Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Plugable TCP congestion control support and newReno |
| 3 | * congestion control. |
| 4 | * Based on ideas from I/O scheduler suport and Web100. |
| 5 | * |
| 6 | * Copyright (C) 2005 Stephen Hemminger <shemminger@osdl.org> |
| 7 | */ |
| 8 | |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 9 | #include <linux/module.h> |
| 10 | #include <linux/mm.h> |
| 11 | #include <linux/types.h> |
| 12 | #include <linux/list.h> |
| 13 | #include <net/tcp.h> |
| 14 | |
John Heffner | 886236c | 2007-03-25 19:21:45 -0700 | [diff] [blame] | 15 | int sysctl_tcp_max_ssthresh = 0; |
| 16 | |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 17 | static DEFINE_SPINLOCK(tcp_cong_list_lock); |
| 18 | static LIST_HEAD(tcp_cong_list); |
| 19 | |
| 20 | /* Simple linear search, don't expect many entries! */ |
| 21 | static struct tcp_congestion_ops *tcp_ca_find(const char *name) |
| 22 | { |
| 23 | struct tcp_congestion_ops *e; |
| 24 | |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 25 | list_for_each_entry_rcu(e, &tcp_cong_list, list) { |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 26 | if (strcmp(e->name, name) == 0) |
| 27 | return e; |
| 28 | } |
| 29 | |
| 30 | return NULL; |
| 31 | } |
| 32 | |
| 33 | /* |
Robert P. J. Day | d08df60 | 2007-02-17 19:07:33 +0100 | [diff] [blame] | 34 | * Attach new congestion control algorithm to the list |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 35 | * of available options. |
| 36 | */ |
| 37 | int tcp_register_congestion_control(struct tcp_congestion_ops *ca) |
| 38 | { |
| 39 | int ret = 0; |
| 40 | |
| 41 | /* all algorithms must implement ssthresh and cong_avoid ops */ |
Stephen Hemminger | 72dc5b9 | 2006-06-05 17:30:08 -0700 | [diff] [blame] | 42 | if (!ca->ssthresh || !ca->cong_avoid) { |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 43 | printk(KERN_ERR "TCP %s does not implement required ops\n", |
| 44 | ca->name); |
| 45 | return -EINVAL; |
| 46 | } |
| 47 | |
| 48 | spin_lock(&tcp_cong_list_lock); |
| 49 | if (tcp_ca_find(ca->name)) { |
| 50 | printk(KERN_NOTICE "TCP %s already registered\n", ca->name); |
| 51 | ret = -EEXIST; |
| 52 | } else { |
Stephen Hemminger | 3d2573f | 2006-09-24 20:11:58 -0700 | [diff] [blame] | 53 | list_add_tail_rcu(&ca->list, &tcp_cong_list); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 54 | printk(KERN_INFO "TCP %s registered\n", ca->name); |
| 55 | } |
| 56 | spin_unlock(&tcp_cong_list_lock); |
| 57 | |
| 58 | return ret; |
| 59 | } |
| 60 | EXPORT_SYMBOL_GPL(tcp_register_congestion_control); |
| 61 | |
| 62 | /* |
| 63 | * Remove congestion control algorithm, called from |
| 64 | * the module's remove function. Module ref counts are used |
| 65 | * to ensure that this can't be done till all sockets using |
| 66 | * that method are closed. |
| 67 | */ |
| 68 | void tcp_unregister_congestion_control(struct tcp_congestion_ops *ca) |
| 69 | { |
| 70 | spin_lock(&tcp_cong_list_lock); |
| 71 | list_del_rcu(&ca->list); |
| 72 | spin_unlock(&tcp_cong_list_lock); |
| 73 | } |
| 74 | EXPORT_SYMBOL_GPL(tcp_unregister_congestion_control); |
| 75 | |
| 76 | /* Assign choice of congestion control. */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 77 | void tcp_init_congestion_control(struct sock *sk) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 78 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 79 | struct inet_connection_sock *icsk = inet_csk(sk); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 80 | struct tcp_congestion_ops *ca; |
| 81 | |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 82 | /* if no choice made yet assign the current value set as default */ |
| 83 | if (icsk->icsk_ca_ops == &tcp_init_congestion_ops) { |
| 84 | rcu_read_lock(); |
| 85 | list_for_each_entry_rcu(ca, &tcp_cong_list, list) { |
