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Thu, 1 Jul 2021 17:24:29 +0000 From: Long Li To: Greg Kroah-Hartman CC: "longli@linuxonhyperv.com" , "linux-kernel@vger.kernel.org" , "linux-hyperv@vger.kernel.org" , Jonathan Corbet , KY Srinivasan , Haiyang Zhang , Stephen Hemminger , Wei Liu , Dexuan Cui , Bjorn Andersson , Hans de Goede , "Williams, Dan J" , Maximilian Luz , Mike Rapoport , Ben Widawsky , Jiri Slaby , Andra Paraschiv , Siddharth Gupta , Hannes Reinecke , "linux-doc@vger.kernel.org" Subject: RE: [Patch v2 2/3] Drivers: hv: add Azure Blob driver Thread-Topic: [Patch v2 2/3] Drivers: hv: add Azure Blob driver Thread-Index: AQHXalTR5lVKFlOZkEmq8/y9Kgt/basqijaAgAMsL9CAAC4xgIAAgSdQ Date: Thu, 1 Jul 2021 17:24:29 +0000 Message-ID: References: <1624689020-9589-1-git-send-email-longli@linuxonhyperv.com> <1624689020-9589-3-git-send-email-longli@linuxonhyperv.com> In-Reply-To: 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=0b452feb-7d61-4194-aeb5-4d3b5639905a;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=2021-07-01T17:19:08Z;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: BY5PR21MB1506.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 6a44b2d5-e570-4b66-70d2-08d93cb5153b X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Jul 2021 17:24:29.0598 (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: bVEZ0qoE1rZVHjnNLUE0iGL7T3fDv8jN26v/JOxzyKD+BainaBjiXUo84xDGjUYh3hbIDTgY3zAv6Kpixz4Bow== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR21MB1221 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Subject: Re: [Patch v2 2/3] Drivers: hv: add Azure Blob driver >=20 > On Thu, Jul 01, 2021 at 06:58:35AM +0000, Long Li wrote: > > > Subject: Re: [Patch v2 2/3] Drivers: hv: add Azure Blob driver > > > > + > > > > +static struct az_blob_device az_blob_dev; > > > > + > > > > +static int az_blob_ringbuffer_size =3D (128 * 1024); > > > > +module_param(az_blob_ringbuffer_size, int, 0444); > > > > +MODULE_PARM_DESC(az_blob_ringbuffer_size, "Ring buffer size > > > > +(bytes)"); > > > > > > This is NOT the 1990's, please do not create new module parameters. > > > Just make this work properly for everyone. > > > > The default value is chosen so that it works best for most workloads wh= ile > not taking too much system resources. It should work out of box for nearl= y all > customers. >=20 > Please wrap your email lines :( >=20 > Anyway, great, it will work for everyone, no need for this to be changed. > Then just drop it. >=20 > > But what we see is that from time to time, some customers still want to > change those values to work best for their workloads. It's hard to predic= t their > workload. They have to recompile the kernel if there is no module paramet= er > to do it. So the intent of this module parameter is that if the default v= alue > works for you, don't mess up with it. >=20 > Can you not just determine at runtime that these workloads are overflowin= g > the buffer and increase the size of it? That would be best otherwise you= are > forced to try to deal with a module parameter that is for code, not for d= evices > (which is why we do not like module parameters for drivers.) >=20 > Please remove this for now and if you _REALLY_ need it in the future, mak= e it > auto-tunable. Or if that is somehow impossible, then make it a per-devic= e > option, through something like sysfs so that it will work correctly per-d= evice. >=20 > thanks, >=20 > greg k-h I got your point, will be removing this.=20 Thanks, Long