1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2007-2008 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 * 10 * This software was developed at the Centre for Advanced Internet 11 * Architectures, Swinburne University of Technology, by Lawrence Stewart and 12 * James Healy, 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 16 * Internet Architectures, Swinburne University of Technology, Melbourne, 17 * Australia by 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 * This software was first released in 2007 by James Healy and Lawrence Stewart 43 * whilst working on the NewTCP research project at Swinburne University of 44 * Technology's Centre for Advanced Internet Architectures, Melbourne, 45 * Australia, which was made possible in part by a grant from the Cisco 46 * University Research Program Fund at Community Foundation Silicon Valley. 47 * More details are available at: 48 * http://caia.swin.edu.au/urp/newtcp/ 49 */ 50 51 #include <sys/cdefs.h> 52 __FBSDID("$FreeBSD$"); 53 #include <opt_cc.h> 54 #include <sys/param.h> 55 #include <sys/kernel.h> 56 #include <sys/libkern.h> 57 #include <sys/lock.h> 58 #include <sys/malloc.h> 59 #include <sys/module.h> 60 #include <sys/mutex.h> 61 #include <sys/queue.h> 62 #include <sys/rwlock.h> 63 #include <sys/sbuf.h> 64 #include <sys/socket.h> 65 #include <sys/socketvar.h> 66 #include <sys/sysctl.h> 67 68 #include <net/vnet.h> 69 70 #include <netinet/in.h> 71 #include <netinet/in_pcb.h> 72 #include <netinet/tcp.h> 73 #include <netinet/tcp_seq.h> 74 #include <netinet/tcp_var.h> 75 #include <netinet/tcp_log_buf.h> 76 #include <netinet/tcp_hpts.h> 77 #include <netinet/cc/cc.h> 78 #include <netinet/cc/cc_module.h> 79 80 /* 81 * Have a sane default if no CC_DEFAULT is specified in the kernel config file. 82 */ 83 #ifndef CC_DEFAULT 84 #define CC_DEFAULT "cubic" 85 #endif 86 87 uint32_t hystart_minrtt_thresh = 4000; 88 uint32_t hystart_maxrtt_thresh = 16000; 89 uint32_t hystart_n_rttsamples = 8; 90 uint32_t hystart_css_growth_div = 4; 91 uint32_t hystart_css_rounds = 5; 92 uint32_t hystart_bblogs = 0; 93 94 MALLOC_DEFINE(M_CC_MEM, "CC Mem", "Congestion Control State memory"); 95 96 /* 97 * List of available cc algorithms on the current system. First element 98 * is used as the system default CC algorithm. 99 */ 100 struct cc_head cc_list = STAILQ_HEAD_INITIALIZER(cc_list); 101 102 /* Protects the cc_list TAILQ. */ 103 struct rwlock cc_list_lock; 104 105 VNET_DEFINE(struct cc_algo *, default_cc_ptr) = NULL; 106 107 VNET_DEFINE(uint32_t, newreno_beta) = 50; 108 #define V_newreno_beta VNET(newreno_beta) 109 VNET_DEFINE(uint32_t, newreno_beta_ecn) = 80; 110 111 void 112 cc_refer(struct cc_algo *algo) 113 { 114 CC_LIST_LOCK_ASSERT(); 115 refcount_acquire(&algo->cc_refcount); 116 } 117 118 void 119 cc_release(struct cc_algo *algo) 120 { 121 CC_LIST_LOCK_ASSERT(); 122 refcount_release(&algo->cc_refcount); 123 } 124 125 126 void 127 cc_attach(struct tcpcb *tp, struct cc_algo *algo) 128 { 129 /* 130 * Attach the tcpcb to the algorithm. 