sched: Add WAKEUP_PREEMPTION feature flag, on by default

As per the recent discussion with Mike and Linus, make it easier to
test with/without this feature. No change in default behavior.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-izoxq4haeg4mTognnDbwcevt@git.kernel.org

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6b800a14b990..f936552b3db1 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2907,7 +2907,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
          * Batch and idle tasks do not preempt non-idle tasks (their preemption
          * is driven by the tick):
          */
-        if (unlikely(p->policy != SCHED_NORMAL))
+        if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
                 return;
 
         find_matching_se(&se, &pse);