linux-kernel - [PATCH 51/70] cpufreq: interactive: resched timer if max freq raised

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Date:	Tue, 27 Oct 2015 18:30:39 +0100
From:	Bálint Czobor <czoborbalint@...il.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	Lianwei Wang <a22439@...orola.com>,
	Bálint Czobor <czoborbalint@...il.com>
Subject: [PATCH 51/70] cpufreq: interactive: resched timer if max freq raised

From: Lianwei Wang <a22439@...orola.com>

When the policy max freq is raised, and before the timer is
rescheduled in idle callback, the cpu freq may stuck at a
lower freq.

The target_freq shall be updated too, else on a high load
situation, the new_freq is always equal to target_freq and
which will cause freq stuck at a lower freq too.

Reschedule the timer on gov limits callback.

Change-Id: I6c187001ab43e859731429b64f75a74eebc37a24
Signed-off-by: Lianwei Wang <a22439@...orola.com>
Signed-off-by: Bálint Czobor <czoborbalint@...il.com>
---
 drivers/cpufreq/cpufreq_interactive.c |   64 +++++++++++++++++++++++++++------
 1 file changed, 54 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c
index 691923d..90958fd 100644
--- a/drivers/cpufreq/cpufreq_interactive.c
+++ b/drivers/cpufreq/cpufreq_interactive.c
@@ -189,6 +189,32 @@ static void cpufreq_interactive_timer_resched(
 	spin_unlock_irqrestore(&pcpu->load_lock, flags);
 }
 
+/* The caller shall take enable_sem write semaphore to avoid any timer race.
+ * The cpu_timer and cpu_slack_timer must be deactivated when calling this
+ * function.
+ */
+static void cpufreq_interactive_timer_start(int cpu)
+{
+	struct cpufreq_interactive_cpuinfo *pcpu = &per_cpu(cpuinfo, cpu);
+	unsigned long expires = jiffies + usecs_to_jiffies(timer_rate);
+	unsigned long flags;
+
+	pcpu->cpu_timer.expires = expires;
+	add_timer_on(&pcpu->cpu_timer, cpu);
+	if (timer_slack_val >= 0 && pcpu->target_freq > pcpu->policy->min) {
+		expires += usecs_to_jiffies(timer_slack_val);
+		pcpu->cpu_slack_timer.expires = expires;
+		add_timer_on(&pcpu->cpu_slack_timer, cpu);
+	}
+
+	spin_lock_irqsave(&pcpu->load_lock, flags);
+	pcpu->time_in_idle =
+		get_cpu_idle_time(cpu, &pcpu->time_in_idle_timestamp);
+	pcpu->cputime_speedadj = 0;
+	pcpu->cputime_speedadj_timestamp = pcpu->time_in_idle_timestamp;
+	spin_unlock_irqrestore(&pcpu->load_lock, flags);
+}
+
 static unsigned int freq_to_above_hispeed_delay(unsigned int freq)
 {
 	int i;
@@ -1058,8 +1084,6 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 			hispeed_freq = policy->max;
 
 		for_each_cpu(j, policy->cpus) {
-			unsigned long expires;
-
 			pcpu = &per_cpu(cpuinfo, j);
 			pcpu->policy = policy;
 			pcpu->target_freq = policy->cur;
@@ -1070,14 +1094,7 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 			pcpu->hispeed_validate_time =
 				pcpu->floor_validate_time;
 			down_write(&pcpu->enable_sem);
-			expires = jiffies + usecs_to_jiffies(timer_rate);
-			pcpu->cpu_timer.expires = expires;
-			add_timer_on(&pcpu->cpu_timer, j);
-			if (timer_slack_val >= 0) {
-				expires += usecs_to_jiffies(timer_slack_val);
-				pcpu->cpu_slack_timer.expires = expires;
-				add_timer_on(&pcpu->cpu_slack_timer, j);
-			}
+			cpufreq_interactive_timer_start(j);
 			pcpu->governor_enabled = 1;
 			up_write(&pcpu->enable_sem);
 		}
@@ -1136,6 +1153,33 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 		else if (policy->min > policy->cur)
 			__cpufreq_driver_target(policy,
 					policy->min, CPUFREQ_RELATION_L);
+		for_each_cpu(j, policy->cpus) {
+			pcpu = &per_cpu(cpuinfo, j);
+
+			/* hold write semaphore to avoid race */
+			down_write(&pcpu->enable_sem);
+			if (pcpu->governor_enabled == 0) {
+				up_write(&pcpu->enable_sem);
+				continue;
+			}
+
+			/* update target_freq firstly */
+			if (policy->max < pcpu->target_freq)
+				pcpu->target_freq = policy->max;
+			else if (policy->min > pcpu->target_freq)
+				pcpu->target_freq = policy->min;
+
+			/* Reschedule timer.
+			 * Delete the timers, else the timer callback may
+			 * return without re-arm the timer when failed
+			 * acquire the semaphore. This race may cause timer
+			 * stopped unexpectedly.
+			 */
+			del_timer_sync(&pcpu->cpu_timer);
+			del_timer_sync(&pcpu->cpu_slack_timer);
+			cpufreq_interactive_timer_start(j);
+			up_write(&pcpu->enable_sem);
+		}
 		break;
 	}
 	return 0;
-- 
1.7.9.5

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