The patch titled
Subject: rbtree: optimize fetching of sibling node
has been removed from the -mm tree. Its filename was
rbtree-optimize-fetching-of-sibling-node.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Michel Lespinasse <walken@xxxxxxxxxx>
Subject: rbtree: optimize fetching of sibling node
When looking to fetch a node's sibling, we went through a sequence of:
- check if node is the parent's left child
- if it is, then fetch the parent's right child
This can be replaced with:
- fetch the parent's right child as an assumed sibling
- check that node is NOT the fetched child
This avoids fetching the parent's left child when node is actually
that child. Saves a bit on code size, though it doesn't seem to make
a large difference in speed.
Signed-off-by: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Daniel Santos <daniel.santos@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/rbtree.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff -puN lib/rbtree.c~rbtree-optimize-fetching-of-sibling-node lib/rbtree.c
--- a/lib/rbtree.c~rbtree-optimize-fetching-of-sibling-node
+++ a/lib/rbtree.c
@@ -107,8 +107,8 @@ void rb_insert_color(struct rb_node *nod
gparent = rb_red_parent(parent);
- if (parent == gparent->rb_left) {
- tmp = gparent->rb_right;
+ tmp = gparent->rb_right;
+ if (parent != tmp) { /* parent == gparent->rb_left */
if (tmp && rb_is_red(tmp)) {
/*
* Case 1 - color flips
@@ -131,7 +131,8 @@ void rb_insert_color(struct rb_node *nod
continue;
}
- if (parent->rb_right == node) {
+ tmp = parent->rb_right;
+ if (node == tmp) {
/*
* Case 2 - left rotate at parent
*
@@ -151,6 +152,7 @@ void rb_insert_color(struct rb_node *nod
RB_BLACK);
rb_set_parent_color(parent, node, RB_RED);
parent = node;
+ tmp = node->rb_right;
}
/*
@@ -162,7 +164,7 @@ void rb_insert_color(struct rb_node *nod
* / \
* n U
*/
- gparent->rb_left = tmp = parent->rb_right;
+ gparent->rb_left = tmp; /* == parent->rb_right */
parent->rb_right = gparent;
if (tmp)
rb_set_parent_color(tmp, gparent, RB_BLACK);
@@ -180,7 +182,8 @@ void rb_insert_color(struct rb_node *nod
continue;
}
- if (parent->rb_left == node) {
+ tmp = parent->rb_left;
+ if (node == tmp) {
/* Case 2 - right rotate at parent */
parent->rb_left = tmp = node->rb_right;
node->rb_right = parent;
@@ -189,10 +192,11 @@ void rb_insert_color(struct rb_node *nod
RB_BLACK);
rb_set_parent_color(parent, node, RB_RED);
parent = node;
+ tmp = node->rb_left;
}
/* Case 3 - left rotate at gparent */
- gparent->rb_right = tmp = parent->rb_left;
+ gparent->rb_right = tmp; /* == parent->rb_left */
parent->rb_left = gparent;
if (tmp)
rb_set_parent_color(tmp, gparent, RB_BLACK);
@@ -223,8 +227,9 @@ static void __rb_erase_color(struct rb_n
break;
} else if (!parent) {
break;
- } else if (parent->rb_left == node) {
- sibling = parent->rb_right;
+ }
+ sibling = parent->rb_right;
+ if (node != sibling) { /* node == parent->rb_left */
if (rb_is_red(sibling)) {
/*
* Case 1 - left rotate at parent
_
Patches currently in -mm which might be from walken@xxxxxxxxxx are
origin.patch
prio_tree-remove-fix.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
