diff options
| author | Jens Axboe <axboe@kernel.dk> | 2018-11-28 18:50:07 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2018-12-03 22:59:16 +0100 |
| commit | fe1f452640d888c4311ef35c8ee497f47c3ea17c (patch) | |
| tree | 9ec97a247b0e748995fafa1ed4725b16f4408613 /block | |
| parent | block: add cmd_flags to print_req_error (diff) | |
| download | linux-fe1f452640d888c4311ef35c8ee497f47c3ea17c.tar.xz linux-fe1f452640d888c4311ef35c8ee497f47c3ea17c.zip | |
blk-mq: don't call ktime_get_ns() if we don't need it
We only need the request fields and the end_io time if we have
stats enabled, or if we have a scheduler attached as those may
use it for completion time stats.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 7dcef565dc0f..e09d7f500077 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -281,6 +281,15 @@ bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx) } EXPORT_SYMBOL(blk_mq_can_queue); +/* + * Only need start/end time stamping if we have stats enabled, or using + * an IO scheduler. + */ +static inline bool blk_mq_need_time_stamp(struct request *rq) +{ + return (rq->rq_flags & RQF_IO_STAT) || rq->q->elevator; +} + static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, unsigned int tag, unsigned int op) { @@ -316,7 +325,10 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, RB_CLEAR_NODE(&rq->rb_node); rq->rq_disk = NULL; rq->part = NULL; - rq->start_time_ns = ktime_get_ns(); + if (blk_mq_need_time_stamp(rq)) + rq->start_time_ns = ktime_get_ns(); + else + rq->start_time_ns = 0; rq->io_start_time_ns = 0; rq->nr_phys_segments = 0; #if defined(CONFIG_BLK_DEV_INTEGRITY) @@ -522,7 +534,10 @@ EXPORT_SYMBOL_GPL(blk_mq_free_request); inline void __blk_mq_end_request(struct request *rq, blk_status_t error) { - u64 now = ktime_get_ns(); + u64 now = 0; + + if (blk_mq_need_time_stamp(rq)) + now = ktime_get_ns(); if (rq->rq_flags & RQF_STATS) { blk_mq_poll_stats_start(rq->q); |