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Commit a5ad24be authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
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gro: Optimise IPv4 packet reception 



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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent aa4b9f53

net/ipv4/af_inet.c

+7 −6
Original line number Diff line number Diff line
@@ -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;

	}