[PATCH 19/20 v3] sched/fair: Take into account slice in EAS

[Vincent Guittot]

When the cost is the same, take into account the slice of a task to try to
select a CPU where is will run first.

Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
---
 kernel/sched/fair.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ea117c3d0dd7..da9c4416f1b5 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9885,13 +9885,22 @@ static bool update_best_cpu(struct energy_cpu_stat *target,
 			    int prev, struct sched_domain *sd,
 			    struct task_struct *p)
 {
+	unsigned long task_slice = p->se.slice;
 	bool target_idle = choose_idle_cpu(target->cpu, p);
 	bool min_idle = choose_idle_cpu(min->cpu, p);
+	bool target_first, min_first;
 
 	/*  Select the one which is idle */
 	if (target_idle != min_idle)
 		return target_idle;
 
+	target_first = task_slice < get_rq_min_slice(cpu_rq(target->cpu));
+	min_first = task_slice < get_rq_min_slice(cpu_rq(min->cpu));
+
+	/*  Select the one where you can run first */
+	if (target_first != min_first)
+		return target_first;
+
 	/* Favor previous CPU */
 	if (target->cpu == prev)
 		return true;
@@ -10055,7 +10064,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
 			 */
 			if (target_perf < min_stat.min_perf)
 				find_pd_cost(pd->em_pd, target_perf, &target_stat);
-			else if (!update_best_cpu(&target_stat, &min_stat, prev_cpu, sd))
+			else if (!update_best_cpu(&target_stat, &min_stat, prev_cpu, sd, p))
 				continue;
 
 			/* Save the new most efficient CPU of the PD */
-- 
2.53.0