[PATCH 3/3] sched: do not consider SCHED_IDLE tasks to be cache hot

[Nikhil Rao <ncrao@google.com>]

This patch adds a check in task_hot to return if the task has SCHED_IDLE
policy. SCHED_IDLE tasks have very low weight, and when run with regular
weight tasks, are typically scheduled many milliseconds apart. There is no
benefit from considering SCHED_IDLE tasks cache hot for load balancing.

Signed-off-by: Nikhil Rao <ncrao@google.com>
---
 kernel/sched.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index ed09d4f..874efde 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2003,6 +2003,9 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
 	if (p->sched_class != &fair_sched_class)
 		return 0;
 
+	if (p->policy == SCHED_IDLE)
+		return 0;
+
 	/*
 	 * Buddy candidates are cache hot:
 	 */
-- 
1.7.1