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Fri, 05 Aug 2022 10:27:24 -0700 (PDT) Message-ID: Date: Fri, 5 Aug 2022 11:27:22 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH 0/4] iopoll support for io_uring/nvme passthrough Content-Language: en-US To: Kanchan Joshi Cc: hch@lst.de, io-uring@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, ming.lei@redhat.com, joshiiitr@gmail.com, gost.dev@samsung.com References: <20220805154226.155008-1-joshi.k@samsung.com> <78f0ac8e-cd45-d71d-4e10-e6d2f910ae45@kernel.dk> <20220805171331.GD17011@test-zns> From: Jens Axboe In-Reply-To: <20220805171331.GD17011@test-zns> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220805_102727_193611_E08A3BB4 X-CRM114-Status: GOOD ( 12.67 ) 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 8/5/22 11:13 AM, Kanchan Joshi wrote: > On Fri, Aug 05, 2022 at 11:04:22AM -0600, Jens Axboe wrote: >> On 8/5/22 9:42 AM, Kanchan Joshi wrote: >>> Hi, >>> >>> Series enables async polling on io_uring command, and nvme passthrough >>> (for io-commands) is wired up to leverage that. >>> >>> 512b randread performance (KIOP) below: >>> >>> QD_batch block passthru passthru-poll block-poll >>> 1_1 80 81 158 157 >>> 8_2 406 470 680 700 >>> 16_4 620 656 931 920 >>> 128_32 879 1056 1120 1132 >> >> Curious on why passthru is slower than block-poll? Are we missing >> something here? > passthru-poll vs block-poll you mean? > passthru does not have bio-cache, while block path is running with that. > Maybe completion-batching is also playing some role, not too sure about that > at the moment. Yeah, see other email on a quick rundown. We should make bio_map_user_iov() use the bio caching, that'd make a big difference. Won't fully close the gap, but will be close if we exclude the lack of fixedbufs. -- Jens Axboe