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Sat, 29 Jun 2019 08:37:53 -0700 (PDT) Subject: Re: [PATCH 0/2] Fix misuse of blk_rq_stats in blk-iolatency From: Pavel Begunkov To: Josef Bacik Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, dennis@kernel.org References: <20190614134037.ie7zs4rb4oyesifr@MacBook-Pro-91.local> <054f3ab6-0a03-ff0e-ac46-5d0fba012cf0@gmail.com> 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== Message-ID: <226043f8-4dc6-1ad3-7c66-8d85312f4cae@gmail.com> Date: Sat, 29 Jun 2019 08:37:48 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <054f3ab6-0a03-ff0e-ac46-5d0fba012cf0@gmail.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ySUwH7HggBUqcKs5YeEEvs73YKqE5tR7c" 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) --ySUwH7HggBUqcKs5YeEEvs73YKqE5tR7c Content-Type: multipart/mixed; boundary="v5kLN8vAby91Sr3PVcyKWxtTXVRGYr39Y"; protected-headers="v1" From: Pavel Begunkov To: Josef Bacik Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, dennis@kernel.org Message-ID: <226043f8-4dc6-1ad3-7c66-8d85312f4cae@gmail.com> Subject: Re: [PATCH 0/2] Fix misuse of blk_rq_stats in blk-iolatency References: <20190614134037.ie7zs4rb4oyesifr@MacBook-Pro-91.local> <054f3ab6-0a03-ff0e-ac46-5d0fba012cf0@gmail.com> In-Reply-To: <054f3ab6-0a03-ff0e-ac46-5d0fba012cf0@gmail.com> --v5kLN8vAby91Sr3PVcyKWxtTXVRGYr39Y Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Ping? On 20/06/2019 10:18, Pavel Begunkov wrote: > Hi, >=20 > Josef, thanks for taking a look. >=20 >=20 > Although, there is nothing critical yet -- just a not working / disable= d > optimisation, but changes in stats could sublty break it. E.g. grouping= > @batch and @mean into a union will increase estimated average by severa= l > orders of magnitude. >=20 > Jens, what do you think? >=20 >=20 >=20 > On 14/06/2019 16:40, Josef Bacik wrote: >> On Fri, Jun 14, 2019 at 02:44:11PM +0300, Pavel Begunkov (Silence) wro= te: >>> From: Pavel Begunkov >>> >>> There are implicit assumptions about struct blk_rq_stats, which make >>> it's very easy to misuse. The first patch fixes consequences, and the= >>> second employs type-system to prevent recurrences. >>> >>> >>> Pavel Begunkov (2): >>> blk-iolatency: Fix zero mean in previous stats >>> blk-stats: Introduce explicit stat staging buffers >>> >> >> I don't have a problem with this, but it's up to Jens I suppose >> >> Acked-by: Josef Bacik >> >> Thanks, >> >> Josef >> >=20 --=20 Yours sincerely, Pavel Begunkov --v5kLN8vAby91Sr3PVcyKWxtTXVRGYr39Y-- --ySUwH7HggBUqcKs5YeEEvs73YKqE5tR7c Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl0XhdAACgkQWt5b1Glr +6Uwug/9Hs36QczpdzxYP9xU48n8FgHR0iCItq9jwDE7TeEd2XvFRYvKPZbGxzzW Pe58YOA8TX/4SUla2/B2rBCnp/mdIEqOid8Z3Aa0xEQm7l26sDhdyPzOS05eaxFj ORvPWdTs6zLHkXcMvgUlG10mTX7RFAaE19QtCdPzg16ccKqHqL9YMXQIqj9YBa5W VMdC/CbiiRw2XE4Zvci7sfq8if+ITQ+lo8incssCnKVh8t9EbaUIVLauSIrVu1bp 0gcNhylaTXj94jkDfhOfq9BiTHJ+lQHqaOxj5c54a9tH+9d2IJ3VLC0C8H9PCvkT XqqtSJmYNzJj3wqhZpOG42pF4rX6qr1UfLJ5Ffakum4wdhm8fOiwiHmQbNuzsF/1 Q/NxxogYmtOQr/UQ6/ZKDoz5I7TkjEBmRK/V0Lw3VfYkdvoDO3j58onjPCGkxPAp imnhuesDFf04yX68NmCwz7n9V9CgLAcRsA6yTndLXc7Q6KynMDjt1ZP1Av3PfJOw STivGVeCPY1GgJ+RGEKBoVR1gNnJl5IZyct/MOFFK78uih4oHwayPoM5mrQj+8o/ SUi53v4YIUHP5vOA/7TNxrPbcGS1KJdEAWzIZ6SxihyWfBoQn9/tXNzyNM2NHwv6 Lcg4ItvG8n1iwpAFGOePxV5Je52RBbhPPT/HZKjSrc0ao/IDavA= =CNpo -----END PGP SIGNATURE----- --ySUwH7HggBUqcKs5YeEEvs73YKqE5tR7c--