[PATCH 5/6] cpufreq: schedutil: avoid utilisation update when not necessary

[Patrick Bellasi]

Under certain conditions (i.e. CPU entering idle and current task being
the sugov thread) we can skip a frequency update.
Thus, let's postpone the collection of the FAIR utilisation when really
needed.

Signed-off-by: Patrick Bellasi <patrick.bellasi@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-pm@xxxxxxxxxxxxxxx
---
 kernel/sched/cpufreq_schedutil.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 44bff37..c8ed645 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -296,8 +296,6 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
 	unsigned int next_f;
 	bool rt_mode;
 
-	sugov_get_util(&util, &max);
-
 	raw_spin_lock(&sg_policy->update_lock);
 
 	/* CPU is entering IDLE, reset flags without triggering an update */
@@ -323,6 +321,7 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
 	else
 		sg_cpu->flags = flags;
 
+	sugov_get_util(&util, &max);
 	sg_cpu->util = util;
 	sg_cpu->max = max;
 
-- 
2.7.4