Re: [PATCH RFC V2 3/3] scsi_mq: enable runtime PM

[Johannes Thumshirn <jthumshirn@suse.de>]

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
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