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| 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 /Documentation | |
| parent | 929f97276bcf7f4a95272ed08a85339b98ba210d (diff) | |
| download | linux-612d6c19db2fd0dc97b0fa370613ecd4a305ffc3.tar.bz2 | |
[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 'Documentation')
0 files changed, 0 insertions, 0 deletions