linux-kernel - [Patch v5 5/6] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping

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Message-Id: <1572979786-20361-6-git-send-email-thara.gopinath@linaro.org>
Date:   Tue,  5 Nov 2019 13:49:45 -0500
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     mingo@...hat.com, peterz@...radead.org, ionela.voinescu@....com,
        vincent.guittot@...aro.org, rui.zhang@...el.com,
        edubezval@...il.com, qperret@...gle.com
Cc:     linux-kernel@...r.kernel.org, amit.kachhap@...il.com,
        javi.merino@...nel.org, daniel.lezcano@...aro.org
Subject: [Patch v5 5/6] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping

Thermal governors can request for a cpu's maximum supported frequency
to be capped in case of an overheat event. This in turn means that the
maximum capacity available for tasks to run on the particular cpu is
reduced. Delta between the original maximum capacity and capped
maximum capacity is known as thermal pressure. Enable cpufreq cooling
device to update the thermal pressure in event of a capped
maximum frequency.

Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
---

v4->v5:
	- fixed issues in update_sched_max_capacity comment header.
	- Updated update_sched_max_capacity to calculate maximum available
	  capacity.

 drivers/thermal/cpu_cooling.c | 36 ++++++++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 391f397..c65b7c4 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -218,6 +218,27 @@ static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
 }
 
 /**
+ * update_sched_max_capacity - update scheduler about change in cpu
+ *				max frequency.
+ * @cpus: list of cpus whose max capacity needs udating in scheduler.
+ * @cur_max_freq: current maximum frequency.
+ * @max_freq: highest possible frequency.
+ */
+static void update_sched_max_capacity(struct cpumask *cpus,
+				      unsigned int cur_max_freq,
+				      unsigned int max_freq)
+{
+	int cpu;
+	unsigned long capacity;
+
+	for_each_cpu(cpu, cpus) {
+		capacity = cur_max_freq * arch_scale_cpu_capacity(cpu);
+		capacity /= max_freq;
+		update_thermal_pressure(cpu, capacity);
+	}
+}
+
+/**
  * get_load() - get load for a cpu since last updated
  * @cpufreq_cdev:	&struct cpufreq_cooling_device for this cpu
  * @cpu:	cpu number
@@ -320,6 +341,7 @@ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 				 unsigned long state)
 {
 	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
+	int ret;
 
 	/* Request state should be less than max_level */
 	if (WARN_ON(state > cpufreq_cdev->max_level))
@@ -331,8 +353,18 @@ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 
 	cpufreq_cdev->cpufreq_state = state;
 
-	return dev_pm_qos_update_request(&cpufreq_cdev->qos_req,
-				cpufreq_cdev->freq_table[state].frequency);
+	ret = dev_pm_qos_update_request
+				(&cpufreq_cdev->qos_req,
+				 cpufreq_cdev->freq_table[state].frequency);
+
+	if (ret > 0) {
+		update_sched_max_capacity
+				(cpufreq_cdev->policy->cpus,
+				 cpufreq_cdev->freq_table[state].frequency,
+				 cpufreq_cdev->policy->cpuinfo.max_freq);
+	}
+
+	return ret;
 }
 
 /**
-- 
2.1.4