sched: get CPU's activity statistic

Monitor the activity level of each group of each sched_domain level. The
activity is the amount of cpu_power that is currently used on a CPU. We use
the runnable_avg_sum and _period to evaluate this activity level. In the
special use case where the CPU is fully loaded by more than 1 task, the
activity level is set above the cpu_power in order to reflect the overload of
The cpu

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 9ff4e45a7ce9..68c1b3606b04 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -179,6 +179,11 @@ void sched_init_granularity(void)
 }
 
 #ifdef CONFIG_SMP
+static unsigned long available_of(int cpu)
+{
+	return cpu_rq(cpu)->cpu_available;
+}
+
 #ifdef CONFIG_SCHED_PACKING_TASKS
 /*
  * Save the id of the optimal CPU that should be used to pack small tasks
@@ -3501,6 +3506,22 @@ done:
 	return target;
 }
 
+static int get_cpu_activity(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	u32 sum = rq->avg.runnable_avg_sum;
+	u32 period = rq->avg.runnable_avg_period;
+
+	sum = min(sum, period);
+
+	if (sum == period) {
+		u32 overload = rq->nr_running > 1 ? 1 : 0;
+		return available_of(cpu) + overload;
+	}
+
+	return (sum * available_of(cpu)) / period;
+}
+
 /*
  * sched_balance_self: balance the current task (running on cpu) in domains
  * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
@@ -4384,6 +4405,7 @@ struct sd_lb_stats {
 	struct sched_group *busiest; /* Busiest group in this sd */
 	struct sched_group *this;  /* Local group in this sd */
 	unsigned long total_load;  /* Total load of all groups in sd */
+	unsigned long total_activity;  /* Total activity of all groups in sd */
 	unsigned long total_pwr;   /*	Total power of all groups in sd */
 	unsigned long avg_load;	   /* Average load across all groups in sd */
 
@@ -4412,6 +4434,7 @@ struct sd_lb_stats {
 struct sg_lb_stats {
 	unsigned long avg_load; /*Avg load across the CPUs of the group */
 	unsigned long group_load; /* Total load over the CPUs of the group */
+	unsigned long group_activity; /* Total activity of the group */
 	unsigned long sum_nr_running; /* Nr tasks running in the group */
 	unsigned long sum_weighted_load; /* Weighted load of group's tasks */
 	unsigned long group_capacity;
@@ -4670,6 +4693,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 		}
 
 		sgs->group_load += load;
+		sgs->group_activity += get_cpu_activity(i);
 		sgs->sum_nr_running += nr_running;
 		sgs->sum_weighted_load += weighted_cpuload(i);
 		if (idle_cpu(i))
@@ -4793,6 +4817,7 @@ static inline void update_sd_lb_stats(struct lb_env *env,
 			return;
 
 		sds->total_load += sgs.group_load;
+		sds->total_activity += sgs.group_activity;
 		sds->total_pwr += sg->sgp->power;
 
 		/*