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

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Message-ID: <20180612142301.GR12217@hirez.programming.kicks-ass.net>
Date:   Tue, 12 Jun 2018 16:23:01 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.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 Tue, Jun 12, 2018 at 02:00:11PM +0200, Daniel Lezcano wrote:
> +static void idle_injection_last_man(struct idle_injection_device *ii_dev)
> +{
> +	unsigned int run_duration_ms;
> +
> +	run_duration_ms = READ_ONCE(ii_dev->run_duration_ms);
> +	if (run_duration_ms) {
> +		hrtimer_start(&ii_dev->timer, ms_to_ktime(run_duration_ms),
> +			      HRTIMER_MODE_REL_PINNED);

What's the point of PINNED here? AFAICT this gets called from a
different CPU every time.

> +		return;
> +	}
> +
> +	complete(&ii_dev->stop_complete);
> +}