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Sat, 14 Sep 2019 03:11:18 -0700 (PDT) Received: from [192.168.43.11] ([109.126.145.74]) by smtp.gmail.com with ESMTPSA id e30sm58062825wra.48.2019.09.14.03.11.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 14 Sep 2019 03:11:18 -0700 (PDT) To: Jens Axboe , Ingo Molnar , Peter Zijlstra , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: From: Pavel Begunkov Openpgp: preference=signencrypt 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: [RFC PATCH 0/2] Optimise io_uring completion waiting Message-ID: Date: Sat, 14 Sep 2019 13:11:08 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="1UpWvQKmHjh63s1q2D5QaIWPw37539xMm" Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --1UpWvQKmHjh63s1q2D5QaIWPw37539xMm Content-Type: multipart/mixed; boundary="n83DNlQnNXXTEpVorGmAy12v3UslHPoME"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , Ingo Molnar , Peter Zijlstra , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: Subject: Re: [RFC PATCH 0/2] Optimise io_uring completion waiting References: In-Reply-To: --n83DNlQnNXXTEpVorGmAy12v3UslHPoME Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable It solves much of the problem, though still have overhead on traversing a wait queue + indirect calls for checking. I've been thinking to either 1. create n wait queues and bucketing waiter. E.g. log2(min_events) bucketing would remove at least half of such calls for arbitary min_events and all if min_events is pow2. 2. or dig deeper and add custom wake_up with perhaps sorted wait_queue. As I see it, it's pretty bulky and over-engineered, but maybe somebody knows an easier way? Anyway, I don't have performance numbers for that, so don't know if this would be justified. On 14/09/2019 03:31, Jens Axboe wrote: > On 9/13/19 4:28 PM, Pavel Begunkov (Silence) wrote: >> From: Pavel Begunkov >> >> There could be a lot of overhead within generic wait_event_*() used fo= r >> waiting for large number of completions. The patchset removes much of >> it by using custom wait event (wait_threshold). >> >> Synthetic test showed ~40% performance boost. (see patch 2) >=20 > Nifty, from an io_uring perspective, I like this a lot. >=20 > The core changes needed to support it look fine as well. I'll await > Peter/Ingo's comments on it. >=20 --=20 Yours sincerely, Pavel Begunkov --n83DNlQnNXXTEpVorGmAy12v3UslHPoME-- --1UpWvQKmHjh63s1q2D5QaIWPw37539xMm Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl18vMEACgkQWt5b1Glr +6XnSw/7BNkPkh3Nd7JZKz/MxlxlDO9WJViWrafCx0DwriU7WUd3uE1u0cEda+hJ lv/biGOrIkhsFFBlnx7e//XdiliS6U9oYRE/2tuyts+bTKnbRvjKHApRFQO8fguO jBHbfUcXVANMq6O3CgeTzPOstPeXvU0va9Ey69AuWQQy1k7bZpn/8PJdTp7vn8l5 aSfX3m/lobS5BG43jh0eThhghjHwwZdj4dybcP2Mzp2yuwzbxkERHIhR0jWN4Tt9 Ngk43SYx8MHaS3X0incND2QR7ZaU0K58ztUf33U+umzV8kLRImiRX2nJu31wHv5g p9GbcUft6YBI6f5oO9Vh6VbxvCYoMenFkhEovf4aunxlDBLMUKFOuF6kfVg4E/oE tskpU2pn88USu0Yzc9ROOilOgBUhruVxToJCErgeQQFRzkI5+xlfAQ6HXmefDWhH ioUOmG5EFxXj8w+Pqjof13U/KczxANlmNGYNUPz2TEiwDyEpC4MpjzAsgZI65lkW l0Mv2GnE9sh7qv3gz+2QJhSH4nD0QYMHvHQVAVZ+N6Fq6Bg6fOkzfdLfI6BQT3OV XrOq8XBGKUK/8hG1r3+eMSGEMlkGg3zviov/Z83WznhvgEgc+yYOBtUrkHle0Iue Jws/PwXpSCl1FpXMPudATZghBG65zM8F1nSHajLlt7qBuzz1Ibg= =jlm/ -----END PGP SIGNATURE----- --1UpWvQKmHjh63s1q2D5QaIWPw37539xMm--