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