Re: [RFC v3 0/5] Add capacity capping support to the CPU controller

Peter Zijlstra
2017-04-12T14:34:21Z

On Wed, Apr 12, 2017 at 02:27:41PM +0100, Patrick Bellasi wrote:
> On 12-Apr 14:48, Peter Zijlstra wrote:
> > On Tue, Apr 11, 2017 at 06:58:33PM +0100, Patrick Bellasi wrote:
> > > > illustrated per your above points in that it affects both, while in
> > > > fact it actually modifies another metric, namely util_avg.
> > >
> > > I don't see it modifying in any direct way util_avg.
> >
> > The point is that clamps called 'capacity' are applied to util. So while
> > you don't modify util directly, you do modify the util signal (for one
> > consumer).
>
> Right, but this consumer (i.e. schedutil) it's already translating
> the util_avg into a next_freq (which ultimately it's a capacity).
>
> Thus, I don't see a big misfit in that code path to "filter" this
> translation with a capacity clamp.

Still strikes me as odd though.