Merge branch 'pm-cpufreq-sched'

* pm-cpufreq-sched:
  cpufreq: schedutil: Always process remote callback with slow switching
  cpufreq: schedutil: Don't restrict kthread to related_cpus unnecessarily
  cpufreq: Return 0 from ->fast_switch() on errors
  cpufreq: Simplify cpufreq_can_do_remote_dvfs()
  cpufreq: Process remote callbacks from any CPU if the platform permits
  sched: cpufreq: Allow remote cpufreq callbacks
  cpufreq: schedutil: Use unsigned int for iowait boost
  cpufreq: schedutil: Make iowait boost more energy efficient

Author: rafaeljw

drivers/cpufreq/cpufreq-dt.c

@@ -274,6 +274,7 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 		transition_latency = CPUFREQ_ETERNAL;
 
 	policy->cpuinfo.transition_latency = transition_latency;
+	policy->dvfs_possible_from_any_cpu = true;
 
 	return 0;
 

drivers/cpufreq/cpufreq.c

@@ -1843,9 +1843,10 @@ EXPORT_SYMBOL(cpufreq_unregister_notifier);
  * twice in parallel for the same policy and that it will never be called in
  * parallel with either ->target() or ->target_index() for the same policy.
  *
- * If CPUFREQ_ENTRY_INVALID is returned by the driver's ->fast_switch()
- * callback to indicate an error condition, the hardware configuration must be
- * preserved.
+ * Returns the actual frequency set for the CPU.
+ *
+ * If 0 is returned by the driver's ->fast_switch() callback to indicate an
+ * error condition, the hardware configuration must be preserved.
  */
 unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
 					unsigned int target_freq)

drivers/cpufreq/cpufreq_governor.c

@@ -272,6 +272,9 @@ static void dbs_update_util_handler(struct update_util_data *data, u64 time,
 	struct policy_dbs_info *policy_dbs = cdbs->policy_dbs;
 	u64 delta_ns, lst;
 
+	if (!cpufreq_can_do_remote_dvfs(policy_dbs->policy))
+		return;
+
 	/*
 	 * The work may not be allowed to be queued up right now.
 	 * Possible reasons:

drivers/cpufreq/intel_pstate.c

@@ -1746,6 +1746,10 @@ static void intel_pstate_update_util_pid(struct update_util_data *data,
 	struct cpudata *cpu = container_of(data, struct cpudata, update_util);
 	u64 delta_ns = time - cpu->sample.time;
 
+	/* Don't allow remote callbacks */
+	if (smp_processor_id() != cpu->cpu)
+		return;
+
 	if ((s64)delta_ns < pid_params.sample_rate_ns)
 		return;
 
@@ -1763,6 +1767,10 @@ static void intel_pstate_update_util(struct update_util_data *data, u64 time,
 	struct cpudata *cpu = container_of(data, struct cpudata, update_util);
 	u64 delta_ns;
 
+	/* Don't allow remote callbacks */
+	if (smp_processor_id() != cpu->cpu)
+		return;
+
 	if (flags & SCHED_CPUFREQ_IOWAIT) {
 		cpu->iowait_boost = int_tofp(1);
 	} else if (cpu->iowait_boost) {

include/linux/cpufreq.h

@@ -127,6 +127,15 @@ struct cpufreq_policy {
 	 */
 	unsigned int		transition_delay_us;
 
+	/*
+	 * Remote DVFS flag (Not added to the driver structure as we don't want
+	 * to access another structure from scheduler hotpath).
+	 *
+	 * Should be set if CPUs can do DVFS on behalf of other CPUs from
+	 * different cpufreq policies.
+	 */
+	bool			dvfs_possible_from_any_cpu;
+
 	 /* Cached frequency lookup from cpufreq_driver_resolve_freq. */
 	unsigned int cached_target_freq;
 	int cached_resolved_idx;
@@ -562,6 +571,17 @@ struct governor_attr {
 			 size_t count);
 };
 
+static inline bool cpufreq_can_do_remote_dvfs(struct cpufreq_policy *policy)
+{
+	/*
+	 * Allow remote callbacks if:
+	 * - dvfs_possible_from_any_cpu flag is set
+	 * - the local and remote CPUs share cpufreq policy
+	 */
+	return policy->dvfs_possible_from_any_cpu ||
+		cpumask_test_cpu(smp_processor_id(), policy->cpus);
+}
+
 /*********************************************************************
  *                     FREQUENCY TABLE HELPERS                       *
  *********************************************************************/

kernel/sched/cpufreq_schedutil.c

@@ -52,9 +52,11 @@ struct sugov_policy {
 struct sugov_cpu {
 	struct update_util_data update_util;
 	struct sugov_policy *sg_policy;
+	unsigned int cpu;
 
