diff options
| author | Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> | 2007-09-20 13:11:07 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2007-09-26 10:54:43 -0700 |
| commit | 6d742fb6e2b8913457e1282e1be77d6f4e45af00 (patch) | |
| tree | 72650556e22def71471f80f1511024bd327b076f /net | |
| parent | eb7bdad82e8af48e1ed1b650268dc85ca7e9ff39 (diff) | |
Fix TCP DSACK cwnd handling
commit 49ff4bb4cd4c04acf8f9e3d3ec2148305a1db445 in mainline.
[TCP]: DSACK signals data receival, be conservative
In case a DSACK is received, it's better to lower cwnd as it's
a sign of data receival.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 091b0617d5b7..5bfda70a6a56 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -103,6 +103,7 @@ int sysctl_tcp_abc __read_mostly; #define FLAG_SLOWPATH 0x100 /* Do not skip RFC checks for window update.*/ #define FLAG_ONLY_ORIG_SACKED 0x200 /* SACKs only non-rexmit sent before RTO */ #define FLAG_SND_UNA_ADVANCED 0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */ +#define FLAG_DSACKING_ACK 0x800 /* SACK blocks contained DSACK info */ #define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED) #define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED) @@ -966,12 +967,14 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ /* Check for D-SACK. */ if (before(ntohl(sp[0].start_seq), TCP_SKB_CB(ack_skb)->ack_seq)) { + flag |= FLAG_DSACKING_ACK; found_dup_sack = 1; tp->rx_opt.sack_ok |= 4; NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV); } else if (num_sacks > 1 && !after(ntohl(sp[0].end_seq), ntohl(sp[1].end_seq)) && !before(ntohl(sp[0].start_seq), ntohl(sp[1].start_seq))) { + flag |= FLAG_DSACKING_ACK; found_dup_sack = 1; tp->rx_opt.sack_ok |= 4; NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV); @@ -1858,7 +1861,7 @@ static void tcp_cwnd_down(struct sock *sk, int flag) struct tcp_sock *tp = tcp_sk(sk); int decr = tp->snd_cwnd_cnt + 1; - if ((flag&FLAG_ANY_PROGRESS) || + if ((flag&(FLAG_ANY_PROGRESS|FLAG_DSACKING_ACK)) || (IsReno(tp) && !(flag&FLAG_NOT_DUP))) { tp->snd_cwnd_cnt = decr&1; decr >>= 1; |