1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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 Vegas congestion control algorithm for FreeBSD, 43 * based on L. S. Brakmo and L. L. Peterson, "TCP Vegas: end to end congestion 44 * avoidance on a global internet", IEEE J. Sel. Areas Commun., vol. 13, no. 8, 45 * pp. 1465-1480, Oct. 1995. The original Vegas duplicate ack policy has not 46 * been implemented, since clock ticks are not as coarse as they were (i.e. 47 * 500ms) when Vegas was designed. Also, packets are timed once per RTT as in 48 * the original paper. 49 * 50 * Originally released as part of the NewTCP research project at Swinburne 51 * University of Technology's Centre for Advanced Internet Architectures, 52 * Melbourne, Australia, which was made possible in part by a grant from the 53 * Cisco University Research Program Fund at Community Foundation Silicon 54 * Valley. More details are available at: 55 * http://caia.swin.edu.au/urp/newtcp/ 56 */ 57 58 #include <sys/cdefs.h> 59 __FBSDID("$FreeBSD$"); 60 61 #include <sys/param.h> 62 #include <sys/kernel.h> 63 #include <sys/khelp.h> 64 #include <sys/malloc.h> 65 #include <sys/module.h> 66 #include <sys/queue.h> 67 #include <sys/socket.h> 68 #include <sys/socketvar.h> 69 #include <sys/sysctl.h> 70 #include <sys/systm.h> 71 72 #include <net/vnet.h> 73 74 #include <netinet/tcp.h> 75 #include <netinet/tcp_timer.h> 76 #include <netinet/tcp_var.h> 77 #include <netinet/cc/cc.h> 78 #include <netinet/cc/cc_module.h> 79 80 #include <netinet/khelp/h_ertt.h> 81 82 /* 83 * Private signal type for rate based congestion signal. 84 * See <netinet/cc.h> for appropriate bit-range to use for private signals. 85 */ 86 #define CC_VEGAS_RATE 0x01000000 87 88 static void vegas_ack_received(struct cc_var *ccv, uint16_t ack_type); 89 static void vegas_cb_destroy(struct cc_var *ccv); 90 static int vegas_cb_init(struct cc_var *ccv); 91 static void vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type); 92 static void vegas_conn_init(struct cc_var *ccv); 93 static int vegas_mod_init(void); 94 95 struct vegas { 96 int slow_start_toggle; 97 }; 98 99 static int32_t ertt_id; 100 101 VNET_DEFINE_STATIC(uint32_t, vegas_alpha) = 1; 102 VNET_DEFINE_STATIC(uint32_t, vegas_beta) = 3; 103 #define V_vegas_alpha VNET(vegas_alpha) 104 #define V_vegas_beta VNET(vegas_beta) 105 106 static MALLOC_DEFINE(M_VEGAS, "vegas data", 107 "Per connection data required for the Vegas congestion control algorithm"); 108 109 struct cc_algo vegas_cc_algo = { 110 .name = "vegas", 111 .ack_received = vegas_ack_received, 112 .cb_destroy = vegas_cb_destroy, 113 .cb_init = vegas_cb_init, 114 .cong_signal = vegas_cong_signal, 115 .conn_init = vegas_conn_init, 116 .mod_init = vegas_mod_init 117 }; 118 119 /* 120 * The vegas window adjustment is done once every RTT, as indicated by the 121 * ERTT_NEW_MEASUREMENT flag. This flag is reset once the new measurment data 122 * has been used. 123 */ 124 static void 125 vegas_ack_received(struct cc_var *ccv, uint16_t ack_type) 126 { 127 struct ertt *e_t; 128 struct vegas *vegas_data; 129 long actual_tx_rate, expected_tx_rate, ndiff; 130 131 e_t = khelp_get_osd(CCV(ccv, osd), ertt_id); 132 vegas_data = ccv->cc_data; 133 134 if (e_t->flags & ERTT_NEW_MEASUREMENT) { /* Once per RTT. */ 135 if (e_t->minrtt && e_t->markedpkt_rtt) { 136 expected_tx_rate = e_t->marked_snd_cwnd / e_t->minrtt; 137 actual_tx_rate = e_t->bytes_tx_in_marked_rtt / 138 e_t->markedpkt_rtt; 139 ndiff = (expected_tx_rate - actual_tx_rate) * 140 e_t->minrtt / CCV(ccv, t_maxseg); 141 142 if (ndiff < V_vegas_alpha) { 143 if (CCV(ccv, snd_cwnd) <= 144 CCV(ccv, snd_ssthresh)) { 145 vegas_data->slow_start_toggle = 146 vegas_data->slow_start_toggle ? 