[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/pipe.c b/fs/pipe.c
index d976866..4384c92 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -675,7 +675,7 @@
return NULL;
}
-static struct vfsmount *pipe_mnt;
+static struct vfsmount *pipe_mnt __read_mostly;
static int pipefs_delete_dentry(struct dentry *dentry)
{
return 1;