[PATCH v4 12/13] fair.c: Use generic rbtree impl in fair scheduler

Daniel Santos
2012-06-23T04:08:00Z

---
kernel/sched/fair.c | 82 +++++++++++++++++----------------------------------
1 files changed, 27 insertions(+), 55 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c099cc6..ac12e303 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -447,6 +447,20 @@ 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;
@@ -472,56 +486,14 @@ static void update_min_vruntime(struct cfs_rq *cfs_rq)
#endif
}

-/*
- * Enqueue an entity into the rb-tree:
- */
-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);
-}
-
-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);
-}
+RB_DEFINE_INTERFACE(
+ fair_tree,
+ struct cfs_rq, tasks_timeline, rb_leftmost, /* no right or count */, ,
+ struct sched_entity, run_node, vruntime,
+ 0, compare_vruntime, /* no augment */,
+ /* find unused */ ,
+ static __flatten, /* let gcc decide rather or not to inline insert */
+ /* find_near unused */, /* insert_near unused */)

struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
{
@@ -1108,7 +1080,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
update_stats_enqueue(cfs_rq, se);
check_spread(cfs_rq, se);
if (se != cfs_rq->curr)
- __enqueue_entity(cfs_rq, se);
+ fair_tree_insert(cfs_rq, se);
se->on_rq = 1;

if (cfs_rq->nr_running == 1) {
@@ -1189,7 +1161,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
clear_buddies(cfs_rq, se);

if (se != cfs_rq->curr)
- __dequeue_entity(cfs_rq, se);
+ fair_tree_remove(cfs_rq, se);
se->on_rq = 0;
update_cfs_load(cfs_rq, 0);
account_entity_dequeue(cfs_rq, se);
@@ -1260,7 +1232,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
* runqueue.
*/
update_stats_wait_end(cfs_rq, se);
- __dequeue_entity(cfs_rq, se);
+ fair_tree_remove(cfs_rq, se);
}

update_stats_curr_start(cfs_rq, se);
@@ -1339,7 +1311,7 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
if (prev->on_rq) {
update_stats_wait_start(cfs_rq, prev);
/* Put 'current' back into the tree. */
- __enqueue_entity(cfs_rq, prev);
+ fair_tree_insert(cfs_rq, prev);
}
cfs_rq->curr = NULL;
}
@@ -3593,7 +3565,7 @@ void update_group_power(struct sched_domain *sd, int cpu)
/*
* !SD_OVERLAP domains can assume that child groups
* span the current group.
- */
+ */

group = child->groups;
do {
--
1.7.3.4