[patch 2/3] radix-tree: small

[Nick Piggin]

Reduce radix tree node memory usage by about a factor of 4 for small
files (< 64K). There are pointer traversal and memory usage costs for
large files with dense pagecache.

Signed-off-by: Nick Piggin <npiggin@xxxxxxx>

Index: linux-2.6/lib/radix-tree.c
===================================================================
--- linux-2.6.orig/lib/radix-tree.c
+++ linux-2.6/lib/radix-tree.c
@@ -33,7 +33,7 @@
 
 
 #ifdef __KERNEL__
-#define RADIX_TREE_MAP_SHIFT	6
+#define RADIX_TREE_MAP_SHIFT	(CONFIG_BASE_SMALL ? 4 : 6)
 #else
 #define RADIX_TREE_MAP_SHIFT	3	/* For more stressful testing */
 #endif
-
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