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Tue, 08 Oct 2019 09:43:21 -0700 (PDT) Received: from [192.168.43.133] ([109.126.138.202]) by smtp.gmail.com with ESMTPSA id z125sm3877572wme.37.2019.10.08.09.43.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Oct 2019 09:43:20 -0700 (PDT) To: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <936cd758d6c694fe1b8b9de050e24cfecdc2e60d.1570489620.git.asml.silence@gmail.com> 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: [PATCH] io_uring: remove wait loop spurious wakeups Message-ID: Date: Tue, 8 Oct 2019 19:43:16 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="hLu72yIEVK9xBJIR5otQrTc17jYRh5NPx" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --hLu72yIEVK9xBJIR5otQrTc17jYRh5NPx Content-Type: multipart/mixed; boundary="2iADUy5gFpKbFUgaLFu9N6SXPlkEiUQwB"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: Subject: Re: [PATCH] io_uring: remove wait loop spurious wakeups References: <936cd758d6c694fe1b8b9de050e24cfecdc2e60d.1570489620.git.asml.silence@gmail.com> In-Reply-To: --2iADUy5gFpKbFUgaLFu9N6SXPlkEiUQwB Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 08/10/2019 06:16, Jens Axboe wrote: > On 10/7/19 5:18 PM, Pavel Begunkov (Silence) wrote: >> From: Pavel Begunkov >> >> Any changes interesting to tasks waiting in io_cqring_wait() are >> commited with io_cqring_ev_posted(). However, io_ring_drop_ctx_refs() >> also tries to do that but with no reason, that means spurious wakeups >> every io_free_req() and io_uring_enter(). >> >> Just use percpu_ref_put() instead. >=20 > Looks good, this is a leftover from when the ctx teardown used > the waitqueue as well. >=20 BTW, is there a reason for ref-counting in struct io_kiocb? I understand the idea behind submission reference, but don't see any actual part needing it. Tested with another ref-counting patch and got +5-8% to nops performance. --=20 Yours sincerely, Pavel Begunkov --2iADUy5gFpKbFUgaLFu9N6SXPlkEiUQwB-- --hLu72yIEVK9xBJIR5otQrTc17jYRh5NPx Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl2cvKgACgkQWt5b1Glr +6XVlA//X8GGiOoLXlFyQO5BZ9N3oU4Qr0hmy3II+7MJFnaD9+idQxE2xbROePEI k0XyR064RJ53xEiP3t8aYrZ1BEpBSMb8pzWUYY5rydmLaCzXIbVVEKKCe8c0ox4D EZUvNI4y7eNF+5PO2fIEcktl5sBeq764yLEQbuGJZFAq2BXU3bHtmg3/zjfj/8Fe DfbNn7cscjFtgY3PFDy7rnCNlquGpbZKBtfXz6YH0s7Qz99LjRRSfU/2RLDjThqV cuZkdgBj3S+oeRXw8phnHLEhGOe49F90Odi4qVqQg5DoafV4zxB90d9RpqdCbIDs cam6wI2PoLBpYiE97uZzs0WxK/ic8yOfPI35zlzlrKq5gVD+q2rUhYsVGPYiy+j2 QZ5UHQE60VLZ4h+C0dKgxMsFs23JbaDqp+8HIUujoTbVuFnqQFUjiEBKInKLc2hq 66izvZxsH9HzmTgR3KAiJWq2z9+Pun7KknxOV5Fy/NczD+POoido7t/mTVcotiyq 1tNvj5Z8HHfAcZf2VnsVa96n8eHdYH5nltML1pHiqj/WEazACq1eRLYMWr5g0Wcn RICsH1bOLwX5XVUXSsDnckyyllJRassam42NtKqgdlYzJfeL046TgugLB3gvkwSi 1z3QxdHGiRAi82halG1Icf4yr0AcspYkPBXyzbPICTlwZX4Q3+8= =VKL6 -----END PGP SIGNATURE----- --hLu72yIEVK9xBJIR5otQrTc17jYRh5NPx--