net: ipv4 only populate IP_PKTINFO when needed
The since the removal of the routing cache computing
fib_compute_spec_dst() does a fib_table lookup for each UDP multicast
packet received. This has introduced a performance regression for some
UDP workloads.
This change skips populating the packet info for sockets that do not have
IP_PKTINFO set.
Benchmark results from a netperf UDP_RR test:
Before 89789.68 transactions/s
After 90587.62 transactions/s
Benchmark results from a fio 1 byte UDP multicast pingpong test
(Multicast one way unicast response):
Before 12.63us RTT
After 12.48us RTT
Signed-off-by: Shawn Bohrer <[email protected]>
Acked-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
diff --git a/include/net/ip.h b/include/net/ip.h
index 16078f4..b39ebe5 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -459,7 +459,7 @@
* Functions provided by ip_sockglue.c
*/
-void ipv4_pktinfo_prepare(struct sk_buff *skb);
+void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb);
void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb);
int ip_cmsg_send(struct net *net, struct msghdr *msg, struct ipcm_cookie *ipc);
int ip_setsockopt(struct sock *sk, int level, int optname, char __user *optval,
