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[66.29.188.166]) by smtp.gmail.com with ESMTPSA id 184sm5166660pfe.106.2019.01.15.09.26.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 15 Jan 2019 09:26:25 -0800 (PST) Subject: Re: [PATCH 05/16] Add io_uring IO interface From: Jens Axboe To: Jonathan Corbet Cc: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org, hch@lst.de, jmoyer@redhat.com, avi@scylladb.com References: <20190115025531.13985-1-axboe@kernel.dk> <20190115025531.13985-6-axboe@kernel.dk> <20190115095134.6286b7d6@lwn.net> <5e1fe0b7-7998-d15d-267b-4dbbc01b0b53@kernel.dk> Message-ID: Date: Tue, 15 Jan 2019 10:26:22 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <5e1fe0b7-7998-d15d-267b-4dbbc01b0b53@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 1/15/19 9:55 AM, Jens Axboe wrote: > On 1/15/19 9:51 AM, Jonathan Corbet wrote: >> On Mon, 14 Jan 2019 19:55:20 -0700 >> Jens Axboe wrote: >> >> So the [0/16] cover letter seems to have gone astray this time? > > It did go out, but I forgot to add a Subject line to it... > > https://marc.info/?l=linux-block&m=154752095709422&w=2 > > >>> The submission queue (SQ) and completion queue (CQ) rings are shared >>> between the application and the kernel. This eliminates the need to >>> copy data back and forth to submit and complete IO. >>> >>> IO submissions use the io_uring_sqe data structure, and completions >>> are generated in the form of io_uring_sqe data structures. The SQ >>> ring is an index into the io_uring_sqe array, which makes it possible >>> to submit a batch of IOs without them being contiguous in the ring. >>> The CQ ring is always contiguous, as completion events are inherently >>> unordered and can point to any io_uring_iocb. >>> >>> Two new system calls are added for this: >>> >>> io_uring_setup(entries, iovecs, params) >>> Sets up a context for doing async IO. On success, returns a file >>> descriptor that the application can mmap to gain access to the >>> SQ ring, CQ ring, and io_uring_iocbs. >> >> Looking at the code, it would appear that the "iovecs" parameter doesn't >> actually exist. > > Indeed, need to update that commit message. and io_uring_iocbs should > now be io_uring_sqes. > > The iovec/file registration is done through io_uring_register(2). Updated commit message which covers both this one, and the IORING_ENTER_GETEVENTS below. http://git.kernel.dk/cgit/linux-block/commit/?h=io_uring&id=d14a06629baef2b0701dbd01ac9c9066f73065ec -- Jens Axboe