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Mon, 24 Feb 2020 10:33:55 -0800 (PST) Received: from [192.168.43.177] ([109.126.137.65]) by smtp.gmail.com with ESMTPSA id q9sm20575512wrx.18.2020.02.24.10.33.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Feb 2020 10:33:55 -0800 (PST) Subject: Re: [PATCH RFC] io_uring: remove retries from io_wq_submit_work() To: Jens Axboe , io-uring@vger.kernel.org References: <843cc96a407b2cbfe869d9665c8120bdde34683e.1582535688.git.asml.silence@gmail.com> <295a86f4-6e70-366a-e056-33894430c7aa@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: Date: Mon, 24 Feb 2020 21:33:08 +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: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="kzPYkzonS5jh8hUz1bzpdy6HFilQdvotF" 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) --kzPYkzonS5jh8hUz1bzpdy6HFilQdvotF Content-Type: multipart/mixed; boundary="yAEbbSWxb05pCtCythePJPem0J8gxK1eY"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org Message-ID: Subject: Re: [PATCH RFC] io_uring: remove retries from io_wq_submit_work() References: <843cc96a407b2cbfe869d9665c8120bdde34683e.1582535688.git.asml.silence@gmail.com> <295a86f4-6e70-366a-e056-33894430c7aa@kernel.dk> In-Reply-To: --yAEbbSWxb05pCtCythePJPem0J8gxK1eY Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 24/02/2020 21:16, Jens Axboe wrote: > On 2/24/20 8:40 AM, Pavel Begunkov wrote: >> On 24/02/2020 18:27, Jens Axboe wrote: >>> On 2/24/20 2:15 AM, Pavel Begunkov wrote: >>>> It seems no opcode may return -EAGAIN for non-blocking case and expe= ct >>>> to be reissued. Remove retry code from io_wq_submit_work(). >>> >>> There's actually a comment right there on how that's possible :-) >> >> Yeah, I saw it and understand the motive, and how it may happen, but c= an't >> find a line, which can actually return -EAGAIN. Could you please point= to an >> example? >=20 > Just give it a whirl, should be easy to reproduce if you just do: >=20 > # echo 2 > /sys/block/nvme0n1/queue/nr_requests > # fio/t/io_uring /dev/nvme0n1 >=20 > or something like that. It's propagated from the kiocb endio handler, > through, req->result at the bottom of io_issue_sqe() I see now, thanks! What a jungle >=20 > if (ctx->flags & IORING_SETUP_IOPOLL) { > const bool in_async =3D io_wq_current_is_worker(); >=20 > if (req->result =3D=3D -EAGAIN) =20 > return -EAGAIN; > [...] >=20 >=20 --=20 Pavel Begunkov --yAEbbSWxb05pCtCythePJPem0J8gxK1eY-- --kzPYkzonS5jh8hUz1bzpdy6HFilQdvotF Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl5UFuQACgkQWt5b1Glr +6XmWQ//Z9zSJzt3nd4cjAV1Q77gzzscwJ5RVloO7Rgbg9INHuC49sQJhJUieLza 7tfPV9fGR6OAEjggHfRQYZXCOMsrjNAIvqf2oudIUFpeT+5WzBQH6t4k7iUEcgml wlrIPNxwxW1+DGKy0ba44+wu6lrMYRXhHoHwGDcQtOz0Hr2D0q/Rr5ITRLiIjng3 fWNTMTI97PbTM3ZiDLtThog+CERrAMQncPqBWHM5qvSQjg7cb1euzQoCt3CVm2AO TVFVG9m0DIfGzXwKLFViXALZlY4ufAPjt8pcCS2zsLNnCcuei9eaokpWD07560Ji nyAUBvmxI4v06Ei6NQ4jhSEI5Vr95pBrGoKLHEy3ClmOAwDQhZRaChJ8qdlmQtRP /oX1Qhsh8HOthA0z3Ip0QP8Nqfmu9tq89aBb8ssv2LjmuspAtkViw3VJrdQWFZEu VQwqTXzF3Jt/F7ScDv2z2j+3x6xgIQwB6EZ2zwDDKsoVR04WuEobL0miU1mFIznD kS15bpeOtk+NxJQGGa2GIoQiWKhuvKdsUCX1693Zfb1nDhs574yXDcP7YG82XWxP +YeAwQt0DueSeK1iUYfyt4knq6LHRNlGWkzn+vwKGXr5gbUQElPI4THSczHwkQhu CGpeml4WQB5zj1Av8rnO2uPGUVniD+I9L2pCtkn3eXCuExViAzE= =aXN9 -----END PGP SIGNATURE----- --kzPYkzonS5jh8hUz1bzpdy6HFilQdvotF--