From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 19 Jul 2018 08:41:24 +0200 From: Johannes Thumshirn To: Alan Stern Cc: Ming Lei , Jens Axboe , Ming Lei , Bart Van Assche , "hch@lst.de" , "linux-block@vger.kernel.org" , "linux-pm@vger.kernel.org" , "martin.petersen@oracle.com" , "hare@suse.de" , "linux-scsi@vger.kernel.org" , "rjw@rjwysocki.net" , "gregkh@linuxfoundation.org" , "jejb@linux.vnet.ibm.com" , "adrian.hunter@intel.com" Subject: Re: [PATCH RFC V2 3/3] scsi_mq: enable runtime PM Message-ID: <20180719064124.fsi6au7x3vd2g7md@linux-x5ow.site> References: <20180718141852.i3aermgwhmvxwjx7@linux-x5ow.site> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: List-ID: On Wed, Jul 18, 2018 at 11:01:52AM -0400, Alan Stern wrote: > On Wed, 18 Jul 2018, Johannes Thumshirn wrote: > > > On Wed, Jul 18, 2018 at 10:12:37AM -0400, Alan Stern wrote: > > > As one extra reminder... People who care about extreme performance can > > > perfectly well disable CONFIG_PM in their kernels. That should remove > > > any overhead due to runtime PM. > > > > Yes but how likely is this for people who are running their data > > center with a distribution kernel. > > Strictly speaking, that's a nonsense question. People who run > distribution kernels are 100% unlikely to change the kernel > configuration, by definition. > > That's not the point. If people really care about getting the utmost > performance, to the extent that they resent the minimal overhead > required for runtime PM, then they should not be running distribution > kernels in the first place. Can we agree to disagree here? Some of the people I know in HPC, HFT, etc... run stock SLE/RHEL and they do file bugs for every single 3-5% performance regression. This is not something I made up, this is the kind of things I have to deal with on my day job. So long, Johannes -- Johannes Thumshirn Storage jthumshirn@suse.de +49 911 74053 689 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg GF: Felix Imend�rffer, Jane Smithard, Graham Norton HRB 21284 (AG N�rnberg) Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850