1 files changed, 86 insertions, 68 deletions

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 75bfbb336722..e12309c1b07b 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -47,6 +47,7 @@ struct sugov_policy {
 	s64 up_rate_delay_ns;
 	s64 down_rate_delay_ns;
 	unsigned int next_freq;
+	unsigned int cached_raw_freq;
 
 	/* The next fields are only needed if fast switch cannot be used. */
 	struct irq_work irq_work;
@@ -63,7 +64,6 @@ struct sugov_cpu {
 	struct update_util_data update_util;
 	struct sugov_policy *sg_policy;
 
-	unsigned int cached_raw_freq;
 	unsigned long iowait_boost;
 	unsigned long iowait_boost_max;
 	u64 last_update;
@@ -72,6 +72,11 @@ struct sugov_cpu {
 	unsigned long util;
 	unsigned long max;
 	unsigned int flags;
+
+	/* The field below is for single-CPU policies only. */
+#ifdef CONFIG_NO_HZ_COMMON
+	unsigned long saved_idle_calls;
+#endif
 };
 
 static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
@@ -127,22 +132,20 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
 	if (sugov_up_down_rate_limit(sg_policy, time, next_freq))
 		return;
 
+	if (sg_policy->next_freq == next_freq)
+		return;
+
+	sg_policy->next_freq = next_freq;
+	sg_policy->last_freq_update_time = time;
+
 	if (policy->fast_switch_enabled) {
-		if (sg_policy->next_freq == next_freq) {
-			trace_cpu_frequency(policy->cur, smp_processor_id());
-			return;
-		}
-		sg_policy->next_freq = next_freq;
-		sg_policy->last_freq_update_time = time;
 		next_freq = cpufreq_driver_fast_switch(policy, next_freq);
 		if (next_freq == CPUFREQ_ENTRY_INVALID)
 			return;
 
 		policy->cur = next_freq;
 		trace_cpu_frequency(next_freq, smp_processor_id());
-	} else if (sg_policy->next_freq != next_freq) {
-		sg_policy->next_freq = next_freq;
-		sg_policy->last_freq_update_time = time;
+	} else {
 		sg_policy->work_in_progress = true;
 		irq_work_queue(&sg_policy->irq_work);
 	}
@@ -150,7 +153,7 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
 
 /**
  * get_next_freq - Compute a new frequency for a given cpufreq policy.
- * @sg_cpu: schedutil cpu object to compute the new frequency for.
+ * @sg_policy: schedutil policy object to compute the new frequency for.
  * @util: Current CPU utilization.
  * @max: CPU capacity.
  *
@@ -170,19 +173,18 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
  * next_freq (as calculated above) is returned, subject to policy min/max and
  * cpufreq driver limitations.
  */
-static unsigned int get_next_freq(struct sugov_cpu *sg_cpu, unsigned long util,
-				  unsigned long max)
+static unsigned int get_next_freq(struct sugov_policy *sg_policy,
+				  unsigned long util, unsigned long max)
 {
-	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 	struct cpufreq_policy *policy = sg_policy->policy;
 	unsigned int freq = arch_scale_freq_invariant() ?
 				policy->cpuinfo.max_freq : policy->cur;
 
 	freq = (freq + (freq >> 2)) * util / max;
 
-	if (freq == sg_cpu->cached_raw_freq && sg_policy->next_freq != UINT_MAX)
+	if (freq == sg_policy->cached_raw_freq && sg_policy->next_freq != UINT_MAX)
 		return sg_policy->next_freq;
-	sg_cpu->cached_raw_freq = freq;
+	sg_policy->cached_raw_freq = freq;
 	return cpufreq_driver_resolve_freq(policy, freq);
 }
 
@@ -248,6 +250,19 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util,
 	sg_cpu->iowait_boost >>= 1;
 }
 
+#ifdef CONFIG_NO_HZ_COMMON
+static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
+{
+	unsigned long idle_calls = tick_nohz_get_idle_calls();
+	bool ret = idle_calls == sg_cpu->saved_idle_calls;
+
+	sg_cpu->saved_idle_calls = idle_calls;
+	return ret;
+}
+#else
+static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
+#endif /* CONFIG_NO_HZ_COMMON */
+
 static void sugov_update_single(struct update_util_data *hook, u64 time,
 				unsigned int flags)
 {
@@ -256,6 +271,7 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
 	struct cpufreq_policy *policy = sg_policy->policy;
 	unsigned long util, max;
 	unsigned int next_f;
+	bool busy;
 
 	sugov_set_iowait_boost(sg_cpu, time, flags);
 	sg_cpu->last_update = time;
@@ -263,40 +279,37 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
 	if (!sugov_should_update_freq(sg_policy, time))
 		return;
 
