Implement rudimentary cpufreq load signalling for schedutil governor to work.

-ck

---
 kernel/sched/bfs.c       |   20 ++++++++++++++++----
 kernel/sched/bfs_sched.h |   14 +++++++++++++-
 2 files changed, 29 insertions(+), 5 deletions(-)

Index: linux-4.7-ck4/kernel/sched/bfs.c
===================================================================
--- linux-4.7-ck4.orig/kernel/sched/bfs.c	2016-09-13 17:21:51.520266396 +1000
+++ linux-4.7-ck4/kernel/sched/bfs.c	2016-09-13 17:21:51.517266465 +1000
@@ -1020,13 +1020,14 @@ static inline void deactivate_task(struc
 #ifdef CONFIG_SMP
 void set_task_cpu(struct task_struct *p, unsigned int cpu)
 {
+	unsigned int tcpu;
 #ifdef CONFIG_LOCKDEP
 	/*
 	 * The caller should hold grq lock.
 	 */
 	WARN_ON_ONCE(debug_locks && !lockdep_is_held(&grq.lock));
 #endif
-	if (task_cpu(p) == cpu)
+	if ((tcpu = task_cpu(p)) == cpu)
 		return;
 	trace_sched_migrate_task(p, cpu);
 	perf_event_task_migrate(p);
@@ -1038,8 +1039,13 @@ void set_task_cpu(struct task_struct *p,
 	 */
 	smp_wmb();
 	if (p->on_rq) {
-		task_rq(p)->soft_affined--;
-		cpu_rq(cpu)->soft_affined++;
+		/*
+		 * set_task_cpu can be set on other CPUs so call cpufreq_trigger
+		 * explicitly telling it what CPU is being updated as the value
+		 * of soft_affined has changed.
+		 */
+		other_cpufreq_trigger(tcpu, grq.niffies, --task_rq(p)->soft_affined);
+		other_cpufreq_trigger(cpu, grq.niffies, ++cpu_rq(cpu)->soft_affined);
 	}
 	task_thread_info(p)->cpu = cpu;
 }
@@ -3093,8 +3099,14 @@ void scheduler_tick(void)
 	update_cpu_clock_tick(rq, rq->curr);
 	if (!rq_idle(rq))
 		task_running_tick(rq);
-	else
+	else {
+		/*
+		 * Trigger cpufreq update while we're idle. Soft affined will
+		 * be zero unless we have uninterruptible tasks.
+		 */
+		cpufreq_trigger(grq.niffies, rq->soft_affined);
 		no_iso_tick();
+	}
 	rq->last_tick = rq->clock;
 	perf_event_task_tick();
 }
Index: linux-4.7-ck4/kernel/sched/bfs_sched.h
===================================================================
--- linux-4.7-ck4.orig/kernel/sched/bfs_sched.h	2016-09-13 17:21:51.520266396 +1000
+++ linux-4.7-ck4/kernel/sched/bfs_sched.h	2016-09-13 17:21:51.518266442 +1000
@@ -203,12 +203,24 @@ static inline void cpufreq_trigger(u64 t
 
        data = rcu_dereference_sched(*this_cpu_ptr(&cpufreq_update_util_data));
        if (data)
-               data->func(data, time, util, 0);
+               data->func(data, time, util, 1);
+}
+
+static inline void other_cpufreq_trigger(int cpu, u64 time, unsigned long util)
+{
+       struct update_util_data *data;
+
+       data = rcu_dereference_sched(*per_cpu_ptr(&cpufreq_update_util_data, cpu));
+       if (data)
+               data->func(data, time, util, 1);
 }
 #else
 static inline void cpufreq_trigger(u64 time, unsigned long util)
 {
 }
+static inline void other_cpufreq_trigger(int cpu, u64 time, unsigned long util)
+{
+}
 #endif /* CONFIG_CPU_FREQ */
 
 #ifdef arch_scale_freq_capacity