]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
[PATCH] radix-tree: direct data
authorNick Piggin <npiggin@suse.de>
Fri, 23 Jun 2006 09:03:22 +0000 (02:03 -0700)
committerLinus Torvalds <torvalds@g5.osdl.org>
Fri, 23 Jun 2006 14:42:49 +0000 (07:42 -0700)
commit612d6c19db2fd0dc97b0fa370613ecd4a305ffc3
tree3ab670895b5c3e389ff922192a572cbfd8159d03
parent929f97276bcf7f4a95272ed08a85339b98ba210d
[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>
include/linux/radix-tree.h
lib/radix-tree.c