1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
5 * The Regents of the University of California.
6 * Copyright (c) 2007-2008,2010,2014
7 * Swinburne University of Technology, Melbourne, Australia.
8 * Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org>
9 * Copyright (c) 2010 The FreeBSD Foundation
10 * All rights reserved.
11 *
12 * This software was developed at the Centre for Advanced Internet
13 * Architectures, Swinburne University of Technology, by Lawrence Stewart, James
14 * Healy and David Hayes, made possible in part by a grant from the Cisco
15 * University Research Program Fund at Community Foundation Silicon Valley.
16 *
17 * Portions of this software were developed at the Centre for Advanced
18 * Internet Architectures, Swinburne University of Technology, Melbourne,
19 * Australia by David Hayes under sponsorship from the FreeBSD Foundation.
20 *
21 * Redistribution and use in source and binary forms, with or without
22 * modification, are permitted provided that the following conditions
23 * are met:
24 * 1. Redistributions of source code must retain the above copyright
25 * notice, this list of conditions and the following disclaimer.
26 * 2. Redistributions in binary form must reproduce the above copyright
27 * notice, this list of conditions and the following disclaimer in the
28 * documentation and/or other materials provided with the distribution.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * SUCH DAMAGE.
41 */
42
43 /*
44 * This software was first released in 2007 by James Healy and Lawrence Stewart
45 * whilst working on the NewTCP research project at Swinburne University of
46 * Technology's Centre for Advanced Internet Architectures, Melbourne,
47 * Australia, which was made possible in part by a grant from the Cisco
48 * University Research Program Fund at Community Foundation Silicon Valley.
49 * More details are available at:
50 * http://caia.swin.edu.au/urp/newtcp/
51 *
52 * Dec 2014 garmitage@swin.edu.au
53 * Borrowed code fragments from cc_cdg.c to add modifiable beta
54 * via sysctls.
55 *
56 */
57
58 #include <sys/param.h>
59 #include <sys/kernel.h>
60 #include <sys/malloc.h>
61 #include <sys/module.h>
62 #include <sys/socket.h>
63 #include <sys/lock.h>
64 #include <sys/mutex.h>
65 #include <sys/socketvar.h>
66 #include <sys/sysctl.h>
67 #include <sys/systm.h>
68
69 #include <net/vnet.h>
70
71 #include <net/route.h>
72 #include <net/route/nhop.h>
73
74 #include <netinet/in_pcb.h>
75 #include <netinet/in.h>
76 #include <netinet/in_pcb.h>
77 #include <netinet/tcp.h>
78 #include <netinet/tcp_seq.h>
79 #include <netinet/tcp_var.h>
80 #include <netinet/tcp_log_buf.h>
81 #include <netinet/tcp_hpts.h>
82 #include <netinet/cc/cc.h>
83 #include <netinet/cc/cc_module.h>
84 #include <netinet/cc/cc_newreno.h>
85
86 static void newreno_cb_destroy(struct cc_var *ccv);
87 static void newreno_ack_received(struct cc_var *ccv, ccsignal_t type);
88 static void newreno_after_idle(struct cc_var *ccv);
89 static void newreno_cong_signal(struct cc_var *ccv, ccsignal_t type);
90 static int newreno_ctl_output(struct cc_var *ccv, struct sockopt *sopt, void *buf);
91 static void newreno_newround(struct cc_var *ccv, uint32_t round_cnt);
92 static void newreno_rttsample(struct cc_var *ccv, uint32_t usec_rtt, uint32_t rxtcnt, uint32_t fas);
93 static int newreno_cb_init(struct cc_var *ccv, void *);
94 static size_t newreno_data_sz(void);
95
96
97 VNET_DECLARE(uint32_t, newreno_beta);
98 #define V_newreno_beta VNET(newreno_beta)
99 VNET_DECLARE(uint32_t, newreno_beta_ecn);
100 #define V_newreno_beta_ecn VNET(newreno_beta_ecn)
101
102 struct cc_algo newreno_cc_algo = {
103 .name = "newreno",
104 .cb_destroy = newreno_cb_destroy,
105 .ack_received = newreno_ack_received,
106 .after_idle = newreno_after_idle,
107 .cong_signal = newreno_cong_signal,
108 .post_recovery = newreno_cc_post_recovery,
109 .ctl_output = newreno_ctl_output,
110 .newround = newreno_newround,
111 .rttsample = newreno_rttsample,
112 .cb_init = newreno_cb_init,
113 .cc_data_sz = newreno_data_sz,
114 };
115
116 static void
newreno_log_hystart_event(struct cc_var * ccv,struct newreno * nreno,uint8_t mod,uint32_t flex1)117 newreno_log_hystart_event(struct cc_var *ccv, struct newreno *nreno, uint8_t mod, uint32_t flex1)
118 {
119 /*
120 * Types of logs (mod value)
121 * 1 - rtt_thresh in flex1, checking to see if RTT is to great.
122 * 2 - rtt is too great, rtt_thresh in flex1.
123 * 3 - CSS is active incr in flex1
124 * 4 - A new round is beginning flex1 is round count
125 * 5 - A new RTT measurement flex1 is the new measurement.
126 * 6 - We enter CA ssthresh is also in flex1.
127 * 7 - Socket option to change hystart executed opt.val in flex1.
128 * 8 - Back out of CSS into SS, flex1 is the css_baseline_minrtt
129 * 9 - We enter CA, via an ECN mark.
130 * 10 - We enter CA, via a loss.
131 * 11 - We have slipped out of SS into CA via cwnd growth.
132 * 12 - After idle has re-enabled hystart++
133 */
134 struct tcpcb *tp;
135
136 if (hystart_bblogs == 0)
137 return;
138 tp = ccv->tp;
139 if (tcp_bblogging_on(tp)) {
140 union tcp_log_stackspecific log;
141 struct timeval tv;
142
143 memset(&log, 0, sizeof(log));
144 log.u_bbr.flex1 = flex1;
145 log.u_bbr.flex2 = nreno->css_current_round_minrtt;
146 log.u_bbr.flex3 = nreno->css_lastround_minrtt;
147 log.u_bbr.flex4 = nreno->css_rttsample_count;
148 log.u_bbr.flex5 = nreno->css_entered_at_round;
149 log.u_bbr.flex6 = nreno->css_baseline_minrtt;
150 /* We only need bottom 16 bits of flags */
151 log.u_bbr.flex7 = nreno->newreno_flags & 0x0000ffff;
152 log.u_bbr.flex8 = mod;
153 log.u_bbr.epoch = nreno->css_current_round;
154 log.u_bbr.timeStamp = tcp_get_usecs(&tv);
155 log.u_bbr.lt_epoch = nreno->css_fas_at_css_entry;
156 log.u_bbr.pkts_out = nreno->css_last_fas;
157 log.u_bbr.delivered = nreno->css_lowrtt_fas;
158 log.u_bbr.pkt_epoch = ccv->flags;
159 TCP_LOG_EVENTP(tp, NULL,
160 &tptosocket(tp)->so_rcv,
161 &tptosocket(tp)->so_snd,
162 TCP_HYSTART, 0,
163 0, &log, false, &tv);
164 }
165 }
166
167 static size_t
newreno_data_sz(void)168 newreno_data_sz(void)
169 {
170 return (sizeof(struct newreno));
171 }
172
173 static int
newreno_cb_init(struct cc_var * ccv,void * ptr)174 newreno_cb_init(struct cc_var *ccv, void *ptr)
175 {
176 struct newreno *nreno;
177
178 INP_WLOCK_ASSERT(tptoinpcb(ccv->tp));
179 if (ptr == NULL) {
180 ccv->cc_data = malloc(sizeof(struct newreno), M_CC_MEM, M_NOWAIT);
181 if (ccv->cc_data == NULL)
182 return (ENOMEM);
183 } else
184 ccv->cc_data = ptr;
185 nreno = (struct newreno *)ccv->cc_data;
186 /* NB: nreno is not zeroed, so initialise all fields. */
187 nreno->beta = V_newreno_beta;
188 nreno->beta_ecn = V_newreno_beta_ecn;
189 /*
190 * We set the enabled flag so that if
191 * the socket option gets strobed and
192 * we have not hit a loss
193 */
194 nreno->newreno_flags = CC_NEWRENO_HYSTART_ENABLED;
195 /* At init set both to infinity */
196 nreno->css_lastround_minrtt = 0xffffffff;
197 nreno->css_current_round_minrtt = 0xffffffff;
198 nreno->css_current_round = 0;
199 nreno->css_baseline_minrtt = 0xffffffff;
200 nreno->css_rttsample_count = 0;
201 nreno->css_entered_at_round = 0;
202 nreno->css_fas_at_css_entry = 0;
203 nreno->css_lowrtt_fas = 0;
204 nreno->css_last_fas = 0;
205 return (0);
206 }
207
208 static void
newreno_cb_destroy(struct cc_var * ccv)209 newreno_cb_destroy(struct cc_var *ccv)
210 {
211 free(ccv->cc_data, M_CC_MEM);
212 }
213
214 static void
newreno_ack_received(struct cc_var * ccv,ccsignal_t type)215 newreno_ack_received(struct cc_var *ccv, ccsignal_t type)
216 {
217 struct newreno *nreno;
218 uint32_t mss = tcp_fixed_maxseg(ccv->tp);
219
220 nreno = ccv->cc_data;
221 if (type == CC_ACK && !IN_RECOVERY(CCV(ccv, t_flags)) &&
222 (ccv->flags & CCF_CWND_LIMITED)) {
223 u_int cw = CCV(ccv, snd_cwnd);
224 u_int incr = mss;
225
226 /*
227 * Regular in-order ACK, open the congestion window.
228 * Method depends on which congestion control state we're
229 * in (slow start or cong avoid) and if ABC (RFC 3465) is
230 * enabled.
231 *
232 * slow start: cwnd <= ssthresh
233 * cong avoid: cwnd > ssthresh
234 *
235 * slow start and ABC (RFC 3465):
236 * Grow cwnd exponentially by the amount of data
237 * ACKed capping the max increment per ACK to
238 * (abc_l_var * maxseg) bytes.
239 *
240 * slow start without ABC (RFC 5681):
241 * Grow cwnd exponentially by maxseg per ACK.
242 *
243 * cong avoid and ABC (RFC 3465):
244 * Grow cwnd linearly by maxseg per RTT for each
245 * cwnd worth of ACKed data.
246 *
247 * cong avoid without ABC (RFC 5681):
248 * Grow cwnd linearly by approximately maxseg per RTT using
249 * maxseg^2 / cwnd per ACK as the increment.
250 * If cwnd > maxseg^2, fix the cwnd increment at 1 byte to
251 * avoid capping cwnd.
252 */
253 if (cw > CCV(ccv, snd_ssthresh)) {
254 if (nreno->newreno_flags & CC_NEWRENO_HYSTART_IN_CSS) {
255 /*
256 * We have slipped into CA with
257 * CSS active. Deactivate all.
258 */
259 /* Turn off the CSS flag */
260 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_IN_CSS;
261 /* Disable use of CSS in the future except long idle */
262 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_ENABLED;
263 newreno_log_hystart_event(ccv, nreno, 11, CCV(ccv, snd_ssthresh));
264 }
265 if (V_tcp_do_rfc3465) {
266 if (ccv->flags & CCF_ABC_SENTAWND)
267 ccv->flags &= ~CCF_ABC_SENTAWND;
268 else
269 incr = 0;
270 } else
271 incr = max((incr * incr / cw), 1);
272 } else if (V_tcp_do_rfc3465) {
273 /*
274 * In slow-start with ABC enabled and no RTO in sight?
275 * (Must not use abc_l_var > 1 if slow starting after
276 * an RTO. On RTO, snd_nxt = snd_una, so the
277 * snd_nxt == snd_max check is sufficient to
278 * handle this).
279 *
280 * XXXLAS: Find a way to signal SS after RTO that
281 * doesn't rely on tcpcb vars.
282 */
283 uint16_t abc_val;
284
285 if (ccv->flags & CCF_USE_LOCAL_ABC)
286 abc_val = ccv->labc;
287 else
288 abc_val = V_tcp_abc_l_var;
289 if ((ccv->flags & CCF_HYSTART_ALLOWED) &&
290 (nreno->newreno_flags & CC_NEWRENO_HYSTART_ENABLED) &&
291 ((nreno->newreno_flags & CC_NEWRENO_HYSTART_IN_CSS) == 0)) {
292 /*
293 * Hystart is allowed and still enabled and we are not yet
294 * in CSS. Lets check to see if we can make a decision on
295 * if we need to go into CSS.
296 */
297 if ((nreno->css_rttsample_count >= hystart_n_rttsamples) &&
298 (nreno->css_current_round_minrtt != 0xffffffff) &&
299 (nreno->css_lastround_minrtt != 0xffffffff)) {
300 uint32_t rtt_thresh;
301
302 /* Clamp (minrtt_thresh, lastround/8, maxrtt_thresh) */
303 rtt_thresh = (nreno->css_lastround_minrtt >> 3);
304 if (rtt_thresh < hystart_minrtt_thresh)
305 rtt_thresh = hystart_minrtt_thresh;
306 if (rtt_thresh > hystart_maxrtt_thresh)
307 rtt_thresh = hystart_maxrtt_thresh;
308 newreno_log_hystart_event(ccv, nreno, 1, rtt_thresh);
309 if (nreno->css_current_round_minrtt >= (nreno->css_lastround_minrtt + rtt_thresh)) {
310 /* Enter CSS */
311 nreno->newreno_flags |= CC_NEWRENO_HYSTART_IN_CSS;
312 nreno->css_fas_at_css_entry = nreno->css_lowrtt_fas;
313 /*
314 * The draft (v4) calls for us to set baseline to css_current_round_min
315 * but that can cause an oscillation. We probably shoudl be using
316 * css_lastround_minrtt, but the authors insist that will cause
317 * issues on exiting early. We will leave the draft version for now
318 * but I suspect this is incorrect.
319 */
320 nreno->css_baseline_minrtt = nreno->css_current_round_minrtt;
321 nreno->css_entered_at_round = nreno->css_current_round;
322 newreno_log_hystart_event(ccv, nreno, 2, rtt_thresh);
323 }
324 }
325 }
326 if (CCV(ccv, snd_nxt) == CCV(ccv, snd_max))
327 incr = min(ccv->bytes_this_ack,
328 ccv->nsegs * abc_val * mss);
329 else
330 incr = min(ccv->bytes_this_ack, mss);
331
332 /* Only if Hystart is enabled will the flag get set */
333 if (nreno->newreno_flags & CC_NEWRENO_HYSTART_IN_CSS) {
334 incr /= hystart_css_growth_div;
335 newreno_log_hystart_event(ccv, nreno, 3, incr);
336 }
337 }
338 /* ABC is on by default, so incr equals 0 frequently. */
339 if (incr > 0)
340 CCV(ccv, snd_cwnd) = min(cw + incr,
341 TCP_MAXWIN << CCV(ccv, snd_scale));
342 }
343 }
344
345 static void
newreno_after_idle(struct cc_var * ccv)346 newreno_after_idle(struct cc_var *ccv)
347 {
348 struct newreno *nreno;
349
350 nreno = ccv->cc_data;
351 newreno_cc_after_idle(ccv);
352 if ((nreno->newreno_flags & CC_NEWRENO_HYSTART_ENABLED) == 0) {
353 /*
354 * Re-enable hystart if we have been idle.
355 */
356 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_IN_CSS;
357 nreno->newreno_flags |= CC_NEWRENO_HYSTART_ENABLED;
358 newreno_log_hystart_event(ccv, nreno, 12, CCV(ccv, snd_ssthresh));
359 }
360 }
361
362 /*
363 * Perform any necessary tasks before we enter congestion recovery.
364 */
365 static void
newreno_cong_signal(struct cc_var * ccv,ccsignal_t type)366 newreno_cong_signal(struct cc_var *ccv, ccsignal_t type)
367 {
368 struct newreno *nreno;
369 uint32_t beta, beta_ecn, cwin, factor, mss, pipe;
370
371 cwin = CCV(ccv, snd_cwnd);
372 mss = tcp_fixed_maxseg(ccv->tp);
373 nreno = ccv->cc_data;
374 beta = (nreno == NULL) ? V_newreno_beta : nreno->beta;
375 beta_ecn = (nreno == NULL) ? V_newreno_beta_ecn : nreno->beta_ecn;
376 /*
377 * Note that we only change the backoff for ECN if the
378 * global sysctl V_cc_do_abe is set <or> the stack itself
379 * has set a flag in our newreno_flags (due to pacing) telling
380 * us to use the lower valued back-off.
381 */
382 if ((type == CC_ECN) &&
383 (V_cc_do_abe ||
384 ((nreno != NULL) && (nreno->newreno_flags & CC_NEWRENO_BETA_ECN_ENABLED))))
385 factor = beta_ecn;
386 else
387 factor = beta;
388
389 /* Catch algos which mistakenly leak private signal types. */
390 KASSERT((type & CC_SIGPRIVMASK) == 0,
391 ("%s: congestion signal type 0x%08x is private\n", __func__, type));
392
393 cwin = max(((uint64_t)cwin * (uint64_t)factor) / (100ULL * (uint64_t)mss),
394 2) * mss;
395
396 switch (type) {
397 case CC_NDUPACK:
398 if (nreno->newreno_flags & CC_NEWRENO_HYSTART_ENABLED) {
399 /* Make sure the flags are all off we had a loss */
400 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_ENABLED;
401 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_IN_CSS;
402 newreno_log_hystart_event(ccv, nreno, 10, CCV(ccv, snd_ssthresh));
403 }
404 if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
405 if (IN_CONGRECOVERY(CCV(ccv, t_flags) &&
406 V_cc_do_abe && V_cc_abe_frlossreduce)) {
407 CCV(ccv, snd_ssthresh) =
408 ((uint64_t)CCV(ccv, snd_ssthresh) *
409 (uint64_t)beta) / (uint64_t)beta_ecn;
410 }
411 if (!IN_CONGRECOVERY(CCV(ccv, t_flags)))
412 CCV(ccv, snd_ssthresh) = cwin;
413 ENTER_RECOVERY(CCV(ccv, t_flags));
414 }
415 break;
416 case CC_ECN:
417 if (nreno->newreno_flags & CC_NEWRENO_HYSTART_ENABLED) {
418 /* Make sure the flags are all off we had a loss */
419 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_ENABLED;
420 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_IN_CSS;
421 newreno_log_hystart_event(ccv, nreno, 9, CCV(ccv, snd_ssthresh));
422 }
423 if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
424 CCV(ccv, snd_ssthresh) = cwin;
425 CCV(ccv, snd_cwnd) = cwin;
426 ENTER_CONGRECOVERY(CCV(ccv, t_flags));
427 }
428 break;
429 case CC_RTO:
430 if (CCV(ccv, t_rxtshift) == 1) {
431 if (V_tcp_do_newsack) {
432 pipe = tcp_compute_pipe(ccv->tp);
433 } else {
434 pipe = CCV(ccv, snd_max) -
435 CCV(ccv, snd_fack) +
436 CCV(ccv, sackhint.sack_bytes_rexmit);
437 }
438 CCV(ccv, snd_ssthresh) = max(2,
439 ((uint64_t)min(CCV(ccv, snd_wnd), pipe) *
440 (uint64_t)factor) /
441 (100ULL * (uint64_t)mss)) * mss;
442 }
443 CCV(ccv, snd_cwnd) = mss;
444 break;
445 default:
446 break;
447 }
448 }
449
450 static int
newreno_ctl_output(struct cc_var * ccv,struct sockopt * sopt,void * buf)451 newreno_ctl_output(struct cc_var *ccv, struct sockopt *sopt, void *buf)
452 {
453 struct newreno *nreno;
454 struct cc_newreno_opts *opt;
455
456 if (sopt->sopt_valsize != sizeof(struct cc_newreno_opts))
457 return (EMSGSIZE);
458
459 if (CC_ALGO(ccv->tp) != &newreno_cc_algo)
460 return (ENOPROTOOPT);
461
462 nreno = (struct newreno *)ccv->cc_data;
463 opt = buf;
464 switch (sopt->sopt_dir) {
465 case SOPT_SET:
466 switch (opt->name) {
467 case CC_NEWRENO_BETA:
468 nreno->beta = opt->val;
469 break;
470 case CC_NEWRENO_BETA_ECN:
471 nreno->beta_ecn = opt->val;
472 nreno->newreno_flags |= CC_NEWRENO_BETA_ECN_ENABLED;
473 break;
474 default:
475 return (ENOPROTOOPT);
476 }
477 break;
478 case SOPT_GET:
479 switch (opt->name) {
480 case CC_NEWRENO_BETA:
481 opt->val = nreno->beta;
482 break;
483 case CC_NEWRENO_BETA_ECN:
484 opt->val = nreno->beta_ecn;
485 break;
486 default:
487 return (ENOPROTOOPT);
