diff options
| author | Neal Cardwell <ncardwell@google.com> | 2011-11-16 12:58:02 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-11-28 03:54:09 +0400 |
| commit | 5628adf1a0ff39b9e76e1a8e1c94dadabfd46914 (patch) | |
| tree | 99f817c26d6405ea23a7e10e34736e38d199b256 /net | |
| parent | 7d2b55f80d62b6b4b72d9ef4318a2a49df3e2830 (diff) | |
| download | linux-5628adf1a0ff39b9e76e1a8e1c94dadabfd46914.tar.xz | |
tcp: use DSACKs that arrive when packets_out is 0
The bug: Senders ignored DSACKs after recovery when there were no
outstanding packets (a common scenario for HTTP servers).
The change: when there are no outstanding packets (the "no_queue" goto
label), call tcp_fastretrans_alert() in order to use DSACKs to undo
congestion window reductions.
Other patches in this series will provide other changes that are
necessary to fully fix this problem.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index f772aaa4319e..b49e41864037 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3788,6 +3788,10 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) return 1; no_queue: + /* If data was DSACKed, see if we can undo a cwnd reduction. */ + if (flag & FLAG_DSACKING_ACK) + tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked, + is_dupack, flag); /* If this ack opens up a zero window, clear backoff. It was * being used to time the probes, and is probably far higher than * it needs to be for normal retransmission. |