linux-kernel - Re: [PATCH v5 05/10] cpufreq/schedutil: get max utilization

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Message-ID: <20180529084009.GE15173@e108498-lin.cambridge.arm.com>
Date:   Tue, 29 May 2018 09:40:09 +0100
From:   Quentin Perret <quentin.perret@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     peterz@...radead.org, mingo@...nel.org,
        linux-kernel@...r.kernel.org, rjw@...ysocki.net,
        juri.lelli@...hat.com, dietmar.eggemann@....com,
        Morten.Rasmussen@....com, viresh.kumar@...aro.org,
        valentin.schneider@....com
Subject: Re: [PATCH v5 05/10] cpufreq/schedutil: get max utilization

Hi Vincent,

On Friday 25 May 2018 at 15:12:26 (+0200), Vincent Guittot wrote:
> Now that we have both the dl class bandwidth requirement and the dl class
> utilization, we can use the max of the 2 values when agregating the
> utilization of the CPU.
> 
> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
> ---
>  kernel/sched/sched.h | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 4526ba6..0eb07a8 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -2194,7 +2194,11 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {}
>  #ifdef CONFIG_CPU_FREQ_GOV_SCHEDUTIL
>  static inline unsigned long cpu_util_dl(struct rq *rq)
>  {
> -	return (rq->dl.running_bw * SCHED_CAPACITY_SCALE) >> BW_SHIFT;
> +	unsigned long util = (rq->dl.running_bw * SCHED_CAPACITY_SCALE) >> BW_SHIFT;
> +
> +	util = max_t(unsigned long, util, READ_ONCE(rq->avg_dl.util_avg));

Would it make sense to use a UTIL_EST version of that signal here ? I
don't think that would make sense for the RT class with your patch-set
since you only really use the blocked part of the signal for RT IIUC,
but would that work for DL ?
> +
> +	return util;
>  }
>  
>  static inline unsigned long cpu_util_cfs(struct rq *rq)
> -- 
> 2.7.4
>