Commit 2bd2d6f2 authored Jul 20, 2011 by Stephan Baerwolf Committed by Ingo Molnar Jul 21, 2011

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@tu-ilmenau.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-ns12mnd2h5w8rb9agd8hnsfk@git.kernel.org


Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent acb5a9ba

kernel/sched_fair.c

+1 −7

Original line number	Diff line number	Diff line
		@@ -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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