linux-kernel - [PATCH] sched/cpufreq: Align trace event behavior of fast switching

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Date:   Wed,  7 Aug 2019 16:33:40 +0100
From:   Douglas RAILLARD <douglas.raillard@....com>
To:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Cc:     rjw@...ysocki.net, viresh.kumar@...aro.org, mingo@...hat.com,
        peterz@...radead.org
Subject: [PATCH] sched/cpufreq: Align trace event behavior of fast switching

Fast switching path only emits an event for the CPU of interest, whereas the
regular path emits an event for all the CPUs that had their frequency changed,
i.e. all the CPUs sharing the same policy.

With the current behavior, looking at cpu_frequency event for a given CPU that
is using the fast switching path will not give the correct frequency signal.

Signed-off-by: Douglas RAILLARD <douglas.raillard@....com>
---
 kernel/sched/cpufreq_schedutil.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 1f82ab108bab..975ccc3de807 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -153,6 +153,7 @@ static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
 			      unsigned int next_freq)
 {
 	struct cpufreq_policy *policy = sg_policy->policy;
+	int cpu;
 
 	if (!sugov_update_next_freq(sg_policy, time, next_freq))
 		return;
@@ -162,7 +163,11 @@ static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
 		return;
 
 	policy->cur = next_freq;
-	trace_cpu_frequency(next_freq, smp_processor_id());
+
+	if (trace_cpu_frequency_enabled()) {
+		for_each_cpu(cpu, policy->cpus)
+			trace_cpu_frequency(next_freq, cpu);
+	}
 }
 
 static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
-- 
2.22.0