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Sun, 22 Mar 2020 13:26:25 -0700 (PDT) Received: from [192.168.43.118] ([109.126.140.227]) by smtp.gmail.com with ESMTPSA id d124sm14608665wmd.37.2020.03.22.13.26.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 22 Mar 2020 13:26:25 -0700 (PDT) To: Jens Axboe , io-uring References: <3454f8c1-3d5a-1f94-569a-41e553fc836a@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 v2] io-wq: handle hashed writes in chains Message-ID: Date: Sun, 22 Mar 2020 23:25:30 +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="CRiAO4ie2qRtd5OyvDeIHZmpu4oehZbx2" 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) --CRiAO4ie2qRtd5OyvDeIHZmpu4oehZbx2 Content-Type: multipart/mixed; boundary="HHLsypKBgtAnbuATg0FO9RifVXFvzZAjH"; 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: --HHLsypKBgtAnbuATg0FO9RifVXFvzZAjH Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 22/03/2020 22:51, Jens Axboe wrote: > commit f1d96a8fcbbbb22d4fbc1d69eaaa678bbb0ff6e2 > Author: Pavel Begunkov > Date: Fri Mar 13 22:29:14 2020 +0300 >=20 > io_uring: NULL-deref for IOSQE_{ASYNC,DRAIN} >=20 > which is what I ran into as well last week... I picked it before testing > The extra memory isn't a bit deal, it's very minor. My main concern > would be fairness, since we'd then be grabbing non-contig hashed chunks= , > before we did not. May not be a concern as long as we ensure the > non-hasned (and differently hashed) work can proceed in parallel. For m= y > end, I deliberately added: Don't think it's really a problem, all ordering/scheduling is up to users= (i.e. io_uring), and it can't infinitely postpone a work, because it's processi= ng spliced requests without taking more, even if new ones hash to the same b= it. > + /* already have hashed work, let new worker get this */ > + if (ret) { > + struct io_wqe_acct *acct; > + > + /* get new worker for unhashed, if none now */ > + acct =3D io_work_get_acct(wqe, work); > + if (!atomic_read(&acct->nr_running)) > + io_wqe_wake_worker(wqe, acct); > + break; > + } >=20 > to try and improve that. Is there performance problems with your patch without this chunk? I may s= ee another problem with yours, I need to think it through. >=20 > I'll run a quick test with yours. --=20 Pavel Begunkov --HHLsypKBgtAnbuATg0FO9RifVXFvzZAjH-- --CRiAO4ie2qRtd5OyvDeIHZmpu4oehZbx2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl53yboACgkQWt5b1Glr +6UXrBAAoTyAPp+HIFpM944rAt5+hdu03j6ephvSmCmljea7/+YZ6wr0dVMcvoKq 4N6s/t1/2Z81MRZwa2YaxYPSaANQLk3KZsvE9ppONIeNtVyhy3jPPSF2B0GLAoPo K9lROY3EfjFijfAtgcYeldN8PHkoO2GdvMz4l8AUsdfDB5WfecZ7ZtnZAyArnVYq zxVq1H/lmcDu/Oo+s7mk4r3SqhDNqzH1n9JTLGqIG2p0NCF47HAsibr8qhyyjuEi 5zo23odE0xHcbk42zLwfayyyNS/wZeE/2xQInw36B9wiZuqKm1pXpwvq4zJc7A1U 5pB/1LfszqOW3xtEHsZUgd7JJLYALZaj2xcEQY8wX1cmOvT4s9LpMjg4/aCqhLw7 N9q6B+yuacELh1XbdRZes8Xkh0xA4j1Yau9PlzJMuVruSgEkMMnQJvUjw+vaZFbM FenekR1rCw9ZIWBQZ7RG/LEmjyljdNtrzMrbBSb/z+rBW1556M//HfaE1DiKDZNq shrKHiLP1UdOIWStBF7jC8XyA1pkwLW9mQRCLxW8u9+4w5SCYiB2z2tafCoqquFz w9W7OqEDsk496cdatdruOj0Ll0bUNwQt31ZkXcA853jVLWsitBqKarfgHrfUa4GX snIA2faxQhM4W/bqGAPYfaXrPVu13Kb4EXVq98e2WiEVgBlw1tM= =LdgA -----END PGP SIGNATURE----- --CRiAO4ie2qRtd5OyvDeIHZmpu4oehZbx2--