131 */ 132 CC_LIST_RLOCK(); 133 CC_ALGO(tp) = algo; 134 cc_refer(algo); 135 CC_LIST_RUNLOCK(); 136 } 137 138 void 139 cc_detach(struct tcpcb *tp) 140 { 141 struct cc_algo *algo; 142 143 CC_LIST_RLOCK(); 144 algo = CC_ALGO(tp); 145 CC_ALGO(tp) = NULL; 146 cc_release(algo); 147 CC_LIST_RUNLOCK(); 148 } 149 150 /* 151 * Sysctl handler to show and change the default CC algorithm. 152 */ 153 static int 154 cc_default_algo(SYSCTL_HANDLER_ARGS) 155 { 156 char default_cc[TCP_CA_NAME_MAX]; 157 struct cc_algo *funcs; 158 int error; 159 160 /* Get the current default: */ 161 CC_LIST_RLOCK(); 162 if (CC_DEFAULT_ALGO() != NULL) 163 strlcpy(default_cc, CC_DEFAULT_ALGO()->name, sizeof(default_cc)); 164 else 165 memset(default_cc, 0, TCP_CA_NAME_MAX); 166 CC_LIST_RUNLOCK(); 167 168 error = sysctl_handle_string(oidp, default_cc, sizeof(default_cc), req); 169 170 /* Check for error or no change */ 171 if (error != 0 || req->newptr == NULL) 172 goto done; 173 174 error = ESRCH; 175 /* Find algo with specified name and set it to default. */ 176 CC_LIST_RLOCK(); 177 STAILQ_FOREACH(funcs, &cc_list, entries) { 178 if (strncmp(default_cc, funcs->name, sizeof(default_cc))) 179 continue; 180 if (funcs->flags & CC_MODULE_BEING_REMOVED) { 181 /* Its being removed, its not eligible */ 182 continue; 183 } 184 V_default_cc_ptr = funcs; 185 error = 0; 186 break; 187 } 188 CC_LIST_RUNLOCK(); 189 done: 190 return (error); 191 } 192 193 /* 194 * Sysctl handler to display the list of available CC algorithms. 195 */ 196 static int 197 cc_list_available(SYSCTL_HANDLER_ARGS) 198 { 199 struct cc_algo *algo; 200 int error, nalgos; 201 int linesz; 202 char *buffer, *cp; 203 size_t bufsz, outsz; 204 205 error = nalgos = 0; 206 CC_LIST_RLOCK(); 207 STAILQ_FOREACH(algo, &cc_list, entries) { 208 nalgos++; 209 } 210 CC_LIST_RUNLOCK(); 211 if (nalgos == 0) { 212 return (ENOENT); 213 } 214 bufsz = (nalgos+2) * ((TCP_CA_NAME_MAX + 13) + 1); 215 buffer = malloc(bufsz, M_TEMP, M_WAITOK); 216 cp = buffer; 217 218 linesz = snprintf(cp, bufsz, "\n%-16s%c %s\n", "CCmod", 'D', 219 "PCB count"); 220 cp += linesz; 221 bufsz -= linesz; 222 outsz = linesz; 223 CC_LIST_RLOCK(); 224 STAILQ_FOREACH(algo, &cc_list, entries) { 225 linesz = snprintf(cp, bufsz, "%-16s%c %u\n", 226 algo->name, 227 (algo == CC_DEFAULT_ALGO()) ? '*' : ' ', 228 algo->cc_refcount); 229 if (linesz >= bufsz) { 230 error = EOVERFLOW; 231 break; 232 } 233 cp += linesz; 234 bufsz -= linesz; 235 outsz += linesz; 236 } 237 CC_LIST_RUNLOCK(); 238 if (error == 0) 239 error = sysctl_handle_string(oidp, buffer, outsz + 1, req); 240 free(buffer, M_TEMP); 241 return (error); 242 } 243 244 /* 245 * Return the number of times a proposed removal_cc is 246 * being used as the default. 247 */ 248 static int 249 cc_check_default(struct cc_algo *remove_cc) 250 { 251 int cnt = 0; 252 VNET_ITERATOR_DECL(vnet_iter); 253 254 CC_LIST_LOCK_ASSERT(); 255 256 VNET_LIST_RLOCK_NOSLEEP(); 257 VNET_FOREACH(vnet_iter) { 258 CURVNET_SET(vnet_iter); 259 if ((CC_DEFAULT_ALGO() != NULL) && 260 strncmp(CC_DEFAULT_ALGO()->name, 261 remove_cc->name, 262 TCP_CA_NAME_MAX) == 0) { 263 cnt++; 264 } 265 CURVNET_RESTORE(); 266 } 267 VNET_LIST_RUNLOCK_NOSLEEP(); 268 return (cnt); 269 } 270 271 /* 272 * Initialise CC subsystem on system boot. 273 */ 274 static void 275 cc_init(void) 276 { 277 CC_LIST_LOCK_INIT(); 278 STAILQ_INIT(&cc_list); 279 } 280 281 /* 282 * Returns non-zero on success, 0 on failure. 