From: Paolo Abeni <pabeni@redhat.com>
Date: Wed, 20 Nov 2019 13:47:35 +0100
Subject: ipv6: introduce and uses route look hints for list input.
Patch-mainline: v5.5-rc1
Git-commit: 197dbf24e360ed8dbbbe8ed17c2c496f501a0bda
References: bsc#1154353
When doing RX batch packet processing, we currently always repeat
the route lookup for each ingress packet. When no custom rules are
in place, and there aren't routes depending on source addresses,
we know that packets with the same destination address will use
the same dst.
This change tries to avoid per packet route lookup caching
the destination address of the latest successful lookup, and
reusing it for the next packet when the above conditions are
in place. Ingress traffic for most servers should fit.
The measured performance delta under UDP flood vs a recvmmsg
receiver is as follow:
vanilla patched delta
Kpps Kpps %
1431 1674 +17
In the worst-case scenario - each packet has a different
destination address - the performance delta is within noise
range.
v3 -> v4:
- support hints for SUBFLOW build, too (David A.)
- several style fixes (Eric)
v2 -> v3:
- add fib6_has_custom_rules() helpers (David A.)
- add ip6_extract_route_hint() helper (Edward C.)
- use hint directly in ip6_list_rcv_finish() (Willem)
v1 -> v2:
- fix build issue with !CONFIG_IPV6_MULTIPLE_TABLES
- fix potential race when fib6_has_custom_rules is set
while processing a packet batch
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
net/ipv6/ip6_input.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -86,11 +86,27 @@ static void ip6_sublist_rcv_finish(struc
}
}
+static bool ip6_can_use_hint(const struct sk_buff *skb,
+ const struct sk_buff *hint)
+{
+ return hint && !skb_dst(skb) &&
+ ipv6_addr_equal(&ipv6_hdr(hint)->daddr, &ipv6_hdr(skb)->daddr);
+}
+
+static struct sk_buff *ip6_extract_route_hint(const struct net *net,
+ struct sk_buff *skb)
+{
+ if (fib6_routes_require_src(net) || fib6_has_custom_rules(net))
+ return NULL;
+
+ return skb;
+}
+
static void ip6_list_rcv_finish(struct net *net, struct sock *sk,
struct list_head *head)
{
+ struct sk_buff *skb, *next, *hint = NULL;
struct dst_entry *curr_dst = NULL;
- struct sk_buff *skb, *next;
struct list_head sublist;
INIT_LIST_HEAD(&sublist);
@@ -104,9 +120,15 @@ static void ip6_list_rcv_finish(struct n
skb = l3mdev_ip6_rcv(skb);
if (!skb)
continue;
- ip6_rcv_finish_core(net, sk, skb);
+
+ if (ip6_can_use_hint(skb, hint))
+ skb_dst_copy(skb, hint);
+ else
+ ip6_rcv_finish_core(net, sk, skb);
dst = skb_dst(skb);
if (curr_dst != dst) {
+ hint = ip6_extract_route_hint(net, skb);
+
/* dispatch old sublist */
if (!list_empty(&sublist))
ip6_sublist_rcv_finish(&sublist);