[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>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 68626de6d69c..02fdda68718d 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -269,7 +269,7 @@
 
 int sysctl_tcp_fin_timeout = TCP_FIN_TIMEOUT;
 
-DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics);
+DEFINE_SNMP_STAT(struct tcp_mib, tcp_statistics) __read_mostly;
 
 atomic_t tcp_orphan_count = ATOMIC_INIT(0);