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[TCP]: Fix stretch ACK performance killer when doing ucopy. 

When we are doing ucopy, we try to defer the ACK generation to
cleanup_rbuf().  This works most of the time very well, but if the
ucopy prequeue is large, this ACKing behavior kills performance.

With TSO, it is possible to fill the prequeue so large that by the
time the ACK is sent and gets back to the sender, most of the window
has emptied of data and performance suffers significantly.

This behavior does help in some cases, so we should think about
re-enabling this trick in the future, using some kind of limit in
order to avoid the bug case.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2005-05-23 12:03:06 -07:00
parent e16fa6b9d2
commit 314324121f
1 changed files with 1 additions and 10 deletions
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11
net/ipv4/tcp_input.c
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@ -4355,16 +4355,7 @@ int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
goto no_ack;
}
if (eaten) {
if (tcp_in_quickack_mode(tp)) {
tcp_send_ack(sk);
} else {
tcp_send_delayed_ack(sk);
}
} else {
__tcp_ack_snd_check(sk, 0);
}
__tcp_ack_snd_check(sk, 0);
no_ack:
if (eaten)
__kfree_skb(skb);