linux-kernel - Re: [PATCH V9] powercap/drivers/idle_injection: Add an idle injection framework

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Date:   Mon, 25 Jun 2018 23:55:16 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Eduardo Valentin <edubezval@...il.com>,
        Javi Merino <javi.merino@...nel.org>,
        Leo Yan <leo.yan@...aro.org>,
        Kevin Wangtao <kevin.wangtao@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Rui Zhang <rui.zhang@...el.com>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrea Parri <andrea.parri@...rulasolutions.com>,
        "open list:POWER MANAGEMENT CORE" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH V9] powercap/drivers/idle_injection: Add an idle injection framework

On Mon, Jun 25, 2018 at 1:52 PM, Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
> On 25/06/2018 10:23, Rafael J. Wysocki wrote:
>
> [ ... ]
>
>>> + * It is up to the user of this framework to provide a lock at an
>>> + * upper level to prevent stupid things to happen, like starting while
>>> + * we are unregistering.
>>> + */
>>
>> The English above and elsewhere needs some polishing IMO, but I can
>> take care of that. :-)
>
> I can give a try and if you are still unhappy, you change them in a
> better way.

Well, I could tell you what I would write, but then it'll take less
time and effort if I just write it myself. :-)

> [ ... ]
>
>>> +static void idle_injection_setup(unsigned int cpu)
>>> +{
>>> +       struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO / 2 };
>>> +
>>> +       set_freezable();
>>
>> Why do you need set_freezable() here?
>
> We don't want to continue injecting idle cycles when the system is
> suspended.

And where's the corresponding try_to_freeze() called?