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Sun, 22 Mar 2020 09:25:43 -0700 (PDT) Received: from [192.168.43.79] ([109.126.140.227]) by smtp.gmail.com with ESMTPSA id y80sm18954678wmc.45.2020.03.22.09.25.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 22 Mar 2020 09:25:42 -0700 (PDT) Subject: Re: [PATCH v2] io-wq: handle hashed writes in chains From: Pavel Begunkov To: Jens Axboe , io-uring References: <3454f8c1-3d5a-1f94-569a-41e553fc836a@gmail.com> 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: Sun, 22 Mar 2020 19:24:49 +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: <3454f8c1-3d5a-1f94-569a-41e553fc836a@gmail.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="A60iNAq1QCxn0GFZdLRkrrbqFyczTzYxl" 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) --A60iNAq1QCxn0GFZdLRkrrbqFyczTzYxl Content-Type: multipart/mixed; boundary="U8VwPFr6ZQYQ787fVczplCsnhptjEJuC7"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , io-uring Message-ID: Subject: Re: [PATCH v2] io-wq: handle hashed writes in chains References: <3454f8c1-3d5a-1f94-569a-41e553fc836a@gmail.com> In-Reply-To: <3454f8c1-3d5a-1f94-569a-41e553fc836a@gmail.com> --U8VwPFr6ZQYQ787fVczplCsnhptjEJuC7 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 22/03/2020 19:09, Pavel Begunkov wrote: > On 19/03/2020 21:56, Jens Axboe wrote: >> We always punt async buffered writes to an io-wq helper, as the core >> kernel does not have IOCB_NOWAIT support for that. Most buffered async= >> writes complete very quickly, as it's just a copy operation. This mean= s >> that doing multiple locking roundtrips on the shared wqe lock for each= >> buffered write is wasteful. Additionally, buffered writes are hashed >> work items, which means that any buffered write to a given file is >> serialized. >> >> When looking for a new work item, build a chain of identicaly hashed >> work items, and then hand back that batch. Until the batch is done, th= e >> caller doesn't have to synchronize with the wqe or worker locks again.= I have an idea, how to do it a bit better. Let me try it. --=20 Pavel Begunkov --U8VwPFr6ZQYQ787fVczplCsnhptjEJuC7-- --A60iNAq1QCxn0GFZdLRkrrbqFyczTzYxl Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl53kVEACgkQWt5b1Glr +6XoTw/9EHO3F1pYAeCt3ZFexMzHWSdeE3+vFkHzZeFLg/3rszaelnfV/J3rMNHg Uvqb+6pCG/XY41lhOCpMfMrkeNA2pHhKG8migkibskwr1vEcFRi1VAqZYGG3LFxK 2rTOGqrJZOos2qDhK0JWhHC+k3eibLHo7ILR0YBxBb8Q9oziXhbaexO//ryyRjhc gKjX9rCqn/CPkrIqdYgbwjTn1++U7zHhtas9b7B5SCITTZEoPy7MvWVNcQYugRny u2qvunawZksie0BVhwWWZV/rMJJ0dTKNDGsyRVyp9cnO4Sp0T2RTH1wSgs0mIun9 2P2BmFSC09WPRq9CkNK7zP/sojKhrKR/KfiDc9cv1jsefmIrI11K+E10xeB0hN0y I7IlXx+EIOgFLIQg25U/jklgQZ2vgKfS7GBqaEH7nZTDL1+lg/RD02oy6EhMofi3 FgD+7b3pOiHrwCsGhKpvWpVPPcw9SdvaXXkMeoCjQOx5oZdVUV+0y4X//TamVC5n f1OHnws0SKm3i3D5Tuk59BPJRT+Kd8sUrt1xxxKmVUpCtt1aljOREPg9qW3b7Pth EIH70lXvxD550ORJ7Xmi2jjUlz+3U0AlN+g//5MX8b41EKLpDcOs/VoWUi2TNq8H aNInJWzRYWGjKeAYKAbONw1mjl0G3EG5DzdN6OnZ0kQhPX/aA8U= =lGob -----END PGP SIGNATURE----- --A60iNAq1QCxn0GFZdLRkrrbqFyczTzYxl--