1/* Tom Kelly's Scalable TCP
 2 *
 3 * See http://www.deneholme.net/tom/scalable/
 4 *
 5 * John Heffner <jheffner@sc.edu>
 6 */
 7
 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
18static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
19{
20	struct tcp_sock *tp = tcp_sk(sk);
21
22	if (!tcp_is_cwnd_limited(sk))
23		return;
24
25	if (tcp_in_slow_start(tp))
26		tcp_slow_start(tp, acked);
27	else
28		tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),
29				  1);
30}
31
32static u32 tcp_scalable_ssthresh(struct sock *sk)
33{
34	const struct tcp_sock *tp = tcp_sk(sk);
35
36	return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
37}
38
 
39static struct tcp_congestion_ops tcp_scalable __read_mostly = {
40	.ssthresh	= tcp_scalable_ssthresh,
41	.undo_cwnd	= tcp_reno_undo_cwnd,
42	.cong_avoid	= tcp_scalable_cong_avoid,
 
43
44	.owner		= THIS_MODULE,
45	.name		= "scalable",
46};
47
48static int __init tcp_scalable_register(void)
49{
50	return tcp_register_congestion_control(&tcp_scalable);
51}
52
53static void __exit tcp_scalable_unregister(void)
54{
55	tcp_unregister_congestion_control(&tcp_scalable);
56}
57
58module_init(tcp_scalable_register);
59module_exit(tcp_scalable_unregister);
60
61MODULE_AUTHOR("John Heffner");
62MODULE_LICENSE("GPL");
63MODULE_DESCRIPTION("Scalable TCP");

 1/* Tom Kelly's Scalable TCP
 2 *
 3 * See http://www.deneholme.net/tom/scalable/
 4 *
 5 * John Heffner <jheffner@sc.edu>
 6 */
 7
 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
18static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
19{
20	struct tcp_sock *tp = tcp_sk(sk);
21
22	if (!tcp_is_cwnd_limited(sk, in_flight))
23		return;
24
25	if (tp->snd_cwnd <= tp->snd_ssthresh)
26		tcp_slow_start(tp);
27	else
28		tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT));
 
29}
30
31static u32 tcp_scalable_ssthresh(struct sock *sk)
32{
33	const struct tcp_sock *tp = tcp_sk(sk);
 
34	return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
35}
36
37
38static struct tcp_congestion_ops tcp_scalable __read_mostly = {
39	.ssthresh	= tcp_scalable_ssthresh,
 
40	.cong_avoid	= tcp_scalable_cong_avoid,
41	.min_cwnd	= tcp_reno_min_cwnd,
42
43	.owner		= THIS_MODULE,
44	.name		= "scalable",
45};
46
47static int __init tcp_scalable_register(void)
48{
49	return tcp_register_congestion_control(&tcp_scalable);
50}
51
52static void __exit tcp_scalable_unregister(void)
53{
54	tcp_unregister_congestion_control(&tcp_scalable);
55}
56
57module_init(tcp_scalable_register);
58module_exit(tcp_scalable_unregister);
59
60MODULE_AUTHOR("John Heffner");
61MODULE_LICENSE("GPL");
62MODULE_DESCRIPTION("Scalable TCP");