Re: [PATCH] sched/fair: Invoke cpufreq hooks for CONFIG_SMP unset

From: Ingo Molnar
Date: Sat May 07 2016 - 02:31:01 EST



* Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> On Fri, May 06, 2016 at 02:58:43PM +0200, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > Commit 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization
> > update callbacks) overlooked the fact that update_load_avg(), where
> > CFS invokes cpufreq utilization update hooks, becomes an empty stub for
> > CONFIG_SMP unset. In consequence, if CONFIG_SMP is not set, cpufreq
> > governors are never invoked from CFS and they do not have a chance to
> > evaluate CPU performace levels and update them often enough. Needless
> > to say, things don't work as expected then.
> >
> > Fix the problem by making the !CONFIG_SMP stub of update_load_avg()
> > invoke cpufreq update hooks too.
> >
> > Fixes: 34e2c555f3e1 (cpufreq: Add mechanism for registering utilization update callbacks)
> > Reported-by: Steve Muckle <steve.muckle@xxxxxxxxxx>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> Rafael; feel free to push this through the pm tree.
>
> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

I already have it in sched/urgent.

Thanks,

Ingo