linux-kernel - Re: [PATCH V6] powercap/drivers/idle_injection: Add an idle injection framework

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Date:   Fri, 15 Jun 2018 10:13:37 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     viresh.kumar@...aro.org, rjw@...ysocki.net,
        linux-kernel@...r.kernel.org, linux-pm@...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>,
        Andrea Parri <andrea.parri@...rulasolutions.com>
Subject: Re: [PATCH V6] powercap/drivers/idle_injection: Add an idle injection
 framework

On 12/06/2018 19:35, Peter Zijlstra wrote:

[ ... ]

>>>> Yes, drifting is not an issue if that happens. This scheme is simpler
>>>> and safer than setting the timer ahead before waking up the tasks with
>>>> the risk it expires before all the tasks ended their idle cycles.
>>>
>>> sloppy though..
>>
>> Ok, do you prefer to see the timer set in the wakeup function and thus
>> having a periodic tick for the idle injection ?
> 
> I think having a HRTIMER_RESTART handler that does hrtimer_forward() is
> the most sensible. You will end up having to deal with threads not being
> ready, but I think that's not a real problem.

Thanks for the restartable timer suggestion. I'm finishing polishing the
code and definitively the result is much more nicer.


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