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09c434b8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
0e57976b JH |
2 | /* Tom Kelly's Scalable TCP |
3 | * | |
a52b8bd3 | 4 | * See http://www.deneholme.net/tom/scalable/ |
0e57976b JH |
5 | * |
6 | * John Heffner <jheffner@sc.edu> | |
7 | */ | |
8 | ||
0e57976b JH |
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 | ||
24901551 | 19 | static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked) |
0e57976b | 20 | { |
6687e988 | 21 | struct tcp_sock *tp = tcp_sk(sk); |
f4805ede | 22 | |
24901551 | 23 | if (!tcp_is_cwnd_limited(sk)) |
0e57976b JH |
24 | return; |
25 | ||
071d5080 | 26 | if (tcp_in_slow_start(tp)) |
9f9843a7 | 27 | tcp_slow_start(tp, acked); |
758ce5c8 | 28 | else |
e73ebb08 NC |
29 | tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT), |
30 | 1); | |
0e57976b JH |
31 | } |
32 | ||
6687e988 | 33 | static u32 tcp_scalable_ssthresh(struct sock *sk) |
0e57976b | 34 | { |
6687e988 | 35 | const struct tcp_sock *tp = tcp_sk(sk); |
688d1945 | 36 | |
0e57976b JH |
37 | return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U); |
38 | } | |
39 | ||
a252bebe | 40 | static struct tcp_congestion_ops tcp_scalable __read_mostly = { |
0e57976b | 41 | .ssthresh = tcp_scalable_ssthresh, |
f1722a1b | 42 | .undo_cwnd = tcp_reno_undo_cwnd, |
0e57976b | 43 | .cong_avoid = tcp_scalable_cong_avoid, |
0e57976b JH |
44 | |
45 | .owner = THIS_MODULE, | |
46 | .name = "scalable", | |
47 | }; | |
48 | ||
49 | static int __init tcp_scalable_register(void) | |
50 | { | |
51 | return tcp_register_congestion_control(&tcp_scalable); | |
52 | } | |
53 | ||
54 | static void __exit tcp_scalable_unregister(void) | |
55 | { | |
56 | tcp_unregister_congestion_control(&tcp_scalable); | |
57 | } | |
58 | ||
59 | module_init(tcp_scalable_register); | |
60 | module_exit(tcp_scalable_unregister); | |
61 | ||
62 | MODULE_AUTHOR("John Heffner"); | |
63 | MODULE_LICENSE("GPL"); | |
64 | MODULE_DESCRIPTION("Scalable TCP"); |