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gro: Optimise IPv4 packet reception

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As this function can be called more than half a million times for
10GbE, it's important to optimise it as much as we can.

This patch does some obvious changes to use 2-byte and 4-byte
operations instead of byte-oriented ones where possible.  Bit
ops are also used to replace logical ops to reduce branching.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2009-02-08 18:00:39 +00:00 committed by David S. Miller
parent aa4b9f533e
commit a5ad24be72
1 changed files with 7 additions and 6 deletions
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13
net/ipv4/af_inet.c
View file

@ -1263,7 +1263,7 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head,
if (!ops || !ops->gro_receive)
goto out_unlock;
if (iph->version != 4 || iph->ihl != 5)
if (*(u8 *)iph != 0x45)
goto out_unlock;
if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
@ -1281,17 +1281,18 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head,
iph2 = ip_hdr(p);
if (iph->protocol != iph2->protocol ||
iph->tos != iph2->tos ||
memcmp(&iph->saddr, &iph2->saddr, 8)) {
if ((iph->protocol ^ iph2->protocol) |
(iph->tos ^ iph2->tos) |
(iph->saddr ^ iph2->saddr) |
(iph->daddr ^ iph2->daddr)) {
NAPI_GRO_CB(p)->same_flow = 0;
continue;
}
/* All fields must match except length and checksum. */
NAPI_GRO_CB(p)->flush |=
memcmp(&iph->frag_off, &iph2->frag_off, 4) ||
(u16)(ntohs(iph2->id) + NAPI_GRO_CB(p)->count) != id;
(iph->ttl ^ iph2->ttl) |
((u16)(ntohs(iph2->id) + NAPI_GRO_CB(p)->count) ^ id);
NAPI_GRO_CB(p)->flush |= flush;
}