-	unsigned long iowait_boost;
-	unsigned long iowait_boost_max;
+	bool iowait_boost_pending;
+	unsigned int iowait_boost;
+	unsigned int iowait_boost_max;
 	u64 last_update;
 
 	/* The fields below are only needed when sharing a policy. */
@@ -76,6 +78,26 @@ static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
 {
 	s64 delta_ns;
 
+	/*
+	 * Since cpufreq_update_util() is called with rq->lock held for
+	 * the @target_cpu, our per-cpu data is fully serialized.
+	 *
+	 * However, drivers cannot in general deal with cross-cpu
+	 * requests, so while get_next_freq() will work, our
+	 * sugov_update_commit() call may not for the fast switching platforms.
+	 *
+	 * Hence stop here for remote requests if they aren't supported
+	 * by the hardware, as calculating the frequency is pointless if
+	 * we cannot in fact act on it.
+	 *
+	 * For the slow switching platforms, the kthread is always scheduled on
+	 * the right set of CPUs and any CPU can find the next frequency and
+	 * schedule the kthread.
+	 */
+	if (sg_policy->policy->fast_switch_enabled &&
+	    !cpufreq_can_do_remote_dvfs(sg_policy->policy))
+		return false;
+
 	if (sg_policy->work_in_progress)
 		return false;
 
@@ -106,7 +128,7 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
 
 	if (policy->fast_switch_enabled) {
 		next_freq = cpufreq_driver_fast_switch(policy, next_freq);
-		if (next_freq == CPUFREQ_ENTRY_INVALID)
+		if (!next_freq)
 			return;
 
 		policy->cur = next_freq;
@@ -154,12 +176,12 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy,
 	return cpufreq_driver_resolve_freq(policy, freq);
 }
 
-static void sugov_get_util(unsigned long *util, unsigned long *max)
+static void sugov_get_util(unsigned long *util, unsigned long *max, int cpu)
 {
-	struct rq *rq = this_rq();
+	struct rq *rq = cpu_rq(cpu);
 	unsigned long cfs_max;
 
-	cfs_max = arch_scale_cpu_capacity(NULL, smp_processor_id());
+	cfs_max = arch_scale_cpu_capacity(NULL, cpu);
 
 	*util = min(rq->cfs.avg.util_avg, cfs_max);
 	*max = cfs_max;
@@ -169,30 +191,54 @@ static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
 				   unsigned int flags)
 {
 	if (flags & SCHED_CPUFREQ_IOWAIT) {
-		sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;
+		if (sg_cpu->iowait_boost_pending)
+			return;
+
+		sg_cpu->iowait_boost_pending = true;
+
+		if (sg_cpu->iowait_boost) {
+			sg_cpu->iowait_boost <<= 1;
+			if (sg_cpu->iowait_boost > sg_cpu->iowait_boost_max)
+				sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;
+		} else {
+			sg_cpu->iowait_boost = sg_cpu->sg_policy->policy->min;
+		}
 	} else if (sg_cpu->iowait_boost) {
 		s64 delta_ns = time - sg_cpu->last_update;
 
 		/* Clear iowait_boost if the CPU apprears to have been idle. */
-		if (delta_ns > TICK_NSEC)
+		if (delta_ns > TICK_NSEC) {
 			sg_cpu->iowait_boost = 0;
+			sg_cpu->iowait_boost_pending = false;
+		}
 	}
 }
 
 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util,
 			       unsigned long *max)
 {
-	unsigned long boost_util = sg_cpu->iowait_boost;
-	unsigned long boost_max = sg_cpu->iowait_boost_max;
+	unsigned int boost_util, boost_max;
 
-	if (!boost_util)
+	if (!sg_cpu->iowait_boost)
 		return;
 
+	if (sg_cpu->iowait_boost_pending) {
+		sg_cpu->iowait_boost_pending = false;
+	} else {
+		sg_cpu->iowait_boost >>= 1;
+		if (sg_cpu->iowait_boost < sg_cpu->sg_policy->policy->min) {
+			sg_cpu->iowait_boost = 0;
+			return;
+		}
+	}
+
+	boost_util = sg_cpu->iowait_boost;
+	boost_max = sg_cpu->iowait_boost_max;
+
 	if (*util * boost_max < *max * boost_util) {
 		*util = boost_util;
 		*max = boost_max;
 	}
-	sg_cpu->iowait_boost >>= 1;
 }
 
