sched: disable sleeper_fairness on SCHED_BATCH

disable sleeper fairness for batch tasks - they are about
batch processing after all.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched_fair.c

@@ -485,7 +485,9 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
 		vruntime += sched_vslice_add(cfs_rq, se);
 
 	if (!initial) {
-		if (sched_feat(NEW_FAIR_SLEEPERS))
+		struct task_struct *p = container_of(se, struct task_struct, se);
+
+		if (sched_feat(NEW_FAIR_SLEEPERS) && p->policy != SCHED_BATCH)
 			vruntime -= sysctl_sched_latency;
 
 		vruntime = max_t(s64, vruntime, se->vruntime);