sched: Do not consider SCHED_IDLE tasks to be cache hot

Commit: ef8002f6848236de5adc613063ebeabddea8a6fb upstream
Author: Nikhil Rao <[email protected]>
AuthorDate: Wed Oct 13 12:09:35 2010 -0700

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 workloads, are typically scheduled many milliseconds apart. There is no need to consider these tasks hot for load balancing.

LKML-Reference: <[email protected]>

---
 kernel/sched.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

index 87e3b2b..0a1fb24 100644
@@ -2014,6 +2014,9 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
 	if (p->sched_class != &fair_sched_class)
 		return 0;
 
+	if (unlikely(p->policy == SCHED_IDLE))
+		return 0;
+
 	/*
 	 * Buddy candidates are cache hot:
 	 */

1.7.4