Commit 738980ff authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
Browse files

[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: default avatarStephen Hemminger <shemminger@osdl.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a42e9d6c

net/ipv4/tcp_highspeed.c

+21 −3
Original line number Diff line number Diff line
@@ -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 &&