From: Yu Kuai <yukuai3@huawei.com>
To: <axboe@kernel.dk>
Cc: <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<yukuai3@huawei.com>, <yi.zhang@huawei.com>,
<zhangxiaoxu5@huawei.com>
Subject: [PATCH 2/3] blk-mq: clear 'active_queues' immediately when 'nr_active' is decreased to 0
Date: Sat, 26 Dec 2020 18:28:07 +0800 [thread overview]
Message-ID: <20201226102808.2534966-3-yukuai3@huawei.com> (raw)
In-Reply-To: <20201226102808.2534966-1-yukuai3@huawei.com>
Currently 'active_queues' is cleared when there is no more IO in 5
secondes. Thus if multiple hardware queues share a tag set, and
some queues occasionally issue small amount of IO, some queues might
can't get enough tags while the utilization rate of total tags is
less than 100% because 'active_queues' is never decreased.
Thus clear 'active_queues' immediately when 'nr_active' is
decreased to 0.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
block/blk-mq.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/block/blk-mq.h b/block/blk-mq.h
index f7212bacfa56..228c5c442be4 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -212,8 +212,10 @@ static inline void __blk_mq_dec_active_requests(struct blk_mq_hw_ctx *hctx)
{
if (blk_mq_is_sbitmap_shared(hctx->flags))
atomic_dec(&hctx->queue->nr_active_requests_shared_sbitmap);
- else if (!atomic_dec_return(&hctx->nr_active))
+ else if (!atomic_dec_return(&hctx->nr_active)) {
+ blk_mq_tag_idle(hctx);
blk_mq_dtag_idle(hctx);
+ }
}
static inline int __blk_mq_active_requests(struct blk_mq_hw_ctx *hctx)
--
2.25.4
next prev parent reply other threads:[~2020-12-26 10:26 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-26 10:28 [PATCH 0/3] fix the performance fluctuation due to shared tagset Yu Kuai
2020-12-26 10:28 ` [PATCH 1/3] blk-mq: allow hardware queue to get more tag while sharing a tag set Yu Kuai
2020-12-27 11:58 ` Ming Lei
2020-12-28 1:56 ` yukuai (C)
2020-12-28 8:28 ` Ming Lei
2020-12-28 9:02 ` yukuai (C)
2020-12-29 1:15 ` Ming Lei
2020-12-29 2:37 ` yukuai (C)
2020-12-26 10:28 ` Yu Kuai [this message]
2020-12-26 10:28 ` [PATCH 3/3] blk-mq: decrease pending_queues when it expires Yu Kuai
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