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Message-Id: <E1LWNK3-0000nr-26@gondolin.me.apana.org.au>
Date: Mon, 09 Feb 2009 15:00:39 +1100
From: Herbert Xu <herbert@...dor.apana.org.au>
To: "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: [PATCH 3/4] gro: Optimise IPv4 packet reception
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: Herbert Xu <herbert@...dor.apana.org.au>
---
net/ipv4/af_inet.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index c790877..627be4d 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -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;
}
--
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