inetpeer: Optimize inet_getid()

While investigating for network latencies, I found inet_getid() was a
contention point for some workloads, as inet_peer_idlock is shared
by all inet_getid() users regardless of peers.

One way to fix this is to make ip_id_count an atomic_t instead
of __u16, and use atomic_add_return().

In order to keep sizeof(struct inet_peer) = 64 on 64bit arches
tcp_ts_stamp is also converted to __u32 instead of "unsigned long".

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ff258b57680b..4284ceef7945 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2852,7 +2852,7 @@ static int rt_fill_info(struct net *net,
         error = rt->u.dst.error;
         expires = rt->u.dst.expires ? rt->u.dst.expires - jiffies : 0;
         if (rt->peer) {
-                id = rt->peer->ip_id_count;
+                id = atomic_read(&rt->peer->ip_id_count) & 0xffff;
                 if (rt->peer->tcp_ts_stamp) {
                         ts = rt->peer->tcp_ts;
                         tsage = get_seconds() - rt->peer->tcp_ts_stamp;