[RFCv3 PATCH 37/48] sched: Determine the current sched_group idle-state

[Morten Rasmussen]

To estimate the energy consumption of a sched_group in
sched_group_energy() it is necessary to know which idle-state the group
is in when it is idle. For now, it is assumed that this is the current
idle-state (though it might be wrong). Based on the individual cpu
idle-states group_idle_state() finds the group idle-state.

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

Signed-off-by: Morten Rasmussen <morten.rasmussen@xxxxxxx>
---
 kernel/sched/fair.c | 32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4251e75..0e95eb5 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4719,6 +4719,28 @@ static int find_new_capacity(struct energy_env *eenv,
 	return idx;
 }
 
+static int group_idle_state(struct sched_group *sg)
+{
+	struct sched_group_energy *sge = sg->sge;
+	int shallowest_state = sge->idle_states_below + sge->nr_idle_states;
+	int i;
+
+	for_each_cpu(i, sched_group_cpus(sg)) {
+		int cpuidle_idx = idle_get_state_idx(cpu_rq(i));
+		int group_idx = cpuidle_idx - sge->idle_states_below + 1;
+
+		if (group_idx <= 0)
+			return 0;
+
+		shallowest_state = min(shallowest_state, group_idx);
+	}
+
+	if (shallowest_state >= sge->nr_idle_states)
+		return sge->nr_idle_states - 1;
+
+	return shallowest_state;
+}
+
 /*
  * sched_group_energy(): Returns absolute energy consumption of cpus belonging
  * to the sched_group including shared resources shared only by members of the
@@ -4762,7 +4784,7 @@ static unsigned int sched_group_energy(struct energy_env *eenv)
 			do {
 				unsigned group_util;
 				int sg_busy_energy, sg_idle_energy;
-				int cap_idx;
+				int cap_idx, idle_idx;
 
 				if (sg_shared_cap && sg_shared_cap->group_weight >= sg->group_weight)
 					eenv->sg_cap = sg_shared_cap;
@@ -4770,11 +4792,13 @@ static unsigned int sched_group_energy(struct energy_env *eenv)
 					eenv->sg_cap = sg;
 
 				cap_idx = find_new_capacity(eenv, sg->sge);
+				idle_idx = group_idle_state(sg);
 				group_util = group_norm_usage(eenv, sg);
 				sg_busy_energy = (group_util * sg->sge->cap_states[cap_idx].power)
-										>> SCHED_CAPACITY_SHIFT;
-				sg_idle_energy = ((SCHED_LOAD_SCALE-group_util) * sg->sge->idle_states[0].power)
-										>> SCHED_CAPACITY_SHIFT;
+								>> SCHED_CAPACITY_SHIFT;
+				sg_idle_energy = ((SCHED_LOAD_SCALE-group_util)
+								* sg->sge->idle_states[idle_idx].power)
+								>> SCHED_CAPACITY_SHIFT;
 
 				total_energy += sg_busy_energy + sg_idle_energy;
 
-- 
1.9.1

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