linux-kernel - Re: [RFC v3 2/6] Improve the tracking of active utilisation

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Message-ID: <20161118154748.GN3142@twins.programming.kicks-ass.net>
Date:   Fri, 18 Nov 2016 16:47:48 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Luca Abeni <luca.abeni@...tn.it>
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@....com>,
        Claudio Scordino <claudio@...dence.eu.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [RFC v3 2/6] Improve the tracking of active utilisation

On Mon, Oct 24, 2016 at 04:06:34PM +0200, Luca Abeni wrote:
> @@ -1074,6 +1161,14 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
>  	}
>  	rcu_read_unlock();
>  
> +	rq = task_rq(p);
> +	raw_spin_lock(&rq->lock);
> +	if (hrtimer_active(&p->dl.inactive_timer)) {
> +		sub_running_bw(&p->dl, &rq->dl);
> +		hrtimer_try_to_cancel(&p->dl.inactive_timer);
> +	}
> +	raw_spin_unlock(&rq->lock);

Its a bit sad having to take rq->lock here...

Also, what happens when hrtimer_try_to_cancel() fails?

> +
>  out:
>  	return cpu;
>  }