[PATCH v1] cpufreq: Add policy_frequency trace event

[Samuel Wu <wusamuel@google.com>]

The existing cpu_frequency trace_event can be verbose, emitting an event
for every CPU in the policy even when their frequencies are identical.

This patch adds a new policy_frequency trace event, which provides a
more efficient alternative to cpu_frequency trace event. This option
allows users who only need frequency at a policy level more concise logs
with simpler analysis.

Signed-off-by: Samuel Wu <wusamuel@google.com>
---
 drivers/cpufreq/cpufreq.c    |  2 ++
 include/trace/events/power.h | 21 +++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 4472bb1ec83c..b65534a4fd9a 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -345,6 +345,7 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy,
 		pr_debug("FREQ: %u - CPUs: %*pbl\n", freqs->new,
 			 cpumask_pr_args(policy->cpus));
 
+		trace_policy_frequency(freqs->new, policy->cpu);
 		for_each_cpu(cpu, policy->cpus)
 			trace_cpu_frequency(freqs->new, cpu);
 
@@ -2214,6 +2215,7 @@ unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
 			    arch_scale_freq_ref(policy->cpu));
 	cpufreq_stats_record_transition(policy, freq);
 
+	trace_policy_frequency(freq, policy->cpu);
 	if (trace_cpu_frequency_enabled()) {
 		for_each_cpu(cpu, policy->cpus)
 			trace_cpu_frequency(freq, cpu);
diff --git a/include/trace/events/power.h b/include/trace/events/power.h
index 82904291c2b8..87dbd53c8ea1 100644
--- a/include/trace/events/power.h
+++ b/include/trace/events/power.h
@@ -188,6 +188,27 @@ DEFINE_EVENT(cpu, cpu_frequency,
 	TP_ARGS(frequency, cpu_id)
 );
 
+TRACE_EVENT(policy_frequency,
+
+	TP_PROTO(unsigned int frequency, unsigned int policy_cpu),
+
+	TP_ARGS(frequency, policy_cpu),
+
+	TP_STRUCT__entry(
+		__field(u32, frequency)
+		__field(u32, policy_cpu)
+	),
+
+	TP_fast_assign(
+		__entry->frequency = frequency;
+		__entry->policy_cpu = policy_cpu;
+	),
+
+	TP_printk("frequency=%lu policy_cpu=%lu",
+		  (unsigned long)__entry->frequency,
+		  (unsigned long)__entry->policy_cpu)
+);
+
 TRACE_EVENT(cpu_frequency_limits,
 
 	TP_PROTO(struct cpufreq_policy *policy),
-- 
2.51.2.1041.gc1ab5b90ca-goog