1 /* 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 3 * The Regents of the University of California. 4 * Copyright (c) 2007-2008,2010 5 * Swinburne University of Technology, Melbourne, Australia. 6 * Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org> 7 * Copyright (c) 2010 The FreeBSD Foundation 8 * All rights reserved. 9 * Copyright (c) 2017 by Delphix. All rights reserved. 10 * 11 * This software was developed at the Centre for Advanced Internet 12 * Architectures, Swinburne University of Technology, by Lawrence Stewart, James 13 * Healy and David Hayes, made possible in part by a grant from the Cisco 14 * University Research Program Fund at Community Foundation Silicon Valley. 15 * 16 * Portions of this software were developed at the Centre for Advanced 17 * Internet Architectures, Swinburne University of Technology, Melbourne, 18 * Australia by David Hayes under sponsorship from the FreeBSD Foundation. 19 * 20 * Redistribution and use in source and binary forms, with or without 21 * modification, are permitted provided that the following conditions 22 * are met: 23 * 1. Redistributions of source code must retain the above copyright 24 * notice, this list of conditions and the following disclaimer. 25 * 2. Redistributions in binary form must reproduce the above copyright 26 * notice, this list of conditions and the following disclaimer in the 27 * documentation and/or other materials provided with the distribution. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 */ 41 42 /* 43 * This software was first released in 2007 by James Healy and Lawrence Stewart 44 * whilst working on the NewTCP research project at Swinburne University of 45 * Technology's Centre for Advanced Internet Architectures, Melbourne, 46 * Australia, which was made possible in part by a grant from the Cisco 47 * University Research Program Fund at Community Foundation Silicon Valley. 48 * More details are available at: 49 * http://caia.swin.edu.au/urp/newtcp/ 50 */ 51 52 #include <sys/errno.h> 53 #include <inet/tcp.h> 54 #include <inet/tcp_impl.h> 55 #include <inet/cc.h> 56 #include <inet/cc/cc_module.h> 57 58 static void newreno_ack_received(struct cc_var *ccv, uint16_t type); 59 static void newreno_after_idle(struct cc_var *ccv); 60 static void newreno_cong_signal(struct cc_var *ccv, uint32_t type); 61 static void newreno_post_recovery(struct cc_var *ccv); 62 63 static struct modlmisc cc_newreno_modlmisc = { 64 &mod_miscops, 65 "New Reno Congestion Control" 66 }; 67 68 static struct modlinkage cc_newreno_modlinkage = { 69 MODREV_1, 70 &cc_newreno_modlmisc, 71 NULL 72 }; 73 74 struct cc_algo newreno_cc_algo = { 75 .name = "newreno", 76 .ack_received = newreno_ack_received, 77 .after_idle = newreno_after_idle, 78 .cong_signal = newreno_cong_signal, 79 .post_recovery = newreno_post_recovery, 80 }; 81 82 int 83 _init(void) 84 { 85 int err; 86 87 if ((err = cc_register_algo(&newreno_cc_algo)) == 0) { 88 if ((err = mod_install(&cc_newreno_modlinkage)) != 0) 89 (void) cc_deregister_algo(&newreno_cc_algo); 90 } 91 return (err); 92 } 93 94 int 95 _fini(void) 96 { 97 /* XXX Not unloadable for now */ 98 return (EBUSY); 99 } 100 101 int 102 _info(struct modinfo *modinfop) 103 { 104 return (mod_info(&cc_newreno_modlinkage, modinfop)); 105 } 106 107 static void 108 newreno_ack_received(struct cc_var *ccv, uint16_t type) 109 { 110 if (type == CC_ACK && !IN_RECOVERY(ccv->flags) && 111 (ccv->flags & CCF_CWND_LIMITED)) { 112 uint_t cw = CCV(ccv, tcp_cwnd); 113 uint_t incr = CCV(ccv, tcp_mss); 114 115 /* 116 * Regular in-order ACK, open the congestion window. 117 * Method depends on which congestion control state we're 118 * in (slow start or cong avoid) and if ABC (RFC 3465) is 119 * enabled. 120 * 121 * slow start: cwnd <= ssthresh 122 * cong avoid: cwnd > ssthresh 123 * 124 * slow start and ABC (RFC 3465): 125 * Grow cwnd exponentially by the amount of data 126 * ACKed capping the max increment per ACK to 127 * (abc_l_var * maxseg) bytes. 