linux-kernel - [RFCv4 6/6] cpufreq: schedutil: add util clamp for RT/DL tasks

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Message-Id: <20170824180857.32103-7-patrick.bellasi@arm.com>
Date:   Thu, 24 Aug 2017 19:08:57 +0100
From:   Patrick Bellasi <patrick.bellasi@....com>
To:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tejun Heo <tj@...nel.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Paul Turner <pjt@...gle.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        John Stultz <john.stultz@...aro.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Juri Lelli <juri.lelli@....com>,
        Tim Murray <timmurray@...gle.com>,
        Todd Kjos <tkjos@...roid.com>,
        Andres Oportus <andresoportus@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: [RFCv4 6/6] cpufreq: schedutil: add util clamp for RT/DL tasks

Currently schedutil enforces a maximum frequency when RT/DL tasks are
RUNNABLE.  Such a mandatory policy can be made more tunable from
userspace thus allowing for example to define a max frequency which is
still reasonable for the execution of a specific RT/DL workload. This
will contribute to make the RT class more friendly for power/energy
sensitive use-cases.

This patch extends the usage of util_{min,max} to the RT/DL classes.
Whenever a task in these classes is RUNNABLE, the util required is
defined by the constraints of the CPU control group the task belongs to.

Signed-off-by: Patrick Bellasi <patrick.bellasi@....com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Cc: linux-kernel@...r.kernel.org
Cc: linux-pm@...r.kernel.org
---
 kernel/sched/cpufreq_schedutil.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index f67c26bbade4..feca60c107bc 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -227,7 +227,10 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
 	busy = sugov_cpu_is_busy(sg_cpu);
 
 	if (flags & SCHED_CPUFREQ_RT_DL) {
-		next_f = policy->cpuinfo.max_freq;
+		util = uclamp_util(smp_processor_id(), SCHED_CAPACITY_SCALE);
+		next_f = (uclamp_enabled && util < SCHED_CAPACITY_SCALE)
+			? get_next_freq(sg_policy, util, policy->cpuinfo.max_freq)
+			: policy->cpuinfo.max_freq;
 	} else {
 		sugov_get_util(&util, &max);
 		sugov_iowait_boost(sg_cpu, &util, &max);
@@ -276,10 +279,15 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 			j_sg_cpu->iowait_boost = 0;
 			continue;
 		}
-		if (j_sg_cpu->flags & SCHED_CPUFREQ_RT_DL)
-			return policy->cpuinfo.max_freq;
 
-		j_util = j_sg_cpu->util;
+		if (j_sg_cpu->flags & SCHED_CPUFREQ_RT_DL) {
+			if (!uclamp_enabled)
+				return policy->cpuinfo.max_freq;
+			j_util = uclamp_util(j, SCHED_CAPACITY_SCALE);
+		} else {
+			j_util = j_sg_cpu->util;
+		}
+
 		j_max = j_sg_cpu->max;
 		if (j_util * max > j_max * util) {
 			util = j_util;
-- 
2.14.1