283 */ 284 static int 285 cc_deregister_algo_locked(struct cc_algo *remove_cc) 286 { 287 struct cc_algo *funcs; 288 int found = 0; 289 290 /* This is unlikely to fail */ 291 STAILQ_FOREACH(funcs, &cc_list, entries) { 292 if (funcs == remove_cc) 293 found = 1; 294 } 295 if (found == 0) { 296 /* Nothing to remove? */ 297 return (ENOENT); 298 } 299 /* We assert it should have been MOD_QUIESCE'd */ 300 KASSERT((remove_cc->flags & CC_MODULE_BEING_REMOVED), 301 ("remove_cc:%p does not have CC_MODULE_BEING_REMOVED flag", remove_cc)); 302 if (cc_check_default(remove_cc)) { 303 return(EBUSY); 304 } 305 if (remove_cc->cc_refcount != 0) { 306 return (EBUSY); 307 } 308 /* Remove algo from cc_list so that new connections can't use it. */ 309 STAILQ_REMOVE(&cc_list, remove_cc, cc_algo, entries); 310 return (0); 311 } 312 313 /* 314 * Returns non-zero on success, 0 on failure. 315 */ 316 int 317 cc_deregister_algo(struct cc_algo *remove_cc) 318 { 319 int ret; 320 321 CC_LIST_WLOCK(); 322 ret = cc_deregister_algo_locked(remove_cc); 323 CC_LIST_WUNLOCK(); 324 return (ret); 325 } 326 327 /* 328 * Returns 0 on success, non-zero on failure. 329 */ 330 int 331 cc_register_algo(struct cc_algo *add_cc) 332 { 333 struct cc_algo *funcs; 334 int err; 335 336 err = 0; 337 338 /* 339 * Iterate over list of registered CC algorithms and make sure 340 * we're not trying to add a duplicate. 341 */ 342 CC_LIST_WLOCK(); 343 STAILQ_FOREACH(funcs, &cc_list, entries) { 344 if (funcs == add_cc || 345 strncmp(funcs->name, add_cc->name, 346 TCP_CA_NAME_MAX) == 0) { 347 err = EEXIST; 348 break; 349 } 350 } 351 /* Init its reference count */ 352 if (err == 0) 353 refcount_init(&add_cc->cc_refcount, 0); 354 /* 355 * The first loaded congestion control module will become 356 * the default until we find the "CC_DEFAULT" defined in 357 * the config (if we do). 358 */ 359 if (!err) { 360 STAILQ_INSERT_TAIL(&cc_list, add_cc, entries); 361 if (strcmp(add_cc->name, CC_DEFAULT) == 0) { 362 V_default_cc_ptr = add_cc; 363 } else if (V_default_cc_ptr == NULL) { 364 V_default_cc_ptr = add_cc; 365 } 366 } 367 CC_LIST_WUNLOCK(); 368 369 return (err); 370 } 371 372 static void 373 vnet_cc_sysinit(void *arg) 374 { 375 struct cc_algo *cc; 376 377 if (IS_DEFAULT_VNET(curvnet)) 378 return; 379 380 CURVNET_SET(vnet0); 381 cc = V_default_cc_ptr; 382 CURVNET_RESTORE(); 383 384 V_default_cc_ptr = cc; 385 } 386 VNET_SYSINIT(vnet_cc_sysinit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY, 387 vnet_cc_sysinit, NULL); 388 389 /* 390 * Perform any necessary tasks before we exit congestion recovery. 391 */ 392 void 393 newreno_cc_post_recovery(struct cc_var *ccv) 394 { 395 int pipe; 396 397 if (IN_FASTRECOVERY(CCV(ccv, t_flags))) { 398 /* 399 * Fast recovery will conclude after returning from this 400 * function. Window inflation should have left us with 401 * approximately snd_ssthresh outstanding data. But in case we 402 * would be inclined to send a burst, better to do it via the 403 * slow start mechanism. 