[PATCH] Use __read_mostly on some hot fs variables

I discovered on oprofile hunting on a SMP platform that dentry lookups were
slowed down because d_hash_mask, d_hash_shift and dentry_hashtable were in
a cache line that contained inodes_stat.  So each time inodes_stats is
changed by a cpu, other cpus have to refill their cache line.

This patch moves some variables to the __read_mostly section, in order to
avoid false sharing.  RCU dentry lookups can go full speed.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/dcookies.c b/fs/dcookies.c
index ef758cfa5565..8749339bf4f6 100644
--- a/fs/dcookies.c
+++ b/fs/dcookies.c
@@ -38,9 +38,9 @@ struct dcookie_struct {
 
 static LIST_HEAD(dcookie_users);
 static DEFINE_MUTEX(dcookie_mutex);
-static kmem_cache_t * dcookie_cache;
-static struct list_head * dcookie_hashtable;
-static size_t hash_size;
+static kmem_cache_t *dcookie_cache __read_mostly;
+static struct list_head *dcookie_hashtable __read_mostly;
+static size_t hash_size __read_mostly;
 
 static inline int is_live(void)
 {