| 86 | if (try_module_get(ca->owner)) { |
| 87 | icsk->icsk_ca_ops = ca; |
| 88 | break; |
| 89 | } |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 90 | |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 91 | /* fallback to next available */ |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 92 | } |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 93 | rcu_read_unlock(); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 94 | } |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 95 | |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 96 | if (icsk->icsk_ca_ops->init) |
| 97 | icsk->icsk_ca_ops->init(sk); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 98 | } |
| 99 | |
| 100 | /* Manage refcounts on socket close. */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 101 | void tcp_cleanup_congestion_control(struct sock *sk) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 102 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 103 | struct inet_connection_sock *icsk = inet_csk(sk); |
| 104 | |
| 105 | if (icsk->icsk_ca_ops->release) |
| 106 | icsk->icsk_ca_ops->release(sk); |
| 107 | module_put(icsk->icsk_ca_ops->owner); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 108 | } |
| 109 | |
| 110 | /* Used by sysctl to change default congestion control */ |
| 111 | int tcp_set_default_congestion_control(const char *name) |
| 112 | { |
| 113 | struct tcp_congestion_ops *ca; |
| 114 | int ret = -ENOENT; |
| 115 | |
| 116 | spin_lock(&tcp_cong_list_lock); |
| 117 | ca = tcp_ca_find(name); |
| 118 | #ifdef CONFIG_KMOD |
Stephen Hemminger | 35bfbc9 | 2006-11-09 16:36:36 -0800 | [diff] [blame] | 119 | if (!ca && capable(CAP_SYS_MODULE)) { |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 120 | spin_unlock(&tcp_cong_list_lock); |
| 121 | |
| 122 | request_module("tcp_%s", name); |
| 123 | spin_lock(&tcp_cong_list_lock); |
| 124 | ca = tcp_ca_find(name); |
| 125 | } |
| 126 | #endif |
| 127 | |
| 128 | if (ca) { |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 129 | ca->flags |= TCP_CONG_NON_RESTRICTED; /* default is always allowed */ |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 130 | list_move(&ca->list, &tcp_cong_list); |
| 131 | ret = 0; |
| 132 | } |
| 133 | spin_unlock(&tcp_cong_list_lock); |
| 134 | |
| 135 | return ret; |
| 136 | } |
| 137 | |
Stephen Hemminger | b1736a7 | 2006-10-31 17:31:33 -0800 | [diff] [blame] | 138 | /* Set default value from kernel configuration at bootup */ |
| 139 | static int __init tcp_congestion_default(void) |
| 140 | { |
| 141 | return tcp_set_default_congestion_control(CONFIG_DEFAULT_TCP_CONG); |
| 142 | } |
| 143 | late_initcall(tcp_congestion_default); |
| 144 | |
| 145 | |
Stephen Hemminger | 3ff825b | 2006-11-09 16:32:06 -0800 | [diff] [blame] | 146 | /* Build string with list of available congestion control values */ |
| 147 | void tcp_get_available_congestion_control(char *buf, size_t maxlen) |
| 148 | { |
| 149 | struct tcp_congestion_ops *ca; |
| 150 | size_t offs = 0; |
| 151 | |
| 152 | rcu_read_lock(); |
| 153 | list_for_each_entry_rcu(ca, &tcp_cong_list, list) { |
| 154 | offs += snprintf(buf + offs, maxlen - offs, |
| 155 | "%s%s", |
| 156 | offs == 0 ? "" : " ", ca->name); |
| 157 | |
| 158 | } |
| 159 | rcu_read_unlock(); |
| 160 | } |
| 161 | |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 162 | /* Get current default congestion control */ |
| 163 | void tcp_get_default_congestion_control(char *name) |
| 164 | { |
| 165 | struct tcp_congestion_ops *ca; |
| 166 | /* We will always have reno... */ |
| 167 | BUG_ON(list_empty(&tcp_cong_list)); |
| 168 | |
| 169 | rcu_read_lock(); |
| 170 | ca = list_entry(tcp_cong_list.next, struct tcp_congestion_ops, list); |
| 171 | strncpy(name, ca->name, TCP_CA_NAME_MAX); |
| 172 | rcu_read_unlock(); |
| 173 | } |