147 0 : 1; 148 } else { 149 vegas_data->slow_start_toggle = 0; 150 CCV(ccv, snd_cwnd) = 151 min(CCV(ccv, snd_cwnd) + 152 CCV(ccv, t_maxseg), 153 TCP_MAXWIN << CCV(ccv, snd_scale)); 154 } 155 } else if (ndiff > V_vegas_beta) { 156 /* Rate-based congestion. */ 157 vegas_cong_signal(ccv, CC_VEGAS_RATE); 158 vegas_data->slow_start_toggle = 0; 159 } 160 } 161 e_t->flags &= ~ERTT_NEW_MEASUREMENT; 162 } 163 164 if (vegas_data->slow_start_toggle) 165 newreno_cc_algo.ack_received(ccv, ack_type); 166 } 167 168 static void 169 vegas_cb_destroy(struct cc_var *ccv) 170 { 171 free(ccv->cc_data, M_VEGAS); 172 } 173 174 static int 175 vegas_cb_init(struct cc_var *ccv) 176 { 177 struct vegas *vegas_data; 178 179 vegas_data = malloc(sizeof(struct vegas), M_VEGAS, M_NOWAIT); 180 181 if (vegas_data == NULL) 182 return (ENOMEM); 183 184 vegas_data->slow_start_toggle = 1; 185 ccv->cc_data = vegas_data; 186 187 return (0); 188 } 189 190 /* 191 * If congestion has been triggered triggered by the Vegas measured rates, it is 192 * handled here, otherwise it falls back to newreno's congestion handling. 193 */ 194 static void 195 vegas_cong_signal(struct cc_var *ccv, uint32_t signal_type) 196 { 197 struct vegas *vegas_data; 198 int presignalrecov; 199 200 vegas_data = ccv->cc_data; 201 202 if (IN_RECOVERY(CCV(ccv, t_flags))) 203 presignalrecov = 1; 204 else 205 presignalrecov = 0; 206 207 switch(signal_type) { 208 case CC_VEGAS_RATE: 209 if (!IN_RECOVERY(CCV(ccv, t_flags))) { 210 CCV(ccv, snd_cwnd) = max(2 * CCV(ccv, t_maxseg), 211 CCV(ccv, snd_cwnd) - CCV(ccv, t_maxseg)); 212 if (CCV(ccv, snd_cwnd) < CCV(ccv, snd_ssthresh)) 213 /* Exit slow start. */ 214 CCV(ccv, snd_ssthresh) = CCV(ccv, snd_cwnd); 215 } 216 break; 217 218 default: 219 newreno_cc_algo.cong_signal(ccv, signal_type); 220 } 221 222 if (IN_RECOVERY(CCV(ccv, t_flags)) && !presignalrecov) 223 vegas_data->slow_start_toggle = 224 (CCV(ccv, snd_cwnd) < CCV(ccv, snd_ssthresh)) ? 1 : 0; 225 } 226 227 static void 228 vegas_conn_init(struct cc_var *ccv) 229 { 230 struct vegas *vegas_data; 231 232 vegas_data = ccv->cc_data; 233 vegas_data->slow_start_toggle = 1; 234 } 235 236 static int 237 vegas_mod_init(void) 238 { 239 240 ertt_id = khelp_get_id("ertt"); 241 if (ertt_id <= 0) { 242 printf("%s: h_ertt module not found\n", __func__); 243 return (ENOENT); 244 } 245 246 vegas_cc_algo.after_idle = newreno_cc_algo.after_idle; 247 vegas_cc_algo.post_recovery = newreno_cc_algo.post_recovery; 248 249 return (0); 250 } 251 252 static int 253 vegas_alpha_handler(SYSCTL_HANDLER_ARGS) 254 { 255 int error; 256 uint32_t new; 257 258 new = V_vegas_alpha; 259 error = sysctl_handle_int(oidp, &new, 0, req); 260 if (error == 0 && req->newptr != NULL) { 261 if (new == 0 || new > V_vegas_beta) 262 error = EINVAL; 263 else 264 V_vegas_alpha = new; 265 } 266 267 return (error); 268 } 269 270 static int 271 vegas_beta_handler(SYSCTL_HANDLER_ARGS) 272 { 273 int error; 274 uint32_t new; 275 276 new = V_vegas_beta; 277 error = sysctl_handle_int(oidp, &new, 0, req); 278 if (error == 0 && req->newptr != NULL) { 279 if (new == 0 || new < V_vegas_alpha) 280 error = EINVAL; 281 else 282 V_vegas_beta = new; 283 } 284 285 return (error); 286 } 287 288 SYSCTL_DECL(_net_inet_tcp_cc_vegas); 289 SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, vegas, 290 CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 291 "Vegas related settings"); 292 293 SYSCTL_PROC(_net_inet_tcp_cc_vegas, OID_AUTO, alpha, 294 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 295 &VNET_NAME(vegas_alpha), 1, &vegas_alpha_handler, "IU", 296 "vegas alpha, specified as number of \"buffers\" (0 < alpha < beta)"); 297 298 SYSCTL_PROC(_net_inet_tcp_cc_vegas, OID_AUTO, beta, 299 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 300 &VNET_NAME(vegas_beta), 3, &vegas_beta_handler, "IU", 301 "vegas beta, specified as number of \"buffers\" (0 < alpha < beta)"); 302 303 DECLARE_CC_MODULE(vegas, &vegas_cc_algo); 304 MODULE_DEPEND(vegas, ertt, 1, 1, 1); 305