linux-kernel - Re: [PATCH v6 06/11] cpufreq/schedutil: use dl utilization tracking

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Message-ID: <20180608123959.GE16089@localhost.localdomain>
Date:   Fri, 8 Jun 2018 14:39:59 +0200
From:   Juri Lelli <juri.lelli@...hat.com>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     peterz@...radead.org, mingo@...nel.org,
        linux-kernel@...r.kernel.org, rjw@...ysocki.net,
        dietmar.eggemann@....com, Morten.Rasmussen@....com,
        viresh.kumar@...aro.org, valentin.schneider@....com,
        patrick.bellasi@....com, joel@...lfernandes.org,
        daniel.lezcano@...aro.org, quentin.perret@....com,
        Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v6 06/11] cpufreq/schedutil: use dl utilization tracking

Hi Vincent,

On 08/06/18 14:09, Vincent Guittot wrote:
> Now that we have both the dl class bandwidth requirement and the dl class
> utilization, we can detect when CPU is fully used so we should run at max.
> Otherwise, we keep using the dl bandwidth requirement to define the
> utilization of the CPU
> 
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
> ---

[...]

> @@ -190,20 +192,24 @@ static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu)
>  	if (rq->rt.rt_nr_running)
>  		return sg_cpu->max;
>  
> -	util = sg_cpu->util_dl;
> -	util += sg_cpu->util_cfs;
> +	util = sg_cpu->util_cfs;
>  	util += sg_cpu->util_rt;
>  
> +	if ((util + sg_cpu->util_dl) >= sg_cpu->max)
> +		return sg_cpu->max;
> +

Mmm, won't we run at max (or reach max) with a, say, 100ms/500ms DL task
running alone?

Best,

- Juri