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| author | Pavel Begunkov <asml.silence@gmail.com> | 2019-10-07 23:16:51 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-10-08 05:19:10 +0200 |
| commit | 8148f0b5647a831c5d94b59da240c8e76dbacae9 (patch) | |
| tree | 2f9511fed5b78056a63ea1c8104e27f79f69823a | |
| parent | blk-mq: Embed counters into struct mq_inflight (diff) | |
| download | linux-8148f0b5647a831c5d94b59da240c8e76dbacae9.tar.xz linux-8148f0b5647a831c5d94b59da240c8e76dbacae9.zip | |
blk-stat: Optimise blk_stat_add()
blk_stat_add() calls {get,put}_cpu_ptr() in a loop, which entails
overhead of disabling/enabling preemption. The loop is under RCU
(i.e.short) anyway, so do get_cpu() in advance.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-stat.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/block/blk-stat.c b/block/blk-stat.c index 940f15d600f8..7da302ff88d0 100644 --- a/block/blk-stat.c +++ b/block/blk-stat.c @@ -53,7 +53,7 @@ void blk_stat_add(struct request *rq, u64 now) struct request_queue *q = rq->q; struct blk_stat_callback *cb; struct blk_rq_stat *stat; - int bucket; + int bucket, cpu; u64 value; value = (now >= rq->io_start_time_ns) ? now - rq->io_start_time_ns : 0; @@ -61,6 +61,7 @@ void blk_stat_add(struct request *rq, u64 now) blk_throtl_stat_add(rq, value); rcu_read_lock(); + cpu = get_cpu(); list_for_each_entry_rcu(cb, &q->stats->callbacks, list) { if (!blk_stat_is_active(cb)) continue; @@ -69,10 +70,10 @@ void blk_stat_add(struct request *rq, u64 now) if (bucket < 0) continue; - stat = &get_cpu_ptr(cb->cpu_stat)[bucket]; + stat = &per_cpu_ptr(cb->cpu_stat, cpu)[bucket]; blk_rq_stat_add(stat, value); - put_cpu_ptr(cb->cpu_stat); } + put_cpu(); rcu_read_unlock(); } |