1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2009-2010
5 * Swinburne University of Technology, Melbourne, Australia
6 * Copyright (c) 2010 Lawrence Stewart <lstewart@freebsd.org>
7 * Copyright (c) 2010-2011 The FreeBSD Foundation
8 * All rights reserved.
9 *
10 * This software was developed at the Centre for Advanced Internet
11 * Architectures, Swinburne University of Technology, by David Hayes and
12 * Lawrence Stewart, made possible in part by a grant from the Cisco University
13 * Research Program Fund at Community Foundation Silicon Valley.
14 *
15 * Portions of this software were developed at the Centre for Advanced Internet
16 * Architectures, Swinburne University of Technology, Melbourne, Australia by
17 * David Hayes under sponsorship from the FreeBSD Foundation.
18 *
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
21 * are met:
22 * 1. Redistributions of source code must retain the above copyright
23 * notice, this list of conditions and the following disclaimer.
24 * 2. Redistributions in binary form must reproduce the above copyright
25 * notice, this list of conditions and the following disclaimer in the
26 * documentation and/or other materials provided with the distribution.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 */
40
41 /*
42 * An implementation of the Hamilton Institute's delay-based congestion control
43 * algorithm for FreeBSD, based on "A strategy for fair coexistence of loss and
44 * delay-based congestion control algorithms," by L. Budzisz, R. Stanojevic, R.
45 * Shorten, and F. Baker, IEEE Commun. Lett., vol. 13, no. 7, pp. 555--557, Jul.
46 * 2009.
47 *
48 * Originally released as part of the NewTCP research project at Swinburne
49 * University of Technology's Centre for Advanced Internet Architectures,
50 * Melbourne, Australia, which was made possible in part by a grant from the
51 * Cisco University Research Program Fund at Community Foundation Silicon
52 * Valley. More details are available at:
53 * http://caia.swin.edu.au/urp/newtcp/
54 */
55
56 #include <sys/param.h>
57 #include <sys/kernel.h>
58 #include <sys/khelp.h>
59 #include <sys/limits.h>
60 #include <sys/malloc.h>
61 #include <sys/module.h>
62 #include <sys/prng.h>
63 #include <sys/queue.h>
64 #include <sys/socket.h>
65 #include <sys/socketvar.h>
66 #include <sys/sysctl.h>
67 #include <sys/systm.h>
68
69 #include <net/vnet.h>
70
71 #include <netinet/in.h>
72 #include <netinet/in_pcb.h>
73 #include <netinet/tcp_seq.h>
74 #include <netinet/tcp_timer.h>
75 #include <netinet/tcp_var.h>
76 #include <netinet/cc/cc.h>
77 #include <netinet/cc/cc_module.h>
78
79 #include <netinet/khelp/h_ertt.h>
80
81 /* Largest possible number returned by prng32(). */
82 #define RANDOM_MAX UINT32_MAX
83
84 static void hd_ack_received(struct cc_var *ccv, ccsignal_t ack_type);
85 static int hd_mod_init(void);
86 static size_t hd_data_sz(void);
87
88 static int ertt_id;
89
90 VNET_DEFINE_STATIC(uint32_t, hd_qthresh) = 20;
91 VNET_DEFINE_STATIC(uint32_t, hd_qmin) = 5;
92 VNET_DEFINE_STATIC(uint32_t, hd_pmax) = 5;
93 #define V_hd_qthresh VNET(hd_qthresh)
94 #define V_hd_qmin VNET(hd_qmin)
95 #define V_hd_pmax VNET(hd_pmax)
96
97 struct cc_algo hd_cc_algo = {
98 .name = "hd",
99 .ack_received = hd_ack_received,
100 .mod_init = hd_mod_init,
101 .cc_data_sz = hd_data_sz,
102 .after_idle = newreno_cc_after_idle,
103 .cong_signal = newreno_cc_cong_signal,
104 .post_recovery = newreno_cc_post_recovery,
105 };
106
107 static size_t
hd_data_sz(void)108 hd_data_sz(void)
109 {
110 return (0);
111 }
112
113 /*
114 * Hamilton backoff function. Returns 1 if we should backoff or 0 otherwise.
