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SubjectRe: [RFC PATCH 06/16] arm: topology: Define TC2 sched energy and provide it to scheduler
On Wed, 4 Jun 2014, Peter Zijlstra wrote:

> On Wed, Jun 04, 2014 at 05:02:30PM +0100, Morten Rasmussen wrote:
> > On Tue, Jun 03, 2014 at 12:50:15PM +0100, Peter Zijlstra wrote:
> > > On Fri, May 23, 2014 at 07:16:33PM +0100, Morten Rasmussen wrote:
> > > > +static struct capacity_state cap_states_cluster_a7[] = {
> > > > + /* Cluster only power */
> > > > + { .cap = 358, .power = 2967, }, /* 350 MHz */
> > > > + { .cap = 410, .power = 2792, }, /* 400 MHz */
> > > > + { .cap = 512, .power = 2810, }, /* 500 MHz */
> > > > + { .cap = 614, .power = 2815, }, /* 600 MHz */
> > > > + { .cap = 717, .power = 2919, }, /* 700 MHz */
> > > > + { .cap = 819, .power = 2847, }, /* 800 MHz */
> > > > + { .cap = 922, .power = 3917, }, /* 900 MHz */
> > > > + { .cap = 1024, .power = 4905, }, /* 1000 MHz */
> > > > + };
> > >
> > > So one thing I remember was that we spoke about restricting this to
> > > frequency levels where the voltage changed.
> > >
> > > Because voltage jumps were the biggest factor to energy usage.
> > >
> > > Any word on that?
> >
> > Since we don't drive P-state changes from the scheduler, I think we
> > could leave out P-states from the table without too much trouble. Good
> > point.
>
> Well, we eventually want to go there I think.

People within Linaro have initial code for this. Should be posted as an
RFC soon.

> Although we still needed
> to come up with something for Intel, because I'm not at all sure how all
> that works.

Our initial code reuse whatever existing platform specific cpufreq
drivers. The idea is to bypass the cpufreq governors.

If Intel hardware doesn't provide/allow much control here then the
platform driver should already tell the cpufreq core (and by extension
the scheduler) about the extent of what can be done.


Nicolas


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