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>

1 files changed, 6 insertions, 0 deletions

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)) {