+	busy = sugov_cpu_is_busy(sg_cpu);
+
 	if (flags & SCHED_CPUFREQ_DL) {
 		next_f = policy->cpuinfo.max_freq;
 	} else {
 		sugov_get_util(&util, &max, time);
 		sugov_iowait_boost(sg_cpu, &util, &max);
-		next_f = get_next_freq(sg_cpu, util, max);
+		next_f = get_next_freq(sg_policy, util, max);
+		/*
+		 * Do not reduce the frequency if the CPU has not been idle
+		 * recently, as the reduction is likely to be premature then.
+		 */
+		if (busy && next_f < sg_policy->next_freq)
+			next_f = sg_policy->next_freq;
 	}
 	sugov_update_commit(sg_policy, time, next_f);
 }
 
-static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu,
-					   unsigned long util, unsigned long max,
-					   unsigned int flags)
+static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu)
 {
 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 	struct cpufreq_policy *policy = sg_policy->policy;
-	unsigned int max_f = policy->cpuinfo.max_freq;
 	u64 last_freq_update_time = sg_policy->last_freq_update_time;
+	unsigned long util = 0, max = 1;
 	unsigned int j;
 
-	if (flags & SCHED_CPUFREQ_DL)
-		return max_f;
-
-	sugov_iowait_boost(sg_cpu, &util, &max);
-
 	for_each_cpu(j, policy->cpus) {
-		struct sugov_cpu *j_sg_cpu;
+		struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
 		unsigned long j_util, j_max;
 		s64 delta_ns;
 
-		if (j == smp_processor_id())
-			continue;
-
-		j_sg_cpu = &per_cpu(sugov_cpu, j);
 		/*
 		 * If the CPU utilization was last updated before the previous
 		 * frequency update and the time elapsed between the last update
@@ -310,7 +323,7 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu,
 			continue;
 		}
 		if (j_sg_cpu->flags & SCHED_CPUFREQ_DL)
-			return max_f;
+			return policy->cpuinfo.max_freq;
 
 		j_util = j_sg_cpu->util;
 		j_max = j_sg_cpu->max;
@@ -322,7 +335,7 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu,
 		sugov_iowait_boost(j_sg_cpu, &util, &max);
 	}
 
-	return get_next_freq(sg_cpu, util, max);
+	return get_next_freq(sg_policy, util, max);
 }
 
 static void sugov_update_shared(struct update_util_data *hook, u64 time,
@@ -345,7 +358,11 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
 	sg_cpu->last_update = time;
 
 	if (sugov_should_update_freq(sg_policy, time)) {
-		next_f = sugov_next_freq_shared(sg_cpu, util, max, flags);
+		if (flags & SCHED_CPUFREQ_DL)
+			next_f = sg_policy->policy->cpuinfo.max_freq;
+		else
+			next_f = sugov_next_freq_shared(sg_cpu);
+
 		sugov_update_commit(sg_policy, time, next_f);
 	}
 
@@ -371,15 +388,15 @@ static void sugov_irq_work(struct irq_work *irq_work)
 	sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
 
 	/*
-	 * For Real Time and Deadline tasks, schedutil governor shoots the
-	 * frequency to maximum. And special care must be taken to ensure that
-	 * this kthread doesn't result in that.
+	 * For RT and deadline tasks, the schedutil governor shoots the
+	 * frequency to maximum. Special care must be taken to ensure that this
+	 * kthread doesn't result in the same behavior.
 	 *
 	 * This is (mostly) guaranteed by the work_in_progress flag. The flag is
-	 * updated only at the end of the sugov_work() and before that schedutil
-	 * rejects all other frequency scaling requests.
+	 * updated only at the end of the sugov_work() function and before that
+	 * the schedutil governor rejects all other frequency scaling requests.
 	 *
-	 * Though there is a very rare case where the RT thread yields right
+	 * There is a very rare case though, where the RT thread yields right
 	 * after the work_in_progress flag is cleared. The effects of that are
 	 * neglected for now.
 	 */
@@ -489,15 +506,12 @@ static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
 		return NULL;
 
 	sg_policy->policy = policy;
-	init_irq_work(&sg_policy->irq_work, sugov_irq_work);
-	mutex_init(&sg_policy->work_lock);
 	raw_spin_lock_init(&sg_policy->update_lock);
 	return sg_policy;
 }
 
 static void sugov_policy_free(struct sugov_policy *sg_policy)
 {
-	mutex_destroy(&sg_policy->work_lock);
 	kfree(sg_policy);
 }
 
