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authorEric Dumazet <edumazet@google.com>2018-11-06 14:25:52 -0800
committerDavid S. Miller <davem@davemloft.net>2018-11-06 14:59:27 -0800
commit0b215b9798640a542c526e3ae69dee83861a4aee (patch)
tree8fd33e25e96051f31213de5f5f02ec2f03417a93 /net/ipv6/ip6_offload.c
parent5e1abdc3fe56939d9ac34209706b1a527b77b61b (diff)
downloadlinux-0b215b9798640a542c526e3ae69dee83861a4aee.tar.bz2
ipv6: gro: do not use slow memcmp() in ipv6_gro_receive()
ipv6_gro_receive() compares 34 bytes using slow memcmp(), while handcoding with a couple of ipv6_addr_equal() is much faster. Before this patch, "perf top -e cycles:pp -C <cpu>" would see memcmp() using ~10% of cpu cycles on a 40Gbit NIC receiving IPv6 TCP traffic. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/ip6_offload.c')
-rw-r--r--net/ipv6/ip6_offload.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index c7e495f12011..70f525c33cb6 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -229,14 +229,21 @@ static struct sk_buff *ipv6_gro_receive(struct list_head *head,
* XXX skbs on the gro_list have all been parsed and pulled
* already so we don't need to compare nlen
* (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
- * memcmp() alone below is suffcient, right?
+ * memcmp() alone below is sufficient, right?
*/
if ((first_word & htonl(0xF00FFFFF)) ||
- memcmp(&iph->nexthdr, &iph2->nexthdr,
- nlen - offsetof(struct ipv6hdr, nexthdr))) {
+ !ipv6_addr_equal(&iph->saddr, &iph2->saddr) ||
+ !ipv6_addr_equal(&iph->daddr, &iph2->daddr) ||
+ *(u16 *)&iph->nexthdr != *(u16 *)&iph2->nexthdr) {
+not_same_flow:
NAPI_GRO_CB(p)->same_flow = 0;
continue;
}
+ if (unlikely(nlen > sizeof(struct ipv6hdr))) {
+ if (memcmp(iph + 1, iph2 + 1,
+ nlen - sizeof(struct ipv6hdr)))
+ goto not_same_flow;
+ }
/* flush if Traffic Class fields are different */
NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
NAPI_GRO_CB(p)->flush |= flush;