Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods

Peter Zijlstra
2017-07-14T15:59:01Z

On Fri, Jul 14, 2017 at 08:52:28AM -0700, Arjan van de Ven wrote:
> On 7/14/2017 8:38 AM, Peter Zijlstra wrote:
> > No, that's wrong. We want to fix the normal C state selection process to
> > pick the right C state.
> >
> > The fast-idle criteria could cut off a whole bunch of available C
> > states. We need to understand why our current C state pick is wrong and
> > amend the algorithm to do better. Not just bolt something on the side.
>
> I can see a fast path through selection if you know the upper bound of any
> selection is just 1 state.
>
> But also, how much of this is about "C1 be fast" versus "selecting C1 is slow"

I got the impression its about we need to select C1 for longer. But the
fact that the patches don't in fact answer any of these questions,
they're wrong in principle ;-)