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Date: Thu, 07 Jun 2012 04:16:24 -0500
From: Daniel Santos <danielfsantos@....net>
To: linux-kernel@...r.kernel.org
Subject: [PATCHv3 6/6] [RFC] kernel/sched/fair.c: Use generic rbtree impl
This is what I'm running on my machine currently
Signed-off-by: Daniel Santos <daniel.santos@...ox.com>
---
kernel/sched/fair.c | 77 ++++++++++++++++++++++++---------------------------
1 files changed, 36 insertions(+), 41 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 939fd63..093ae7f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -448,6 +448,20 @@ static inline int entity_before(struct sched_entity *a,
return (s64)(a->vruntime - b->vruntime) < 0;
}
+static inline long compare_vruntime(u64 *a, u64 *b)
+{
+#if __BITS_PER_LONG >= 64
+ return (long)((s64)*a - (s64)*b);
+#else
+/* This is hacky, but is done to reduce instructions -- we wont use this for
+ * rbtree lookups, only inserts, and since our relationship is defined as
+ * non-unique, we only need to return positive if a > b and any other value
+ * means less than.
+ */
+ return (long)(*a > *b);
+#endif
+}
+
static void update_min_vruntime(struct cfs_rq *cfs_rq)
{
u64 vruntime = cfs_rq->min_vruntime;
@@ -473,57 +487,38 @@ static void update_min_vruntime(struct cfs_rq *cfs_rq)
#endif
}
+RB_DEFINE_INTERFACE(
+ fair_tree,
+ struct cfs_rq, tasks_timeline, rb_leftmost, /* no rightmost */,
+ struct sched_entity, run_node, vruntime,
+ 0, compare_vruntime, 0)
+
+#ifndef __flatten
+#define __flatten __attribute__((flatten))
+#endif
+
/*
- * Enqueue an entity into the rb-tree:
+ * Enqueue an entity into the rb-tree:(these are wrappers so that inline
+ * expansion happens in only one place)
+ *
+ * NOTE: When compiling under gcc 4.5 and 4.6 (amd64), it decided to inline
+ * these anyway. I would be interested in profiling this as-is and declaring
+ * each function __flatten noinline (forcing all in-lining in the function, but
+ * preventing them from being inlined themselves). Also, it may not do this on
+ * other archs where the (not sure, gcc docs don't seem to say anything about
+ * arch influence).
*/
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;
- int leftmost = 1;
-
- /*
- * Find the right place in the rbtree:
- */
- while (*link) {
- parent = *link;
- entry = rb_entry(parent, struct sched_entity, run_node);
- /*
- * We dont care about collisions. Nodes with
- * the same key stay together.
- */
- if (entity_before(se, entry)) {
- link = &parent->rb_left;
- } else {
- link = &parent->rb_right;
- leftmost = 0;
- }
- }
-
- /*
- * Maintain a cache of leftmost tree entries (it is frequently
- * used):
- */
- if (leftmost)
- cfs_rq->rb_leftmost = &se->run_node;
-
- rb_link_node(&se->run_node, parent, link);
- rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
+ fair_tree_insert(cfs_rq, se);
}
static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- if (cfs_rq->rb_leftmost == &se->run_node) {
- struct rb_node *next_node;
-
- next_node = rb_next(&se->run_node);
- cfs_rq->rb_leftmost = next_node;
- }
-
- rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
+ fair_tree_remove(cfs_rq, se);
}
+
struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
{
struct rb_node *left = cfs_rq->rb_leftmost;
--
1.7.3.4
--
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