404 * 405 * XXXLAS: Find a way to do this without needing curack 406 */ 407 if (V_tcp_do_newsack) 408 pipe = tcp_compute_pipe(ccv->ccvc.tcp); 409 else 410 pipe = CCV(ccv, snd_max) - ccv->curack; 411 if (pipe < CCV(ccv, snd_ssthresh)) 412 /* 413 * Ensure that cwnd does not collapse to 1 MSS under 414 * adverse conditions. Implements RFC6582 415 */ 416 CCV(ccv, snd_cwnd) = max(pipe, CCV(ccv, t_maxseg)) + 417 CCV(ccv, t_maxseg); 418 else 419 CCV(ccv, snd_cwnd) = CCV(ccv, snd_ssthresh); 420 } 421 } 422 423 void 424 newreno_cc_after_idle(struct cc_var *ccv) 425 { 426 uint32_t rw; 427 /* 428 * If we've been idle for more than one retransmit timeout the old 429 * congestion window is no longer current and we have to reduce it to 430 * the restart window before we can transmit again. 431 * 432 * The restart window is the initial window or the last CWND, whichever 433 * is smaller. 434 * 435 * This is done to prevent us from flooding the path with a full CWND at 436 * wirespeed, overloading router and switch buffers along the way. 437 * 438 * See RFC5681 Section 4.1. "Restarting Idle Connections". 439 * 440 * In addition, per RFC2861 Section 2, the ssthresh is set to the 441 * maximum of the former ssthresh or 3/4 of the old cwnd, to 442 * not exit slow-start prematurely. 443 */ 444 rw = tcp_compute_initwnd(tcp_maxseg(ccv->ccvc.tcp)); 445 446 CCV(ccv, snd_ssthresh) = max(CCV(ccv, snd_ssthresh), 447 CCV(ccv, snd_cwnd)-(CCV(ccv, snd_cwnd)>>2)); 448 449 CCV(ccv, snd_cwnd) = min(rw, CCV(ccv, snd_cwnd)); 450 } 451 452 /* 453 * Perform any necessary tasks before we enter congestion recovery. 454 */ 455 void 456 newreno_cc_cong_signal(struct cc_var *ccv, uint32_t type) 457 { 458 uint32_t cwin, factor; 459 u_int mss; 460 461 cwin = CCV(ccv, snd_cwnd); 462 mss = tcp_fixed_maxseg(ccv->ccvc.tcp); 463 /* 464 * Other TCP congestion controls use newreno_cong_signal(), but 465 * with their own private cc_data. Make sure the cc_data is used 466 * correctly. 467 */ 468 factor = V_newreno_beta; 469 470 /* Catch algos which mistakenly leak private signal types. */ 471 KASSERT((type & CC_SIGPRIVMASK) == 0, 472 ("%s: congestion signal type 0x%08x is private\n", __func__, type)); 473 474 cwin = max(((uint64_t)cwin * (uint64_t)factor) / (100ULL * (uint64_t)mss), 475 2) * mss; 476 477 switch (type) { 478 case CC_NDUPACK: 479 if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) { 480 if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) 481 CCV(ccv, snd_ssthresh) = cwin; 482 ENTER_RECOVERY(CCV(ccv, t_flags)); 483 } 484 break; 485 case CC_ECN: 486 if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) { 487 CCV(ccv, snd_ssthresh) = cwin; 488 CCV(ccv, snd_cwnd) = cwin; 489 ENTER_CONGRECOVERY(CCV(ccv, t_flags)); 490 } 491 break; 492 case CC_RTO: 493 CCV(ccv, snd_ssthresh) = max(min(CCV(ccv, snd_wnd), 494 CCV(ccv, snd_cwnd)) / 2 / mss, 495 2) * mss; 496 CCV(ccv, snd_cwnd) = mss; 497 break; 498 } 499 } 500 501 void 502 newreno_cc_ack_received(struct cc_var *ccv, uint16_t type) 503 { 504 if (type == CC_ACK && !IN_RECOVERY(CCV(ccv, t_flags)) && 505 (ccv->flags & CCF_CWND_LIMITED)) { 506 u_int cw = CCV(ccv, snd_cwnd); 507 u_int incr = CCV(ccv, t_maxseg); 508 509 /* 510 * Regular in-order ACK, open the congestion window. 