6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sultan Alsawaf (unemployed) <sultan@xxxxxxxxxxxxxxx>
[ Upstream commit 8e461a1cb43d69d2fc8a97e61916dce571e6bb31 ]
A redundant frequency update is only truly needed when there is a policy
limits change with a driver that specifies CPUFREQ_NEED_UPDATE_LIMITS.
In spite of that, drivers specifying CPUFREQ_NEED_UPDATE_LIMITS receive a
frequency update _all the time_, not just for a policy limits change,
because need_freq_update is never cleared.
Furthermore, ignore_dl_rate_limit()'s usage of need_freq_update also leads
to a redundant frequency update, regardless of whether or not the driver
specifies CPUFREQ_NEED_UPDATE_LIMITS, when the next chosen frequency is the
same as the current one.
Fix the superfluous updates by only honoring CPUFREQ_NEED_UPDATE_LIMITS
when there's a policy limits change, and clearing need_freq_update when a
requisite redundant update occurs.
This is neatly achieved by moving up the CPUFREQ_NEED_UPDATE_LIMITS test
and instead setting need_freq_update to false in sugov_update_next_freq().
Fixes: 600f5badb78c ("cpufreq: schedutil: Don't skip freq update when limits change")
Signed-off-by: Sultan Alsawaf (unemployed) <sultan@xxxxxxxxxxxxxxx>
Reviewed-by: Christian Loehle <christian.loehle@xxxxxxx>
Link: https://patch.msgid.link/20241212015734.41241-2-sultan@xxxxxxxxxxxxxxx
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/sched/cpufreq_schedutil.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 28c77904ea749..e51d5ce730be1 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -83,7 +83,7 @@ static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
if (unlikely(sg_policy->limits_changed)) {
sg_policy->limits_changed = false;
- sg_policy->need_freq_update = true;
+ sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
return true;
}
@@ -96,7 +96,7 @@ static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
unsigned int next_freq)
{
if (sg_policy->need_freq_update)
- sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
+ sg_policy->need_freq_update = false;
else if (sg_policy->next_freq == next_freq)
return false;
--
2.39.5
