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[87.52.80.167]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-52ea6bf34e0sm109541e87.172.2024.07.05.01.16.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 Jul 2024 01:16:56 -0700 (PDT) Message-ID: <46d73c73-b1cb-4124-96ca-378563fbdfb8@kernel.dk> Date: Fri, 5 Jul 2024 02:16:55 -0600 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] nvme-tcp: per-controller I/O workqueues To: Hannes Reinecke , Christoph Hellwig Cc: Tejun Heo , Sagi Grimberg , Hannes Reinecke , Keith Busch , linux-nvme@lists.infradead.org References: <20240703135021.34143-1-hare@kernel.org> <20240703135021.34143-2-hare@kernel.org> <7e4444d0-f156-439e-9363-4beb86bb6248@grimberg.me> <9de5d83c-4b05-4f69-8ab4-b4aa65e5ec62@suse.de> <20240705071022.GA13302@lst.de> <8beb0e36-af31-4633-ae2a-afa6bcec5a14@suse.de> Content-Language: en-US From: Jens Axboe In-Reply-To: <8beb0e36-af31-4633-ae2a-afa6bcec5a14@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240705_011700_271083_0BC91FC1 X-CRM114-Status: GOOD ( 10.97 ) 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 On 7/5/24 2:11 AM, Hannes Reinecke wrote: > On 7/5/24 09:10, Christoph Hellwig wrote: >> Btw, I don't think brd is what we should optimize for.  brd does >> synchronous I/O from ->submit_bio which makes it very non-typical. >> Trying to get this as good as possible for QD=1 might be fine, >> but once we have deeper queue depth and/or bigger I/O size it will >> use a lot more time in the submission context (aka the workqueues here) >> than a real device. Agree, using brd is the backend is useless if you want to optimize for the real world, and may be actively misleading. > Hmm. brd was the simplest choice to get a high-bandwidth target. > I'll check if a get a similar performance with null-blk. Just use a normal flash drive? Even basic drives these days do millions of iops and 7-8GB/sec. -- Jens Axboe