sched/fair: Name utilization related data and functions consistently

Use the advent of the per-entity load tracking rewrite to streamline the
naming of utilization related data and functions by using
{prefix_}util{_suffix} consistently. Moreover call both signals
({se,cfs}.avg.util_avg) utilization.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dietmar Eggemann <Dietmar.Eggemann@arm.com>
Cc: Juri Lelli <Juri.Lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: daniel.lezcano@linaro.org
Cc: mturquette@baylibre.com
Cc: pang.xunlei@zte.com.cn
Cc: rjw@rjwysocki.net
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1439569394-11974-5-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

@@ -4863,31 +4863,32 @@ done:
 	return target;
 }
 /*
- * get_cpu_usage returns the amount of capacity of a CPU that is used by CFS
+ * cpu_util returns the amount of capacity of a CPU that is used by CFS
  * tasks. The unit of the return value must be the one of capacity so we can
- * compare the usage with the capacity of the CPU that is available for CFS
- * task (ie cpu_capacity).
+ * compare the utilization with the capacity of the CPU that is available for
+ * CFS task (ie cpu_capacity).
  * cfs.avg.util_avg is the sum of running time of runnable tasks on a
  * CPU. It represents the amount of utilization of a CPU in the range
- * [0..SCHED_LOAD_SCALE].  The usage of a CPU can't be higher than the full
- * capacity of the CPU because it's about the running time on this CPU.
+ * [0..SCHED_LOAD_SCALE]. The utilization of a CPU can't be higher than the
+ * full capacity of the CPU because it's about the running time on this CPU.
  * Nevertheless, cfs.avg.util_avg can be higher than SCHED_LOAD_SCALE
  * because of unfortunate rounding in util_avg or just
  * after migrating tasks until the average stabilizes with the new running
- * time. So we need to check that the usage stays into the range
+ * time. So we need to check that the utilization stays into the range
  * [0..cpu_capacity_orig] and cap if necessary.
- * Without capping the usage, a group could be seen as overloaded (CPU0 usage
- * at 121% + CPU1 usage at 80%) whereas CPU1 has 20% of available capacity
+ * Without capping the utilization, a group could be seen as overloaded (CPU0
+ * utilization at 121% + CPU1 utilization at 80%) whereas CPU1 has 20% of
+ * available capacity.
  */
-static int get_cpu_usage(int cpu)
+static int cpu_util(int cpu)
 {
-	unsigned long usage = cpu_rq(cpu)->cfs.avg.util_avg;
+	unsigned long util = cpu_rq(cpu)->cfs.avg.util_avg;
 	unsigned long capacity = capacity_orig_of(cpu);
 
-	if (usage >= SCHED_LOAD_SCALE)
+	if (util >= SCHED_LOAD_SCALE)
 		return capacity;
 
-	return (usage * capacity) >> SCHED_LOAD_SHIFT;
+	return (util * capacity) >> SCHED_LOAD_SHIFT;
 }
 
 /*
@@ -5979,7 +5980,7 @@ struct sg_lb_stats {
 	unsigned long sum_weighted_load; /* Weighted load of group's tasks */
 	unsigned long load_per_task;
 	unsigned long group_capacity;
-	unsigned long group_usage; /* Total usage of the group */
+	unsigned long group_util; /* Total utilization of the group */
 	unsigned int sum_nr_running; /* Nr tasks running in the group */
 	unsigned int idle_cpus;
 	unsigned int group_weight;
@@ -6212,8 +6213,8 @@ static inline int sg_imbalanced(struct sched_group *group)
  * group_has_capacity returns true if the group has spare capacity that could
  * be used by some tasks.
  * We consider that a group has spare capacity if the  * number of task is
- * smaller than the number of CPUs or if the usage is lower than the available
- * capacity for CFS tasks.
+ * smaller than the number of CPUs or if the utilization is lower than the
+ * available capacity for CFS tasks.
  * For the latter, we use a threshold to stabilize the state, to take into
  * account the variance of the tasks' load and to return true if the available
  * capacity in meaningful for the load balancer.
@@ -6227,7 +6228,7 @@ group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs)
 		return true;
 
 	if ((sgs->group_capacity * 100) >
-			(sgs->group_usage * env->sd->imbalance_pct))
+			(sgs->group_util * env->sd->imbalance_pct))
 		return true;
 
 	return false;
@@ -6248,7 +6249,7 @@ group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs)
 		return false;
 
 	if ((sgs->group_capacity * 100) <
-			(sgs->group_usage * env->sd->imbalance_pct))
+			(sgs->group_util * env->sd->imbalance_pct))
 		return true;
 
 	return false;
@@ -6296,7 +6297,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 			load = source_load(i, load_idx);
 
 		sgs->group_load += load;
-		sgs->group_usage += get_cpu_usage(i);
+		sgs->group_util += cpu_util(i);
 		sgs->sum_nr_running += rq->cfs.h_nr_running;
 
 		if (rq->nr_running > 1)