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From: Qiliang Yuan <odys.yuan@gmail.com>
To: Jens Axboe <axboe@kernel.dk>, Ming Lei <tom.leiming@gmail.com>,
	Wen Xiong <wenxiong@linux.ibm.com>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH] blk-mq: run the hw queue synchronously for unplugged scheduler inserts
Date: Sat, 10 Oct 2026 10:35:47 +0800	[thread overview]
Message-ID: <20261010023548.3666200-1-odys.yuan@gmail.com> (raw)
In-Reply-To: <20260930-bug-blk-mq-noplug-sched-dispatch-v1-1-ff1e49e52b00@gmail.com>

Hi Jens, Ming,

Gentle ping on this one. It fixes a v7.2 regression from 9cbbac29d752
("block: Remove redundant plug in __submit_bio()"): unplugged I/O to a
device with an I/O scheduler is now run from kblockd, and the kworker
preempts the submitter once per I/O. A single-queue null_blk device with
mq-deadline drops from 289K to 193K IOPS, and a single-queue ublk device
from 265K to 113K.

Every single-queue device that defaults to mq-deadline is affected, so it
would be good to get this fixed in 7.3. Any comments are welcome.

Thanks,
Qiliang

  reply	other threads:[~2026-10-10  2:36 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-30  7:38 Qiliang Yuan
2026-10-10  2:35 ` Qiliang Yuan [this message]
2026-10-10  3:05   ` Ming Lei

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