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authorHerbert Xu <herbert@gondor.apana.org.au>2009-02-08 18:00:40 +0000
committerDavid S. Miller <davem@davemloft.net>2009-02-08 20:22:19 -0800
commitaa6320d336971171df1d13c1c284facf10804881 (patch)
tree3e659464dd24b9634897d631931f334ab1c22179
parenta5ad24be728d4352b71a81fba471aa41eb71f83a (diff)
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>
-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 73266b79c19..90b2f3c192f 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;