From b03db9cd816ce9909c21aeb8bb852bca74cf8e07 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Wed, 4 Jan 2023 19:54:58 +0800 Subject: [PATCH] blk-mq: set default elevator as deadline in case of hctx shared tagset mainline inclusion from mainline-v5.13-rc1 commit 580dca8143d215977811bd2ff881e1e4f6ff39f0 category: performance bugzilla: 187991,https://gitee.com/openeuler/kernel/issues/I66VDN CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=580dca8143d215977811bd2ff881e1e4f6ff39f0 ---------------------------------------- Yanhui found that write performance is degraded a lot after applying hctx shared tagset on one test machine with megaraid_sas. And turns out it is caused by none scheduler which becomes default elevator caused by hctx shared tagset patchset. Given more scsi HBAs will apply hctx shared tagset, and the similar performance exists for them too. So keep previous behavior by still using default mq-deadline for queues which apply hctx shared tagset, just like before. Fixes: 32bc15afed04 ("blk-mq: Facilitate a shared sbitmap per tagset") Reported-by: Yanhui Ma Cc: John Garry Cc: Hannes Reinecke Signed-off-by: Ming Lei Reviewed-by: Martin K. Petersen Reviewed-by: Bart Van Assche Reviewed-by: John Garry Link: https://lore.kernel.org/r/20210406031933.767228-1-ming.lei@redhat.com Signed-off-by: Jens Axboe Conflict: block/elevator.c Signed-off-by: Zhong Jinghua Reviewed-by: Hou Tao Signed-off-by: Zheng Zengkai --- block/elevator.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/elevator.c b/block/elevator.c index 76f70f679a1b..b66afb571e15 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -630,7 +630,8 @@ static struct elevator_type *elevator_get_default(struct request_queue *q) if (q->tag_set && q->tag_set->flags & BLK_MQ_F_NO_SCHED_BY_DEFAULT) return NULL; - if (q->nr_hw_queues != 1) + if (q->nr_hw_queues != 1 && + !blk_mq_is_sbitmap_shared(q->tag_set->flags)) return NULL; return elevator_get(q, "mq-deadline", false); -- GitLab