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");

 
 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
18struct scalable {
19	u32 loss_cwnd;
20};
21
22static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
23{
24	struct tcp_sock *tp = tcp_sk(sk);
25
26	if (!tcp_is_cwnd_limited(sk))
27		return;
28
29	if (tcp_in_slow_start(tp))
30		tcp_slow_start(tp, acked);
31	else
32		tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),
33				  1);
34}
35
36static u32 tcp_scalable_ssthresh(struct sock *sk)
37{
38	const struct tcp_sock *tp = tcp_sk(sk);
39	struct scalable *ca = inet_csk_ca(sk);
40
41	ca->loss_cwnd = tp->snd_cwnd;
42
43	return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
44}
45
46static u32 tcp_scalable_cwnd_undo(struct sock *sk)
47{
48	const struct scalable *ca = inet_csk_ca(sk);
49
50	return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd);
51}
52
53static struct tcp_congestion_ops tcp_scalable __read_mostly = {
54	.ssthresh	= tcp_scalable_ssthresh,
55	.undo_cwnd	= tcp_scalable_cwnd_undo,
56	.cong_avoid	= tcp_scalable_cong_avoid,
57
58	.owner		= THIS_MODULE,
59	.name		= "scalable",
60};
61
62static int __init tcp_scalable_register(void)
63{
64	return tcp_register_congestion_control(&tcp_scalable);
65}
66
67static void __exit tcp_scalable_unregister(void)
68{
69	tcp_unregister_congestion_control(&tcp_scalable);
70}
71
72module_init(tcp_scalable_register);
73module_exit(tcp_scalable_unregister);
74
75MODULE_AUTHOR("John Heffner");
76MODULE_LICENSE("GPL");
77MODULE_DESCRIPTION("Scalable TCP");