@@ -531,6 +545,9 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy)
 
 	sg_policy->thread = thread;
 	kthread_bind_mask(thread, policy->related_cpus);
+	init_irq_work(&sg_policy->irq_work, sugov_irq_work);
+	mutex_init(&sg_policy->work_lock);
+
 	wake_up_process(thread);
 
 	return 0;
@@ -544,6 +561,7 @@ static void sugov_kthread_stop(struct sugov_policy *sg_policy)
 
 	flush_kthread_worker(&sg_policy->worker);
 	kthread_stop(sg_policy->thread);
+	mutex_destroy(&sg_policy->work_lock);
 }
 
 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
@@ -578,9 +596,13 @@ static int sugov_init(struct cpufreq_policy *policy)
 	if (policy->governor_data)
 		return -EBUSY;
 
+	cpufreq_enable_fast_switch(policy);
+
 	sg_policy = sugov_policy_alloc(policy);
-	if (!sg_policy)
-		return -ENOMEM;
+	if (!sg_policy) {
+		ret = -ENOMEM;
+		goto disable_fast_switch;
+	}
 
 	ret = sugov_kthread_create(sg_policy);
 	if (ret)
@@ -623,13 +645,11 @@ static int sugov_init(struct cpufreq_policy *policy)
 	if (ret)
 		goto fail;
 
- out:
+out:
 	mutex_unlock(&global_tunables_lock);
-
-	cpufreq_enable_fast_switch(policy);
 	return 0;
 
- fail:
+fail:
 	policy->governor_data = NULL;
 	sugov_tunables_free(tunables);
 
@@ -640,6 +660,10 @@ free_sg_policy:
 	mutex_unlock(&global_tunables_lock);
 
 	sugov_policy_free(sg_policy);
+
+disable_fast_switch:
+	cpufreq_disable_fast_switch(policy);
+
 	pr_err("initialization failed (error %d)\n", ret);
 	return ret;
 }
@@ -650,8 +674,6 @@ static int sugov_exit(struct cpufreq_policy *policy)
 	struct sugov_tunables *tunables = sg_policy->tunables;
 	unsigned int count;
 
-	cpufreq_disable_fast_switch(policy);
-
 	mutex_lock(&global_tunables_lock);
 
 	count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
@@ -664,6 +686,7 @@ static int sugov_exit(struct cpufreq_policy *policy)
 	sugov_kthread_stop(sg_policy);
 	sugov_policy_free(sg_policy);
 
+	cpufreq_disable_fast_switch(policy);
 	return 0;
 }
 
@@ -681,25 +704,19 @@ static int sugov_start(struct cpufreq_policy *policy)
 	sg_policy->next_freq = UINT_MAX;
 	sg_policy->work_in_progress = false;
 	sg_policy->need_freq_update = false;
+	sg_policy->cached_raw_freq = 0;
 
 	for_each_cpu(cpu, policy->cpus) {
 		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 
+		memset(sg_cpu, 0, sizeof(*sg_cpu));
 		sg_cpu->sg_policy = sg_policy;
-		if (policy_is_shared(policy)) {
-			sg_cpu->util = 0;
-			sg_cpu->max = 0;
-			sg_cpu->flags = SCHED_CPUFREQ_DL;
-			sg_cpu->last_update = 0;
-			sg_cpu->cached_raw_freq = 0;
-			sg_cpu->iowait_boost = 0;
-			sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq;
-			cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
-						     sugov_update_shared);
-		} else {
-			cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
-						     sugov_update_single);
-		}
+		sg_cpu->flags = SCHED_CPUFREQ_DL;
+		sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq;
+		cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
+					     policy_is_shared(policy) ?
+							sugov_update_shared :
+							sugov_update_single);
 	}
 	return 0;
 }
@@ -714,9 +731,10 @@ static int sugov_stop(struct cpufreq_policy *policy)
 
 	synchronize_sched();
 
-	irq_work_sync(&sg_policy->irq_work);
-	kthread_cancel_work_sync(&sg_policy->work);
-
+	if (!policy->fast_switch_enabled) {
+		irq_work_sync(&sg_policy->irq_work);
+		kthread_cancel_work_sync(&sg_policy->work);
+	}
 	return 0;
 }