Re: [RFC PATCH 0/3] CFS idle injection

Jacob Pan
2015-11-06T19:11:27Z

On Fri, 6 Nov 2015 18:30:01 +0000
Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:

> On 05/11/15 10:12, Peter Zijlstra wrote:
> >
> > People, trim your emails!
> >
> > On Wed, Nov 04, 2015 at 08:58:30AM -0800, Jacob Pan wrote:
> >
> >>> I also like #2 too. Specially now that it is not limited to a
> >>> specific platform. One question though, could you still keep the
> >>> cooling device support of it? In some systems, it might make
> >>> sense to enable / disable idle injections based on temperature.
> >
> >> One of the key difference between 1 and 2 is that #2 is open loop
> >> control, since we don't have CPU c-states info baked into
> >> scheduler.
> >
> > _yet_, there's people working on that. The whole power aware
> > scheduling stuff needs that.
>
> Isn't the idle state information (rq->idle_state) already used in
> find_idlest_cpu()?
>
> What we use in energy aware scheduling is quite similar but since
> we're interested in the index information of the c-state (to access
> the right element of the idle_state vectors of the energy model, we
> added rq->idle_state_idx.
>
what i am interested is not per cpu idle state but rather at the package
level or domain. It must be an indication for the overlapped idle time.
Usually has to come from HW counters.