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[141.239.149.160]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fac1537373sm106683025ad.135.2024.07.03.12.17.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Jul 2024 12:17:27 -0700 (PDT) Date: Wed, 3 Jul 2024 09:17:26 -1000 From: Tejun Heo To: Sagi Grimberg Cc: Hannes Reinecke , Hannes Reinecke , Christoph Hellwig , Keith Busch , linux-nvme@lists.infradead.org Subject: Re: [PATCH 1/4] nvme-tcp: per-controller I/O workqueues Message-ID: References: <20240703135021.34143-1-hare@kernel.org> <20240703135021.34143-2-hare@kernel.org> <7e4444d0-f156-439e-9363-4beb86bb6248@grimberg.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240703_121728_947077_82ED8638 X-CRM114-Status: GOOD ( 12.77 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org Hello, On Wed, Jul 03, 2024 at 10:14:14PM +0300, Sagi Grimberg wrote: ... > None of these reasons are the claimed reason to use separate workqueues in > this patch. The claim is that it is more efficient, i.e. has less overhead. > > The commit msg is the following: > "Implement per-controller I/O workqueues to reduce workqueue contention > during I/O." Hmm... it's not impossible for the concurrency accounting in pool_workqueues to show up if the issue rate is *really* high but I'd be surprised if that actually matters given that the backend pool is shared. Maybe I'm missing something but I don't see a reason why multiple workqueues would be more efficient than a shared one. Thanks. -- tejun