blk-mq: optimise *end_request non-stat path

We already have a blk_mq_need_time_stamp() check in
__blk_mq_end_request() to get a timestamp, hide all the statistics
accounting under it. It cuts some cycles for requests that don't need
stats, and is free otherwise.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/e0f2ea812e93a8adcd07101212e7d7e70ca304e7.1634115360.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index b7b8437f0a046ac09058b9f022b8a098d6e2e3c8..568773de9a7fe3154563ac8f7f570cb3f7e9fe80 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -579,20 +579,18 @@ void blk_mq_free_plug_rqs(struct blk_plug *plug)
 
 inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
 {
-       u64 now = 0;
+       if (blk_mq_need_time_stamp(rq)) {
+               u64 now = ktime_get_ns();
 
-       if (blk_mq_need_time_stamp(rq))
-               now = ktime_get_ns();
+               if (rq->rq_flags & RQF_STATS) {
+                       blk_mq_poll_stats_start(rq->q);
+                       blk_stat_add(rq, now);
+               }
 
-       if (rq->rq_flags & RQF_STATS) {
-               blk_mq_poll_stats_start(rq->q);
-               blk_stat_add(rq, now);
+               blk_mq_sched_completed_request(rq, now);
+               blk_account_io_done(rq, now);
        }
 
-       blk_mq_sched_completed_request(rq, now);
-
-       blk_account_io_done(rq, now);
-
        if (rq->end_io) {
                rq_qos_done(rq->q, rq);
                rq->end_io(rq, error);