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References: <20190807153340.11516-1-douglas.raillard@arm.com>
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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Wed, 7 Aug 2019 22:40:23 +0200
Message-ID: <CAJZ5v0gqqoOzjUMhUgqKzaj8tCegddJphr+MHj5HD2_VAc1QYQ@mail.gmail.com>
Subject: Re: [PATCH] sched/cpufreq: Align trace event behavior of fast switching
To:     Douglas RAILLARD <douglas.raillard@arm.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>
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On Wed, Aug 7, 2019 at 5:34 PM Douglas RAILLARD
<douglas.raillard@arm.com> wrote:
>
> Fast switching path only emits an event for the CPU of interest, whereas the
> regular path emits an event for all the CPUs that had their frequency changed,
> i.e. all the CPUs sharing the same policy.
>
> With the current behavior, looking at cpu_frequency event for a given CPU that
> is using the fast switching path will not give the correct frequency signal.

Do you actually have any systems where that is a problem?  If so, then
what are they?