From d5274261ea46f0aae93820fe36628249120d2f75 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Sun, 8 Jan 2006 01:01:41 -0800 Subject: [PATCH] [PATCH] radix tree: early termination of tag clearing Correctly determine the tags to be cleared in radix_tree_delete() so we don't keep moving up the tree clearing tags that we don't need to. For example, if a tag is simply not set in the deleted item, nor anywhere up the tree, radix_tree_delete() would attempt to clear it up the entire height of the tree. Also, tag_set() was made conditional so as not to dirty too many cachelines high up in the radix tree. Instead, put this logic into radix_tree_tag_set(). Signed-off-by: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/radix-tree.c | 42 ++++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 18 deletions(-) diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 1403e2c8bb3e..336852f23592 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -137,18 +137,17 @@ out: static inline void tag_set(struct radix_tree_node *node, int tag, int offset) { - if (!test_bit(offset, &node->tags[tag][0])) - __set_bit(offset, &node->tags[tag][0]); + __set_bit(offset, node->tags[tag]); } static inline void tag_clear(struct radix_tree_node *node, int tag, int offset) { - __clear_bit(offset, &node->tags[tag][0]); + __clear_bit(offset, node->tags[tag]); } static inline int tag_get(struct radix_tree_node *node, int tag, int offset) { - return test_bit(offset, &node->tags[tag][0]); + return test_bit(offset, node->tags[tag]); } /* @@ -375,7 +374,8 @@ void *radix_tree_tag_set(struct radix_tree_root *root, int offset; offset = (index >> shift) & RADIX_TREE_MAP_MASK; - tag_set(slot, tag, offset); + if (!tag_get(slot, tag, offset)) + tag_set(slot, tag, offset); slot = slot->slots[offset]; BUG_ON(slot == NULL); shift -= RADIX_TREE_MAP_SHIFT; @@ -435,6 +435,8 @@ void *radix_tree_tag_clear(struct radix_tree_root *root, goto out; do { + if (!tag_get(pathp->node, tag, pathp->offset)) + goto out; tag_clear(pathp->node, tag, pathp->offset); if (any_tag_set(pathp->node, tag)) goto out; @@ -695,6 +697,8 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) void *ret = NULL; char tags[RADIX_TREE_TAGS]; int nr_cleared_tags; + int tag; + int offset; height = root->height; if (index > radix_tree_maxindex(height)) @@ -705,16 +709,14 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) slot = root->rnode; for ( ; height > 0; height--) { - int offset; - if (slot == NULL) goto out; - offset = (index >> shift) & RADIX_TREE_MAP_MASK; - pathp[1].offset = offset; - pathp[1].node = slot; - slot = slot->slots[offset]; pathp++; + offset = (index >> shift) & RADIX_TREE_MAP_MASK; + pathp->offset = offset; + pathp->node = slot; + slot = slot->slots[offset]; shift -= RADIX_TREE_MAP_SHIFT; } @@ -727,24 +729,28 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) /* * Clear all tags associated with the just-deleted item */ - memset(tags, 0, sizeof(tags)); - do { - int tag; + nr_cleared_tags = 0; + for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { + if (tag_get(pathp->node, tag, pathp->offset)) { + tag_clear(pathp->node, tag, pathp->offset); + tags[tag] = 0; + nr_cleared_tags++; + } else + tags[tag] = 1; + } - nr_cleared_tags = RADIX_TREE_TAGS; + for (pathp--; nr_cleared_tags && pathp->node; pathp--) { for (tag = 0; tag < RADIX_TREE_TAGS; tag++) { if (tags[tag]) continue; tag_clear(pathp->node, tag, pathp->offset); - if (any_tag_set(pathp->node, tag)) { tags[tag] = 1; nr_cleared_tags--; } } - pathp--; - } while (pathp->node && nr_cleared_tags); + } /* Now free the nodes we do not need anymore */ for (pathp = orig_pathp; pathp->node; pathp--) {