sched: optimize vruntime based scheduling

optimize vruntime based scheduling.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

kernel/sched_fair.c

@@ -336,6 +336,9 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
 	}
 	curr->vruntime += delta_exec_weighted;
 
+	if (!sched_feat(FAIR_SLEEPERS))
+		return;
+
 	if (unlikely(!load))
 		return;