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[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>
This commit is contained in:
Stephen Hemminger 2006-06-05 17:30:56 -07:00 committed by David S. Miller
parent a42e9d6ce8
commit 738980ffa6
1 changed files with 21 additions and 3 deletions
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24
net/ipv4/tcp_highspeed.c
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@ -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 &&