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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>
Herbert Xu 16 роки тому
батько
коміт
aa6320d336
1 змінених файлів з 8 додано та 7 видалено
  1. 8 7
      net/ipv4/tcp.c

+ 8 - 7
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;
 	struct tcphdr *th2;
 	unsigned int thlen;
 	unsigned int thlen;
 	unsigned int flags;
 	unsigned int flags;
-	unsigned int total;
 	unsigned int mss = 1;
 	unsigned int mss = 1;
 	int flush = 1;
 	int flush = 1;
+	int i;
 
 
 	th = skb_gro_header(skb, sizeof(*th));
 	th = skb_gro_header(skb, sizeof(*th));
 	if (unlikely(!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);
 		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;
 			NAPI_GRO_CB(p)->same_flow = 0;
 			continue;
 			continue;
 		}
 		}
@@ -2519,14 +2519,15 @@ found:
 	flush |= flags & TCP_FLAG_CWR;
 	flush |= flags & TCP_FLAG_CWR;
 	flush |= (flags ^ tcp_flag_word(th2)) &
 	flush |= (flags ^ tcp_flag_word(th2)) &
 		  ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH);
 		  ~(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;
 	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)) {
 	if (flush || skb_gro_receive(head, skb)) {
 		mss = 1;
 		mss = 1;