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0e57976b JH |
1 | /* Tom Kelly's Scalable TCP |
2 | * | |
3 | * See htt://www-lce.eng.cam.ac.uk/~ctk21/scalable/ | |
4 | * | |
5 | * John Heffner <jheffner@sc.edu> | |
6 | */ | |
7 | ||
8 | #include <linux/config.h> | |
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 | ||
6687e988 | 19 | static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 rtt, |
0e57976b JH |
20 | u32 in_flight, int flag) |
21 | { | |
6687e988 | 22 | struct tcp_sock *tp = tcp_sk(sk); |
f4805ede SH |
23 | |
24 | if (!tcp_is_cwnd_limited(sk, in_flight)) | |
0e57976b JH |
25 | return; |
26 | ||
27 | if (tp->snd_cwnd <= tp->snd_ssthresh) { | |
28 | tp->snd_cwnd++; | |
29 | } else { | |
30 | tp->snd_cwnd_cnt++; | |
31 | if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){ | |
32 | tp->snd_cwnd++; | |
33 | tp->snd_cwnd_cnt = 0; | |
34 | } | |
35 | } | |
36 | tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp); | |
37 | tp->snd_cwnd_stamp = tcp_time_stamp; | |
38 | } | |
39 | ||
6687e988 | 40 | static u32 tcp_scalable_ssthresh(struct sock *sk) |
0e57976b | 41 | { |
6687e988 | 42 | const struct tcp_sock *tp = tcp_sk(sk); |
0e57976b JH |
43 | return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U); |
44 | } | |
45 | ||
46 | ||
47 | static struct tcp_congestion_ops tcp_scalable = { | |
48 | .ssthresh = tcp_scalable_ssthresh, | |
49 | .cong_avoid = tcp_scalable_cong_avoid, | |
50 | .min_cwnd = tcp_reno_min_cwnd, | |
51 | ||
52 | .owner = THIS_MODULE, | |
53 | .name = "scalable", | |
54 | }; | |
55 | ||
56 | static int __init tcp_scalable_register(void) | |
57 | { | |
58 | return tcp_register_congestion_control(&tcp_scalable); | |
59 | } | |
60 | ||
61 | static void __exit tcp_scalable_unregister(void) | |
62 | { | |
63 | tcp_unregister_congestion_control(&tcp_scalable); | |
64 | } | |
65 | ||
66 | module_init(tcp_scalable_register); | |
67 | module_exit(tcp_scalable_unregister); | |
68 | ||
69 | MODULE_AUTHOR("John Heffner"); | |
70 | MODULE_LICENSE("GPL"); | |
71 | MODULE_DESCRIPTION("Scalable TCP"); |