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SubjectRe: [PATCH v2] cpufreq: trace frequency limits change
On Tue, Jul 24, 2018 at 09:49:32AM -0400, Steven Rostedt wrote:
> On Fri, 20 Jul 2018 15:21:14 -0700
> Joel Fernandes <joel@joelfernandes.org> wrote:
>
> > From: Ruchi Kandoi <kandoiruchi@google.com>
> >
> > systrace used for tracing for Android systems has carried a patch for
> > many years in the Android tree that traces when the cpufreq limits
> > change. With the help of this information, systrace can know when the
> > policy limits change and can visually display the data. Lets add
> > upstream support for the same.
> >
> > Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>
> > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> > ---
> > v1->v2: Minor changes suggested by Viresh
> >
> > Documentation/trace/events-power.rst | 1 +
> > drivers/cpufreq/cpufreq.c | 1 +
> > include/trace/events/power.h | 25 +++++++++++++++++++++++++
> > 3 files changed, 27 insertions(+)
> >
> > diff --git a/Documentation/trace/events-power.rst b/Documentation/trace/events-power.rst
> > index a77daca75e30..2ef318962e29 100644
> > --- a/Documentation/trace/events-power.rst
> > +++ b/Documentation/trace/events-power.rst
> > @@ -27,6 +27,7 @@ cpufreq.
> >
> > cpu_idle "state=%lu cpu_id=%lu"
> > cpu_frequency "state=%lu cpu_id=%lu"
> > + cpu_frequency_limits "min=%lu max=%lu cpu_id=%lu"
> >
> > A suspend event is used to indicate the system going in and out of the
> > suspend mode:
> > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> > index b0dfd3222013..4fd935df101e 100644
> > --- a/drivers/cpufreq/cpufreq.c
> > +++ b/drivers/cpufreq/cpufreq.c
> > @@ -2236,6 +2236,7 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
> >
> > policy->min = new_policy->min;
> > policy->max = new_policy->max;
> > + trace_cpu_frequency_limits(policy->min, policy->max, policy->cpu);
>
> Wouldn't it make more sense just to pass in "policy"?

Yes I agree, good idea.

> >
> > policy->cached_target_freq = UINT_MAX;
> >
> > diff --git a/include/trace/events/power.h b/include/trace/events/power.h
> > index 908977d69783..f5bec45108b6 100644
> > --- a/include/trace/events/power.h
> > +++ b/include/trace/events/power.h
> > @@ -148,6 +148,31 @@ DEFINE_EVENT(cpu, cpu_frequency,
> > TP_ARGS(frequency, cpu_id)
> > );
> >
> > +TRACE_EVENT(cpu_frequency_limits,
> > +
> > + TP_PROTO(unsigned int min_freq, unsigned int max_freq,
> > + unsigned int cpu_id),
> > +
> > + TP_ARGS(min_freq, max_freq, cpu_id),
> > +
> > + TP_STRUCT__entry(
> > + __field(u32, min_freq)
> > + __field(u32, max_freq)
> > + __field(u32, cpu_id)
> > + ),
> > +
> > + TP_fast_assign(
> > + __entry->min_freq = min_freq;
> > + __entry->max_freq = max_freq;
> > + __entry->cpu_id = cpu_id;
>
> Then have here:
>
> __entry->min_freq = policy->min;
> __entry->max_freq = policy->max;
> __entry->puc_id = policy->cpu;
>
> It would also make the footprint of the tracepoint in the code smaller
> as it would pass fewer parameters to the trace event.

Yes, that's a great idea. I'll make the change and post v3.

-Joel


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