Re: [RFC][PATCH v2 2/2] cpufreq: schedutil: Avoid decreasing frequency of busy CPUs

[Peter Zijlstra]

On Tue, Mar 21, 2017 at 03:16:19PM +0100, Vincent Guittot wrote:
> On 21 March 2017 at 15:03, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> 
> > On Tue, Mar 21, 2017 at 02:37:08PM +0100, Vincent Guittot wrote:
> > > On 21 March 2017 at 14:22, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> >
> > > For the not overloaded case, it makes sense to immediately update to
> > > OPP to be aligned with the new utilization of the CPU even if it was
> > > not idle in the past couple of ticks
> >
> > Yeah, but we cannot know. Also, who cares?
> >
> 
> embedded system that doesn't want to stay at higest OPP if significant part
> of the utilzation has moved away as an example
> AFAICT, schedutil tries to select the best OPP according to the current
> utilization of the CPU so if the utilization decreases, the OPP should also
> decrease

Sure I get that; but given the lack of crystal ball instructions we
cannot know if this is the case or not.

And if we really dropped below 100% utilization, we should hit idle
fairly soon.