sched: Remove FAIR_SLEEPERS feature

Our preemption model relies too heavily on sleeper fairness to disable it
without dire consequences.  Remove the feature, and save a branch or two.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301520.6785.40.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched_fair.c

@@ -738,7 +738,7 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
 		vruntime += sched_vslice(cfs_rq, se);
 
 	/* sleeps up to a single latency don't count. */
-	if (!initial && sched_feat(FAIR_SLEEPERS)) {
+	if (!initial) {
 		unsigned long thresh = sysctl_sched_latency;
 
 		/*

kernel/sched_features.h

@@ -1,10 +1,3 @@
-/*
- * Disregards a certain amount of sleep time (sched_latency_ns) and
- * considers the task to be running during that period. This gives it
- * a service deficit on wakeup, allowing it to run sooner.
- */
-SCHED_FEAT(FAIR_SLEEPERS, 1)
-
 /*
  * Only give sleepers 50% of their service deficit. This allows
  * them to run sooner, but does not allow tons of sleepers to