cpufreq: schedutil: Reduce frequencies slower

The schedutil governor reduces frequencies too fast in some
situations which cases undesirable performance drops to
appear.

To address that issue, make schedutil reduce the frequency slower by
setting it to the average of the value chosen during the previous
iteration of governor computations and the new one coming from its
frequency selection formula.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=194963
Reported-by: John <john.ettedgui@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 848cb47094cd..b1fedf9932d6 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -101,6 +101,9 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
         if (sg_policy->next_freq == next_freq)
                 return;
 
+        if (sg_policy->next_freq > next_freq)
+                next_freq = (sg_policy->next_freq + next_freq) >> 1;
+
         sg_policy->next_freq = next_freq;
         sg_policy->last_freq_update_time = time;