1 /* Tom Kelly's Scalable TCP
3 * See http://www.deneholme.net/tom/scalable/
5 * John Heffner <jheffner@sc.edu>
8 #include <linux/module.h>
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
15 #define TCP_SCALABLE_AI_CNT 50U
16 #define TCP_SCALABLE_MD_SCALE 3
22 static void tcp_scalable_cong_avoid(struct sock
*sk
, u32 ack
, u32 acked
)
24 struct tcp_sock
*tp
= tcp_sk(sk
);
26 if (!tcp_is_cwnd_limited(sk
))
29 if (tcp_in_slow_start(tp
))
30 tcp_slow_start(tp
, acked
);
32 tcp_cong_avoid_ai(tp
, min(tp
->snd_cwnd
, TCP_SCALABLE_AI_CNT
),
36 static u32
tcp_scalable_ssthresh(struct sock
*sk
)
38 const struct tcp_sock
*tp
= tcp_sk(sk
);
39 struct scalable
*ca
= inet_csk_ca(sk
);
41 ca
->loss_cwnd
= tp
->snd_cwnd
;
43 return max(tp
->snd_cwnd
- (tp
->snd_cwnd
>>TCP_SCALABLE_MD_SCALE
), 2U);
46 static u32
tcp_scalable_cwnd_undo(struct sock
*sk
)
48 const struct scalable
*ca
= inet_csk_ca(sk
);
50 return max(tcp_sk(sk
)->snd_cwnd
, ca
->loss_cwnd
);
53 static struct tcp_congestion_ops tcp_scalable __read_mostly
= {
54 .ssthresh
= tcp_scalable_ssthresh
,
55 .undo_cwnd
= tcp_scalable_cwnd_undo
,
56 .cong_avoid
= tcp_scalable_cong_avoid
,
62 static int __init
tcp_scalable_register(void)
64 return tcp_register_congestion_control(&tcp_scalable
);
67 static void __exit
tcp_scalable_unregister(void)
69 tcp_unregister_congestion_control(&tcp_scalable
);
72 module_init(tcp_scalable_register
);
73 module_exit(tcp_scalable_unregister
);
75 MODULE_AUTHOR("John Heffner");
76 MODULE_LICENSE("GPL");
77 MODULE_DESCRIPTION("Scalable TCP");