linux-kernel - [RFC][PATCH 2/7] rbtree, sched/fair: Use rb_add

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Date:   Wed, 29 Apr 2020 17:33:00 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     linux-kernel@...r.kernel.org
Cc:     walken@...gle.com, dave@...olabs.net, mingo@...nel.org,
        tglx@...utronix.de, oleg@...hat.com, irogers@...gle.com,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        peterz@...radead.org
Subject: [RFC][PATCH 2/7] rbtree, sched/fair: Use rb_add_cached()



Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/sched/fair.c |   46 ++++++++++++++--------------------------------
 1 file changed, 14 insertions(+), 32 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -533,12 +533,15 @@ static inline u64 min_vruntime(u64 min_v
 	return min_vruntime;
 }
 
-static inline int entity_before(struct sched_entity *a,
+static inline bool entity_before(struct sched_entity *a,
 				struct sched_entity *b)
 {
 	return (s64)(a->vruntime - b->vruntime) < 0;
 }
 
+#define __node_2_se(node) \
+	rb_entry((node), struct sched_entity, run_node)
+
 static void update_min_vruntime(struct cfs_rq *cfs_rq)
 {
 	struct sched_entity *curr = cfs_rq->curr;
@@ -554,8 +557,7 @@ static void update_min_vruntime(struct c
 	}
 
 	if (leftmost) { /* non-empty tree */
-		struct sched_entity *se;
-		se = rb_entry(leftmost, struct sched_entity, run_node);
+		struct sched_entity *se = __node_2_se(leftmost);
 
 		if (!curr)
 			vruntime = se->vruntime;
@@ -571,37 +573,17 @@ static void update_min_vruntime(struct c
 #endif
 }
 
+static inline bool __entity_less(struct rb_node *a, const struct rb_node *b)
+{
+	return entity_before(__node_2_se(a), __node_2_se(b));
+}
+
 /*
  * 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_root.rb_node;
-	struct rb_node *parent = NULL;
-	struct sched_entity *entry;
-	bool leftmost = true;
-
-	/*
-	 * 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 = false;
-		}
-	}
-
-	rb_link_node(&se->run_node, parent, link);
-	rb_insert_color_cached(&se->run_node,
-			       &cfs_rq->tasks_timeline, leftmost);
+	rb_add_cached(&cfs_rq->tasks_timeline, &se->run_node, __entity_less);
 }
 
 static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
@@ -616,7 +598,7 @@ struct sched_entity *__pick_first_entity
 	if (!left)
 		return NULL;
 
-	return rb_entry(left, struct sched_entity, run_node);
+	return __node_2_se(left);
 }
 
 static struct sched_entity *__pick_next_entity(struct sched_entity *se)
@@ -626,7 +608,7 @@ static struct sched_entity *__pick_next_
 	if (!next)
 		return NULL;
 
-	return rb_entry(next, struct sched_entity, run_node);
+	return __node_2_se(next);
 }
 
 #ifdef CONFIG_SCHED_DEBUG
@@ -637,7 +619,7 @@ struct sched_entity *__pick_last_entity(
 	if (!last)
 		return NULL;
 
-	return rb_entry(last, struct sched_entity, run_node);
+	return __node_2_se(last);
 }
 
 /**************************************************************