tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/* Tom Kelly's Scalable TCP
2 *
3 * See htt://www-lce.eng.cam.ac.uk/~ctk21/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,
19 u32 in_flight, int flag)
20{
21 struct tcp_sock *tp = tcp_sk(sk);
22
23 if (!tcp_is_cwnd_limited(sk, in_flight))
24 return;
25
26 if (tp->snd_cwnd <= tp->snd_ssthresh)
27 tcp_slow_start(tp);
28 else {
29 tp->snd_cwnd_cnt++;
30 if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){
31 if (tp->snd_cwnd < tp->snd_cwnd_clamp)
32 tp->snd_cwnd++;
33 tp->snd_cwnd_cnt = 0;
34 }
35 }
36}
37
38static u32 tcp_scalable_ssthresh(struct sock *sk)
39{
40 const struct tcp_sock *tp = tcp_sk(sk);
41 return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
42}
43
44
45static struct tcp_congestion_ops tcp_scalable = {
46 .ssthresh = tcp_scalable_ssthresh,
47 .cong_avoid = tcp_scalable_cong_avoid,
48 .min_cwnd = tcp_reno_min_cwnd,
49
50 .owner = THIS_MODULE,
51 .name = "scalable",
52};
53
54static int __init tcp_scalable_register(void)
55{
56 return tcp_register_congestion_control(&tcp_scalable);
57}
58
59static void __exit tcp_scalable_unregister(void)
60{
61 tcp_unregister_congestion_control(&tcp_scalable);
62}
63
64module_init(tcp_scalable_register);
65module_exit(tcp_scalable_unregister);
66
67MODULE_AUTHOR("John Heffner");
68MODULE_LICENSE("GPL");
69MODULE_DESCRIPTION("Scalable TCP");