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tcp: fix double-counted receiver RTT when leaving receiver fast path

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We should not update ts_recent and call tcp_rcv_rtt_measure_ts() both
before and after going to step5. That wastes CPU and double-counts the
receiver-side RTT sample.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Neal Cardwell 2013-03-04 06:23:05 +00:00 committed by David S. Miller
parent d2123be0e5
commit aab2b4bf22
1 changed files with 3 additions and 3 deletions
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6
net/ipv4/tcp_input.c
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@ -5485,6 +5485,9 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
if (tcp_checksum_complete_user(sk, skb))
goto csum_error;
if ((int)skb->truesize > sk->sk_forward_alloc)
goto step5;
/* Predicted packet is in window by definition.
* seq == rcv_nxt and rcv_wup <= rcv_nxt.
* Hence, check seq<=rcv_wup reduces to:
@ -5496,9 +5499,6 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
tcp_rcv_rtt_measure_ts(sk, skb);
if ((int)skb->truesize > sk->sk_forward_alloc)
goto step5;
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPHITS);
/* Bulk data transfer: receiver */