[linux-2.6-block.git] / net / ipv4 / tcp_scalable.c

/* Tom Kelly's Scalable TCP
 *
 * See htt://www-lce.eng.cam.ac.uk/~ctk21/scalable/
 *
 * John Heffner <jheffner@sc.edu>
 */

#include <linux/module.h>
#include <net/tcp.h>

/* These factors derived from the recommended values in the aer:
 * .01 and and 7/8. We use 50 instead of 100 to account for
 * delayed ack.
 */
#define TCP_SCALABLE_AI_CNT	50U
#define TCP_SCALABLE_MD_SCALE	3

static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
{
	struct tcp_sock *tp = tcp_sk(sk);

	if (!tcp_is_cwnd_limited(sk, in_flight))
		return;

	if (tp->snd_cwnd <= tp->snd_ssthresh)
		tcp_slow_start(tp);
	else {
		tp->snd_cwnd_cnt++;
		if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){
			if (tp->snd_cwnd < tp->snd_cwnd_clamp)
				tp->snd_cwnd++;
			tp->snd_cwnd_cnt = 0;
		}
	}
}

static u32 tcp_scalable_ssthresh(struct sock *sk)
{
	const struct tcp_sock *tp = tcp_sk(sk);
	return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
}


static struct tcp_congestion_ops tcp_scalable = {
	.ssthresh	= tcp_scalable_ssthresh,
	.cong_avoid	= tcp_scalable_cong_avoid,
	.min_cwnd	= tcp_reno_min_cwnd,

	.owner		= THIS_MODULE,
	.name		= "scalable",
};

static int __init tcp_scalable_register(void)
{
	return tcp_register_congestion_control(&tcp_scalable);
}

static void __exit tcp_scalable_unregister(void)
{
	tcp_unregister_congestion_control(&tcp_scalable);
}

module_init(tcp_scalable_register);
module_exit(tcp_scalable_unregister);

MODULE_AUTHOR("John Heffner");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Scalable TCP");
Commit	Line	Data
0e57976b JH	1	/* Tom Kelly's Scalable TCP
	2	*
	3	* See htt://www-lce.eng.cam.ac.uk/~ctk21/scalable/
	4	*
	5	* John Heffner <jheffner@sc.edu>
	6	*/
	7
0e57976b JH	8	#include <linux/module.h>
	9	#include <net/tcp.h>
	10
	11	/* These factors derived from the recommended values in the aer:
	12	* .01 and and 7/8. We use 50 instead of 100 to account for
	13	* delayed ack.
	14	*/
	15	#define TCP_SCALABLE_AI_CNT 50U
	16	#define TCP_SCALABLE_MD_SCALE 3
	17
c3a05c60	18	static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
0e57976b	19	{
6687e988	20	struct tcp_sock *tp = tcp_sk(sk);
f4805ede SH	21
f4805ede SH	22	if (!tcp_is_cwnd_limited(sk, in_flight))
0e57976b JH	23	return;
0e57976b JH	24
7faffa1c SH	25	if (tp->snd_cwnd <= tp->snd_ssthresh)
	26	tcp_slow_start(tp);
	27	else {
0e57976b JH	28	tp->snd_cwnd_cnt++;
0e57976b JH	29	if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){
7faffa1c SH	30	if (tp->snd_cwnd < tp->snd_cwnd_clamp)
7faffa1c SH	31	tp->snd_cwnd++;
0e57976b JH	32	tp->snd_cwnd_cnt = 0;
	33	}
	34	}
0e57976b JH	35	}
0e57976b JH	36
6687e988	37	static u32 tcp_scalable_ssthresh(struct sock *sk)
0e57976b	38	{
6687e988	39	const struct tcp_sock *tp = tcp_sk(sk);
0e57976b JH	40	return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
	41	}
	42
	43
	44	static struct tcp_congestion_ops tcp_scalable = {
	45	.ssthresh = tcp_scalable_ssthresh,
	46	.cong_avoid = tcp_scalable_cong_avoid,
	47	.min_cwnd = tcp_reno_min_cwnd,
	48
	49	.owner = THIS_MODULE,
	50	.name = "scalable",
	51	};
	52
	53	static int __init tcp_scalable_register(void)
	54	{
	55	return tcp_register_congestion_control(&tcp_scalable);
	56	}
	57
	58	static void __exit tcp_scalable_unregister(void)
	59	{
	60	tcp_unregister_congestion_control(&tcp_scalable);
	61	}
	62
	63	module_init(tcp_scalable_register);
	64	module_exit(tcp_scalable_unregister);
	65
	66	MODULE_AUTHOR("John Heffner");
	67	MODULE_LICENSE("GPL");
	68	MODULE_DESCRIPTION("Scalable TCP");