drivers/thermal/cpufreq_cooling : Refactor thermal_power_cpu_get_power tracing

Simplify the thermal_power_cpu_get_power trace event by removing
complicated cpumask and variable length array. Now the tools parsing trace
output don't have to hassle to get this power data. The simplified format
version uses 'policy->cpu'. Remove also the 'load' information completely
since there is very little value of it in this trace event. To get the
CPUs' load (or utilization) there are other dedicated trace hooks in the
kernel. This patch also simplifies and speeds-up the main cooling code
when that trace event is enabled.

Rename the trace event to avoid confusion of tools which parse the trace
file.
Acked-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NLukasz Luba <lukasz.luba@arm.com>
Link: https://lore.kernel.org/r/20220613124327.30766-3-lukasz.luba@arm.comSigned-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>

drivers/thermal/cpufreq_cooling.c

@@ -216,16 +216,9 @@ static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
 	u32 total_load = 0;
 	struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
 	struct cpufreq_policy *policy = cpufreq_cdev->policy;
-	u32 *load_cpu = NULL;
 
 	freq = cpufreq_quick_get(policy->cpu);
 
-	if (trace_thermal_power_cpu_get_power_enabled()) {
-		u32 ncpus = cpumask_weight(policy->related_cpus);
-
-		load_cpu = kcalloc(ncpus, sizeof(*load_cpu), GFP_KERNEL);
-	}
-
 	for_each_cpu(cpu, policy->related_cpus) {
 		u32 load;
 
@@ -235,22 +228,13 @@ static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
 			load = 0;
 
 		total_load += load;
-		if (load_cpu)
-			load_cpu[i] = load;
-
-		i++;
 	}
 
 	cpufreq_cdev->last_load = total_load;
 
 	*power = get_dynamic_power(cpufreq_cdev, freq);
 
-	if (load_cpu) {
-		trace_thermal_power_cpu_get_power(policy->related_cpus, freq,
-						  load_cpu, i, *power);
-
-		kfree(load_cpu);
-	}
+	trace_thermal_power_cpu_get_power_simple(policy->cpu, *power);
 
 	return 0;
 }

include/trace/events/thermal.h

@@ -92,34 +92,22 @@ TRACE_EVENT(thermal_zone_trip,
 );
 
 #ifdef CONFIG_CPU_THERMAL
-TRACE_EVENT(thermal_power_cpu_get_power,
-	TP_PROTO(const struct cpumask *cpus, unsigned long freq, u32 *load,
-		size_t load_len, u32 dynamic_power),
+TRACE_EVENT(thermal_power_cpu_get_power_simple,
+	TP_PROTO(int cpu, u32 power),
 
-	TP_ARGS(cpus, freq, load, load_len, dynamic_power),
+	TP_ARGS(cpu, power),
 
 	TP_STRUCT__entry(
-		__bitmask(cpumask, num_possible_cpus())
-		__field(unsigned long, freq          )
-		__dynamic_array(u32,   load, load_len)
-		__field(size_t,        load_len      )
-		__field(u32,           dynamic_power )
+		__field(int, cpu)
+		__field(u32, power)
 	),
 
 	TP_fast_assign(
-		__assign_bitmask(cpumask, cpumask_bits(cpus),
-				num_possible_cpus());
-		__entry->freq = freq;
-		memcpy(__get_dynamic_array(load), load,
-			load_len * sizeof(*load));
-		__entry->load_len = load_len;
-		__entry->dynamic_power = dynamic_power;
+		__entry->cpu = cpu;
+		__entry->power = power;
 	),
 
-	TP_printk("cpus=%s freq=%lu load={%s} dynamic_power=%d",
-		__get_bitmask(cpumask), __entry->freq,
-		__print_array(__get_dynamic_array(load), __entry->load_len, 4),
-		__entry->dynamic_power)
+	TP_printk("cpu=%d power=%u", __entry->cpu, __entry->power)
 );
 
 TRACE_EVENT(thermal_power_cpu_limit,