[RFC PATCH v1 10/11] cpuidle: update cpuidle governor when needed

[Aubrey Li]

From: Aubrey Li <aubrey.li@xxxxxxxxxxxxxxx>

Reflect the data to cpuidle governor when there is an update
---
 drivers/cpuidle/cpuidle.c |  6 ++++--
 include/linux/cpuidle.h   |  1 +
 kernel/sched/idle.c       | 14 ++++++++++++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 97aacab..9c84c5c 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -387,9 +387,11 @@ unsigned int cpuidle_predict(void)
 	/*
 	 * Give the governor an opportunity to update on the outcome
 	 */
-	cpuidle_update(drv, dev);
-
 	gov_stat = (struct cpuidle_governor_stat *)&(dev->gov_stat);
+	if (gov_stat->needs_update) {
+		cpuidle_update(drv, dev);
+		gov_stat->needs_update = 0;
+	}
 
 	gov_stat->next_timer_us = ktime_to_us(tick_nohz_get_sleep_length());
 	get_iowait_load(&nr_iowaiters, &cpu_load);
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index b9964ec..c6a805f 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -79,6 +79,7 @@ struct cpuidle_state {
 
 struct cpuidle_governor_stat {
 	int             last_state_idx;
+	int		needs_update;
 
 	unsigned int	next_timer_us;
 	unsigned int	predicted_us;
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 16a766c..3358db2 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -187,6 +187,7 @@ static void cpuidle_idle_call(void)
 		 * Give the governor an opportunity to reflect on the outcome
 		 */
 		cpuidle_reflect(dev, entered_state);
+		dev->gov_stat.needs_update = 1;
 	}
 
 exit_idle:
@@ -206,6 +207,10 @@ static void cpuidle_idle_call(void)
  */
 static void cpuidle_fast(void)
 {
+	struct cpuidle_device *dev = cpuidle_get_device();
+	ktime_t time_start, time_end;
+	s64 diff;
+
 	while (!need_resched()) {
 		check_pgt_cache();
 		rmb();
@@ -218,7 +223,16 @@ static void cpuidle_fast(void)
 		local_irq_disable();
 		arch_cpu_idle_enter();
 
+		time_start = ns_to_ktime(local_clock());
 		default_idle_call();
+		time_end = ns_to_ktime(local_clock());
+
+		diff = ktime_us_delta(time_end, time_start);
+		if (diff > INT_MAX)
+		        diff = INT_MAX;
+
+		dev->last_residency = (int) diff;
+		dev->gov_stat.needs_update = 1;
 
 		arch_cpu_idle_exit();
 	}
-- 
2.7.4