Commit | Line | Data |
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0e57976b JH |
1 | /* Tom Kelly's Scalable TCP |
2 | * | |
a52b8bd3 | 3 | * See http://www.deneholme.net/tom/scalable/ |
0e57976b JH |
4 | * |
5 | * John Heffner <jheffner@sc.edu> | |
6 | */ | |
7 | ||
0e57976b JH |
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 | ||
85f7e750 FW |
18 | struct scalable { |
19 | u32 loss_cwnd; | |
20 | }; | |
21 | ||
24901551 | 22 | static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked) |
0e57976b | 23 | { |
6687e988 | 24 | struct tcp_sock *tp = tcp_sk(sk); |
f4805ede | 25 | |
24901551 | 26 | if (!tcp_is_cwnd_limited(sk)) |
0e57976b JH |
27 | return; |
28 | ||
071d5080 | 29 | if (tcp_in_slow_start(tp)) |
9f9843a7 | 30 | tcp_slow_start(tp, acked); |
758ce5c8 | 31 | else |
e73ebb08 NC |
32 | tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT), |
33 | 1); | |
0e57976b JH |
34 | } |
35 | ||
6687e988 | 36 | static u32 tcp_scalable_ssthresh(struct sock *sk) |
0e57976b | 37 | { |
6687e988 | 38 | const struct tcp_sock *tp = tcp_sk(sk); |
85f7e750 FW |
39 | struct scalable *ca = inet_csk_ca(sk); |
40 | ||
41 | ca->loss_cwnd = tp->snd_cwnd; | |
688d1945 | 42 | |
0e57976b JH |
43 | return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U); |
44 | } | |
45 | ||
85f7e750 FW |
46 | static u32 tcp_scalable_cwnd_undo(struct sock *sk) |
47 | { | |
48 | const struct scalable *ca = inet_csk_ca(sk); | |
49 | ||
50 | return max(tcp_sk(sk)->snd_cwnd, ca->loss_cwnd); | |
51 | } | |
52 | ||
a252bebe | 53 | static struct tcp_congestion_ops tcp_scalable __read_mostly = { |
0e57976b | 54 | .ssthresh = tcp_scalable_ssthresh, |
85f7e750 | 55 | .undo_cwnd = tcp_scalable_cwnd_undo, |
0e57976b | 56 | .cong_avoid = tcp_scalable_cong_avoid, |
0e57976b JH |
57 | |
58 | .owner = THIS_MODULE, | |
59 | .name = "scalable", | |
60 | }; | |
61 | ||
62 | static int __init tcp_scalable_register(void) | |
63 | { | |
64 | return tcp_register_congestion_control(&tcp_scalable); | |
65 | } | |
66 | ||
67 | static void __exit tcp_scalable_unregister(void) | |
68 | { | |
69 | tcp_unregister_congestion_control(&tcp_scalable); | |
70 | } | |
71 | ||
72 | module_init(tcp_scalable_register); | |
73 | module_exit(tcp_scalable_unregister); | |
74 | ||
75 | MODULE_AUTHOR("John Heffner"); | |
76 | MODULE_LICENSE("GPL"); | |
77 | MODULE_DESCRIPTION("Scalable TCP"); |