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authorPeter Zijlstra <peterz@infradead.org>2010-05-29 15:31:43 +0200
committerIngo Molnar <mingo@elte.hu>2010-07-05 14:43:50 +0200
commitb945d6b2554d550fe95caadc61e521c0ad71fb9c (patch)
tree0b76cdb978bead82188de40cae6d24bd88d71b7d /lib
parentx86, Calgary: Limit the max PHB number to 256 (diff)
downloadlinux-dev-b945d6b2554d550fe95caadc61e521c0ad71fb9c.tar.xz
linux-dev-b945d6b2554d550fe95caadc61e521c0ad71fb9c.zip
rbtree: Undo augmented trees performance damage and regression
Reimplement augmented RB-trees without sprinkling extra branches all over the RB-tree code (which lives in the scheduler hot path). This approach is 'borrowed' from Fabio's BFQ implementation and relies on traversing the rebalance path after the RB-tree-op to correct the heap property for insertion/removal and make up for the damage done by the tree rotations. For insertion the rebalance path is trivially that from the new node upwards to the root, for removal it is that from the deepest node in the path from the to be removed node that will still be around after the removal. [ This patch also fixes a video driver regression reported by Ali Gholami Rudi - the memtype->subtree_max_end was updated incorrectly. ] Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: Venkatesh Pallipadi <venki@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Ali Gholami Rudi <ali@rudi.ir> Cc: Fabio Checconi <fabio@gandalf.sssup.it> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <1275414172.27810.27961.camel@twins> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to '')
-rw-r--r--lib/rbtree.c116
1 files changed, 72 insertions, 44 deletions
diff --git a/lib/rbtree.c b/lib/rbtree.c
index 15e10b1afdd2..4693f79195d3 100644
--- a/lib/rbtree.c
+++ b/lib/rbtree.c
@@ -44,11 +44,6 @@ static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
else
root->rb_node = right;
rb_set_parent(node, right);
-
- if (root->augment_cb) {
- root->augment_cb(node);
- root->augment_cb(right);
- }
}
static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
@@ -72,20 +67,12 @@ static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
else
root->rb_node = left;
rb_set_parent(node, left);
-
- if (root->augment_cb) {
- root->augment_cb(node);
- root->augment_cb(left);
- }
}
void rb_insert_color(struct rb_node *node, struct rb_root *root)
{
struct rb_node *parent, *gparent;
- if (root->augment_cb)
- root->augment_cb(node);
-
while ((parent = rb_parent(node)) && rb_is_red(parent))
{
gparent = rb_parent(parent);
@@ -240,15 +227,12 @@ void rb_erase(struct rb_node *node, struct rb_root *root)
else
{
struct rb_node *old = node, *left;
- int old_parent_cb = 0;
- int successor_parent_cb = 0;
node = node->rb_right;
while ((left = node->rb_left) != NULL)
node = left;
if (rb_parent(old)) {
- old_parent_cb = 1;
if (rb_parent(old)->rb_left == old)
rb_parent(old)->rb_left = node;
else
@@ -263,10 +247,8 @@ void rb_erase(struct rb_node *node, struct rb_root *root)
if (parent == old) {
parent = node;
} else {
- successor_parent_cb = 1;
if (child)
rb_set_parent(child, parent);
-
parent->rb_left = child;
node->rb_right = old->rb_right;
@@ -277,24 +259,6 @@ void rb_erase(struct rb_node *node, struct rb_root *root)
node->rb_left = old->rb_left;
rb_set_parent(old->rb_left, node);
- if (root->augment_cb) {
- /*
- * Here, three different nodes can have new children.
- * The parent of the successor node that was selected
- * to replace the node to be erased.
- * The node that is getting erased and is now replaced
- * by its successor.
- * The parent of the node getting erased-replaced.
- */
- if (successor_parent_cb)
- root->augment_cb(parent);
-
- root->augment_cb(node);
-
- if (old_parent_cb)
- root->augment_cb(rb_parent(old));
- }
-
goto color;
}
@@ -303,19 +267,15 @@ void rb_erase(struct rb_node *node, struct rb_root *root)
if (child)
rb_set_parent(child, parent);
-
- if (parent) {
+ if (parent)
+ {
if (parent->rb_left == node)
parent->rb_left = child;
else
parent->rb_right = child;
-
- if (root->augment_cb)
- root->augment_cb(parent);
-
- } else {
- root->rb_node = child;
}
+ else
+ root->rb_node = child;
color:
if (color == RB_BLACK)
@@ -323,6 +283,74 @@ void rb_erase(struct rb_node *node, struct rb_root *root)
}
EXPORT_SYMBOL(rb_erase);
+static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data)
+{
+ struct rb_node *parent;
+
+up:
+ func(node, data);
+ parent = rb_parent(node);
+ if (!parent)
+ return;
+
+ if (node == parent->rb_left && parent->rb_right)
+ func(parent->rb_right, data);
+ else if (parent->rb_left)
+ func(parent->rb_left, data);
+
+ node = parent;
+ goto up;
+}
+
+/*
+ * after inserting @node into the tree, update the tree to account for
+ * both the new entry and any damage done by rebalance
+ */
+void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data)
+{
+ if (node->rb_left)
+ node = node->rb_left;
+ else if (node->rb_right)
+ node = node->rb_right;
+
+ rb_augment_path(node, func, data);
+}
+
+/*
+ * before removing the node, find the deepest node on the rebalance path
+ * that will still be there after @node gets removed
+ */
+struct rb_node *rb_augment_erase_begin(struct rb_node *node)
+{
+ struct rb_node *deepest;
+
+ if (!node->rb_right && !node->rb_left)
+ deepest = rb_parent(node);
+ else if (!node->rb_right)
+ deepest = node->rb_left;
+ else if (!node->rb_left)
+ deepest = node->rb_right;
+ else {
+ deepest = rb_next(node);
+ if (deepest->rb_right)
+ deepest = deepest->rb_right;
+ else if (rb_parent(deepest) != node)
+ deepest = rb_parent(deepest);
+ }
+
+ return deepest;
+}
+
+/*
+ * after removal, update the tree to account for the removed entry
+ * and any rebalance damage.
+ */
+void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data)
+{
+ if (node)
+ rb_augment_path(node, func, data);
+}
+
/*
* This function returns the first node (in sort order) of the tree.
*/