128 * 129 * slow start without ABC (RFC 5681): 130 * Grow cwnd exponentially by maxseg per ACK. 131 * 132 * cong avoid and ABC (RFC 3465): 133 * Grow cwnd linearly by maxseg per RTT for each 134 * cwnd worth of ACKed data. 135 * 136 * cong avoid without ABC (RFC 5681): 137 * Grow cwnd linearly by approximately maxseg per RTT using 138 * maxseg^2 / cwnd per ACK as the increment. 139 * If cwnd > maxseg^2, fix the cwnd increment at 1 byte to 140 * avoid capping cwnd. 141 */ 142 if (cw > CCV(ccv, tcp_cwnd_ssthresh)) { 143 if (CC_ABC(ccv)) { 144 if (ccv->flags & CCF_ABC_SENTAWND) 145 ccv->flags &= ~CCF_ABC_SENTAWND; 146 else 147 incr = 0; 148 } else 149 incr = max((incr * incr / cw), 1); 150 } else if (CC_ABC(ccv)) { 151 /* 152 * In slow-start with ABC enabled and no RTO in sight? 153 * (Must not use abc_l_var > 1 if slow starting after 154 * an RTO. 155 */ 156 if (ccv->flags & CCF_RTO) { 157 incr = min(ccv->bytes_this_ack, 158 CCV(ccv, tcp_mss)); 159 } else { 160 incr = min(ccv->bytes_this_ack, 161 CC_ABC_L_VAR(ccv) * CCV(ccv, tcp_mss)); 162 } 163 164 } 165 /* ABC is on by default, so incr equals 0 frequently. */ 166 if (incr > 0) 167 CCV(ccv, tcp_cwnd) = min(cw + incr, 168 TCP_MAXWIN << CCV(ccv, tcp_snd_ws)); 169 } 170 } 171 172 static void 173 newreno_after_idle(struct cc_var *ccv) 174 { 175 int rw; 176 177 /* 178 * If we've been idle for more than one retransmit timeout the old 179 * congestion window is no longer current and we have to reduce it to 180 * the restart window before we can transmit again. 181 * 182 * The restart window is the initial window or the last CWND, whichever 183 * is smaller. 184 * 185 * This is done to prevent us from flooding the path with a full CWND at 186 * wirespeed, overloading router and switch buffers along the way. 187 * 188 * See RFC5681 Section 4.1. "Restarting Idle Connections". 189 */ 190 if (CCV(ccv, tcp_init_cwnd) != 0) { 191 /* 192 * The TCP_INIT_CWND socket option was used to override the 193 * default. 194 */ 195 rw = CCV(ccv, tcp_init_cwnd) * CCV(ccv, tcp_mss); 196 } else if (CCSV(ccv, tcps_slow_start_initial) != 0) { 197 /* The _slow_start_initial tunable was explicitly set. */ 198 rw = min(TCP_MAX_INIT_CWND, CCSV(ccv, tcps_slow_start_initial)) 199 * CCV(ccv, tcp_mss); 200 } else { 201 /* Do RFC 3390 */ 202 rw = min(4 * CCV(ccv, tcp_mss), 203 max(2 * CCV(ccv, tcp_mss), 4380)); 204 } 205 206 CCV(ccv, tcp_cwnd) = min(rw, CCV(ccv, tcp_cwnd)); 207 } 208 209 /* 210 * Perform any necessary tasks before we enter congestion recovery. 211 */ 212 static void 213 newreno_cong_signal(struct cc_var *ccv, uint32_t type) 214 { 215 uint32_t cwin, ssthresh_on_loss; 216 uint32_t mss; 217 218 cwin = CCV(ccv, tcp_cwnd); 219 mss = CCV(ccv, tcp_mss); 220 ssthresh_on_loss = 221 max((CCV(ccv, tcp_snxt) - CCV(ccv, tcp_suna)) / 2 / mss, 2) 222 * mss; 223 224 /* Catch algos which mistakenly leak private signal types. */ 225 ASSERT((type & CC_SIGPRIVMASK) == 0); 226 227 cwin = max(cwin / 2 / mss, 2) * mss; 228 229 switch (type) { 230 case CC_NDUPACK: 231 if (!IN_FASTRECOVERY(ccv->flags)) { 232 if (!IN_CONGRECOVERY(ccv->flags)) { 233 CCV(ccv, tcp_cwnd_ssthresh) = ssthresh_on_loss; 234 CCV(ccv, tcp_cwnd) = cwin; 235 } 236 ENTER_RECOVERY(ccv->flags); 237 } 238 break; 239 case CC_ECN: 240 if (!IN_CONGRECOVERY(ccv->flags)) { 241 CCV(ccv, tcp_cwnd_ssthresh) = ssthresh_on_loss; 242 CCV(ccv, tcp_cwnd) = cwin; 243 ENTER_CONGRECOVERY(ccv->flags); 244 } 245 break; 246 case CC_RTO: 247 CCV(ccv, tcp_cwnd_ssthresh) = ssthresh_on_loss; 248 CCV(ccv, tcp_cwnd) = mss; 249 break; 250 } 251 } 252 253 /* 254 * Perform any necessary tasks before we exit congestion recovery. 255 */ 256 static void 257 newreno_post_recovery(struct cc_var *ccv) 258 { 259 if (IN_FASTRECOVERY(ccv->flags)) { 260 /* 261 * Fast recovery will conclude after returning from this 262 * function. 263 */ 264 if (CCV(ccv, tcp_cwnd) > CCV(ccv, tcp_cwnd_ssthresh)) { 265 CCV(ccv, tcp_cwnd) = CCV(ccv, tcp_cwnd_ssthresh); 266 } 267 } 268 } 269