[NET]: use __read_mostly on kmem_cache_t , DEFINE_SNMP_STAT pointers

This patch puts mostly read only data in the right section
(read_mostly), to help sharing of these data between CPUS without
memory ping pongs.

On one of my production machine, tcp_statistics was sitting in a
heavily modified cache line, so *every* SNMP update had to force a
reload.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/socket.c b/net/socket.c
index ce69b78..94fe638 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -274,7 +274,7 @@
 
 #define SOCKFS_MAGIC 0x534F434B
 
-static kmem_cache_t * sock_inode_cachep;
+static kmem_cache_t * sock_inode_cachep __read_mostly;
 
 static struct inode *sock_alloc_inode(struct super_block *sb)
 {
@@ -333,7 +333,7 @@
 	return get_sb_pseudo(fs_type, "socket:", &sockfs_ops, SOCKFS_MAGIC);
 }
 
-static struct vfsmount *sock_mnt;
+static struct vfsmount *sock_mnt __read_mostly;
 
 static struct file_system_type sock_fs_type = {
 	.name =		"sockfs",