Commit a628d29b authored by John Heffner's avatar John Heffner Committed by David S. Miller
Browse files

[TCP]: Add High Speed TCP congestion control module. 



Sally Floyd's high speed TCP congestion control.
This is useful for comparison and research.

Signed-off-by: default avatarJohn Heffner <jheffner@psc.edu>
Signed-off-by: default avatarStephen Hemminger <shemminger@osdl.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 87270762

net/ipv4/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -467,6 +467,17 @@ config TCP_CONG_WESTWOOD 
	TCP Westwood+ significantly increases fairness wrt TCP Reno in

	wired networks and throughput over wireless links.



config TCP_CONG_HSTCP

	tristate "High Speed TCP"

	depends on INET && EXPERIMENTAL

	default n

	---help---

	Sally Floyd's High Speed TCP (RFC 3649) congestion control.

	A modification to TCP's congestion control mechanism for use

	with large congestion windows. A table indicates how much to

	increase the congestion window by when an ACK is received.

 	For more detail	see http://www.icir.org/floyd/hstcp.html



endmenu



source "net/ipv4/ipvs/Kconfig"

net/ipv4/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ obj-$(CONFIG_IP_TCPDIAG) += tcp_diag.o 
obj-$(CONFIG_IP_ROUTE_MULTIPATH_CACHED) += multipath.o

obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o

obj-$(CONFIG_TCP_CONG_WESTWOOD) += tcp_westwood.o

obj-$(CONFIG_TCP_CONG_HSTCP) += tcp_highspeed.o



obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \

		      xfrm4_output.o

net/ipv4/tcp_highspeed.c

0 → 100644
+181 −0
Original line number Diff line number Diff line 
/*

 * Sally Floyd's High Speed TCP (RFC 3649) congestion control

 *

 * See http://www.icir.org/floyd/hstcp.html

 *

 * John Heffner <jheffner@psc.edu>

 */



#include <linux/config.h>

#include <linux/module.h>

#include <net/tcp.h>





/* From AIMD tables from RFC 3649 appendix B,

 * with fixed-point MD scaled <<8.

 */

static const struct hstcp_aimd_val {

        unsigned int cwnd;

        unsigned int md;

