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/config.h>
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 rtt,
20 u32 in_flight, int flag)
21{
22 struct tcp_sock *tp = tcp_sk(sk);
23
24 if (!tcp_is_cwnd_limited(sk, in_flight))
25 return;
26
27 if (tp->snd_cwnd <= tp->snd_ssthresh)
28 tcp_slow_start(tp);
29 else {
30 tp->snd_cwnd_cnt++;
31 if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){
32 if (tp->snd_cwnd < tp->snd_cwnd_clamp)
33 tp->snd_cwnd++;
34 tp->snd_cwnd_cnt = 0;
35 }
36 }
37}
38
39static u32 tcp_scalable_ssthresh(struct sock *sk)
40{
41 const struct tcp_sock *tp = tcp_sk(sk);
42 return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
43}
44
45
46static struct tcp_congestion_ops tcp_scalable = {
47 .ssthresh = tcp_scalable_ssthresh,
48 .cong_avoid = tcp_scalable_cong_avoid,
49 .min_cwnd = tcp_reno_min_cwnd,
50
51 .owner = THIS_MODULE,
52 .name = "scalable",
53};
54
55static int __init tcp_scalable_register(void)
56{
57 return tcp_register_congestion_control(&tcp_scalable);
58}
59
60static void __exit tcp_scalable_unregister(void)
61{
62 tcp_unregister_congestion_control(&tcp_scalable);
63}
64
65module_init(tcp_scalable_register);
66module_exit(tcp_scalable_unregister);
67
68MODULE_AUTHOR("John Heffner");
69MODULE_LICENSE("GPL");
70MODULE_DESCRIPTION("Scalable TCP");