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Sun, 12 Jan 2020 13:21:47 -0800 (PST) To: Mark Papadakis , io-uring@vger.kernel.org References: 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== Subject: Re: Feature: zero-copy splice API/opcode Message-ID: <457632cf-614c-ac55-b869-39b50a61e1fd@gmail.com> Date: Mon, 13 Jan 2020 00:21:04 +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="Uozf36OHpdV8rWpAPZhSwjfPluBM7XOBp" 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) --Uozf36OHpdV8rWpAPZhSwjfPluBM7XOBp Content-Type: multipart/mixed; boundary="eZlxHQrl51HcwXqKQsC06GFbHZwSz0OQV"; protected-headers="v1" From: Pavel Begunkov To: Mark Papadakis , io-uring@vger.kernel.org Message-ID: <457632cf-614c-ac55-b869-39b50a61e1fd@gmail.com> Subject: Re: Feature: zero-copy splice API/opcode References: In-Reply-To: --eZlxHQrl51HcwXqKQsC06GFbHZwSz0OQV Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 09/01/2020 17:58, Mark Papadakis wrote: > Greetings, >=20 > I =E2=80=98ve been trying to replicate the benefits provided by sendfil= e() using e.g O_DIRECT access, together with IOSQE_IO_LINK in SQE flags a= nd MSG_ZEROCOPY, but it doesn=E2=80=99t appear to work. Other ideas didn=E2= =80=99t work either. >=20 > I would really appreciate a sendfile like SQE opcode, but maybe some so= rt of generic DMA/zero-copy based opcode based on splice semantics could = be implemented, so that e.g a vmsplice() like alternative could also work= =2E >=20 Sounds interesting, I'll look into this. First, I want to dig a bit into kernel's zero-copy and get an idea how to cover all use cases with a sing= le opcode, and that's probably keeping in mind p2p. The obvious nuisance from perspective is that it needs 2 fds. Any other = concerns? >=20 > (That would be the last remaining bit of functionality missing from io_= uring, now that Jens has implemented support for IOSQE_ASYNC, IORING_REGI= STER_EVENTFD_ASYNC and for managing epoll FDs, for enabling support for i= o_uring on https://github.com/phaistos-networks/TANK ). >=20 > Thank you, > @markpapadakis >=20 --=20 Pavel Begunkov --eZlxHQrl51HcwXqKQsC06GFbHZwSz0OQV-- --Uozf36OHpdV8rWpAPZhSwjfPluBM7XOBp Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl4bjcUACgkQWt5b1Glr +6UEvhAArrFhTQrYIN2HN7qdpKQj1JyRZt+ncf7HVilrcsrkvPSMRLjVu/UdzYxX fzVF0GX1w6G68/l4EfYX/XHuZ7RBcsLpi3hV48SvfJ8ifzFWZJeKtjcWs12AXicb CV3pADiV4+SdRtFbACV8YAyzDt4s8OUnuK+nXGisCW+R1ichGvY4HFF38+r3JD8V k3+zPWwGFFl76LrBLjJ8x/z80PDDoN3btA0/WjBdKZTM7230sNLqnQV3KF6sy5hD ZaprqQkRNQCRHnLtUXBnZo1zfsuK/1tLcEvig4kl41LltQXcLXueRFLUb7TnN/sX ApJAJYYtIErCj9Vfq85J9WrrwTzpshusVukZG853fGOSiXiOd8ozkyz+YjHm3sU2 aQO6QaSEvCidw+FC+oLoT0H9mDzg5ritSfdG7ed8Y+Lmx6Gse6k3Fx9C2FcesB1y QM1m17GsEyiWSsYVDG5wFvIvgvAFvBOOKOOyQcl41dH8BMgYCNA3+DxYl0n9Ptme ZOgvuRsVljecDuJZogc5R8poHHTZ8I6sHkb84FhqVqR/WktbHTzWOhTelvvdCw0L zRLCsbxgsAb88F2xT5JTRYCm1e+vj+/rz1X/tG83mhak4iIlJs5NZmihWHcYLrtX Yoe7yhBcPoepf7QgmeSHdBMtOrpFPvGEbxy+xPLeN8ZG8DA1uX4= =80sK -----END PGP SIGNATURE----- --Uozf36OHpdV8rWpAPZhSwjfPluBM7XOBp--