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Linux kernel mirror (for testing)
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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");