netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* [PATCH net-next] net: ipv6: Add early demux handler for UDP unicast
@ 2017-03-08 18:24 Subash Abhinov Kasiviswanathan
  2017-03-08 18:40 ` Eric Dumazet
  0 siblings, 1 reply; 8+ messages in thread
From: Subash Abhinov Kasiviswanathan @ 2017-03-08 18:24 UTC (permalink / raw)
  To: netdev, eric.dumazet; +Cc: Subash Abhinov Kasiviswanathan

While running a single stream UDPv6 test, we observed that amount
of CPU spent in NET_RX softirq was much greater than UDPv4 for an
equivalent receive rate. The test here was run on an ARM64 based
Android system. On further analysis with perf, we found that UDPv6
was spending significant time in the statistics netfilter targets
which did socket lookup per packet. These statistics rules perform
a lookup when there is no socket associated with the skb. Since
there are multiple instances of these rules based on UID, there
will be equal number of lookups per skb.

By introducing early demux for UDPv6, we avoid the redundant lookups.
This also helped to improve the performance (800Mbps -> 870Mbps) on a
CPU limited system in a single stream UDPv6 receive test with 1450
byte sized datagrams using iperf.

Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
---
 net/ipv6/udp.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 221825a..76501ce 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -851,6 +851,65 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
 	return 0;
 }
 
+static struct sock *__udp6_lib_demux_lookup(struct net *net,
+			__be16 loc_port, const struct in6_addr *loc_addr,
+			__be16 rmt_port, const struct in6_addr *rmt_addr,
+			int dif)
+{
+	struct sock *sk;
+
+	rcu_read_lock();
+	sk = __udp6_lib_lookup(net, rmt_addr, rmt_port, loc_addr, loc_port,
+			       dif, &udp_table, NULL);
+	if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
+		sk = NULL;
+	rcu_read_unlock();
+
+	return sk;
+}
+
+static void udp_v6_early_demux(struct sk_buff *skb)
+{
+	struct net *net = dev_net(skb->dev);
+	const struct udphdr *uh;
+	struct sock *sk;
+	struct dst_entry *dst;
+	int dif = skb->dev->ifindex;
+
+	if (!pskb_may_pull(skb, skb_transport_offset(skb) +
+	    sizeof(struct udphdr)))
+		return;
+
+	uh = udp_hdr(skb);
+
+	if (skb->pkt_type == PACKET_HOST)
+		sk = __udp6_lib_demux_lookup(net, uh->dest,
+					     &ipv6_hdr(skb)->daddr,
+					     uh->source, &ipv6_hdr(skb)->saddr,
+					     dif);
+	else
+		return;
+
+	if (!sk)
+		return;
+
+	skb->sk = sk;
+
+	skb->destructor = sock_efree;
+	dst = READ_ONCE(sk->sk_rx_dst);
+
+	if (dst)
+		dst = dst_check(dst, 0);
+	if (dst) {
+		if (dst->flags & DST_NOCACHE) {
+			if (likely(atomic_inc_not_zero(&dst->__refcnt)))
+				skb_dst_set(skb, dst);
+		} else {
+			skb_dst_set_noref(skb, dst);
+		}
+	}
+}
+
 static __inline__ int udpv6_rcv(struct sk_buff *skb)
 {
 	return __udp6_lib_rcv(skb, &udp_table, IPPROTO_UDP);
@@ -1365,6 +1424,7 @@ int compat_udpv6_getsockopt(struct sock *sk, int level, int optname,
 #endif
 
 static const struct inet6_protocol udpv6_protocol = {
+	.early_demux	=	udp_v6_early_demux,
 	.handler	=	udpv6_rcv,
 	.err_handler	=	udpv6_err,
 	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2017-04-18 23:07 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-03-08 18:24 [PATCH net-next] net: ipv6: Add early demux handler for UDP unicast Subash Abhinov Kasiviswanathan
2017-03-08 18:40 ` Eric Dumazet
2017-03-08 19:11   ` Subash Abhinov Kasiviswanathan
2017-03-08 19:22     ` Eric Dumazet
2017-04-18  8:09       ` Simon Horman
2017-04-18 15:16         ` David Miller
2017-04-18 18:09           ` Hannes Frederic Sowa
2017-04-18 23:06             ` Simon Horman

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).