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 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/cdefs.h> 57__FBSDID("$FreeBSD$"); 58 59#include <sys/param.h> 60#include <sys/kernel.h> 61#include <sys/khelp.h> 62#include <sys/limits.h> 63#include <sys/malloc.h> 64#include <sys/module.h> 65#include <sys/queue.h> 66#include <sys/socket.h> 67#include <sys/socketvar.h> 68#include <sys/sysctl.h> 69#include <sys/systm.h> 70 71#include <net/vnet.h> 72 73#include <netinet/tcp.h> 74#include <netinet/tcp_seq.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/* Largest possible number returned by random(). */ 83#define RANDOM_MAX INT_MAX 84 85static void hd_ack_received(struct cc_var *ccv, uint16_t ack_type); 86static int hd_mod_init(void); 87 88static int ertt_id; 89 90VNET_DEFINE_STATIC(uint32_t, hd_qthresh) = 20; 91VNET_DEFINE_STATIC(uint32_t, hd_qmin) = 5; 92VNET_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 97struct cc_algo hd_cc_algo = { 98 .name = "hd", 99 .ack_received = hd_ack_received, 100 .mod_init = hd_mod_init 101}; 102 103/* 104 * Hamilton backoff function. Returns 1 if we should backoff or 0 otherwise. 105 */ 106static __inline int 107should_backoff(int qdly, int maxqdly) 108{ 109 unsigned long p; 110 111 if (qdly < V_hd_qthresh) { 112 p = (((RANDOM_MAX / 100) * V_hd_pmax) / 113 (V_hd_qthresh - V_hd_qmin)) * (qdly - V_hd_qmin); 114 } else { 115 if (qdly > V_hd_qthresh) 116 p = (((RANDOM_MAX / 100) * V_hd_pmax) / 117 (maxqdly - V_hd_qthresh)) * (maxqdly - qdly); 118 else 119 p = (RANDOM_MAX / 100) * V_hd_pmax; 120 } 121 122 return (random() < p); 123} 124 125/* 126 * If the ack type is CC_ACK, and the inferred queueing delay is greater than 127 * the Qmin threshold, cwnd is reduced probabilistically. When backing off due 128 * to delay, HD behaves like NewReno when an ECN signal is received. HD behaves 129 * as NewReno in all other circumstances. 130 */ 131static void 132hd_ack_received(struct cc_var *ccv, uint16_t ack_type) 133{ 134 struct ertt *e_t; 135 int qdly; 136 137 if (ack_type == CC_ACK) { 138 e_t = khelp_get_osd(CCV(ccv, osd), ertt_id); 139 140 if (e_t->rtt && e_t->minrtt && V_hd_qthresh > 0) { 141 qdly = e_t->rtt - e_t->minrtt; 142 143 if (qdly > V_hd_qmin && 144 !IN_RECOVERY(CCV(ccv, t_flags))) { 145 /* Probabilistic backoff of cwnd. */ 146 if (should_backoff(qdly, 147 e_t->maxrtt - e_t->minrtt)) { 148 /* 149 * Update cwnd and ssthresh update to 150 * half cwnd and behave like an ECN (ie 151 * not a packet loss). 152 */ 153 newreno_cc_algo.cong_signal(ccv, 154 CC_ECN); 155 return; 156 } 157 } 158 } 159 } 160 newreno_cc_algo.ack_received(ccv, ack_type); /* As for NewReno. */ 161} 162 163static int 164hd_mod_init(void) 165{ 166 167 ertt_id = khelp_get_id("ertt"); 168 if (ertt_id <= 0) { 169 printf("%s: h_ertt module not found\n", __func__); 170 return (ENOENT); 171 } 172 173 hd_cc_algo.after_idle = newreno_cc_algo.after_idle; 174 hd_cc_algo.cong_signal = newreno_cc_algo.cong_signal; 175 hd_cc_algo.post_recovery = newreno_cc_algo.post_recovery; 176 177 return (0); 178} 179 180static int 181hd_pmax_handler(SYSCTL_HANDLER_ARGS) 182{ 183 int error; 184 uint32_t new; 185 186 new = V_hd_pmax; 187 error = sysctl_handle_int(oidp, &new, 0, req); 188 if (error == 0 && req->newptr != NULL) { 189 if (new == 0 || new > 100) 190 error = EINVAL; 191 else 192 V_hd_pmax = new; 193 } 194 195 return (error); 196} 197 198static int 199hd_qmin_handler(SYSCTL_HANDLER_ARGS) 200{ 201 int error; 202 uint32_t new; 203 204 new = V_hd_qmin; 205 error = sysctl_handle_int(oidp, &new, 0, req); 206 if (error == 0 && req->newptr != NULL) { 207 if (new > V_hd_qthresh) 208 error = EINVAL; 209 else 210 V_hd_qmin = new; 211 } 212 213 return (error); 214} 215 216static int 217hd_qthresh_handler(SYSCTL_HANDLER_ARGS) 218{ 219 int error; 220 uint32_t new; 221 222 new = V_hd_qthresh; 223 error = sysctl_handle_int(oidp, &new, 0, req); 224 if (error == 0 && req->newptr != NULL) { 225 if (new == 0 || new < V_hd_qmin) 226 error = EINVAL; 227 else 228 V_hd_qthresh = new; 229 } 230 231 return (error); 232} 233 234SYSCTL_DECL(_net_inet_tcp_cc_hd); 235SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, hd, CTLFLAG_RW, NULL, 236 "Hamilton delay-based congestion control related settings"); 237 238SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_threshold, 239 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, &VNET_NAME(hd_qthresh), 20, 240 &hd_qthresh_handler, "IU", "queueing congestion threshold (qth) in ticks"); 241 242SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, pmax, 243 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, &VNET_NAME(hd_pmax), 5, 244 &hd_pmax_handler, "IU", 245 "per packet maximum backoff probability as a percentage"); 246 247SYSCTL_PROC(_net_inet_tcp_cc_hd, OID_AUTO, queue_min, 248 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, &VNET_NAME(hd_qmin), 5, 249 &hd_qmin_handler, "IU", "minimum queueing delay threshold (qmin) in ticks"); 250 251DECLARE_CC_MODULE(hd, &hd_cc_algo); 252MODULE_VERSION(hd, 1); 253MODULE_DEPEND(hd, ertt, 1, 1, 1); 254