| 174 | |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 175 | /* Built list of non-restricted congestion control values */ |
| 176 | void tcp_get_allowed_congestion_control(char *buf, size_t maxlen) |
| 177 | { |
| 178 | struct tcp_congestion_ops *ca; |
| 179 | size_t offs = 0; |
| 180 | |
| 181 | *buf = '\0'; |
| 182 | rcu_read_lock(); |
| 183 | list_for_each_entry_rcu(ca, &tcp_cong_list, list) { |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 184 | if (!(ca->flags & TCP_CONG_NON_RESTRICTED)) |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 185 | continue; |
| 186 | offs += snprintf(buf + offs, maxlen - offs, |
| 187 | "%s%s", |
| 188 | offs == 0 ? "" : " ", ca->name); |
| 189 | |
| 190 | } |
| 191 | rcu_read_unlock(); |
| 192 | } |
| 193 | |
| 194 | /* Change list of non-restricted congestion control */ |
| 195 | int tcp_set_allowed_congestion_control(char *val) |
| 196 | { |
| 197 | struct tcp_congestion_ops *ca; |
| 198 | char *clone, *name; |
| 199 | int ret = 0; |
| 200 | |
| 201 | clone = kstrdup(val, GFP_USER); |
| 202 | if (!clone) |
| 203 | return -ENOMEM; |
| 204 | |
| 205 | spin_lock(&tcp_cong_list_lock); |
| 206 | /* pass 1 check for bad entries */ |
| 207 | while ((name = strsep(&clone, " ")) && *name) { |
| 208 | ca = tcp_ca_find(name); |
| 209 | if (!ca) { |
| 210 | ret = -ENOENT; |
| 211 | goto out; |
| 212 | } |
| 213 | } |
| 214 | |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 215 | /* pass 2 clear old values */ |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 216 | list_for_each_entry_rcu(ca, &tcp_cong_list, list) |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 217 | ca->flags &= ~TCP_CONG_NON_RESTRICTED; |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 218 | |
| 219 | /* pass 3 mark as allowed */ |
| 220 | while ((name = strsep(&val, " ")) && *name) { |
| 221 | ca = tcp_ca_find(name); |
| 222 | WARN_ON(!ca); |
| 223 | if (ca) |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 224 | ca->flags |= TCP_CONG_NON_RESTRICTED; |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 225 | } |
| 226 | out: |
| 227 | spin_unlock(&tcp_cong_list_lock); |
| 228 | |
| 229 | return ret; |
| 230 | } |
| 231 | |
| 232 | |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 233 | /* Change congestion control for socket */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 234 | int tcp_set_congestion_control(struct sock *sk, const char *name) |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 235 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 236 | struct inet_connection_sock *icsk = inet_csk(sk); |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 237 | struct tcp_congestion_ops *ca; |
| 238 | int err = 0; |
| 239 | |
| 240 | rcu_read_lock(); |
| 241 | ca = tcp_ca_find(name); |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 242 | |
Stephen Hemminger | 35bfbc9 | 2006-11-09 16:36:36 -0800 | [diff] [blame] | 243 | /* no change asking for existing value */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 244 | if (ca == icsk->icsk_ca_ops) |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 245 | goto out; |
| 246 | |
Stephen Hemminger | 35bfbc9 | 2006-11-09 16:36:36 -0800 | [diff] [blame] | 247 | #ifdef CONFIG_KMOD |
| 248 | /* not found attempt to autoload module */ |
| 249 | if (!ca && capable(CAP_SYS_MODULE)) { |
| 250 | rcu_read_unlock(); |
| 251 | request_module("tcp_%s", name); |
| 252 | rcu_read_lock(); |
| 253 | ca = tcp_ca_find(name); |
| 254 | } |
| 255 | #endif |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 256 | if (!ca) |
| 257 | err = -ENOENT; |
| 258 | |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 259 | else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) || capable(CAP_NET_ADMIN))) |
Stephen Hemminger | ce7bc3b | 2006-11-09 16:35:15 -0800 | [diff] [blame] | 260 | err = -EPERM; |
