sync);
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spin_unlock_irqrestore(&blkg->stats_lock, flags);
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
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@ -1342,7 +1328,7 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
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BLKIO_STAT_WAIT_TIME, 1, 0);
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case BLKIO_PROP_io_merged:
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return blkio_read_blkg_stats(blkcg, cft, cb,
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BLKIO_STAT_CPU_MERGED, 1, 1);
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BLKIO_STAT_MERGED, 1, 0);
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case BLKIO_PROP_io_queued:
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return blkio_read_blkg_stats(blkcg, cft, cb,
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BLKIO_STAT_QUEUED, 1, 0);
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@ -29,10 +29,12 @@ enum blkio_policy_id {
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#ifdef CONFIG_BLK_CGROUP
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enum stat_type {
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/* Number of IOs merged */
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BLKIO_STAT_MERGED,
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/* Total time spent (in ns) between request dispatch to the driver and
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* request completion for IOs doen by this cgroup. This may not be
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* accurate when NCQ is turned on. */
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BLKIO_STAT_SERVICE_TIME = 0,
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BLKIO_STAT_SERVICE_TIME,
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/* Total time spent waiting in scheduler queue in ns */
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BLKIO_STAT_WAIT_TIME,
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/* Number of IOs queued up */
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@ -57,8 +59,6 @@ enum stat_type_cpu {
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BLKIO_STAT_CPU_SERVICE_BYTES,
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/* Total IOs serviced, post merge */
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BLKIO_STAT_CPU_SERVICED,
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/* Number of IOs merged */
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BLKIO_STAT_CPU_MERGED,
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BLKIO_STAT_CPU_NR
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};
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