linux-kernel - [Patch v10 7/9] sched/fair: update cpu_capacity to reflect thermal pressure

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Message-Id: <20200222005213.3873-8-thara.gopinath@linaro.org>
Date:   Fri, 21 Feb 2020 19:52:11 -0500
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     mingo@...hat.com, peterz@...radead.org, ionela.voinescu@....com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rui.zhang@...el.com, qperret@...gle.com, daniel.lezcano@...aro.org,
        viresh.kumar@...aro.org, rostedt@...dmis.org, will@...nel.org,
        catalin.marinas@....com, sudeep.holla@....com,
        juri.lelli@...hat.com, corbet@....net
Cc:     linux-kernel@...r.kernel.org, amit.kachhap@...il.com,
        javi.merino@...nel.org, amit.kucheria@...durent.com
Subject: [Patch v10 7/9] sched/fair: update cpu_capacity to reflect thermal pressure

cpu_capacity initially reflects the maximum possible capacity of a cpu.
Thermal pressure on a cpu means this maximum possible capacity is
unavailable due to thermal events. This patch subtracts the average
thermal pressure for a cpu from its maximum possible capacity so that
cpu_capacity reflects the remaining maximum capacity.

Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
---
v8->v9:
	- Use thermal_load_avg to read rq->avg_thermal.load_avg.

 kernel/sched/fair.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 00b21a5b71f0..10e867e540ab 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7800,8 +7800,15 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu)
 	if (unlikely(irq >= max))
 		return 1;
 
+	/*
+	 * avg_rt.util_avg and avg_dl.util_avg track binary signals
+	 * (running and not running) with weights 0 and 1024 respectively.
+	 * avg_thermal.load_avg tracks thermal pressure and the weighted
+	 * average uses the actual delta max capacity(load).
+	 */
 	used = READ_ONCE(rq->avg_rt.util_avg);
 	used += READ_ONCE(rq->avg_dl.util_avg);
+	used += thermal_load_avg(rq);
 
 	if (unlikely(used >= max))
 		return 1;
-- 
2.20.1