[RFC][PATCH 3/7] cpufreq / sched: Check cpu_of(rq) in cpufreq_update_util()

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

All of the callers of cpufreq_update_util() check whether or not
cpu_of(rq) is equal to smp_processor_id() before calling it and pass
rq_clock(rq) to it as the time argument, so rework it to take a
runqueue pointer as the argument and move the cpu_of(rq) check and
the rq_clock(rq) evaluation into it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
 kernel/sched/deadline.c |    3 +--
 kernel/sched/fair.c     |    5 +----
 kernel/sched/rt.c       |    3 +--
 kernel/sched/sched.h    |   11 +++++++----
 4 files changed, 10 insertions(+), 12 deletions(-)

Index: linux-pm/kernel/sched/deadline.c
===================================================================
--- linux-pm.orig/kernel/sched/deadline.c
+++ linux-pm/kernel/sched/deadline.c
@@ -733,8 +733,7 @@ static void update_curr_dl(struct rq *rq
 	}
 
 	/* kick cpufreq (see the comment in kernel/sched/sched.h). */
-	if (cpu_of(rq) == smp_processor_id())
-		cpufreq_update_util(rq_clock(rq));
+	cpufreq_update_util(rq);
 
 	schedstat_set(curr->se.statistics.exec_max,
 		      max(curr->se.statistics.exec_max, delta_exec));
Index: linux-pm/kernel/sched/fair.c
===================================================================
--- linux-pm.orig/kernel/sched/fair.c
+++ linux-pm/kernel/sched/fair.c
@@ -2871,8 +2871,6 @@ static inline u64 cfs_rq_clock_task(stru
 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);
-
 		/*
 		 * There are a few boundary cases this might miss but it should
 		 * get called often enough that that should (hopefully) not be
@@ -2889,8 +2887,7 @@ static inline void cfs_rq_util_change(st
 		 *
 		 * See cpu_util().
 		 */
-		if (cpu_of(rq) == smp_processor_id())
-			cpufreq_update_util(rq_clock(rq));
+		cpufreq_update_util(rq_of(cfs_rq));
 	}
 }
 
Index: linux-pm/kernel/sched/rt.c
===================================================================
--- linux-pm.orig/kernel/sched/rt.c
+++ linux-pm/kernel/sched/rt.c
@@ -958,8 +958,7 @@ static void update_curr_rt(struct rq *rq
 		return;
 
 	/* Kick cpufreq (see the comment in kernel/sched/sched.h). */
-	if (cpu_of(rq) == smp_processor_id())
-		cpufreq_update_util(rq_clock(rq));
+	cpufreq_update_util(rq);
 
 	schedstat_set(curr->se.statistics.exec_max,
 		      max(curr->se.statistics.exec_max, delta_exec));
Index: linux-pm/kernel/sched/sched.h
===================================================================
--- linux-pm.orig/kernel/sched/sched.h
+++ linux-pm/kernel/sched/sched.h
@@ -1760,7 +1760,7 @@ DECLARE_PER_CPU(struct update_util_data
 
 /**
  * cpufreq_update_util - Take a note about CPU utilization changes.
- * @time: Current time.
+ * @rq: Runqueue to carry out the update for.
  *
  * This function is called by the scheduler on every invocation of
  * update_load_avg() on the CPU whose utilization is being updated.
@@ -1779,16 +1779,19 @@ DECLARE_PER_CPU(struct update_util_data
  * but that really is a band-aid.  Going forward it should be replaced with
  * solutions targeted more specifically at RT and DL tasks.
  */
-static inline void cpufreq_update_util(u64 time)
+static inline void cpufreq_update_util(struct rq *rq)
 {
 	struct update_util_data *data;
 
+	if (cpu_of(rq) != smp_processor_id())
+		return;
+
 	data = rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data));
 	if (data)
-		data->func(data, time);
+		data->func(data, rq_clock(rq));
 }
 #else
-static inline void cpufreq_update_util(u64 time) {}
+static inline void cpufreq_update_util(struct rq *rq) {}
 #endif /* CONFIG_CPU_FREQ */
 
 #ifdef arch_scale_freq_capacity