From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , Alan Stern , Christoph Hellwig , Bart Van Assche , Jianchao Wang , Hannes Reinecke , Johannes Thumshirn , Adrian Hunter , "James E.J. Bottomley" , "Martin K. Petersen" , linux-scsi@vger.kernel.org Subject: [RFC PATCH V2 04/17] blk-mq: don't reserve tags for admin queue Date: Sat, 11 Aug 2018 15:12:07 +0800 Message-Id: <20180811071220.357-5-ming.lei@redhat.com> In-Reply-To: <20180811071220.357-1-ming.lei@redhat.com> References: <20180811071220.357-1-ming.lei@redhat.com> List-ID: Not necessary to reserve tags for admin queue since there isn't many inflight commands in admin queue usually. This change won't starve admin queue too because each blocked queue has equal priority to get one new tag when one driver tag is released, no matter it is freed from any queue. So that IO performance won't be affected after admin queue(shared tags with IO queues) is introduced in the following patches. Cc: Alan Stern Cc: Christoph Hellwig Cc: Bart Van Assche Cc: Jianchao Wang Cc: Hannes Reinecke Cc: Johannes Thumshirn Cc: Adrian Hunter Cc: "James E.J. Bottomley" Cc: "Martin K. Petersen" Cc: linux-scsi@vger.kernel.org Signed-off-by: Ming Lei --- block/blk-mq-tag.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index 816923bf874d..7cd09fd16f5a 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -30,7 +30,8 @@ bool blk_mq_has_free_tags(struct blk_mq_tags *tags) bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx) { if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) && - !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) + !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) && + !blk_queue_admin(hctx->queue)) atomic_inc(&hctx->tags->active_queues); return true; @@ -57,7 +58,8 @@ void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) return; - atomic_dec(&tags->active_queues); + if (!blk_queue_admin(hctx->queue)) + atomic_dec(&tags->active_queues); blk_mq_tag_wakeup_all(tags, false); } -- 2.9.5