CoCalc -- tcp_highspeed.c

GitHub Repository: awilliam/linux-vfio
Path: blob/master/net/ipv4/tcp_highspeed.c
¹⁵¹⁰⁹ views
1
/*
2
 * Sally Floyd's High Speed TCP (RFC 3649) congestion control
3
 *
4
 * See http://www.icir.org/floyd/hstcp.html
5
 *
6
 * John Heffner <[email protected]>
7
 */
8

9
#include <linux/module.h>
10
#include <net/tcp.h>
11

12

13
/* From AIMD tables from RFC 3649 appendix B,
14
 * with fixed-point MD scaled <<8.
15
 */
16
static 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

96
struct hstcp {
97
	u32	ai;
98
};
99

100
static 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

112
static void hstcp_cong_avoid(struct sock *sk, u32 adk, u32 in_flight)
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, in_flight))
118
		return;
119

120
	if (tp->snd_cwnd <= tp->snd_ssthresh)
121
		tcp_slow_start(tp);
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

151
static u32 hstcp_ssthresh(struct sock *sk)
152
{
153
	const struct tcp_sock *tp = tcp_sk(sk);
154
	const 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

160

161
static struct tcp_congestion_ops tcp_highspeed __read_mostly = {
162
	.init		= hstcp_init,
163
	.ssthresh	= hstcp_ssthresh,
164
	.cong_avoid	= hstcp_cong_avoid,
165
	.min_cwnd	= tcp_reno_min_cwnd,
166

167
	.owner		= THIS_MODULE,
168
	.name		= "highspeed"
169
};
170

171
static int __init hstcp_register(void)
172
{
173
	BUILD_BUG_ON(sizeof(struct hstcp) > ICSK_CA_PRIV_SIZE);
174
	return tcp_register_congestion_control(&tcp_highspeed);
175
}
176

177
static void __exit hstcp_unregister(void)
178
{
179
	tcp_unregister_congestion_control(&tcp_highspeed);
180
}
181

182
module_init(hstcp_register);
183
module_exit(hstcp_unregister);
184

185
MODULE_AUTHOR("John Heffner");
186
MODULE_LICENSE("GPL");
187
MODULE_DESCRIPTION("High Speed TCP");
188

189
Product

Resources

Company
