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/queue.h> 63 #include <sys/socket.h> 64 #include <sys/socketvar.h> 65 #include <sys/sysctl.h> 66 #include <sys/systm.h> 67 68 #include <net/vnet.h> 69 70 #include <netinet/in.h> 71 #include <netinet/in_pcb.h> 72 #include <netinet/tcp_seq.h> 73 #include <netinet/tcp_timer.h> 74 #include <netinet/tcp_var.h> 75 #include <netinet/cc/cc.h> 76 #include <netinet/cc/cc_module.h> 77 78 #include <netinet/khelp/h_ertt.h> 79 80 /* Largest possible number returned by random(). */ 81 #define RANDOM_MAX INT_MAX 82 83 static void hd_ack_received(struct cc_var *ccv, uint16_t ack_type); 84 static int hd_mod_init(void); 85 static size_t hd_data_sz(void); 86 87 static int ertt_id; 88 89 VNET_DEFINE_STATIC(uint32_t, hd_qthresh) = 20; 90 VNET_DEFINE_STATIC(uint32_t, hd_qmin) = 5; 91 VNET_DEFINE_STATIC(uint32_t, hd_pmax) = 5; 92 #define V_hd_qthresh VNET(hd_qthresh) 93 #define V_hd_qmin VNET(hd_qmin) 94 #define V_hd_pmax VNET(hd_pmax) 95 96 struct cc_algo hd_cc_algo = { 97 .name = "hd", 98 .ack_received = hd_ack_received, 99 .mod_init = hd_mod_init, 100 .cc_data_sz = hd_data_sz, 101 .after_idle = newreno_cc_after_idle, 102 .cong_signal = newreno_cc_cong_signal, 103 .post_recovery = newreno_cc_post_recovery, 104 }; 105 106 static size_t 107 hd_data_sz(void) 108 { 109 return (0); 110 } 111 112 /* 113 * Hamilton backoff function. Returns 1 if we should backoff or 0 otherwise. 114 */ 115 static __inline int 116 should_backoff(int qdly, int maxqdly) 117 { 118 unsigned long p; 119 120 if (qdly < V_hd_qthresh) { 121 p = (((RANDOM_MAX / 100) * V_hd_pmax) / 122 (V_hd_qthresh - V_hd_qmin)) * (qdly - V_hd_qmin); 123 } else { 124 if (qdly > V_hd_qthresh) 125 p = (((RANDOM_MAX / 100) * V_hd_pmax) / 126 (maxqdly - V_hd_qthresh)) * (maxqdly - qdly); 127 else 128 p = (RANDOM_MAX / 100) * V_hd_pmax; 129 } 130 131 return (random() < p); 132 } 133 134 /* 135 * If the ack type is CC_ACK, and the inferred queueing delay is greater than 136 * the Qmin threshold, cwnd is reduced probabilistically. When backing off due 137 * to delay, HD behaves like NewReno when an ECN signal is received. HD behaves 138 * as NewReno in all other circumstances. 139 */ 140 static void 141 hd_ack_received(struct cc_var *ccv, uint16_t ack_type) 142 { 143 struct ertt *e_t; 144 int qdly; 145 146 if (ack_type == CC_ACK) { 147 e_t = khelp_get_osd(&CCV(ccv, t_osd), ertt_id); 148 149 if (e_t->rtt && e_t->minrtt && V_hd_qthresh > 0) { 150 qdly = e_t->rtt - e_t->minrtt; 151 152 if (qdly > V_hd_qmin && 153 !IN_RECOVERY(CCV(ccv, t_flags))) { 154 /* Probabilistic backoff of cwnd. */ 155 if (should_backoff(qdly, 156 e_t->maxrtt - e_t->minrtt)) { 157 /* 158 * Update cwnd and ssthresh update to 159 * half cwnd and behave like an ECN (ie 160 * not a packet loss). 161 */ 162 newreno_cc_cong_signal(ccv, 163 CC_ECN); 164 return; 165 } 166 } 167 } 168 } 169 newreno_cc_ack_received(ccv, ack_type); 170 } 171 172 static int 173 hd_mod_init(void) 174 { 175 176 ertt_id = khelp_get_id("ertt"); 177 if (ertt_id <= 0) { 178 printf("%s: h_ertt module not found\n", __func__); 179 return (ENOENT); 180 } 181 return (0); 182 } 183 184 static int 185 hd_pmax_handler(SYSCTL_HANDLER_ARGS) 186 { 187 int error; 188 uint32_t new; 189 190 new = V_hd_pmax; 191 error = sysctl_handle_int(oidp, &new, 0, req); 192 if (error == 0 && req->newptr != NULL) { 193 if (new == 0 || new > 100) 194 error = EINVAL; 195 else 196 V_hd_pmax = new; 197 } 198 199 return (error); 200 } 201 202 static int 203 hd_qmin_handler(SYSCTL_HANDLER_ARGS) 204 { 205 int error; 206 uint32_t new; 207 208 new = V_hd_qmin; 209 error = sysctl_handle_int(oidp, &new, 0, req); 210 if (error == 0 && req->newptr != NULL) { 211 if (new > V_hd_qthresh) 212 error = EINVAL; 213 else 214 V_hd_qmin = new; 215 } 216 217 return (error); 218 } 219 220 static int 221 hd_qthresh_handler(SYSCTL_HANDLER_ARGS) 222 { 223 int error; 224 uint32_t new; 225 226 new = V_hd_qthresh; 227 error = sysctl_handle_int(oidp, &new, 0, req); 228 if (error == 0 && req->newptr != NULL) { 229 if (new == 0 || new < V_hd_qmin) 230 error = EINVAL; 231 else 232 V_hd_qthresh = new; 233 } 234 235 return (error); 236 } 237 238 SYSCTL_DECL(_net_inet_tcp_cc_hd); 239 SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, hd, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 240 "Hamilton delay-based congestion control related settings"); 241 242 SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_threshold, 243 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 244 &VNET_NAME(hd_qthresh), 20, &hd_qthresh_handler, "IU", 245 "queueing congestion threshold (qth) in ticks"); 246 247 SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, pmax, 248 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 249 &VNET_NAME(hd_pmax), 5, &hd_pmax_handler, "IU", 250 "per packet maximum backoff probability as a percentage"); 251 252 SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_min, 253 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 254 &VNET_NAME(hd_qmin), 5, &hd_qmin_handler, "IU", 255 "minimum queueing delay threshold (qmin) in ticks"); 256 257 DECLARE_CC_MODULE(hd, &hd_cc_algo); 258 MODULE_VERSION(hd, 2); 259 MODULE_DEPEND(hd, ertt, 1, 1, 1); 260