diff options
| author | Nick Piggin <npiggin@suse.de> | 2006-06-23 02:03:22 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-23 07:42:49 -0700 |
| commit | 612d6c19db2fd0dc97b0fa370613ecd4a305ffc3 (patch) | |
| tree | 3ab670895b5c3e389ff922192a572cbfd8159d03 /include | |
| parent | 929f97276bcf7f4a95272ed08a85339b98ba210d (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')
| -rw-r--r-- | include/linux/radix-tree.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index dd83cca2800..9158a68140c 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); |