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 7/8. |
14 | */ |
15 | #define TCP_SCALABLE_AI_CNT 100U |
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 | acked = tcp_slow_start(tp, acked); |
27 | if (!acked) |
28 | return; |
29 | } |
30 | tcp_cong_avoid_ai(tp, min(tcp_snd_cwnd(tp), TCP_SCALABLE_AI_CNT), |
31 | acked); |
32 | } |
33 | |
34 | static u32 tcp_scalable_ssthresh(struct sock *sk) |
35 | { |
36 | const struct tcp_sock *tp = tcp_sk(sk); |
37 | |
38 | return max(tcp_snd_cwnd(tp) - (tcp_snd_cwnd(tp)>>TCP_SCALABLE_MD_SCALE), 2U); |
39 | } |
40 | |
41 | static struct tcp_congestion_ops tcp_scalable __read_mostly = { |
42 | .ssthresh = tcp_scalable_ssthresh, |
43 | .undo_cwnd = tcp_reno_undo_cwnd, |
44 | .cong_avoid = tcp_scalable_cong_avoid, |
45 | |
46 | .owner = THIS_MODULE, |
47 | .name = "scalable" , |
48 | }; |
49 | |
50 | static int __init tcp_scalable_register(void) |
51 | { |
52 | return tcp_register_congestion_control(type: &tcp_scalable); |
53 | } |
54 | |
55 | static void __exit tcp_scalable_unregister(void) |
56 | { |
57 | tcp_unregister_congestion_control(type: &tcp_scalable); |
58 | } |
59 | |
60 | module_init(tcp_scalable_register); |
61 | module_exit(tcp_scalable_unregister); |
62 | |
63 | MODULE_AUTHOR("John Heffner" ); |
64 | MODULE_LICENSE("GPL" ); |
65 | MODULE_DESCRIPTION("Scalable TCP" ); |
66 | |