511 * Method depends on which congestion control state we're 512 * in (slow start or cong avoid) and if ABC (RFC 3465) is 513 * enabled. 514 * 515 * slow start: cwnd <= ssthresh 516 * cong avoid: cwnd > ssthresh 517 * 518 * slow start and ABC (RFC 3465): 519 * Grow cwnd exponentially by the amount of data 520 * ACKed capping the max increment per ACK to 521 * (abc_l_var * maxseg) bytes. 522 * 523 * slow start without ABC (RFC 5681): 524 * Grow cwnd exponentially by maxseg per ACK. 525 * 526 * cong avoid and ABC (RFC 3465): 527 * Grow cwnd linearly by maxseg per RTT for each 528 * cwnd worth of ACKed data. 529 * 530 * cong avoid without ABC (RFC 5681): 531 * Grow cwnd linearly by approximately maxseg per RTT using 532 * maxseg^2 / cwnd per ACK as the increment. 533 * If cwnd > maxseg^2, fix the cwnd increment at 1 byte to 534 * avoid capping cwnd. 535 */ 536 if (cw > CCV(ccv, snd_ssthresh)) { 537 if (V_tcp_do_rfc3465) { 538 if (ccv->flags & CCF_ABC_SENTAWND) 539 ccv->flags &= ~CCF_ABC_SENTAWND; 540 else 541 incr = 0; 542 } else 543 incr = max((incr * incr / cw), 1); 544 } else if (V_tcp_do_rfc3465) { 545 /* 546 * In slow-start with ABC enabled and no RTO in sight? 547 * (Must not use abc_l_var > 1 if slow starting after 548 * an RTO. On RTO, snd_nxt = snd_una, so the 549 * snd_nxt == snd_max check is sufficient to 550 * handle this). 551 * 552 * XXXLAS: Find a way to signal SS after RTO that 553 * doesn't rely on tcpcb vars. 554 */ 555 uint16_t abc_val; 556 557 if (ccv->flags & CCF_USE_LOCAL_ABC) 558 abc_val = ccv->labc; 559 else 560 abc_val = V_tcp_abc_l_var; 561 if (CCV(ccv, snd_nxt) == CCV(ccv, snd_max)) 562 incr = min(ccv->bytes_this_ack, 563 ccv->nsegs * abc_val * 564 CCV(ccv, t_maxseg)); 565 else 566 incr = min(ccv->bytes_this_ack, CCV(ccv, t_maxseg)); 567 568 } 569 /* ABC is on by default, so incr equals 0 frequently. */ 570 if (incr > 0) 571 CCV(ccv, snd_cwnd) = min(cw + incr, 572 TCP_MAXWIN << CCV(ccv, snd_scale)); 573 } 574 } 575 576 static int 577 cc_stop_new_assignments(struct cc_algo *algo) 578 { 579 CC_LIST_WLOCK(); 580 if (cc_check_default(algo)) { 581 /* A default cannot be removed */ 582 CC_LIST_WUNLOCK(); 583 return (EBUSY); 584 } 585 algo->flags |= CC_MODULE_BEING_REMOVED; 586 CC_LIST_WUNLOCK(); 587 return (0); 588 } 589 590 /* 591 * Handles kld related events. Returns 0 on success, non-zero on failure. 592 */ 593 int 594 cc_modevent(module_t mod, int event_type, void *data) 595 { 596 struct cc_algo *algo; 597 int err; 598 599 err = 0; 600 algo = (struct cc_algo *)data; 601 602 switch(event_type) { 603 case MOD_LOAD: 604 if ((algo->cc_data_sz == NULL) && (algo->cb_init != NULL)) { 605 /* 606 * A module must have a cc_data_sz function 607 * even if it has no data it should return 0. 608 */ 609 printf("Module Load Fails, it lacks a cc_data_sz() function but has a cb_init()!