Re: [regression] cross core scheduling frequency drop bisected to 0c313cb20732

Mike Galbraith
2016-04-10T15:40:05Z

On Sat, 2016-04-09 at 14:31 +0200, Rafael J. Wysocki wrote:
> On Sat, Apr 9, 2016 at 1:07 PM, Peter Zijlstra <peterz@infradead.org>
> wrote:
> > On Fri, Apr 08, 2016 at 10:59:59PM +0200, Rafael J. Wysocki wrote:
> > > On Friday, April 08, 2016 08:50:54 AM Mike Galbraith wrote:
> > > > On Fri, 2016-04-08 at 08:45 +0200, Peter Zijlstra wrote:
> > > >
> > > > > Cute, I thought you used governor=performance for your runs?
> > > >
> > > > I do, and those numbers are with it thus set.
> > >
> > > Well, this is a trade-off.
> > >
> > > 4.5 introduced a power regression here so this one goes back to
> > > the previous
> > > state of things.
> >
> > Just for my elucidation; how can gov=performance have a 'power'
> > regression?
>
> Because of what is used as the "default" idle state most of the time.
>
> C1 was used before 4.5 and that changed to polling in 4.5.

Should the default idle state not then be governor dependent? When I
set gov=performance, I'm expecting box to go just as fast as it can go
without melting. Does polling risk CPU -> lava conversion?

-Mike