[PATCH] x86_64: group memnodemap and memnodeshift in a memnode structure
pfn_to_page() and others need to access both memnode_shift and the very
first bytes of memnodemap[]. If we force memnode_shift to be just before the
memnodemap array, we can reduce the memory footprint to one cache line
instead of two for most setups. This patch introduce a 'memnode' structure
where shift and map[] are carefully placed.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-x86_64/mmzone.h b/include/asm-x86_64/mmzone.h
index 972c935..937f99b 100644
--- a/include/asm-x86_64/mmzone.h
+++ b/include/asm-x86_64/mmzone.h
@@ -15,8 +15,13 @@
#define NODEMAPSIZE 0xfff
/* Simple perfect hash to map physical addresses to node numbers */
-extern int memnode_shift;
-extern u8 memnodemap[NODEMAPSIZE];
+struct memnode {
+ int shift;
+ u8 map[NODEMAPSIZE];
+} ____cacheline_aligned;
+extern struct memnode memnode;
+#define memnode_shift memnode.shift
+#define memnodemap memnode.map
extern struct pglist_data *node_data[];