linux-kernel - Re: [PATCH] cpufreq: schedutil: Always trace frequency if it does not change

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Message-ID: <20170322041653.GW25659@vireshk-i7>
Date:   Wed, 22 Mar 2017 09:46:53 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [PATCH] cpufreq: schedutil: Always trace frequency if it does
 not change

On 22-03-17, 01:56, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> sugov_update_commit() calls trace_cpu_frequency() to record the
> current CPU frequency if it has not changed in the fast switch case
> to prevent utilities from getting confused (they may report that the
> CPU is idle if the frequency has not been recorded for too long, for
> example).
> 
> However, the same problem may occur for a cpufreq driver that doesn't
> support fast frequency switching and implements the ->target callback
> (that is, it doesn't use frequency tables), but trace_cpu_frequency()
> is not called if frequency updates are skipped in that case.
> 
> For this reason, modify sugov_update_commit() to always call
> trace_cpu_frequency() when the new frequency to be set is equal to
> the one that was set previously and reorganize the code in there to
> reduce duplication somewhat.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  kernel/sched/cpufreq_schedutil.c |   18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh