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