| 261 | |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 262 | else if (!try_module_get(ca->owner)) |
| 263 | err = -EBUSY; |
| 264 | |
| 265 | else { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 266 | tcp_cleanup_congestion_control(sk); |
| 267 | icsk->icsk_ca_ops = ca; |
Stephen Hemminger | 4d4d3d1 | 2007-04-23 22:32:11 -0700 | [diff] [blame] | 268 | |
| 269 | if (sk->sk_state != TCP_CLOSE && icsk->icsk_ca_ops->init) |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 270 | icsk->icsk_ca_ops->init(sk); |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 271 | } |
| 272 | out: |
| 273 | rcu_read_unlock(); |
| 274 | return err; |
| 275 | } |
| 276 | |
Stephen Hemminger | 40efc6f | 2006-01-03 16:03:49 -0800 | [diff] [blame] | 277 | |
| 278 | /* |
Stephen Hemminger | a02ba04 | 2007-05-17 00:04:18 -0700 | [diff] [blame] | 279 | * Slow start is used when congestion window is less than slow start |
| 280 | * threshold. This version implements the basic RFC2581 version |
| 281 | * and optionally supports: |
| 282 | * RFC3742 Limited Slow Start - growth limited to max_ssthresh |
| 283 | * RFC3465 Appropriate Byte Counting - growth limited by bytes acknowledged |
Stephen Hemminger | 40efc6f | 2006-01-03 16:03:49 -0800 | [diff] [blame] | 284 | */ |
| 285 | void tcp_slow_start(struct tcp_sock *tp) |
| 286 | { |
Stephen Hemminger | a02ba04 | 2007-05-17 00:04:18 -0700 | [diff] [blame] | 287 | int cnt; /* increase in packets */ |
John Heffner | 886236c | 2007-03-25 19:21:45 -0700 | [diff] [blame] | 288 | |
Stephen Hemminger | a02ba04 | 2007-05-17 00:04:18 -0700 | [diff] [blame] | 289 | /* RFC3465: ABC Slow start |
| 290 | * Increase only after a full MSS of bytes is acked |
| 291 | * |
| 292 | * TCP sender SHOULD increase cwnd by the number of |
| 293 | * previously unacknowledged bytes ACKed by each incoming |
| 294 | * acknowledgment, provided the increase is not more than L |
| 295 | */ |
| 296 | if (sysctl_tcp_abc && tp->bytes_acked < tp->mss_cache) |
| 297 | return; |
John Heffner | 886236c | 2007-03-25 19:21:45 -0700 | [diff] [blame] | 298 | |
Stephen Hemminger | a02ba04 | 2007-05-17 00:04:18 -0700 | [diff] [blame] | 299 | if (sysctl_tcp_max_ssthresh > 0 && tp->snd_cwnd > sysctl_tcp_max_ssthresh) |
| 300 | cnt = sysctl_tcp_max_ssthresh >> 1; /* limited slow start */ |
John Heffner | 886236c | 2007-03-25 19:21:45 -0700 | [diff] [blame] | 301 | else |
Stephen Hemminger | a02ba04 | 2007-05-17 00:04:18 -0700 | [diff] [blame] | 302 | cnt = tp->snd_cwnd; /* exponential increase */ |
John Heffner | 886236c | 2007-03-25 19:21:45 -0700 | [diff] [blame] | 303 | |
Stephen Hemminger | a02ba04 | 2007-05-17 00:04:18 -0700 | [diff] [blame] | 304 | /* RFC3465: ABC |
| 305 | * We MAY increase by 2 if discovered delayed ack |
| 306 | */ |
John Heffner | 886236c | 2007-03-25 19:21:45 -0700 | [diff] [blame] | 307 | if (sysctl_tcp_abc > 1 && tp->bytes_acked >= 2*tp->mss_cache) |
| 308 | cnt <<= 1; |
Stephen Hemminger | 40efc6f | 2006-01-03 16:03:49 -0800 | [diff] [blame] | 309 | tp->bytes_acked = 0; |
| 310 | |
John Heffner | 886236c | 2007-03-25 19:21:45 -0700 | [diff] [blame] | 311 | tp->snd_cwnd_cnt += cnt; |
| 312 | while (tp->snd_cwnd_cnt >= tp->snd_cwnd) { |
| 313 | tp->snd_cwnd_cnt -= tp->snd_cwnd; |
| 314 | if (tp->snd_cwnd < tp->snd_cwnd_clamp) |
| 315 | tp->snd_cwnd++; |
| 316 | } |
Stephen Hemminger | 40efc6f | 2006-01-03 16:03:49 -0800 | [diff] [blame] | 317 | } |
| 318 | EXPORT_SYMBOL_GPL(tcp_slow_start); |
| 319 | |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 320 | /* |
| 321 | * TCP Reno congestion control |
| 322 | * This is special case used for fallback as well. |
| 323 | */ |
| 324 | /* This is Jacobson's slow start and congestion avoidance. |
| 325 | * SIGCOMM '88, p. 328. |
