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 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 u32 in_flight)
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, acked);
28 else
29 tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT));
30}
31
32static u32 tcp_scalable_ssthresh(struct sock *sk)
33{
34 const struct tcp_sock *tp = tcp_sk(sk);
35 return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
36}
37
38
39static struct tcp_congestion_ops tcp_scalable __read_mostly = {
40 .ssthresh = tcp_scalable_ssthresh,
41 .cong_avoid = tcp_scalable_cong_avoid,
42
43 .owner = THIS_MODULE,
44 .name = "scalable",
45};
46
47static int __init tcp_scalable_register(void)
48{
49 return tcp_register_congestion_control(&tcp_scalable);
50}
51
52static void __exit tcp_scalable_unregister(void)
53{
54 tcp_unregister_congestion_control(&tcp_scalable);
55}
56
57module_init(tcp_scalable_register);
58module_exit(tcp_scalable_unregister);
59
60MODULE_AUTHOR("John Heffner");
61MODULE_LICENSE("GPL");
62MODULE_DESCRIPTION("Scalable TCP");