From bc490f81731e181b07b8d7577425c06ae91692c8 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 18 Oct 2021 10:12:12 -0600 Subject: block: change plugging to use a singly linked list Use a singly linked list for the blk_plug. This saves 8 bytes in the blk_plug struct, and makes for faster list manipulations than doubly linked lists. As we don't use the doubly linked lists for anything, singly linked is just fine. This yields a bump in default (merging enabled) performance from 7.0 to 7.1M IOPS, and ~7.5M IOPS with merging disabled. Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- block/blk-merge.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'block/blk-merge.c') diff --git a/block/blk-merge.c b/block/blk-merge.c index c273b58378ce..3e6fa449caff 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -1090,11 +1090,11 @@ bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, struct request *rq; plug = blk_mq_plug(q, bio); - if (!plug || list_empty(&plug->mq_list)) + if (!plug || rq_list_empty(plug->mq_list)) return false; /* check the previously added entry for a quick merge attempt */ - rq = list_last_entry(&plug->mq_list, struct request, queuelist); + rq = rq_list_peek(&plug->mq_list); if (rq->q == q) { /* * Only blk-mq multiple hardware queues case checks the rq in -- cgit v1.2.3