[PATCH] cpufreq: schedutil: Skip busy-CPU hold when NOHZ is disabled

[Avi Weiss]

With nohz=off, tick_nohz_idle_stop_tick() can return without
incrementing idle_calls. sugov_hold_freq() then treats an unchanged
counter as continuous CPU activity and can prevent frequency reductions
even after the CPU has been idle.

Skip the busy-CPU hold heuristic when NOHZ is disabled.

Fixes: b7eaf1aab9f8 ("cpufreq: schedutil: Avoid reducing frequency of busy CPUs prematurely")
Signed-off-by: Avi Weiss <thnkslprpt@xxxxxxxxx>
---
 kernel/sched/cpufreq_schedutil.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 14405a614991..111582876954 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -397,6 +397,9 @@ static bool sugov_hold_freq(struct sugov_cpu *sg_cpu)
 	if (uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)))
 		return false;
 
+	if (!tick_nohz_enabled)
+		return false;
+
 	/*
 	 * Maintain the frequency if the CPU has not been idle recently, as
 	 * reduction is likely to be premature.

base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
-- 
2.53.0