sched: Remove ASYM_GRAN feature

This features has been enabled for quite a while, after testing showed that
easing preemption for light tasks was harmful to high priority threads.

Remove the feature flag.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1268301675.6785.44.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 1d99535..9357ecd 100644 (file)
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1583,24 +1583,18 @@ wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
        /*
         * Since its curr running now, convert the gran from real-time
         * to virtual-time in his units.
+        *
+        * By using 'se' instead of 'curr' we penalize light tasks, so
+        * they get preempted easier. That is, if 'se' < 'curr' then
+        * the resulting gran will be larger, therefore penalizing the
+        * lighter, if otoh 'se' > 'curr' then the resulting gran will
+        * be smaller, again penalizing the lighter task.
+        *
+        * This is especially important for buddies when the leftmost
+        * task is higher priority than the buddy.
         */
-       if (sched_feat(ASYM_GRAN)) {
-               /*
-                * By using 'se' instead of 'curr' we penalize light tasks, so
-                * they get preempted easier. That is, if 'se' < 'curr' then
-                * the resulting gran will be larger, therefore penalizing the
-                * lighter, if otoh 'se' > 'curr' then the resulting gran will
-                * be smaller, again penalizing the lighter task.
-                *
-                * This is especially important for buddies when the leftmost
-                * task is higher priority than the buddy.
-                */
-               if (unlikely(se->load.weight != NICE_0_LOAD))
-                       gran = calc_delta_fair(gran, se);
-       } else {
-               if (unlikely(curr->load.weight != NICE_0_LOAD))
-                       gran = calc_delta_fair(gran, curr);
-       }
+       if (unlikely(se->load.weight != NICE_0_LOAD))
+               gran = calc_delta_fair(gran, se);
 
        return gran;
 }

diff --git a/kernel/sched_features.h b/kernel/sched_features.h
index f54b6f9..83c66e8 100644 (file)
--- a/kernel/sched_features.h
+++ b/kernel/sched_features.h
@@ -16,12 +16,6 @@ SCHED_FEAT(START_DEBIT, 1)
  */
 SCHED_FEAT(WAKEUP_PREEMPT, 1)
 
-/*
- * When converting the wakeup granularity to virtual time, do it such
- * that heavier tasks preempting a lighter task have an edge.
- */
-SCHED_FEAT(ASYM_GRAN, 1)
-
 /*
  * Based on load and program behaviour, see if it makes sense to place
  * a newly woken task on the same cpu as the task that woke it --