linux-kernel - Re: [PATCH v6 09/16] sched/cpufreq: uclamp: Add utilization clamping for RT tasks

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Message-ID: <20190123102821.GW27931@hirez.programming.kicks-ass.net>
Date:   Wed, 23 Jan 2019 11:28:21 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Patrick Bellasi <patrick.bellasi@....com>
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-api@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Tejun Heo <tj@...nel.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Paul Turner <pjt@...gle.com>,
        Quentin Perret <quentin.perret@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Todd Kjos <tkjos@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Steve Muckle <smuckle@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>
Subject: Re: [PATCH v6 09/16] sched/cpufreq: uclamp: Add utilization clamping
 for RT tasks

On Tue, Jan 15, 2019 at 10:15:06AM +0000, Patrick Bellasi wrote:
> -	util = (type == ENERGY_UTIL)
> -		? util_cfs
> -		: uclamp_util(rq, util_cfs);
> -	util += cpu_util_rt(rq);
> +	util = cpu_util_rt(rq);
> +	if (type == FREQUENCY_UTIL) {
> +		util += cpu_util_cfs(rq);
> +		util  = uclamp_util(rq, util);
> +	} else {
> +		util += util_cfs;
> +	}

Or the combined thing:

-       util = util_cfs;
-       util += cpu_util_rt(rq);
+       util = cpu_util_rt(rq);
+       if (type == FREQUENCY_UTIL) {
+               util += cpu_util_cfs(rq);
+               util  = uclamp_util(rq, util);
+       } else {
+               util += util_cfs;
+       }


Leaves me confused.

When type == FREQ, util_cfs should already be cpu_util_cfs(), per
sugov_get_util().

So should that not end up like:

	util = util_cfs;
	util += cpu_util_rt(rq);
+	if (type == FREQUENCY_UTIL)
+		util = uclamp_util(rq, util);

instead?