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([23.254.208.9]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3537ca67b21sm10057666eec.11.2026.10.09.19.35.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Oct 2026 19:36:05 -0700 (PDT) From: Qiliang Yuan To: Jens Axboe , Ming Lei , Wen Xiong 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 Message-ID: <20261010023548.3666200-1-odys.yuan@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260930-bug-blk-mq-noplug-sched-dispatch-v1-1-ff1e49e52b00@gmail.com> References: <20260930-bug-blk-mq-noplug-sched-dispatch-v1-1-ff1e49e52b00@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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