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// SPDX-License-Identifier: GPL-2.0-only
 2/* Tom Kelly's Scalable TCP
 3 *
 4 * See http://www.deneholme.net/tom/scalable/
 5 *
 6 * John Heffner <jheffner@sc.edu>
 7 */
 8
 9#include <linux/module.h>
10#include <net/tcp.h>
11
12/* These factors derived from the recommended values in the aer:
13 * .01 and and 7/8. We use 50 instead of 100 to account for
14 * delayed ack.
15 */
16#define TCP_SCALABLE_AI_CNT	50U
17#define TCP_SCALABLE_MD_SCALE	3
18
19static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
20{
21	struct tcp_sock *tp = tcp_sk(sk);
22
23	if (!tcp_is_cwnd_limited(sk))
24		return;
25
26	if (tcp_in_slow_start(tp))
27		tcp_slow_start(tp, acked);
28	else
29		tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),
30				  1);
31}
32
33static u32 tcp_scalable_ssthresh(struct sock *sk)
34{
35	const struct tcp_sock *tp = tcp_sk(sk);
36
37	return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
38}
39
40static struct tcp_congestion_ops tcp_scalable __read_mostly = {
41	.ssthresh	= tcp_scalable_ssthresh,
42	.undo_cwnd	= tcp_reno_undo_cwnd,
43	.cong_avoid	= tcp_scalable_cong_avoid,
44
45	.owner		= THIS_MODULE,
46	.name		= "scalable",
47};
48
49static int __init tcp_scalable_register(void)
50{
51	return tcp_register_congestion_control(&tcp_scalable);
52}
53
54static void __exit tcp_scalable_unregister(void)
55{
56	tcp_unregister_congestion_control(&tcp_scalable);
57}
58
59module_init(tcp_scalable_register);
60module_exit(tcp_scalable_unregister);
61
62MODULE_AUTHOR("John Heffner");
63MODULE_LICENSE("GPL");
64MODULE_DESCRIPTION("Scalable TCP");