| 326 | */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 327 | void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 rtt, u32 in_flight, |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 328 | int flag) |
| 329 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 330 | struct tcp_sock *tp = tcp_sk(sk); |
| 331 | |
Stephen Hemminger | f4805ed | 2005-11-10 16:53:30 -0800 | [diff] [blame] | 332 | if (!tcp_is_cwnd_limited(sk, in_flight)) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 333 | return; |
| 334 | |
Stephen Hemminger | 7faffa1 | 2005-11-10 17:07:24 -0800 | [diff] [blame] | 335 | /* In "safe" area, increase. */ |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 336 | if (tp->snd_cwnd <= tp->snd_ssthresh) |
Stephen Hemminger | 7faffa1 | 2005-11-10 17:07:24 -0800 | [diff] [blame] | 337 | tcp_slow_start(tp); |
Stephen Hemminger | 9772efb | 2005-11-10 17:09:53 -0800 | [diff] [blame] | 338 | |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 339 | /* In dangerous area, increase slowly. */ |
Stephen Hemminger | 9772efb | 2005-11-10 17:09:53 -0800 | [diff] [blame] | 340 | else if (sysctl_tcp_abc) { |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 341 | /* RFC3465: Appropriate Byte Count |
| 342 | * increase once for each full cwnd acked |
| 343 | */ |
| 344 | if (tp->bytes_acked >= tp->snd_cwnd*tp->mss_cache) { |
| 345 | tp->bytes_acked -= tp->snd_cwnd*tp->mss_cache; |
| 346 | if (tp->snd_cwnd < tp->snd_cwnd_clamp) |
| 347 | tp->snd_cwnd++; |
| 348 | } |
| 349 | } else { |
| 350 | /* In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd */ |
| 351 | if (tp->snd_cwnd_cnt >= tp->snd_cwnd) { |
| 352 | if (tp->snd_cwnd < tp->snd_cwnd_clamp) |
| 353 | tp->snd_cwnd++; |
| 354 | tp->snd_cwnd_cnt = 0; |
| 355 | } else |
| 356 | tp->snd_cwnd_cnt++; |
| 357 | } |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 358 | } |
| 359 | EXPORT_SYMBOL_GPL(tcp_reno_cong_avoid); |
| 360 | |
| 361 | /* Slow start threshold is half the congestion window (min 2) */ |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 362 | u32 tcp_reno_ssthresh(struct sock *sk) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 363 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 364 | const struct tcp_sock *tp = tcp_sk(sk); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 365 | return max(tp->snd_cwnd >> 1U, 2U); |
| 366 | } |
| 367 | EXPORT_SYMBOL_GPL(tcp_reno_ssthresh); |
| 368 | |
Stephen Hemminger | 72dc5b9 | 2006-06-05 17:30:08 -0700 | [diff] [blame] | 369 | /* Lower bound on congestion window with halving. */ |
| 370 | u32 tcp_reno_min_cwnd(const struct sock *sk) |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 371 | { |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 372 | const struct tcp_sock *tp = tcp_sk(sk); |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 373 | return tp->snd_ssthresh/2; |
| 374 | } |
| 375 | EXPORT_SYMBOL_GPL(tcp_reno_min_cwnd); |
| 376 | |
| 377 | struct tcp_congestion_ops tcp_reno = { |
Stephen Hemminger | 164891a | 2007-04-23 22:26:16 -0700 | [diff] [blame] | 378 | .flags = TCP_CONG_NON_RESTRICTED, |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 379 | .name = "reno", |
| 380 | .owner = THIS_MODULE, |
| 381 | .ssthresh = tcp_reno_ssthresh, |
| 382 | .cong_avoid = tcp_reno_cong_avoid, |
| 383 | .min_cwnd = tcp_reno_min_cwnd, |
| 384 | }; |
| 385 | |
Stephen Hemminger | 5f8ef48 | 2005-06-23 20:37:36 -0700 | [diff] [blame] | 386 | /* Initial congestion control used (until SYN) |
| 387 | * really reno under another name so we can tell difference |
| 388 | * during tcp_set_default_congestion_control |
| 389 | */ |
| 390 | struct tcp_congestion_ops tcp_init_congestion_ops = { |
| 391 | .name = "", |
| 392 | .owner = THIS_MODULE, |
| 393 | .ssthresh = tcp_reno_ssthresh, |
| 394 | .cong_avoid = tcp_reno_cong_avoid, |
| 395 | .min_cwnd = tcp_reno_min_cwnd, |
| 396 | }; |
| 397 | EXPORT_SYMBOL_GPL(tcp_init_congestion_ops); |