Re: [PATCH] x86: PM: Register syscore_ops for scale invariance

[Rafael J. Wysocki]

On Tue, Jan 12, 2021 at 4:02 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Fri, Jan 08, 2021 at 07:05:59PM +0100, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> >
> > On x86 scale invariace tends to be disabled during resume from
> > suspend-to-RAM, because the MPERF or APERF MSR values are not as
> > expected then due to updates taking place after the platform
> > firmware has been invoked to complete the suspend transition.
> >
> > That, of course, is not desirable, especially if the schedutil
> > scaling governor is in use, because the lack of scale invariance
> > causes it to be less reliable.
> >
> > To counter that effect, modify init_freq_invariance() to register
> > a syscore_ops object for scale invariance with the ->resume callback
> > pointing to init_counter_refs() which will run on the CPU starting
> > the resume transition (the other CPUs will be taken care of the
> > "online" operations taking place later).
> >
> > Fixes: e2b0d619b400 ("x86, sched: check for counters overflow in frequency invariant accounting")
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> Thanks!, I'll take it through the sched/urgent tree?

That works, thanks!