[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>
diff --git a/fs/dnotify.c b/fs/dnotify.c
index f3b540d..f932591 100644
--- a/fs/dnotify.c
+++ b/fs/dnotify.c
@@ -21,9 +21,9 @@
#include <linux/spinlock.h>
#include <linux/slab.h>
-int dir_notify_enable = 1;
+int dir_notify_enable __read_mostly = 1;
-static kmem_cache_t *dn_cache;
+static kmem_cache_t *dn_cache __read_mostly;
static void redo_inode_mask(struct inode *inode)
{
