[RFCv3 PATCH 39/48] sched: Introduce energy awareness into update_sg_lb_stats

[Morten Rasmussen]

From: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>

To be able to identify the least efficient (costliest) sched group
introduce group_eff as the efficiency of the sched group into sg_lb_stats.
The group efficiency is defined as the ratio between the group usage and
the group energy consumption.

cc: Ingo Molnar <mingo@xxxxxxxxxx>
cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
---
 kernel/sched/fair.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 45c784f..bfa335e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6345,6 +6345,7 @@ struct sg_lb_stats {
 	unsigned long load_per_task;
 	unsigned long group_capacity;
 	unsigned long group_usage; /* Total usage of the group */
+	unsigned long group_eff;
 	unsigned int sum_nr_running; /* Nr tasks running in the group */
 	unsigned int idle_cpus;
 	unsigned int group_weight;
@@ -6715,6 +6716,21 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 
 	sgs->group_no_capacity = group_is_overloaded(env, sgs);
 	sgs->group_type = group_classify(env, group, sgs);
+
+	if (env->use_ea) {
+		struct energy_env eenv = {
+			.sg_top         = group,
+			.usage_delta    = 0,
+			.src_cpu        = -1,
+			.dst_cpu        = -1,
+		};
+		unsigned long group_energy = sched_group_energy(&eenv);
+
+		if (group_energy)
+			sgs->group_eff = 1024*sgs->group_usage/group_energy;
+		else
+			sgs->group_eff = ULONG_MAX;
+	}
 }
 
 /**
-- 
1.9.1

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