[PATCH 13/20] sched/eevdf: Try to push short slice task on a better CPU

[Vincent Guittot]

When a task is put back in the runnable list, we check if we should try to
push it on a better CPU, i.e. when fair is preempted by a higher class or
the task is preempted by another fair task.

Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
---
 kernel/sched/fair.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 980eda9c935a..3923587b66e0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10112,6 +10112,23 @@ static bool __check_pushable_fair_task(struct rq *rq, struct task_struct *p)
 	return true;
 }
 
+static bool check_pushable_short_task(struct rq *rq, struct task_struct *p)
+{
+	struct sched_entity *pse = &p->se;
+	struct cfs_rq *cfs_rq = &rq->cfs;
+
+	if (cfs_rq->h_nr_runnable <= 1)
+		return false;
+
+	if (!entity_eligible(cfs_rq, pse))
+		return false;
+
+	if (pse->slice < cfs_rq_max_slice(cfs_rq))
+		return true;
+
+	return false;
+}
+
 static bool fair_check_pushable_task(struct rq *rq, struct task_struct *p, struct task_struct *next)
 {
 	if (!__check_pushable_fair_task(rq, p))
@@ -10120,6 +10137,12 @@ static bool fair_check_pushable_task(struct rq *rq, struct task_struct *p, struc
 	if (next == p)
 		return false;
 
+	if (next && next->sched_class != p->sched_class)
+		return true;
+
+	if (check_pushable_short_task(rq, p))
+		return true;
+
 	return false;
 }
 
-- 
2.53.0