115 */
116 static __inline int
should_backoff(int qdly,int maxqdly)117 should_backoff(int qdly, int maxqdly)
118 {
119 unsigned long p;
120
121 if (qdly < V_hd_qthresh) {
122 p = (((RANDOM_MAX / 100) * V_hd_pmax) /
123 (V_hd_qthresh - V_hd_qmin)) * (qdly - V_hd_qmin);
124 } else {
125 if (qdly > V_hd_qthresh)
126 p = (((RANDOM_MAX / 100) * V_hd_pmax) /
127 (maxqdly - V_hd_qthresh)) * (maxqdly - qdly);
128 else
129 p = (RANDOM_MAX / 100) * V_hd_pmax;
130 }
131
132 return (prng32() < p);
133 }
134
135 /*
136 * If the ack type is CC_ACK, and the inferred queueing delay is greater than
137 * the Qmin threshold, cwnd is reduced probabilistically. When backing off due
138 * to delay, HD behaves like NewReno when an ECN signal is received. HD behaves
139 * as NewReno in all other circumstances.
140 */
141 static void
hd_ack_received(struct cc_var * ccv,ccsignal_t ack_type)142 hd_ack_received(struct cc_var *ccv, ccsignal_t ack_type)
143 {
144 struct ertt *e_t;
145 int qdly;
146
147 if (ack_type == CC_ACK) {
148 e_t = khelp_get_osd(&CCV(ccv, t_osd), ertt_id);
149
150 if (e_t->rtt && e_t->minrtt && V_hd_qthresh > 0) {
151 qdly = e_t->rtt - e_t->minrtt;
152
153 if (qdly > V_hd_qmin &&
154 !IN_RECOVERY(CCV(ccv, t_flags))) {
155 /* Probabilistic backoff of cwnd. */
156 if (should_backoff(qdly,
157 e_t->maxrtt - e_t->minrtt)) {
158 /*
159 * Update cwnd and ssthresh update to
160 * half cwnd and behave like an ECN (ie
161 * not a packet loss).
162 */
163 newreno_cc_cong_signal(ccv,
164 CC_ECN);
165 return;
166 }
167 }
168 }
169 }
170 newreno_cc_ack_received(ccv, ack_type);
171 }
172
173 static int
hd_mod_init(void)174 hd_mod_init(void)
175 {
176
177 ertt_id = khelp_get_id("ertt");
178 if (ertt_id <= 0) {
179 printf("%s: h_ertt module not found\n", __func__);
180 return (ENOENT);
181 }
182 return (0);
183 }
184
185 static int
hd_pmax_handler(SYSCTL_HANDLER_ARGS)186 hd_pmax_handler(SYSCTL_HANDLER_ARGS)
187 {
188 int error;
189 uint32_t new;
190
191 new = V_hd_pmax;
192 error = sysctl_handle_int(oidp, &new, 0, req);
193 if (error == 0 && req->newptr != NULL) {
194 if (new == 0 || new > 100)
195 error = EINVAL;
196 else
197 V_hd_pmax = new;
198 }
199
200 return (error);
201 }
202
203 static int
hd_qmin_handler(SYSCTL_HANDLER_ARGS)204 hd_qmin_handler(SYSCTL_HANDLER_ARGS)
205 {
206 int error;
207 uint32_t new;
208
209 new = V_hd_qmin;
210 error = sysctl_handle_int(oidp, &new, 0, req);
211 if (error == 0 && req->newptr != NULL) {
212 if (new > V_hd_qthresh)
213 error = EINVAL;
214 else
215 V_hd_qmin = new;
216 }
217
218 return (error);
219 }
220
221 static int
hd_qthresh_handler(SYSCTL_HANDLER_ARGS)222 hd_qthresh_handler(SYSCTL_HANDLER_ARGS)
223 {
224 int error;
225 uint32_t new;
226
227 new = V_hd_qthresh;
228 error = sysctl_handle_int(oidp, &new, 0, req);
229 if (error == 0 && req->newptr != NULL) {
230 if (new == 0 || new < V_hd_qmin)
231 error = EINVAL;
232 else
233 V_hd_qthresh = new;
234 }
235
236 return (error);
237 }
238
239 SYSCTL_DECL(_net_inet_tcp_cc_hd);
240 SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, hd, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
241 "Hamilton delay-based congestion control related settings");
242
243 SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_threshold,
244 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
245 &VNET_NAME(hd_qthresh), 20, &hd_qthresh_handler, "IU",
246 "queueing congestion threshold (qth) in ticks");
247
248 SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, pmax,
249 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
250 &VNET_NAME(hd_pmax), 5, &hd_pmax_handler, "IU",
251 "per packet maximum backoff probability as a percentage");
252
253 SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_min,
254 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
255 &VNET_NAME(hd_qmin), 5, &hd_qmin_handler, "IU",
256 "minimum queueing delay threshold (qmin) in ticks");
257
258 DECLARE_CC_MODULE(hd, &hd_cc_algo);
259 MODULE_VERSION(hd, 2);
260 MODULE_DEPEND(hd, ertt, 1, 1, 1);
261