diff options
| author | Stephen Hemminger <shemminger@osdl.org> | 2006-06-05 17:30:56 -0700 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2006-06-17 21:29:33 -0700 |
| commit | 738980ffa658c86bd494ebb242ce8e44aff16a9e (patch) | |
| tree | 92076c6d40f3024d760a5439e564473d70511af0 /net | |
| parent | a42e9d6ce89cfd19aee9f990b7231ce697f0d00f (diff) | |
| download | lwn-738980ffa658c86bd494ebb242ce8e44aff16a9e.tar.gz lwn-738980ffa658c86bd494ebb242ce8e44aff16a9e.zip | |
[TCP]: Limited slow start for Highspeed TCP
Implementation of RFC3742 limited slow start. Added as part
of the TCP highspeed congestion control module.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_highspeed.c | 24 |
1 files changed, 21 insertions, 3 deletions
diff --git a/net/ipv4/tcp_highspeed.c b/net/ipv4/tcp_highspeed.c index ba7c63ca5bb1..1120245b2373 100644 --- a/net/ipv4/tcp_highspeed.c +++ b/net/ipv4/tcp_highspeed.c @@ -98,6 +98,10 @@ struct hstcp { u32 ai; }; +static int max_ssthresh = 100; +module_param(max_ssthresh, int, 0644); +MODULE_PARM_DESC(max_ssthresh, "limited slow start threshold (RFC3742)"); + static void hstcp_init(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); @@ -119,9 +123,23 @@ static void hstcp_cong_avoid(struct sock *sk, u32 adk, u32 rtt, if (!tcp_is_cwnd_limited(sk, in_flight)) return; - if (tp->snd_cwnd <= tp->snd_ssthresh) - tcp_slow_start(tp); - else { + if (tp->snd_cwnd <= tp->snd_ssthresh) { + /* RFC3742: limited slow start + * the window is increased by 1/K MSS for each arriving ACK, + * for K = int(cwnd/(0.5 max_ssthresh)) + */ + if (max_ssthresh > 0 && tp->snd_cwnd > max_ssthresh) { + u32 k = max(tp->snd_cwnd / (max_ssthresh >> 1), 1U); + if (++tp->snd_cwnd_cnt >= k) { + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; + tp->snd_cwnd_cnt = 0; + } + } else { + if (tp->snd_cwnd < tp->snd_cwnd_clamp) + tp->snd_cwnd++; + } + } else { /* Update AIMD parameters */ if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) { while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd && |