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v5.4
  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Sally Floyd's High Speed TCP (RFC 3649) congestion control
  4 *
  5 * See http://www.icir.org/floyd/hstcp.html
  6 *
  7 * John Heffner <jheffner@psc.edu>
  8 */
  9
 10#include <linux/module.h>
 11#include <net/tcp.h>
 12
 13/* From AIMD tables from RFC 3649 appendix B,
 14 * with fixed-point MD scaled <<8.
 15 */
 16static const struct hstcp_aimd_val {
 17	unsigned int cwnd;
 18	unsigned int md;
 19} hstcp_aimd_vals[] = {
 20	{     38,  128, /*  0.50 */ },
 21	{    118,  112, /*  0.44 */ },
 22	{    221,  104, /*  0.41 */ },
 23	{    347,   98, /*  0.38 */ },
 24	{    495,   93, /*  0.37 */ },
 25	{    663,   89, /*  0.35 */ },
 26	{    851,   86, /*  0.34 */ },
 27	{   1058,   83, /*  0.33 */ },
 28	{   1284,   81, /*  0.32 */ },
 29	{   1529,   78, /*  0.31 */ },
 30	{   1793,   76, /*  0.30 */ },
 31	{   2076,   74, /*  0.29 */ },
 32	{   2378,   72, /*  0.28 */ },
 33	{   2699,   71, /*  0.28 */ },
 34	{   3039,   69, /*  0.27 */ },
 35	{   3399,   68, /*  0.27 */ },
 36	{   3778,   66, /*  0.26 */ },
 37	{   4177,   65, /*  0.26 */ },
 38	{   4596,   64, /*  0.25 */ },
 39	{   5036,   62, /*  0.25 */ },
 40	{   5497,   61, /*  0.24 */ },
 41	{   5979,   60, /*  0.24 */ },
 42	{   6483,   59, /*  0.23 */ },
 43	{   7009,   58, /*  0.23 */ },
 44	{   7558,   57, /*  0.22 */ },
 45	{   8130,   56, /*  0.22 */ },
 46	{   8726,   55, /*  0.22 */ },
 47	{   9346,   54, /*  0.21 */ },
 48	{   9991,   53, /*  0.21 */ },
 49	{  10661,   52, /*  0.21 */ },
 50	{  11358,   52, /*  0.20 */ },
 51	{  12082,   51, /*  0.20 */ },
 52	{  12834,   50, /*  0.20 */ },
 53	{  13614,   49, /*  0.19 */ },
 54	{  14424,   48, /*  0.19 */ },
 55	{  15265,   48, /*  0.19 */ },
 56	{  16137,   47, /*  0.19 */ },
 57	{  17042,   46, /*  0.18 */ },
 58	{  17981,   45, /*  0.18 */ },
 59	{  18955,   45, /*  0.18 */ },
 60	{  19965,   44, /*  0.17 */ },
 61	{  21013,   43, /*  0.17 */ },
 62	{  22101,   43, /*  0.17 */ },
 63	{  23230,   42, /*  0.17 */ },
 64	{  24402,   41, /*  0.16 */ },
 65	{  25618,   41, /*  0.16 */ },
 66	{  26881,   40, /*  0.16 */ },
 67	{  28193,   39, /*  0.16 */ },
 68	{  29557,   39, /*  0.15 */ },
 69	{  30975,   38, /*  0.15 */ },
 70	{  32450,   38, /*  0.15 */ },
 71	{  33986,   37, /*  0.15 */ },
 72	{  35586,   36, /*  0.14 */ },
 73	{  37253,   36, /*  0.14 */ },
 74	{  38992,   35, /*  0.14 */ },
 75	{  40808,   35, /*  0.14 */ },
 76	{  42707,   34, /*  0.13 */ },
 77	{  44694,   33, /*  0.13 */ },
 78	{  46776,   33, /*  0.13 */ },
 79	{  48961,   32, /*  0.13 */ },
 80	{  51258,   32, /*  0.13 */ },
 81	{  53677,   31, /*  0.12 */ },
 82	{  56230,   30, /*  0.12 */ },
 83	{  58932,   30, /*  0.12 */ },
 84	{  61799,   29, /*  0.12 */ },
 85	{  64851,   28, /*  0.11 */ },
 86	{  68113,   28, /*  0.11 */ },
 87	{  71617,   27, /*  0.11 */ },
 88	{  75401,   26, /*  0.10 */ },
 89	{  79517,   26, /*  0.10 */ },
 90	{  84035,   25, /*  0.10 */ },
 91	{  89053,   24, /*  0.10 */ },
 92};
 93
 94#define HSTCP_AIMD_MAX	ARRAY_SIZE(hstcp_aimd_vals)
 95
 96struct hstcp {
 97	u32	ai;
 98};
 99
100static void hstcp_init(struct sock *sk)
101{
102	struct tcp_sock *tp = tcp_sk(sk);
103	struct hstcp *ca = inet_csk_ca(sk);
104
105	ca->ai = 0;
106
107	/* Ensure the MD arithmetic works.  This is somewhat pedantic,
108	 * since I don't think we will see a cwnd this large. :) */
109	tp->snd_cwnd_clamp = min_t(u32, tp->snd_cwnd_clamp, 0xffffffff/128);
110}
111
112static void hstcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
113{
114	struct tcp_sock *tp = tcp_sk(sk);
115	struct hstcp *ca = inet_csk_ca(sk);
116
117	if (!tcp_is_cwnd_limited(sk))
118		return;
119
120	if (tcp_in_slow_start(tp))
121		tcp_slow_start(tp, acked);
122	else {
123		/* Update AIMD parameters.
124		 *
125		 * We want to guarantee that:
126		 *     hstcp_aimd_vals[ca->ai-1].cwnd <
127		 *     snd_cwnd <=
128		 *     hstcp_aimd_vals[ca->ai].cwnd
129		 */
130		if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) {
131			while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&
132			       ca->ai < HSTCP_AIMD_MAX - 1)
133				ca->ai++;
134		} else if (ca->ai && tp->snd_cwnd <= hstcp_aimd_vals[ca->ai-1].cwnd) {
135			while (ca->ai && tp->snd_cwnd <= hstcp_aimd_vals[ca->ai-1].cwnd)
136				ca->ai--;
137		}
138
139		/* Do additive increase */
140		if (tp->snd_cwnd < tp->snd_cwnd_clamp) {
141			/* cwnd = cwnd + a(w) / cwnd */
142			tp->snd_cwnd_cnt += ca->ai + 1;
143			if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
144				tp->snd_cwnd_cnt -= tp->snd_cwnd;
145				tp->snd_cwnd++;
146			}
147		}
148	}
149}
150
151static u32 hstcp_ssthresh(struct sock *sk)
152{
153	const struct tcp_sock *tp = tcp_sk(sk);
154	struct hstcp *ca = inet_csk_ca(sk);
155
156	/* Do multiplicative decrease */
157	return max(tp->snd_cwnd - ((tp->snd_cwnd * hstcp_aimd_vals[ca->ai].md) >> 8), 2U);
158}
159
160static struct tcp_congestion_ops tcp_highspeed __read_mostly = {
161	.init		= hstcp_init,
162	.ssthresh	= hstcp_ssthresh,
163	.undo_cwnd	= tcp_reno_undo_cwnd,
164	.cong_avoid	= hstcp_cong_avoid,
165
166	.owner		= THIS_MODULE,
167	.name		= "highspeed"
168};
169
170static int __init hstcp_register(void)
171{
172	BUILD_BUG_ON(sizeof(struct hstcp) > ICSK_CA_PRIV_SIZE);
173	return tcp_register_congestion_control(&tcp_highspeed);
174}
175
176static void __exit hstcp_unregister(void)
177{
178	tcp_unregister_congestion_control(&tcp_highspeed);
179}
180
181module_init(hstcp_register);
182module_exit(hstcp_unregister);
183
184MODULE_AUTHOR("John Heffner");
185MODULE_LICENSE("GPL");
186MODULE_DESCRIPTION("High Speed TCP");
v6.9.4
  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Sally Floyd's High Speed TCP (RFC 3649) congestion control
  4 *
  5 * See https://www.icir.org/floyd/hstcp.html
  6 *
  7 * John Heffner <jheffner@psc.edu>
  8 */
  9
 10#include <linux/module.h>
 11#include <net/tcp.h>
 12
 13/* From AIMD tables from RFC 3649 appendix B,
 14 * with fixed-point MD scaled <<8.
 15 */
 16static const struct hstcp_aimd_val {
 17	unsigned int cwnd;
 18	unsigned int md;
 19} hstcp_aimd_vals[] = {
 20	{     38,  128, /*  0.50 */ },
 21	{    118,  112, /*  0.44 */ },
 22	{    221,  104, /*  0.41 */ },
 23	{    347,   98, /*  0.38 */ },
 24	{    495,   93, /*  0.37 */ },
 25	{    663,   89, /*  0.35 */ },
 26	{    851,   86, /*  0.34 */ },
 27	{   1058,   83, /*  0.33 */ },
 28	{   1284,   81, /*  0.32 */ },
 29	{   1529,   78, /*  0.31 */ },
 30	{   1793,   76, /*  0.30 */ },
 31	{   2076,   74, /*  0.29 */ },
 32	{   2378,   72, /*  0.28 */ },
 33	{   2699,   71, /*  0.28 */ },
 34	{   3039,   69, /*  0.27 */ },
 35	{   3399,   68, /*  0.27 */ },
 36	{   3778,   66, /*  0.26 */ },
 37	{   4177,   65, /*  0.26 */ },
 38	{   4596,   64, /*  0.25 */ },
 39	{   5036,   62, /*  0.25 */ },
 40	{   5497,   61, /*  0.24 */ },
 41	{   5979,   60, /*  0.24 */ },
 42	{   6483,   59, /*  0.23 */ },
 43	{   7009,   58, /*  0.23 */ },
 44	{   7558,   57, /*  0.22 */ },
 45	{   8130,   56, /*  0.22 */ },
 46	{   8726,   55, /*  0.22 */ },
 47	{   9346,   54, /*  0.21 */ },
 48	{   9991,   53, /*  0.21 */ },
 49	{  10661,   52, /*  0.21 */ },
 50	{  11358,   52, /*  0.20 */ },
 51	{  12082,   51, /*  0.20 */ },
 52	{  12834,   50, /*  0.20 */ },
 53	{  13614,   49, /*  0.19 */ },
 54	{  14424,   48, /*  0.19 */ },
 55	{  15265,   48, /*  0.19 */ },
 56	{  16137,   47, /*  0.19 */ },
 57	{  17042,   46, /*  0.18 */ },
 58	{  17981,   45, /*  0.18 */ },
 59	{  18955,   45, /*  0.18 */ },
 60	{  19965,   44, /*  0.17 */ },
 61	{  21013,   43, /*  0.17 */ },
 62	{  22101,   43, /*  0.17 */ },
 63	{  23230,   42, /*  0.17 */ },
 64	{  24402,   41, /*  0.16 */ },
 65	{  25618,   41, /*  0.16 */ },
 66	{  26881,   40, /*  0.16 */ },
 67	{  28193,   39, /*  0.16 */ },
 68	{  29557,   39, /*  0.15 */ },
 69	{  30975,   38, /*  0.15 */ },
 70	{  32450,   38, /*  0.15 */ },
 71	{  33986,   37, /*  0.15 */ },
 72	{  35586,   36, /*  0.14 */ },
 73	{  37253,   36, /*  0.14 */ },
 74	{  38992,   35, /*  0.14 */ },
 75	{  40808,   35, /*  0.14 */ },
 76	{  42707,   34, /*  0.13 */ },
 77	{  44694,   33, /*  0.13 */ },
 78	{  46776,   33, /*  0.13 */ },
 79	{  48961,   32, /*  0.13 */ },
 80	{  51258,   32, /*  0.13 */ },
 81	{  53677,   31, /*  0.12 */ },
 82	{  56230,   30, /*  0.12 */ },
 83	{  58932,   30, /*  0.12 */ },
 84	{  61799,   29, /*  0.12 */ },
 85	{  64851,   28, /*  0.11 */ },
 86	{  68113,   28, /*  0.11 */ },
 87	{  71617,   27, /*  0.11 */ },
 88	{  75401,   26, /*  0.10 */ },
 89	{  79517,   26, /*  0.10 */ },
 90	{  84035,   25, /*  0.10 */ },
 91	{  89053,   24, /*  0.10 */ },
 92};
 93
 94#define HSTCP_AIMD_MAX	ARRAY_SIZE(hstcp_aimd_vals)
 95
 96struct hstcp {
 97	u32	ai;
 98};
 99
100static void hstcp_init(struct sock *sk)
101{
102	struct tcp_sock *tp = tcp_sk(sk);
103	struct hstcp *ca = inet_csk_ca(sk);
104
105	ca->ai = 0;
106
107	/* Ensure the MD arithmetic works.  This is somewhat pedantic,
108	 * since I don't think we will see a cwnd this large. :) */
109	tp->snd_cwnd_clamp = min_t(u32, tp->snd_cwnd_clamp, 0xffffffff/128);
110}
111
112static void hstcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
113{
114	struct tcp_sock *tp = tcp_sk(sk);
115	struct hstcp *ca = inet_csk_ca(sk);
116
117	if (!tcp_is_cwnd_limited(sk))
118		return;
119
120	if (tcp_in_slow_start(tp))
121		tcp_slow_start(tp, acked);
122	else {
123		/* Update AIMD parameters.
124		 *
125		 * We want to guarantee that:
126		 *     hstcp_aimd_vals[ca->ai-1].cwnd <
127		 *     snd_cwnd <=
128		 *     hstcp_aimd_vals[ca->ai].cwnd
129		 */
130		if (tcp_snd_cwnd(tp) > hstcp_aimd_vals[ca->ai].cwnd) {
131			while (tcp_snd_cwnd(tp) > hstcp_aimd_vals[ca->ai].cwnd &&
132			       ca->ai < HSTCP_AIMD_MAX - 1)
133				ca->ai++;
134		} else if (ca->ai && tcp_snd_cwnd(tp) <= hstcp_aimd_vals[ca->ai-1].cwnd) {
135			while (ca->ai && tcp_snd_cwnd(tp) <= hstcp_aimd_vals[ca->ai-1].cwnd)
136				ca->ai--;
137		}
138
139		/* Do additive increase */
140		if (tcp_snd_cwnd(tp) < tp->snd_cwnd_clamp) {
141			/* cwnd = cwnd + a(w) / cwnd */
142			tp->snd_cwnd_cnt += ca->ai + 1;
143			if (tp->snd_cwnd_cnt >= tcp_snd_cwnd(tp)) {
144				tp->snd_cwnd_cnt -= tcp_snd_cwnd(tp);
145				tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) + 1);
146			}
147		}
148	}
149}
150
151static u32 hstcp_ssthresh(struct sock *sk)
152{
153	const struct tcp_sock *tp = tcp_sk(sk);
154	struct hstcp *ca = inet_csk_ca(sk);
155
156	/* Do multiplicative decrease */
157	return max(tcp_snd_cwnd(tp) - ((tcp_snd_cwnd(tp) * hstcp_aimd_vals[ca->ai].md) >> 8), 2U);
158}
159
160static struct tcp_congestion_ops tcp_highspeed __read_mostly = {
161	.init		= hstcp_init,
162	.ssthresh	= hstcp_ssthresh,
163	.undo_cwnd	= tcp_reno_undo_cwnd,
164	.cong_avoid	= hstcp_cong_avoid,
165
166	.owner		= THIS_MODULE,
167	.name		= "highspeed"
168};
169
170static int __init hstcp_register(void)
171{
172	BUILD_BUG_ON(sizeof(struct hstcp) > ICSK_CA_PRIV_SIZE);
173	return tcp_register_congestion_control(&tcp_highspeed);
174}
175
176static void __exit hstcp_unregister(void)
177{
178	tcp_unregister_congestion_control(&tcp_highspeed);
179}
180
181module_init(hstcp_register);
182module_exit(hstcp_unregister);
183
184MODULE_AUTHOR("John Heffner");
185MODULE_LICENSE("GPL");
186MODULE_DESCRIPTION("High Speed TCP");