From f3bdc62fd82ed93dbe4d049eacba310de7eb2a6a Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Wed, 17 Jun 2020 15:58:23 +0200 Subject: 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 Signed-off-by: Jens Axboe --- include/trace/events/block.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/trace') diff --git a/include/trace/events/block.h b/include/trace/events/block.h index 93b114226af8..34d64ca306b1 100644 --- a/include/trace/events/block.h +++ b/include/trace/events/block.h @@ -211,6 +211,21 @@ DEFINE_EVENT(block_rq, block_rq_issue, TP_ARGS(q, rq) ); +/** + * block_rq_merge - merge request with another one in the elevator + * @q: queue holding operation + * @rq: block IO operation operation request + * + * Called when block operation request @rq from queue @q is merged to another + * request queued in the elevator. + */ +DEFINE_EVENT(block_rq, block_rq_merge, + + TP_PROTO(struct request_queue *q, struct request *rq), + + TP_ARGS(q, rq) +); + /** * block_bio_bounce - used bounce buffer when processing block operation * @q: queue holding the block operation -- cgit v1.2.3-59-g8ed1b