 #ifdef CONFIG_NO_HZ_COMMON
@@ -229,7 +275,7 @@ static void sugov_update_single(struct update_util_data *hook, u64 time,
 	if (flags & SCHED_CPUFREQ_RT_DL) {
 		next_f = policy->cpuinfo.max_freq;
 	} else {
-		sugov_get_util(&util, &max);
+		sugov_get_util(&util, &max, sg_cpu->cpu);
 		sugov_iowait_boost(sg_cpu, &util, &max);
 		next_f = get_next_freq(sg_policy, util, max);
 		/*
@@ -264,6 +310,7 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 		delta_ns = time - j_sg_cpu->last_update;
 		if (delta_ns > TICK_NSEC) {
 			j_sg_cpu->iowait_boost = 0;
+			j_sg_cpu->iowait_boost_pending = false;
 			continue;
 		}
 		if (j_sg_cpu->flags & SCHED_CPUFREQ_RT_DL)
@@ -290,7 +337,7 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time,
 	unsigned long util, max;
 	unsigned int next_f;
 
-	sugov_get_util(&util, &max);
+	sugov_get_util(&util, &max, sg_cpu->cpu);
 
 	raw_spin_lock(&sg_policy->update_lock);
 
@@ -445,7 +492,11 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy)
 	}
 
 	sg_policy->thread = thread;
-	kthread_bind_mask(thread, policy->related_cpus);
+
+	/* Kthread is bound to all CPUs by default */
+	if (!policy->dvfs_possible_from_any_cpu)
+		kthread_bind_mask(thread, policy->related_cpus);
+
 	init_irq_work(&sg_policy->irq_work, sugov_irq_work);
 	mutex_init(&sg_policy->work_lock);
 
@@ -663,6 +714,11 @@ struct cpufreq_governor *cpufreq_default_governor(void)
 
 static int __init sugov_register(void)
 {
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		per_cpu(sugov_cpu, cpu).cpu = cpu;
+
 	return cpufreq_register_governor(&schedutil_gov);
 }
 fs_initcall(sugov_register);

kernel/sched/deadline.c

@@ -1136,7 +1136,7 @@ static void update_curr_dl(struct rq *rq)
 	}
 
 	/* kick cpufreq (see the comment in kernel/sched/sched.h). */
-	cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_DL);
+	cpufreq_update_util(rq, SCHED_CPUFREQ_DL);
 
 	schedstat_set(curr->se.statistics.exec_max,
 		      max(curr->se.statistics.exec_max, delta_exec));

kernel/sched/fair.c

@@ -3278,7 +3278,9 @@ static inline void set_tg_cfs_propagate(struct cfs_rq *cfs_rq) {}
 
 static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq)
 {
-	if (&this_rq()->cfs == cfs_rq) {
+	struct rq *rq = rq_of(cfs_rq);
+
+	if (&rq->cfs == cfs_rq) {
 		/*
 		 * There are a few boundary cases this might miss but it should
 		 * get called often enough that that should (hopefully) not be
@@ -3295,7 +3297,7 @@ static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq)
 		 *
 		 * See cpu_util().
 		 */
-		cpufreq_update_util(rq_of(cfs_rq), 0);
+		cpufreq_update_util(rq, 0);
 	}
 }
 
@@ -4875,7 +4877,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 	 * passed.
 	 */
 	if (p->in_iowait)
-		cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_IOWAIT);
+		cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT);
 
 	for_each_sched_entity(se) {
 		if (se->on_rq)

kernel/sched/rt.c

@@ -970,7 +970,7 @@ static void update_curr_rt(struct rq *rq)
 		return;
 
 	/* Kick cpufreq (see the comment in kernel/sched/sched.h). */
-	cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_RT);
+	cpufreq_update_util(rq, SCHED_CPUFREQ_RT);
 
 	schedstat_set(curr->se.statistics.exec_max,
 		      max(curr->se.statistics.exec_max, delta_exec));

kernel/sched/sched.h

@@ -2070,19 +2070,13 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags)
 {
 	struct update_util_data *data;
 
-	data = rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data));
+	data = rcu_dereference_sched(*per_cpu_ptr(&cpufreq_update_util_data,
+						  cpu_of(rq)));
 	if (data)
 		data->func(data, rq_clock(rq), flags);
 }
-
-static inline void cpufreq_update_this_cpu(struct rq *rq, unsigned int flags)
-{
-	if (cpu_of(rq) == smp_processor_id())
-		cpufreq_update_util(rq, flags);
-}
 #else
 static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {}
-static inline void cpufreq_update_this_cpu(struct rq *rq, unsigned int flags) {}
 #endif /* CONFIG_CPU_FREQ */
 
 #ifdef arch_scale_freq_capacity