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authorNick Piggin <npiggin@suse.de>2006-06-23 02:03:22 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-23 07:42:49 -0700
commit612d6c19db2fd0dc97b0fa370613ecd4a305ffc3 (patch)
tree3ab670895b5c3e389ff922192a572cbfd8159d03 /include/linux/radix-tree.h
parent929f97276bcf7f4a95272ed08a85339b98ba210d (diff)
[PATCH] radix-tree: direct data
The ability to have height 0 radix trees (a direct pointer to the data item rather than going through a full node->slot) quietly disappeared with old-2.6-bkcvs commit ffee171812d51652f9ba284302d9e5c5cc14bdfd. On 64-bit machines this causes nearly 600 bytes to be used for every <= 4K file in pagecache. Re-introduce this feature, root tags stored in spare ->gfp_mask bits. Simplify radix_tree_delete's complex tag clearing arrangement (which would become even more complex) by just falling back to tag clearing functions (the pagecache radix-tree never uses this path anyway, so the icache savings will mean it's actually a speedup). On my 4GB G5, this saves 8MB RAM per kernel kernel source+object tree in pagecache. Pagecache lookup, insertion, and removal speed for small files will also be improved. This makes RCU radix tree harder, but it's worth it. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/radix-tree.h')
-rw-r--r--include/linux/radix-tree.h5
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index dd83cca28001..9158a68140c9 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -23,6 +23,9 @@
#include <linux/preempt.h>
#include <linux/types.h>
+#define RADIX_TREE_MAX_TAGS 2
+
+/* root tags are stored in gfp_mask, shifted by __GFP_BITS_SHIFT */
struct radix_tree_root {
unsigned int height;
gfp_t gfp_mask;
@@ -45,8 +48,6 @@ do { \
(root)->rnode = NULL; \
} while (0)
-#define RADIX_TREE_MAX_TAGS 2
-
int radix_tree_insert(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_lookup(struct radix_tree_root *, unsigned long);
void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long);