From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 15 Oct 2007 15:00:18 +0000 (+0200)
Subject: sched: do not wakeup-preempt with SCHED_BATCH tasks
X-Git-Tag: firefly_0821_release~25905^2~20
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=91c234b4e3419c786cac2d5b7a7b96443e512e3a;p=firefly-linux-kernel-4.4.55.git

sched: do not wakeup-preempt with SCHED_BATCH tasks

do not wakeup-preempt with SCHED_BATCH tasks, their preemption
is batched too, driven by the tick.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ec1592eb8d08..c240b72b4e62 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -828,6 +828,12 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
 		resched_task(curr);
 		return;
 	}
+	/*
+	 * Batch tasks do not preempt (their preemption is driven by
+	 * the tick):
+	 */
+	if (unlikely(p->policy == SCHED_BATCH))
+		return;
 
 	if (sched_feat(WAKEUP_PREEMPT)) {
 		while (!is_same_group(se, pse)) {