diff options
| author | Jan Kara <jack@suse.cz> | 2020-06-17 15:58:23 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-06-25 21:06:11 -0600 |
| commit | f3bdc62fd82ed93dbe4d049eacba310de7eb2a6a (patch) | |
| tree | eefbacc996ba10e58a127a7a2df8924e4bbb0179 /kernel/trace | |
| parent | 621c1f42945e76015c3a585e7a9fe6e71665eba0 (diff) | |
blktrace: Provide event for request merging
Currently blk-mq does not report any event when two requests get merged
in the elevator. This then results in difficult to understand sequence
of events like:
...
8,0 34 1579 0.608765271 2718 I WS 215023504 + 40 [dbench]
8,0 34 1584 0.609184613 2719 A WS 215023544 + 56 <- (8,4) 2160568
8,0 34 1585 0.609184850 2719 Q WS 215023544 + 56 [dbench]
8,0 34 1586 0.609188524 2719 G WS 215023544 + 56 [dbench]
8,0 3 602 0.609684162 773 D WS 215023504 + 96 [kworker/3:1H]
8,0 34 1591 0.609843593 0 C WS 215023504 + 96 [0]
and you can only guess (after quite some headscratching since the above
excerpt is intermixed with a lot of other IO) that request 215023544+56
got merged to request 215023504+40. Provide proper event for request
merging like we used to do in the legacy block layer.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/blktrace.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index c086c38f4954..7ba62d68885a 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -860,6 +860,13 @@ static void blk_add_trace_rq_issue(void *ignore, blk_trace_request_get_cgid(q, rq)); } +static void blk_add_trace_rq_merge(void *ignore, + struct request_queue *q, struct request *rq) +{ + blk_add_trace_rq(rq, 0, blk_rq_bytes(rq), BLK_TA_BACKMERGE, + blk_trace_request_get_cgid(q, rq)); +} + static void blk_add_trace_rq_requeue(void *ignore, struct request_queue *q, struct request *rq) @@ -1144,6 +1151,8 @@ static void blk_register_tracepoints(void) WARN_ON(ret); ret = register_trace_block_rq_issue(blk_add_trace_rq_issue, NULL); WARN_ON(ret); + ret = register_trace_block_rq_merge(blk_add_trace_rq_merge, NULL); + WARN_ON(ret); ret = register_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL); WARN_ON(ret); ret = register_trace_block_rq_complete(blk_add_trace_rq_complete, NULL); @@ -1190,6 +1199,7 @@ static void blk_unregister_tracepoints(void) unregister_trace_block_bio_bounce(blk_add_trace_bio_bounce, NULL); unregister_trace_block_rq_complete(blk_add_trace_rq_complete, NULL); unregister_trace_block_rq_requeue(blk_add_trace_rq_requeue, NULL); + unregister_trace_block_rq_merge(blk_add_trace_rq_merge, NULL); unregister_trace_block_rq_issue(blk_add_trace_rq_issue, NULL); unregister_trace_block_rq_insert(blk_add_trace_rq_insert, NULL); |