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Content-Language: en-US To: Christoph Hellwig , Kanchan Joshi Cc: Kanchan Joshi , io-uring@vger.kernel.org, linux-nvme@lists.infradead.org, Pavel Begunkov , Ming Lei , Luis Chamberlain , Pankaj Raghav , =?UTF-8?Q?Javier_Gonz=c3=a1lez?= , Anuj Gupta References: <20220401110310.611869-1-joshi.k@samsung.com> <20220401110310.611869-6-joshi.k@samsung.com> <20220404072016.GD444@lst.de> <20220405060224.GE23698@lst.de> From: Jens Axboe In-Reply-To: <20220405060224.GE23698@lst.de> 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-20220405_084053_688095_F2133E59 X-CRM114-Status: GOOD ( 15.35 ) 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 4/5/22 12:02 AM, Christoph Hellwig wrote: > On Mon, Apr 04, 2022 at 07:55:05PM +0530, Kanchan Joshi wrote: >>> Something like this (untested) patch should help to separate >>> the much better: >> >> It does, thanks. But the only thing is - it would be good to support >> vectored-passthru too (i.e. NVME_IOCTL_IO64_CMD_VEC) for this path. >> For the new opcode "NVME_URING_CMD_IO" , either we can change the >> cmd-structure or flag-based handling so that vectored-io is supported. >> Or we introduce NVME_URING_CMD_IO_VEC also for that. >> Which one do you prefer? > > I agree vectored I/O support is useful. > > Do we even need to support the non-vectored case? I would argue that 99% of the use cases will be non-vectored, and non-vectored is a lot cheaper to handle for deferrals as there's no iovec to keep persistent on the io_uring side. So yes, I'd say we _definitely_ want to have non-vectored be available and the default thing that applications use unless they explicitly want more than 1 segment in a request. -- Jens Axboe