} hstcp_aimd_vals[] = {

 {     38,  128, /*  0.50 */ },

 {    118,  112, /*  0.44 */ },

 {    221,  104, /*  0.41 */ },

 {    347,   98, /*  0.38 */ },

 {    495,   93, /*  0.37 */ },

 {    663,   89, /*  0.35 */ },

 {    851,   86, /*  0.34 */ },

 {   1058,   83, /*  0.33 */ },

 {   1284,   81, /*  0.32 */ },

 {   1529,   78, /*  0.31 */ },

 {   1793,   76, /*  0.30 */ },

 {   2076,   74, /*  0.29 */ },

 {   2378,   72, /*  0.28 */ },

 {   2699,   71, /*  0.28 */ },

 {   3039,   69, /*  0.27 */ },

 {   3399,   68, /*  0.27 */ },

 {   3778,   66, /*  0.26 */ },

 {   4177,   65, /*  0.26 */ },

 {   4596,   64, /*  0.25 */ },

 {   5036,   62, /*  0.25 */ },

 {   5497,   61, /*  0.24 */ },

 {   5979,   60, /*  0.24 */ },

 {   6483,   59, /*  0.23 */ },

 {   7009,   58, /*  0.23 */ },

 {   7558,   57, /*  0.22 */ },

 {   8130,   56, /*  0.22 */ },

 {   8726,   55, /*  0.22 */ },

 {   9346,   54, /*  0.21 */ },

 {   9991,   53, /*  0.21 */ },

 {  10661,   52, /*  0.21 */ },

 {  11358,   52, /*  0.20 */ },

 {  12082,   51, /*  0.20 */ },

 {  12834,   50, /*  0.20 */ },

 {  13614,   49, /*  0.19 */ },

 {  14424,   48, /*  0.19 */ },

 {  15265,   48, /*  0.19 */ },

 {  16137,   47, /*  0.19 */ },

 {  17042,   46, /*  0.18 */ },

 {  17981,   45, /*  0.18 */ },

 {  18955,   45, /*  0.18 */ },

 {  19965,   44, /*  0.17 */ },

 {  21013,   43, /*  0.17 */ },

 {  22101,   43, /*  0.17 */ },

 {  23230,   42, /*  0.17 */ },

 {  24402,   41, /*  0.16 */ },

 {  25618,   41, /*  0.16 */ },

 {  26881,   40, /*  0.16 */ },

 {  28193,   39, /*  0.16 */ },

 {  29557,   39, /*  0.15 */ },

 {  30975,   38, /*  0.15 */ },

 {  32450,   38, /*  0.15 */ },

 {  33986,   37, /*  0.15 */ },

 {  35586,   36, /*  0.14 */ },

 {  37253,   36, /*  0.14 */ },

 {  38992,   35, /*  0.14 */ },

 {  40808,   35, /*  0.14 */ },

 {  42707,   34, /*  0.13 */ },

 {  44694,   33, /*  0.13 */ },

 {  46776,   33, /*  0.13 */ },

 {  48961,   32, /*  0.13 */ },

 {  51258,   32, /*  0.13 */ },

 {  53677,   31, /*  0.12 */ },

 {  56230,   30, /*  0.12 */ },

 {  58932,   30, /*  0.12 */ },

 {  61799,   29, /*  0.12 */ },

 {  64851,   28, /*  0.11 */ },

 {  68113,   28, /*  0.11 */ },

 {  71617,   27, /*  0.11 */ },

 {  75401,   26, /*  0.10 */ },

 {  79517,   26, /*  0.10 */ },

 {  84035,   25, /*  0.10 */ },

 {  89053,   24, /*  0.10 */ },

};



#define HSTCP_AIMD_MAX	ARRAY_SIZE(hstcp_aimd_vals)



struct hstcp {

	u32	ai;

};



static void hstcp_init(struct tcp_sock *tp)

{

	struct hstcp *ca = tcp_ca(tp);



	ca->ai = 0;



	/* Ensure the MD arithmetic works.  This is somewhat pedantic,

	 * since I don't think we will see a cwnd this large. :) */

	tp->snd_cwnd_clamp = min_t(u32, tp->snd_cwnd_clamp, 0xffffffff/128);

}



static void hstcp_cong_avoid(struct tcp_sock *tp, u32 adk, u32 rtt,

			     u32 in_flight, int good)

{

	struct hstcp *ca = tcp_ca(tp);



	if (in_flight < tp->snd_cwnd)

		return;



	if (tp->snd_cwnd <= tp->snd_ssthresh) {

		if (tp->snd_cwnd < tp->snd_cwnd_clamp)

			tp->snd_cwnd++;

	} else {

		/* Update AIMD parameters */

		if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) {

			while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&

			       ca->ai < HSTCP_AIMD_MAX)

				ca->ai++;

		} else if (tp->snd_cwnd < hstcp_aimd_vals[ca->ai].cwnd) {

			while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&

			       ca->ai > 0)

				ca->ai--;

		}



		/* Do additive increase */

		if (tp->snd_cwnd < tp->snd_cwnd_clamp) {

			tp->snd_cwnd_cnt += ca->ai;

			if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {

				tp->snd_cwnd++;

				tp->snd_cwnd_cnt -= tp->snd_cwnd;

			}

		}

	}

}



static u32 hstcp_ssthresh(struct tcp_sock *tp)

{

	struct hstcp *ca = tcp_ca(tp);



	/* Do multiplicative decrease */

	return max(tp->snd_cwnd - ((tp->snd_cwnd * hstcp_aimd_vals[ca->ai].md) >> 8), 2U);

}





static struct tcp_congestion_ops tcp_highspeed = {

	.init		= hstcp_init,

	.ssthresh	= hstcp_ssthresh,

	.cong_avoid	= hstcp_cong_avoid,

	.min_cwnd	= tcp_reno_min_cwnd,



	.owner		= THIS_MODULE,

	.name		= "highspeed"

};



static int __init hstcp_register(void)

{

	BUG_ON(sizeof(struct hstcp) > TCP_CA_PRIV_SIZE);

	return tcp_register_congestion_control(&tcp_highspeed);

}



static void __exit hstcp_unregister(void)

{

	tcp_unregister_congestion_control(&tcp_highspeed);

}



module_init(hstcp_register);

module_exit(hstcp_unregister);



MODULE_AUTHOR("John Heffner");

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("High Speed TCP");