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McKenney" , Josh Triplett , "Rafael J. Wysocki" , "jejb@linux.ibm.com" , "martin.petersen@oracle.com" , "linux-scsi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "hch@lst.de" , "bvanassche@acm.org" , "hare@suse.de" , Michael Kelley , Long Li , "linux-hyperv@vger.kernel.org" , "wei.liu@kernel.org" , Stephen Hemminger , Haiyang Zhang , KY Srinivasan , "linux-pm@vger.kernel.org" Subject: RE: [PATCH] scsi: storvsc: Fix a panic in the hibernation procedure Thread-Topic: [PATCH] scsi: storvsc: Fix a panic in the hibernation procedure Thread-Index: AQHWGEVb6DFeJK2tFE2eFTHRpRyDH6iEXZcAgAArmvCAAAOn4IAAUhWAgACLYPA= Date: Wed, 22 Apr 2020 18:01:36 +0000 Message-ID: References: <1587514644-47058-1-git-send-email-decui@microsoft.com> <20200422012814.GB299948@T590> <20200422020134.GC299948@T590> <20200422030807.GK17661@paulmck-ThinkPad-P72> <20200422041629.GE299948@T590> <20200422092351.GF299948@T590> In-Reply-To: <20200422092351.GF299948@T590> 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_Enabled=True; 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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: c71d91af-fa71-4ab1-4d6b-08d7e6e733f8 X-MS-Exchange-CrossTenant-originalarrivaltime: 22 Apr 2020 18:01:36.3628 (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: 1pm0CdwY+O7sr5YGCUzkyXVYRUUU4ZSogpJttWtBzzlMxKyA0Bmr5ZQWLlsSew7Y5oma54zMgMtp6d0s9lbeaA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: HK0P153MB0147 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > From: Ming Lei > Sent: Wednesday, April 22, 2020 2:24 AM > > ... > > storvsc_suspend() -> scsi_host_block() is only called in the hibernatio= n > > path, which is not a hot path at all, so IMHO we don't really care if i= t > > takes 10ms or 100ms or even 1s. :-) BTW, in my test, typically the >=20 > Are you sure the 'we' can cover all users? I actully only meant I don't have any performance concern in this path storvsc_suspend() -> scsi_host_block() :-) Thanks for your effort to improve the scsi_host_block() API in the patch [PATCH] scsi: avoid to run synchronize_rcu for each device in scsi_host_blo= ck. =20 > > scsi_host_block() here takes about 3ms in my 40-vCPU VM. >=20 > If more LUNs are added, the time should be increased proportionallly, > that is why I think scsi_host_block() is bad. >=20 > Thanks, > Ming FWIW, if the time increases linearly against the number of the LUNs, it looks typically it's still fast enough for storvsc_suspend(). Thanks, -- Dexuan