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authorHerbert Xu <herbert@gondor.apana.org.au>2009-02-08 18:00:40 (GMT)
committerDavid S. Miller <davem@davemloft.net>2009-02-09 04:22:19 (GMT)
commitaa6320d336971171df1d13c1c284facf10804881 (patch)
tree3e659464dd24b9634897d631931f334ab1c22179 /net/ipv4
parenta5ad24be728d4352b71a81fba471aa41eb71f83a (diff)
downloadlinux-aa6320d336971171df1d13c1c284facf10804881.tar.xz
gro: Optimise TCP packet reception
gro: Optimise TCP 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 uses bit ops to logical ops, as well as open coding memcmp to exploit alignment properties. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 73266b7..90b2f3c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2478,9 +2478,9 @@ struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
struct tcphdr *th2;
unsigned int thlen;
unsigned int flags;
- unsigned int total;
unsigned int mss = 1;
int flush = 1;
+ int i;
th = skb_gro_header(skb, sizeof(*th));
if (unlikely(!th))
@@ -2504,7 +2504,7 @@ struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
th2 = tcp_hdr(p);
- if (th->source != th2->source || th->dest != th2->dest) {
+ if ((th->source ^ th2->source) | (th->dest ^ th2->dest)) {
NAPI_GRO_CB(p)->same_flow = 0;
continue;
}
@@ -2519,14 +2519,15 @@ found:
flush |= flags & TCP_FLAG_CWR;
flush |= (flags ^ tcp_flag_word(th2)) &
~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH);
- flush |= th->ack_seq != th2->ack_seq || th->window != th2->window;
- flush |= memcmp(th + 1, th2 + 1, thlen - sizeof(*th));
+ flush |= (th->ack_seq ^ th2->ack_seq) | (th->window ^ th2->window);
+ for (i = sizeof(*th); !flush && i < thlen; i += 4)
+ flush |= *(u32 *)((u8 *)th + i) ^
+ *(u32 *)((u8 *)th2 + i);
- total = skb_gro_len(p);
mss = skb_shinfo(p)->gso_size;
- flush |= skb_gro_len(skb) > mss || !skb_gro_len(skb);
- flush |= ntohl(th2->seq) + total != ntohl(th->seq);
+ flush |= (skb_gro_len(skb) > mss) | !skb_gro_len(skb);
+ flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
if (flush || skb_gro_receive(head, skb)) {
mss = 1;