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Petersen" CC: "linux-scsi@vger.kernel.org" , "target-devel@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] target/file: don't zero iter before iov_iter_bvec Thread-Topic: [PATCH] target/file: don't zero iter before iov_iter_bvec Thread-Index: AQHW5qBkaWm3Wnjfmk+XiYs/GS5+eQ== Date: Sat, 9 Jan 2021 20:52:15 +0000 Message-ID: References: <34cd22d6cec046e3adf402accb1453cc255b9042.1610207523.git.asml.silence@gmail.com> <4d063dde-c710-44e3-31b9-8fb6b7e1d952@gmail.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: gmail.com; dkim=none (message not signed) header.d=none;gmail.com; dmarc=none action=none header.from=wdc.com; x-originating-ip: [199.255.45.62] x-ms-publictraffictype: Email x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 49a88bea-d636-4365-8859-08d8b4e07210 x-ms-traffictypediagnostic: BY5PR04MB6961: x-microsoft-antispam-prvs: wdcipoutbound: EOP-TRUE x-ms-oob-tlc-oobclassifiers: OLM:605; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: dG8X2Fatk7XQ9kvdZfzXeBdR00HJVZI/9V4vcv8HXUBlIqodAnbgd5poHvZah4nIuzil2wzBdZ0EpXdg7BsO2bIpecSbZ/ufYqVPiSMwqTpbNQse2ODdfh7Ac8spf5sjwYpFa42cXZmkirskrb8akJeLJERvNfC8alnaX2LkB73cfMeW4FTzty2BGxGfS9BlheJiOISPfA8MMKXCWif7gOb1eJjsPqwbB53VGeQ8Y6Q/Q135s2X8UA3MPBxufh/xgNvyHHWeISP4rA9fDCSWdhVHYkr38K5CjAQOKUP2hJ5dmBtyp5Nuj0c+9LcN4Akbr953sIJ4VUChSVZ0/MMmm/N3ukHRnl7Ek3mJI0RFMlzh1HXj8bbOae0WqeoZG15jhpyoFfaXhQDVhNgmuFme3Q== x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR04MB4965.namprd04.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(346002)(366004)(376002)(396003)(136003)(39860400002)(66556008)(478600001)(2906002)(8936002)(53546011)(6506007)(186003)(26005)(110136005)(54906003)(316002)(86362001)(55016002)(71200400001)(33656002)(9686003)(8676002)(7696005)(52536014)(76116006)(66446008)(4326008)(4744005)(5660300002)(66476007)(64756008)(66946007);DIR:OUT;SFP:1102; x-ms-exchange-antispam-messagedata: =?us-ascii?Q?qHRr21L76EIwma8ShmYdd2OGjagterdg5Ry5br/mmxEQFLQjoQd3Zp1OkVvs?= =?us-ascii?Q?iwM4F88P/H0THUYcgK1G8DRyHO+3ejHHhPF2ADpBzv88vii1lP+afdCOCX2/?= =?us-ascii?Q?jHV3pbSkvrSjvUuA9rmuQlzjYwcmlgyNazYbZ7L/6PZXSjCS2XrtF/KeiBQh?= =?us-ascii?Q?IQ5U17rNBjhSfJUA5QMCBfI+zDJVMRVB8ScMysBgAtwi2TFQJ4Qyomadfc8j?= =?us-ascii?Q?KIjlWHQy2rgL9NCiZEtgM2L0U+QrWQEAt35n7ys60s95lB87sdMB71mnkX1/?= =?us-ascii?Q?mVf4g7Ydal4Ka5TzrujE+n2J+hzxTDg2bbT0eoNOzyiw0RtyrGTWpaEBd2Xy?= =?us-ascii?Q?F3odfqAXKaaZw6UZQTjH3b6wUX++7Jz5T0mRH7ggmsriRatHJps6KtyB0AsJ?= =?us-ascii?Q?YYwBUiuDMY0zuwo1TG6n0RoktYP+EuhGJct/+iIh29FSQyUiRdHKNdVeVYMc?= =?us-ascii?Q?mr/ELMM2H4cqdqjCn1H7UMxWKEySNhRYvLW1zpCl5B83CE30yds6Q+17gnj+?= =?us-ascii?Q?XU7fVpvSQ0VEPiAzw+4gRuiXwj7OiHjEfhaeBY0vvrX0tUmuaRSGAt9kiAfY?= =?us-ascii?Q?P6gbkrlPvmfYBnzhYrxxbBzRkn/0OU+SMT0BF4NDniPzxz5eJhkSZA3oP3OM?= =?us-ascii?Q?U+zZC9zzAl93rCp96xGfdcIyzRo4xrCG6AZhkx9kUV8iRsIfMZBYGOwoIwcL?= =?us-ascii?Q?yoQBbrC+3oK3xBf6CX4OkR+ndc/cqvNxr+Q/EsmY1DH9IEH+u+BWhLEY+28x?= =?us-ascii?Q?51Va5jmiJ/84Ekzn0fhygcQzt121mB+o4NaKtjHTNpXorzpRAbgHo6Ic/Kwv?= =?us-ascii?Q?SbD1s26XqNOp3INUkaizHmb9NpJCpCDJRGuB3bOwoW1TRPA44+oZFLGQlpGO?= =?us-ascii?Q?fKIH/nFK79f22BQ0EMt6HCGXaWj/Z1FPJbYhDGCEvTpr4gHtMKZf2w2WlnFP?= =?us-ascii?Q?DcREeakoqrR5QqGLjEotDg3dAjQDA8ZdSZ0ZOVFk8yeRQKs23tl07wGrWz/Z?= =?us-ascii?Q?CdYg?= x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BYAPR04MB4965.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 49a88bea-d636-4365-8859-08d8b4e07210 X-MS-Exchange-CrossTenant-originalarrivaltime: 09 Jan 2021 20:52:15.0718 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: IpeMAOA1WsGK1j6erhKN3dJdNkO5/zXW+CcfUK9S4Ev9mm2AY4r7sy1ShUAL7hz3P1yLVvD2ZniomyJbEQ47Tr9Uj22/qEPbaaoi4+tajjc= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR04MB6961 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/9/21 12:40, Pavel Begunkov wrote:=0A= > I expect you won't find any, but such little things can pile up=0A= > into a not-easy-to-spot overhead over time.=0A= =0A= That is what I suspected with the resulting assembly. The commit log=0A= needs to document that there is no direct impact on the performance=0A= which can be seen with this patch, but this is nice to have=0A= micro-optimization in the long run.=0A= =0A= =0A=