net: Use a percpu_counter for sockets_allocated

Instead of using one atomic_t per protocol, use a percpu_counter
for "sockets_allocated", to reduce cache line contention on
heavy duty network servers. 

Note : We revert commit (248969ae31e1b3276fc4399d67ce29a5d81e6fd9
net: af_unix can make unix_nr_socks visbile in /proc),
since it is not anymore used after sock_prot_inuse_add() addition

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index cab2458f86fd..26b9030747cc 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1797,7 +1797,7 @@ static int tcp_v4_init_sock(struct sock *sk)
         sk->sk_sndbuf = sysctl_tcp_wmem[1];
         sk->sk_rcvbuf = sysctl_tcp_rmem[1];
 
-        atomic_inc(&tcp_sockets_allocated);
+        percpu_counter_inc(&tcp_sockets_allocated);
 
         return 0;
 }
@@ -1845,7 +1845,7 @@ void tcp_v4_destroy_sock(struct sock *sk)
                 sk->sk_sndmsg_page = NULL;
         }
 
-        atomic_dec(&tcp_sockets_allocated);
+        percpu_counter_dec(&tcp_sockets_allocated);
 }
 
 EXPORT_SYMBOL(tcp_v4_destroy_sock);