\n"); 610 err = EINVAL; 611 break; 612 } 613 if (algo->mod_init != NULL) 614 err = algo->mod_init(); 615 if (!err) 616 err = cc_register_algo(algo); 617 break; 618 619 case MOD_SHUTDOWN: 620 break; 621 case MOD_QUIESCE: 622 /* Stop any new assigments */ 623 err = cc_stop_new_assignments(algo); 624 break; 625 case MOD_UNLOAD: 626 /* 627 * Deregister and remove the module from the list 628 */ 629 CC_LIST_WLOCK(); 630 /* Even with -f we can't unload if its the default */ 631 if (cc_check_default(algo)) { 632 /* A default cannot be removed */ 633 CC_LIST_WUNLOCK(); 634 return (EBUSY); 635 } 636 /* 637 * If -f was used and users are still attached to 638 * the algorithm things are going to go boom. 639 */ 640 err = cc_deregister_algo_locked(algo); 641 CC_LIST_WUNLOCK(); 642 if ((err == 0) && (algo->mod_destroy != NULL)) { 643 algo->mod_destroy(); 644 } 645 break; 646 default: 647 err = EINVAL; 648 break; 649 } 650 651 return (err); 652 } 653 654 SYSINIT(cc, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_FIRST, cc_init, NULL); 655 656 /* Declare sysctl tree and populate it. */ 657 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, cc, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 658 "Congestion control related settings"); 659 660 SYSCTL_PROC(_net_inet_tcp_cc, OID_AUTO, algorithm, 661 CTLFLAG_VNET | CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE, 662 NULL, 0, cc_default_algo, "A", 663 "Default congestion control algorithm"); 664 665 SYSCTL_PROC(_net_inet_tcp_cc, OID_AUTO, available, 666 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 667 NULL, 0, cc_list_available, "A", 668 "List available congestion control algorithms"); 669 670 SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, hystartplusplus, 671 CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 672 "New Reno related HyStart++ settings"); 673 674 SYSCTL_UINT(_net_inet_tcp_cc_hystartplusplus, OID_AUTO, minrtt_thresh, 675 CTLFLAG_RW, 676 &hystart_minrtt_thresh, 4000, 677 "HyStarts++ minimum RTT thresh used in clamp (in microseconds)"); 678 679 SYSCTL_UINT(_net_inet_tcp_cc_hystartplusplus, OID_AUTO, maxrtt_thresh, 680 CTLFLAG_RW, 681 &hystart_maxrtt_thresh, 16000, 682 "HyStarts++ maximum RTT thresh used in clamp (in microseconds)"); 683 684 SYSCTL_UINT(_net_inet_tcp_cc_hystartplusplus, OID_AUTO, n_rttsamples, 685 CTLFLAG_RW, 686 &hystart_n_rttsamples, 8, 687 "The number of RTT samples that must be seen to consider HyStart++"); 688 689 SYSCTL_UINT(_net_inet_tcp_cc_hystartplusplus, OID_AUTO, css_growth_div, 690 CTLFLAG_RW, 691 &hystart_css_growth_div, 4, 692 "The divisor to the growth when in Hystart++ CSS"); 693 694 SYSCTL_UINT(_net_inet_tcp_cc_hystartplusplus, OID_AUTO, css_rounds, 695 CTLFLAG_RW, 696 &hystart_css_rounds, 5, 697 "The number of rounds HyStart++ lasts in CSS before falling to CA"); 698 699 SYSCTL_UINT(_net_inet_tcp_cc_hystartplusplus, OID_AUTO, bblogs, 700 CTLFLAG_RW, 701 &hystart_bblogs, 0, 702 "Do we enable HyStart++ Black Box logs to be generated if BB logging is on"); 703 704 VNET_DEFINE(int, cc_do_abe) = 0; 705 SYSCTL_INT(_net_inet_tcp_cc, OID_AUTO, abe, CTLFLAG_VNET | CTLFLAG_RW, 706 &VNET_NAME(cc_do_abe), 0, 707 "Enable draft-ietf-tcpm-alternativebackoff-ecn (TCP Alternative Backoff with ECN)"); 708 709 VNET_DEFINE(int, cc_abe_frlossreduce) = 0; 710 SYSCTL_INT(_net_inet_tcp_cc, OID_AUTO, abe_frlossreduce, CTLFLAG_VNET | CTLFLAG_RW, 711 &VNET_NAME(cc_abe_frlossreduce), 0, 712 "Apply standard beta instead of ABE-beta during ECN-signalled congestion " 713 "recovery episodes if loss also needs to be repaired"); 714