net/ipv4: add dst cache support for gre lwtunnels

In case of UDP traffic with datagram length below MTU this
gives about 4% performance increase

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Suggested-and-Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 65748db..917c2c1 100644 (file)
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -540,9 +540,16 @@ static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev)
                goto err_free_skb;
 
        key = &tun_info->key;
-       rt = gre_get_rt(skb, dev, &fl, key);
-       if (IS_ERR(rt))
-               goto err_free_skb;
+       rt = !skb->mark ? dst_cache_get_ip4(&tun_info->dst_cache, &fl.saddr) :
+                        NULL;
+       if (!rt) {
+               rt = gre_get_rt(skb, dev, &fl, key);
+               if (IS_ERR(rt))
+                               goto err_free_skb;
+               if (!skb->mark)
+                       dst_cache_set_ip4(&tun_info->dst_cache, &rt->dst,
+                                         fl.saddr);
+       }
 
        tunnel_hlen = ip_gre_calc_hlen(key->tun_flags);