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From: Steve Muckle <steve.muckle@linaro.org>
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Date: Thu, 19 May 2016 16:04:19 -0700
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Steve Muckle <steve.muckle@linaro.org>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
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        Viresh Kumar <viresh.kumar@linaro.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Len Brown <lenb@kernel.org>
Subject: Re: [PATCH 3/5] sched: cpufreq: call cpufreq hook from remote CPUs
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On Thu, May 19, 2016 at 11:06:14PM +0200, Rafael J. Wysocki wrote:
> > In the case of a remote update the hook has to run (or not) after it is
> > known whether preemption will occur so we don't do needless work or
> > IPIs. If the policy CPUs aren't known in the scheduler then the early
> > hook will always need to be called along with an indication that it is
> > the early hook being called. If it turns out to be a remote update it
> > could then be deferred to the later hook, which would only be called
> > when a remote update has been deferred and preemption has not occurred.
> >
> > This means two hook inovcations for a remote non-preempting wakeup
> > though instead of one.  Perhaps this is a good middle ground on code
> > churn vs. optimization though.
> 
> I would think so.

Ok, I will pursue this approach.

thanks,
Steve