On Wednesday, March 16, 2016 07:14:20 PM Peter Zijlstra wrote:

On Wed, Mar 16, 2016 at 03:59:18PM +0100, Rafael J. Wysocki wrote:

quoted

+static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
+				unsigned int next_freq)
+{
+	struct cpufreq_policy *policy = sg_policy->policy;
+
+	if (next_freq > policy->max)
+		next_freq = policy->max;
+	else if (next_freq < policy->min)
+		next_freq = policy->min;
+
+	sg_policy->last_freq_update_time = time;
+	if (sg_policy->next_freq == next_freq) {
+		if (policy->fast_switch_enabled)
+			trace_cpu_frequency(policy->cur, smp_processor_id());
+
+		return;
+	}
+
+	sg_policy->next_freq = next_freq;
+	if (policy->fast_switch_enabled) {
+		unsigned int freq;
+
+		freq = cpufreq_driver_fast_switch(policy, next_freq);

So you're assuming a RELATION_L for ->fast_switch() ?

Yes, I am.

quoted

+		if (freq == CPUFREQ_ENTRY_INVALID)
+			return;
+
+		policy->cur = freq;
+		trace_cpu_frequency(freq, smp_processor_id());
+	} else {
+		sg_policy->work_in_progress = true;
+		irq_work_queue(&sg_policy->irq_work);
+	}
+}

quoted

+static void sugov_work(struct work_struct *work)
+{
+	struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
+
+	mutex_lock(&sg_policy->work_lock);
+	__cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq,
+				CPUFREQ_RELATION_L);

As per here, which I assume matches semantics on that point.

Correct.