[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/arch/x86_64/mm/numa.c b/arch/x86_64/mm/numa.c
index 07471a3..63c7264 100644
--- a/arch/x86_64/mm/numa.c
+++ b/arch/x86_64/mm/numa.c
@@ -25,8 +25,7 @@
struct pglist_data *node_data[MAX_NUMNODES] __read_mostly;
bootmem_data_t plat_node_bdata[MAX_NUMNODES];
-int memnode_shift;
-u8 memnodemap[NODEMAPSIZE];
+struct memnode memnode;
unsigned char cpu_to_node[NR_CPUS] __read_mostly = {
[0 ... NR_CPUS-1] = NUMA_NO_NODE
@@ -367,8 +366,7 @@
EXPORT_SYMBOL(cpu_to_node);
EXPORT_SYMBOL(node_to_cpumask);
-EXPORT_SYMBOL(memnode_shift);
-EXPORT_SYMBOL(memnodemap);
+EXPORT_SYMBOL(memnode);
EXPORT_SYMBOL(node_data);
#ifdef CONFIG_DISCONTIGMEM
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[];