linux-kernel - Re: [PATCH v9 02/15] sched/cpufreq: Prepare schedutil for Energy Aware Scheduling

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Date:   Tue, 20 Nov 2018 10:16:02 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Quentin Perret <quentin.perret@....com>
Cc:     peterz@...radead.org, rjw@...ysocki.net,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        gregkh@...uxfoundation.org, mingo@...hat.com,
        dietmar.eggemann@....com, morten.rasmussen@....com,
        chris.redpath@....com, patrick.bellasi@....com,
        valentin.schneider@....com, vincent.guittot@...aro.org,
        thara.gopinath@...aro.org, tkjos@...gle.com,
        joel@...lfernandes.org, smuckle@...gle.com,
        adharmap@...eaurora.org, skannan@...eaurora.org,
        pkondeti@...eaurora.org, juri.lelli@...hat.com,
        edubezval@...il.com, srinivas.pandruvada@...ux.intel.com,
        currojerez@...eup.net, javi.merino@...nel.org
Subject: Re: [PATCH v9 02/15] sched/cpufreq: Prepare schedutil for Energy
 Aware Scheduling

On 19-11-18, 14:18, Quentin Perret wrote:
> @@ -223,20 +222,33 @@ static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu)

> -	if ((util + cpu_util_dl(rq)) >= max)
> -		return max;
> +	if (type == FREQUENCY_UTIL) {
> +		/*
> +		 * For frequency selection we do not make cpu_util_dl() a
> +		 * permanent part of this sum because we want to use
> +		 * cpu_bw_dl() later on, but we need to check if the
> +		 * CFS+RT+DL sum is saturated (ie. no idle time) such
> +		 * that we select f_max when there is no idle time.
> +		 *
> +		 * NOTE: numerical errors or stop class might cause us
> +		 * to not quite hit saturation when we should --
> +		 * something for later.
> +		 */
> +
> +		if ((util + cpu_util_dl(rq)) >= max)
> +			return max;
> +	} else {
> +		/*
> +		 * OTOH, for energy computation we need the estimated
> +		 * running time, so include util_dl and ignore dl_bw.
> +		 */
> +		util += cpu_util_dl(rq);
> +		if (util >= max)
> +			return max;
> +	}

Maybe write above as:

        dl_util = cpu_util_dl(rq);

        if ((util + dl_util) >= max)
                return max;

	if (type != FREQUENCY_UTIL)
		util += dl_util;


as both the if/else parts were doing almost the same thing.

-- 
viresh