John Heffner | 0e57976 | 2005-06-23 12:29:07 -0700 | [diff] [blame] | 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 | |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 19 | static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 rtt, |
John Heffner | 0e57976 | 2005-06-23 12:29:07 -0700 | [diff] [blame] | 20 | u32 in_flight, int flag) |
| 21 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 22 | struct tcp_sock *tp = tcp_sk(sk); |
John Heffner | 0e57976 | 2005-06-23 12:29:07 -0700 | [diff] [blame] | 23 | if (in_flight < tp->snd_cwnd) |
| 24 | return; |
| 25 | |
| 26 | if (tp->snd_cwnd <= tp->snd_ssthresh) { |
| 27 | tp->snd_cwnd++; |
| 28 | } else { |
| 29 | tp->snd_cwnd_cnt++; |
| 30 | if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){ |
| 31 | tp->snd_cwnd++; |
| 32 | tp->snd_cwnd_cnt = 0; |
| 33 | } |
| 34 | } |
| 35 | tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp); |
| 36 | tp->snd_cwnd_stamp = tcp_time_stamp; |
| 37 | } |
| 38 | |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 39 | static u32 tcp_scalable_ssthresh(struct sock *sk) |
John Heffner | 0e57976 | 2005-06-23 12:29:07 -0700 | [diff] [blame] | 40 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 41 | const struct tcp_sock *tp = tcp_sk(sk); |
John Heffner | 0e57976 | 2005-06-23 12:29:07 -0700 | [diff] [blame] | 42 | return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U); |
| 43 | } |
| 44 | |
| 45 | |
| 46 | static struct tcp_congestion_ops tcp_scalable = { |
| 47 | .ssthresh = tcp_scalable_ssthresh, |
| 48 | .cong_avoid = tcp_scalable_cong_avoid, |
| 49 | .min_cwnd = tcp_reno_min_cwnd, |
| 50 | |
| 51 | .owner = THIS_MODULE, |
| 52 | .name = "scalable", |
| 53 | }; |
| 54 | |
| 55 | static int __init tcp_scalable_register(void) |
| 56 | { |
| 57 | return tcp_register_congestion_control(&tcp_scalable); |
| 58 | } |
| 59 | |
| 60 | static void __exit tcp_scalable_unregister(void) |
| 61 | { |
| 62 | tcp_unregister_congestion_control(&tcp_scalable); |
| 63 | } |
| 64 | |
| 65 | module_init(tcp_scalable_register); |
| 66 | module_exit(tcp_scalable_unregister); |
| 67 | |
| 68 | MODULE_AUTHOR("John Heffner"); |
| 69 | MODULE_LICENSE("GPL"); |
| 70 | MODULE_DESCRIPTION("Scalable TCP"); |