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Sat, 14 Dec 2019 06:44:46 -0800 (PST) Subject: Re: [PATCH v2] io_uring: don't wait when under-submitting To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <5caa38be87f069eb4cc921d58ee1a98ff5d53978.1576223348.git.asml.silence@gmail.com> <6256169d519f72fe592e70be47a04aa0e9c3b9a1.1576333754.git.asml.silence@gmail.com> <55f01a72-fcbc-a3e4-d9db-7dd2a7ef1acd@kernel.dk> From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Message-ID: <28db945c-080f-1951-b4ff-b315f2d0be68@gmail.com> Date: Sat, 14 Dec 2019 17:44:23 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <55f01a72-fcbc-a3e4-d9db-7dd2a7ef1acd@kernel.dk> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="i3rnraO7zOAROH2n7N9jLcB59RVYA2D7k" Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --i3rnraO7zOAROH2n7N9jLcB59RVYA2D7k Content-Type: multipart/mixed; boundary="R6aEDUDfRRE2I8zWq1o0o6OWYoHULpCPw"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <28db945c-080f-1951-b4ff-b315f2d0be68@gmail.com> Subject: Re: [PATCH v2] io_uring: don't wait when under-submitting References: <5caa38be87f069eb4cc921d58ee1a98ff5d53978.1576223348.git.asml.silence@gmail.com> <6256169d519f72fe592e70be47a04aa0e9c3b9a1.1576333754.git.asml.silence@gmail.com> <55f01a72-fcbc-a3e4-d9db-7dd2a7ef1acd@kernel.dk> In-Reply-To: <55f01a72-fcbc-a3e4-d9db-7dd2a7ef1acd@kernel.dk> --R6aEDUDfRRE2I8zWq1o0o6OWYoHULpCPw Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 14/12/2019 17:39, Jens Axboe wrote: > On 12/14/19 7:31 AM, Pavel Begunkov wrote: >> There is no reliable way to submit and wait in a single syscall, as >> io_submit_sqes() may under-consume sqes (in case of an early error). >> Then it will wait for not-yet-submitted requests, deadlocking the user= >> in most cases. >> >> Don't wait/poll if can't submit all sqes, and return -EAGAIN >> >> Signed-off-by: Pavel Begunkov >> --- >> >> v2: cap min_complete if submitted partially (Jens Axboe) >=20 > Can you update the commit message as well, doesn't really reflect the > current state of it... Apart from that, looks good to me! >=20 Right, thanks for noticing! --=20 Pavel Begunkov --R6aEDUDfRRE2I8zWq1o0o6OWYoHULpCPw-- --i3rnraO7zOAROH2n7N9jLcB59RVYA2D7k Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl309UsACgkQWt5b1Glr +6XNSBAAh9DDpRL9bYvDQc79J4TpMuJU6ToJNihLy31tGupizwsWQSt8awYf/Vx6 9RtaDNi/4xLKms0hBQbSn30kA7xk7G0rAoDouwHLW4Hie9+1Jq0X8qmzAl244ToU GMt9MKiLmq2lneeZdAJ094ga+57L1jAtOzAtGg3T9uPhiUBtNRClo2ib/OqqS779 zxxewbF0oXh1Ksgi63ytW7C9CskMMWwaE/T1xCsWRqqWQklE7dXMxYdpJ6QBLxkZ h4626aPRtrK5OBCyW7XgynM3TKfeLwqYbp9h1Ks0itu0S2TUV/PupQwyzdaDe7/+ FSeXyop1iNiMHOSgfsxr6ptfZoFBuJntaj90VNwtBSMeNav8guk1uDtKAWnaQoHz LvqVcjZVH0D84c6oQLWRSyNzl2MdqMcCRXjVzr6cpXBpaBbu50i7cFWMj8vK6F0a CmEs0ha5MZmGMe30+yf6c5kzGYFSRqDVaGsF65lmTeQz55MNpyr9M6eJpG5DaHbQ Wg+y9dT0qHdqnIMljB2LM5qaGOz/fgQfag8lYeZ4zan5QZ8QqceRiROy/9iFTzuP ieUDzB+cXDSX0kNe6HbM0wLo1YgDfNsIYNczhmI/7Vwwt7CVivWZQeWkdVz3/eZn 6Vg8uycAeslsCofwRbFiKhpNN7SFzy+hkbiKlzBRHgS4xOFtNp0= =B8m+ -----END PGP SIGNATURE----- --i3rnraO7zOAROH2n7N9jLcB59RVYA2D7k--