linux-kernel - [tip:sched/core] sched: Replace use of entity

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Date:	Thu, 21 Jul 2011 18:31:28 GMT
From:	tip-bot for Stephan Baerwolf <stephan.baerwolf@...ilmenau.de>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	a.p.zijlstra@...llo.nl, stephan.baerwolf@...ilmenau.de,
	tglx@...utronix.de, mingo@...e.hu
Subject: [tip:sched/core] sched: Replace use of entity_key()

Commit-ID:  2bd2d6f2dc952fc44fc52887de36e51896da96b9
Gitweb:     http://git.kernel.org/tip/2bd2d6f2dc952fc44fc52887de36e51896da96b9
Author:     Stephan Baerwolf <stephan.baerwolf@...ilmenau.de>
AuthorDate: Wed, 20 Jul 2011 14:46:59 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
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 <stephan.baerwolf@...ilmenau.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/n/tip-ns12mnd2h5w8rb9agd8hnsfk@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 kernel/sched_fair.c |    8 +-------
 1 files changed, 1 insertions(+), 7 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 0588c0b..a2ecbaa 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -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;
--
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