DEBUG: sched,cpufreq: add cpu_capacity change tracepoint

This is useful when we want to compare cpu utilization and
cpu curr capacity side by side.

Signed-off-by: Juri Lelli <juri.lelli@arm.com>

drivers/cpufreq/cpufreq.c

@@ -29,6 +29,7 @@
 #include <linux/suspend.h>
 #include <linux/syscore_ops.h>
 #include <linux/tick.h>
+#include <linux/sched.h>
 #include <trace/events/power.h>
 
 static LIST_HEAD(cpufreq_policy_list);
@@ -473,6 +474,7 @@ static void cpufreq_notify_post_transition(struct cpufreq_policy *policy,
 void cpufreq_freq_transition_begin(struct cpufreq_policy *policy,
 		struct cpufreq_freqs *freqs)
 {
+	int cpu;
 
 	/*
 	 * Catch double invocations of _begin() which lead to self-deadlock.
@@ -501,6 +503,8 @@ wait:
 	spin_unlock(&policy->transition_lock);
 
 	scale_freq_capacity(policy, freqs);
+	for_each_cpu(cpu, policy->cpus)
+		trace_cpu_capacity(capacity_curr_of(cpu), cpu);
 
 	cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
 }

include/linux/sched.h

@@ -1046,6 +1046,8 @@ struct sched_group_energy {
 	struct capacity_state *cap_states; /* ptr to capacity state array */
 };
 
+unsigned long capacity_curr_of(int cpu);
+
 struct sched_group;
 
 struct sched_domain {

include/trace/events/power.h

@@ -120,6 +120,13 @@ DEFINE_EVENT(cpu, cpu_frequency,
 	TP_ARGS(frequency, cpu_id)
 );
 
+DEFINE_EVENT(cpu, cpu_capacity,
+
+	TP_PROTO(unsigned int capacity, unsigned int cpu_id),
+
+	TP_ARGS(capacity, cpu_id)
+);
+
 TRACE_EVENT(device_pm_callback_start,
 
 	TP_PROTO(struct device *dev, const char *pm_ops, int event),

kernel/sched/fair.c

@@ -4698,6 +4698,17 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
 
 #endif
 
+/*
+ * Returns the current capacity of cpu after applying both
+ * cpu and freq scaling.
+ */
+unsigned long capacity_curr_of(int cpu)
+{
+	return cpu_rq(cpu)->cpu_capacity_orig *
+	       arch_scale_freq_capacity(NULL, cpu)
+	       >> SCHED_CAPACITY_SHIFT;
+}
+
 static inline bool energy_aware(void)
 {
 	return sched_feat(ENERGY_AWARE);

kernel/sched/sched.h

@@ -1512,17 +1512,6 @@ static inline unsigned long cpu_util(int cpu)
 	return __cpu_util(cpu, 0);
 }
 
-/*
- * Returns the current capacity of cpu after applying both
- * cpu and freq scaling.
- */
-static inline unsigned long capacity_curr_of(int cpu)
-{
-	return cpu_rq(cpu)->cpu_capacity_orig *
-	       arch_scale_freq_capacity(NULL, cpu)
-	       >> SCHED_CAPACITY_SHIFT;
-}
-
 #endif
 
 #ifdef CONFIG_CPU_FREQ_GOV_SCHED