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Petersen" , "linux-scsi@vger.kernel.org" Subject: RE: [PATCH 1/3] scsi: storvsc: Fix max_outstanding_req_per_channel for Win8 and newer Thread-Topic: [PATCH 1/3] scsi: storvsc: Fix max_outstanding_req_per_channel for Win8 and newer Thread-Index: AQHW1LPvCXblZaSOtUCrOLiJZky2uan7zR/A Date: Thu, 17 Dec 2020 21:31:15 +0000 Message-ID: References: <20201217203321.4539-1-parri.andrea@gmail.com> <20201217203321.4539-2-parri.andrea@gmail.com> In-Reply-To: <20201217203321.4539-2-parri.andrea@gmail.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: msip_labels: MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_ActionId=3fa860d4-1247-46b2-a7ad-a827cadc343b;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_ContentBits=0;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Enabled=true;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Method=Standard;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Name=Internal;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_SetDate=2020-12-17T21:26:21Z;MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_SiteId=72f988bf-86f1-41af-91ab-2d7cd011db47; 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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: MW4PR21MB1857.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1d3c6225-a926-4529-bce8-08d8a2d315ad X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Dec 2020 21:31:15.6779 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: CJqd98+/zJrbtfaiVzbtHrkgb2rnG7aAxg1jbCTE8zU8TP9F5D9gwHV/S7LknYh1LBVWnGTqZM9wVzzgpS4smQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW2PR2101MB1052 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > From: Andrea Parri (Microsoft) > Sent: Thursday, December 17, 2020 12:33 PM >=20 > Current code overestimates the value of max_outstanding_req_per_channel > for Win8 and newer hosts, since vmscsi_size_delta is set to the initial > value of sizeof(vmscsi_win8_extension) rather than zero. This may lead > to wrong decisions when using ring_avail_percent_lowater equals to zero. > The estimate of max_outstanding_req_per_channel is 'exact' for Win7 and > older hosts. A better choice, keeping the algorithm for the estimation > simple, is to err the other way around, i.e., to underestimate for Win7 > and older but to use the exact value for Win8 and newer. >=20 > Suggested-by: Dexuan Cui > Signed-off-by: Andrea Parri (Microsoft) > Cc: "James E.J. Bottomley" > Cc: "Martin K. Petersen" > Cc: linux-scsi@vger.kernel.org Reviewed-by: Dexuan Cui