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Petersen" , Naohiro Aota CC: "linux-btrfs@vger.kernel.org" , "dsterba@suse.com" , "hare@suse.com" , "linux-fsdevel@vger.kernel.org" , Johannes Thumshirn Subject: Re: [PATCH v8 01/41] block: add bio_add_zone_append_page Thread-Topic: [PATCH v8 01/41] block: add bio_add_zone_append_page Thread-Index: AQHWmCICMDDhRg8S9EGeqVQ0V4cAqg== Date: Mon, 5 Oct 2020 01:46:34 +0000 Message-ID: References: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: oracle.com; dkim=none (message not signed) header.d=none;oracle.com; dmarc=none action=none header.from=wdc.com; x-originating-ip: [2400:2411:43c0:6000:809a:93a5:8305:e8b2] x-ms-publictraffictype: Email x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: fd9c6c9c-3e66-4872-1e1e-08d868d07e07 x-ms-traffictypediagnostic: CY4PR0401MB3587: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: wdcipoutbound: EOP-TRUE x-ms-oob-tlc-oobclassifiers: OLM:10000; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: CdPdCW92f2TdFGwd/CPW0TVDjB2XyZRxD2lkVJv8bZxStRDPRsf4XOGtohbMvC/qQ7j1QwnYfVLco/riuybqfBsRyQzOp9bxYF00CPvHr1OYpwx9tqsthGXeomRBRn9BpQicke4tZPg4+z0lFJocqSGWnd/UtH7C0PN6dzIULbt5geXgIZfUHC0s4sjz9zR8vekz0lZIsaCQ5lpI8AOKnpLNFoe4h9kV23dqemRRL1Ob9IShoaazCFl5+6DoSScsH6G5Eq3OOOIlC4oxosfp5JAk+4ne5eKHHkivx9ZAq60Bj6OTM7y7pn3GlKzEBUasDHtTTzN9+J1VvuQTwXzzyA== x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CY4PR04MB3751.namprd04.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(136003)(376002)(346002)(366004)(396003)(39860400002)(7696005)(33656002)(54906003)(8936002)(6636002)(110136005)(66556008)(64756008)(2906002)(53546011)(66476007)(66446008)(4326008)(66946007)(6506007)(76116006)(91956017)(8676002)(86362001)(71200400001)(55016002)(83380400001)(9686003)(478600001)(5660300002)(186003)(52536014)(316002);DIR:OUT;SFP:1102; x-ms-exchange-antispam-messagedata: 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 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: CY4PR04MB3751.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: fd9c6c9c-3e66-4872-1e1e-08d868d07e07 X-MS-Exchange-CrossTenant-originalarrivaltime: 05 Oct 2020 01:46:34.7868 (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: T4/NE9acpNt3YTSmFjTFbzXYf4C7EOmA4DpFnD3AyN0/WBgrqrVxyDtOR62v8FhkXMtnyMdqE6RwFU8s4rngeg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR0401MB3587 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 2020/10/02 22:39, Martin K. Petersen wrote:=0A= > =0A= > Naohiro/Johannes,=0A= > =0A= >> Add bio_add_zone_append_page(), a wrapper around bio_add_hw_page() which= =0A= >> is intended to be used by file systems that directly add pages to a bio= =0A= >> instead of using bio_iov_iter_get_pages().=0A= > =0A= > Why use the hardware limit? For filesystem I/O we generally use the=0A= > queue soft limit to prevent I/Os getting too big which can lead to very= =0A= > unpredictable latency in mixed workloads.=0A= =0A= max_zone_append_sectors is already gated by max_hw_sectors, but it is not g= ated=0A= by max_sectors/BLK_DEF_MAX_SECTORS. If we add such gating to=0A= blk_queue_max_zone_append_sectors(), max_zone_append_sectors would become a= soft=0A= limit too. So should we have max_zone_append_sectors and=0A= max_hw_zone_append_sectors ?=0A= =0A= Which also means that we should tweak queue_max_sectors_store() to gate=0A= max_zone_append_sectors to that limit upon a user change.=0A= =0A= > =0A= > max_zone_append_sectors also appears to be gated exclusively by hardware= =0A= > constraints. Is there user-controllable limit in place for append=0A= > operations?=0A= =0A= No, none that I know of. At the HW level, max_zone_append_sectors is basica= lly=0A= max_hw_sectors. That is gated by the zone size in=0A= blk_queue_max_zone_append_sectors(). If as mentioned above we tweak=0A= queue_max_sectors_store() to change max_zone_append_sectors too if needed, = we=0A= would then have an indirect user-controllable limit. Or we could implement = a=0A= queue_zone_append_max_store() too I guess. Yet, having everything indirectl= y=0A= controlled through queue_max_sectors_store() is probably simpler I think.= =0A= =0A= -- =0A= Damien Le Moal=0A= Western Digital Research=0A=