sched: Replace use of entity_key()

tip:sched/core tip-bot for Stephan Baerwolf 1 participant 1 message Jul 21, 2011

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2011-07-21 18:31 UTC #0 lore raw

Commit-ID:  2bd2d6f2dc952fc44fc52887de36e51896da96b9
Gitweb:     http://git.kernel.org/tip/2bd2d6f2dc952fc44fc52887de36e51896da96b9
Author:     Stephan Baerwolf <[email protected]>
AuthorDate: Wed, 20 Jul 2011 14:46:59 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Thu, 21 Jul 2011 18:01:55 +0200

sched: Replace use of entity_key()

"entity_key()" is only used in "__enqueue_entity()" and its only function is to subtract a tasks vruntime by its groups minvruntime.
Before this patch a rbtree enqueue-decision is done by comparing two tasks in the style:

	"if (entity_key(cfs_rq, se) < entity_key(cfs_rq, entry))"

which would be

	"if (se->vruntime-cfs_rq->min_vruntime < entry->vruntime-cfs_rq->min_vruntime)"

or (if reducing cfs_rq->min_vruntime out)

	"if (se->vruntime < entry->vruntime)"

which is

	"if (entity_before(se, entry))"

So we do not need "entity_key()".
If "entity_before()" is inline we will also save one subtraction (only one, because "entity_key(cfs_rq, se)" was cached in "key")

Signed-off-by Stephan Baerwolf <[email protected]>

Signed-off-by Peter Zijlstra <[email protected]>

Link http://lkml.kernel.org/n/[email protected] open here

Signed-off-by Ingo Molnar <[email protected]>

---
 kernel/sched_fair.c |    8 +-------
 1 files changed, 1 insertions(+), 7 deletions(-)

kernel/sched_fair.c +1 -7

index 0588c0b..a2ecbaa 100644
@@ -321,11 +321,6 @@ static inline int entity_before(struct sched_entity *a,
 	return (s64)(a->vruntime - b->vruntime) < 0;
 }
 
-static inline s64 entity_key(struct cfs_rq *cfs_rq, struct sched_entity *se)
-{
-	return se->vruntime - cfs_rq->min_vruntime;
-}
-
 static void update_min_vruntime(struct cfs_rq *cfs_rq)
 {
 	u64 vruntime = cfs_rq->min_vruntime;

@@ -359,7 +354,6 @@ static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 	struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
 	struct rb_node *parent = NULL;
 	struct sched_entity *entry;
-	s64 key = entity_key(cfs_rq, se);
 	int leftmost = 1;
 
 	/*

@@ -372,7 +366,7 @@ static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 		 * We dont care about collisions. Nodes with
 		 * the same key stay together.
 		 */
-		if (key < entity_key(cfs_rq, entry)) {
+		if (entity_before(se, entry)) {
 			link = &parent->rb_left;
 		} else {
 			link = &parent->rb_right;