linux/net/ipv4/tcp_scalable.c
Ilpo Järvinen 758ce5c8d1 tcp: add helper for AI algorithm
It seems that implementation in yeah was inconsistent to what
other did as it would increase cwnd one ack earlier than the
others do.

Size benefits:

  bictcp_cong_avoid |  -36
  tcp_cong_avoid_ai |  +52
  bictcp_cong_avoid |  -34
  tcp_scalable_cong_avoid |  -36
  tcp_veno_cong_avoid |  -12
  tcp_yeah_cong_avoid |  -38

= -104 bytes total

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-02 03:00:15 -08:00

62 lines
1.4 KiB
C

/* Tom Kelly's Scalable TCP
*
* See http://www.deneholme.net/tom/scalable/
*
* John Heffner <jheffner@sc.edu>
*/
#include <linux/module.h>
#include <net/tcp.h>
/* These factors derived from the recommended values in the aer:
* .01 and and 7/8. We use 50 instead of 100 to account for
* delayed ack.
*/
#define TCP_SCALABLE_AI_CNT 50U
#define TCP_SCALABLE_MD_SCALE 3
static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
{
struct tcp_sock *tp = tcp_sk(sk);
if (!tcp_is_cwnd_limited(sk, in_flight))
return;
if (tp->snd_cwnd <= tp->snd_ssthresh)
tcp_slow_start(tp);
else
tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT));
}
static u32 tcp_scalable_ssthresh(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
return max(tp->snd_cwnd - (tp->snd_cwnd>>TCP_SCALABLE_MD_SCALE), 2U);
}
static struct tcp_congestion_ops tcp_scalable = {
.ssthresh = tcp_scalable_ssthresh,
.cong_avoid = tcp_scalable_cong_avoid,
.min_cwnd = tcp_reno_min_cwnd,
.owner = THIS_MODULE,
.name = "scalable",
};
static int __init tcp_scalable_register(void)
{
return tcp_register_congestion_control(&tcp_scalable);
}
static void __exit tcp_scalable_unregister(void)
{
tcp_unregister_congestion_control(&tcp_scalable);
}
module_init(tcp_scalable_register);
module_exit(tcp_scalable_unregister);
MODULE_AUTHOR("John Heffner");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Scalable TCP");