[linux.git] / net / ipv4 / tcp_scalable.c

/* Tom Kelly's Scalable TCP
 *
 * See http://www.deneholme.net/tom/scalable/
 *
 * John Heffner <[email protected]>
 */

#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 acked)
{
	struct tcp_sock *tp = tcp_sk(sk);

	if (!tcp_is_cwnd_limited(sk))
		return;

	if (tcp_in_slow_start(tp))
		tcp_slow_start(tp, acked);
	else
		tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),
				  1);
}

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 __read_mostly = {
	.ssthresh	= tcp_scalable_ssthresh,
	.undo_cwnd	= tcp_reno_undo_cwnd,
	.cong_avoid	= tcp_scalable_cong_avoid,

	.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
0e57976b JH	2	*
a52b8bd3	3	* See http://www.deneholme.net/tom/scalable/
0e57976b JH	4	*
	5	* John Heffner <[email protected]>
	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
24901551	18	static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
0e57976b	19	{
6687e988	20	struct tcp_sock *tp = tcp_sk(sk);
f4805ede	21
24901551	22	if (!tcp_is_cwnd_limited(sk))
0e57976b JH	23	return;
0e57976b JH	24
071d5080	25	if (tcp_in_slow_start(tp))
9f9843a7	26	tcp_slow_start(tp, acked);
758ce5c8	27	else
e73ebb08 NC	28	tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),
e73ebb08 NC	29	1);
0e57976b JH	30	}
0e57976b JH	31
6687e988	32	static u32 tcp_scalable_ssthresh(struct sock *sk)
0e57976b	33	{
6687e988	34	const struct tcp_sock *tp = tcp_sk(sk);
688d1945	35
0e57976b JH	36	return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
	37	}
	38
a252bebe	39	static struct tcp_congestion_ops tcp_scalable __read_mostly = {
0e57976b	40	.ssthresh = tcp_scalable_ssthresh,
f1722a1b	41	.undo_cwnd = tcp_reno_undo_cwnd,
0e57976b	42	.cong_avoid = tcp_scalable_cong_avoid,
0e57976b JH	43
	44	.owner = THIS_MODULE,
	45	.name = "scalable",
	46	};
	47
	48	static int __init tcp_scalable_register(void)
	49	{
	50	return tcp_register_congestion_control(&tcp_scalable);
	51	}
	52
	53	static void __exit tcp_scalable_unregister(void)
	54	{
	55	tcp_unregister_congestion_control(&tcp_scalable);
	56	}
	57
	58	module_init(tcp_scalable_register);
	59	module_exit(tcp_scalable_unregister);
	60
	61	MODULE_AUTHOR("John Heffner");
	62	MODULE_LICENSE("GPL");
	63	MODULE_DESCRIPTION("Scalable TCP");