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| author | Eric Dumazet <edumazet@google.com> | 2018-11-07 01:25:52 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-11-07 01:59:27 +0300 |
| commit | 0b215b9798640a542c526e3ae69dee83861a4aee (patch) | |
| tree | 8fd33e25e96051f31213de5f5f02ec2f03417a93 | |
| parent | 5e1abdc3fe56939d9ac34209706b1a527b77b61b (diff) | |
| download | linux-0b215b9798640a542c526e3ae69dee83861a4aee.tar.xz | |
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>
| -rw-r--r-- | net/ipv6/ip6_offload.c | 13 |
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; |