From 7d9e5f422150ed00de744e02a80734d74cc9704d Mon Sep 17 00:00:00 2001 From: Wei Wang Date: Thu, 20 Jun 2019 17:36:41 -0700 Subject: ipv6: convert major tx path to use RT6_LOOKUP_F_DST_NOREF For tx path, in most cases, we still have to take refcnt on the dst cause the caller is caching the dst somewhere. But it still is beneficial to make use of RT6_LOOKUP_F_DST_NOREF flag while doing the route lookup. It is cause this flag prevents manipulating refcnt on net->ipv6.ip6_null_entry when doing fib6_rule_lookup() to traverse each routing table. The null_entry is a shared object and constant updates on it cause false sharing. We converted the current major lookup function ip6_route_output_flags() to make use of RT6_LOOKUP_F_DST_NOREF. Together with the change in the rx path, we see noticable performance boost: I ran synflood tests between 2 hosts under the same switch. Both hosts have 20G mlx NIC, and 8 tx/rx queues. Sender sends pure SYN flood with random src IPs and ports using trafgen. Receiver has a simple TCP listener on the target port. Both hosts have multiple custom rules: - For incoming packets, only local table is traversed. - For outgoing packets, 3 tables are traversed to find the route. The packet processing rate on the receiver is as follows: - Before the fix: 3.78Mpps - After the fix: 5.50Mpps Signed-off-by: Wei Wang Signed-off-by: David S. Miller --- include/net/ip6_route.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/net/ip6_route.h') diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h index 0709835c01ad..89ad7917b98d 100644 --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -84,6 +84,10 @@ struct dst_entry *ip6_route_input_lookup(struct net *net, struct flowi6 *fl6, const struct sk_buff *skb, int flags); +struct dst_entry *ip6_route_output_flags_noref(struct net *net, + const struct sock *sk, + struct flowi6 *fl6, int flags); + struct dst_entry *ip6_route_output_flags(struct net *net, const struct sock *sk, struct flowi6 *fl6, int flags); -- cgit v1.2.3-59-g8ed1b