1 /* Tom Kelly's Scalable TCP 2 * 3 * See http://www.deneholme.net/tom/scalable/ 4 * 5 * John Heffner <jheffner@sc.edu> 6 */ 7 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 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 tcp_slow_start(tp, acked); 27 else 28 tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT), 29 1); 30 } 31 32 static u32 tcp_scalable_ssthresh(struct sock *sk) 33 { 34 const struct tcp_sock *tp = tcp_sk(sk); 35 36 return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U); 37 } 38 39 static struct tcp_congestion_ops tcp_scalable __read_mostly = { 40 .ssthresh = tcp_scalable_ssthresh, 41 .undo_cwnd = tcp_reno_undo_cwnd, 42 .cong_avoid = tcp_scalable_cong_avoid, 43 44 .owner = THIS_MODULE, 45 .name = "scalable", 46 }; 47 48 static int __init tcp_scalable_register(void) 49 { 50 return tcp_register_congestion_control(&tcp_scalable); 51 } 52 53 static void __exit tcp_scalable_unregister(void) 54 { 55 tcp_unregister_congestion_control(&tcp_scalable); 56 } 57 58 module_init(tcp_scalable_register); 59 module_exit(tcp_scalable_unregister); 60 61 MODULE_AUTHOR("John Heffner"); 62 MODULE_LICENSE("GPL"); 63 MODULE_DESCRIPTION("Scalable TCP"); 64