488 }
489 break;
490 default:
491 return (EINVAL);
492 }
493
494 return (0);
495 }
496
497 static int
newreno_beta_handler(SYSCTL_HANDLER_ARGS)498 newreno_beta_handler(SYSCTL_HANDLER_ARGS)
499 {
500 int error;
501 uint32_t new;
502
503 new = *(uint32_t *)arg1;
504 error = sysctl_handle_int(oidp, &new, 0, req);
505 if (error == 0 && req->newptr != NULL ) {
506 if (arg1 == &VNET_NAME(newreno_beta_ecn) && !V_cc_do_abe)
507 error = EACCES;
508 else if (new == 0 || new > 100)
509 error = EINVAL;
510 else
511 *(uint32_t *)arg1 = new;
512 }
513
514 return (error);
515 }
516
517 static void
newreno_newround(struct cc_var * ccv,uint32_t round_cnt)518 newreno_newround(struct cc_var *ccv, uint32_t round_cnt)
519 {
520 struct newreno *nreno;
521
522 nreno = (struct newreno *)ccv->cc_data;
523 /* We have entered a new round */
524 nreno->css_lastround_minrtt = nreno->css_current_round_minrtt;
525 nreno->css_current_round_minrtt = 0xffffffff;
526 nreno->css_rttsample_count = 0;
527 nreno->css_current_round = round_cnt;
528 if ((nreno->newreno_flags & CC_NEWRENO_HYSTART_IN_CSS) &&
529 ((round_cnt - nreno->css_entered_at_round) >= hystart_css_rounds)) {
530 /* Enter CA */
531 if (ccv->flags & CCF_HYSTART_CAN_SH_CWND) {
532 /*
533 * We engage more than snd_ssthresh, engage
534 * the brakes!! Though we will stay in SS to
535 * creep back up again, so lets leave CSS active
536 * and give us hystart_css_rounds more rounds.
537 */
538 if (ccv->flags & CCF_HYSTART_CONS_SSTH) {
539 CCV(ccv, snd_ssthresh) = ((nreno->css_lowrtt_fas + nreno->css_fas_at_css_entry) / 2);
540 } else {
541 CCV(ccv, snd_ssthresh) = nreno->css_lowrtt_fas;
542 }
543 CCV(ccv, snd_cwnd) = nreno->css_fas_at_css_entry;
544 nreno->css_entered_at_round = round_cnt;
545 } else {
546 CCV(ccv, snd_ssthresh) = CCV(ccv, snd_cwnd);
547 /* Turn off the CSS flag */
548 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_IN_CSS;
549 /* Disable use of CSS in the future except long idle */
550 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_ENABLED;
551 }
552 newreno_log_hystart_event(ccv, nreno, 6, CCV(ccv, snd_ssthresh));
553 }
554 if (nreno->newreno_flags & CC_NEWRENO_HYSTART_ENABLED)
555 newreno_log_hystart_event(ccv, nreno, 4, round_cnt);
556 }
557
558 static void
newreno_rttsample(struct cc_var * ccv,uint32_t usec_rtt,uint32_t rxtcnt,uint32_t fas)559 newreno_rttsample(struct cc_var *ccv, uint32_t usec_rtt, uint32_t rxtcnt, uint32_t fas)
560 {
561 struct newreno *nreno;
562
563 nreno = (struct newreno *)ccv->cc_data;
564 if (rxtcnt > 1) {
565 /*
566 * Only look at RTT's that are non-ambiguous.
567 */
568 return;
569 }
570 nreno->css_rttsample_count++;
571 nreno->css_last_fas = fas;
572 if (nreno->css_current_round_minrtt > usec_rtt) {
573 nreno->css_current_round_minrtt = usec_rtt;
574 nreno->css_lowrtt_fas = nreno->css_last_fas;
575 }
576 if ((nreno->css_rttsample_count >= hystart_n_rttsamples) &&
577 (nreno->css_current_round_minrtt != 0xffffffff) &&
578 (nreno->css_current_round_minrtt < nreno->css_baseline_minrtt) &&
579 (nreno->css_lastround_minrtt != 0xffffffff)) {
580 /*
581 * We were in CSS and the RTT is now less, we
582 * entered CSS erroneously.
583 */
584 nreno->newreno_flags &= ~CC_NEWRENO_HYSTART_IN_CSS;
585 newreno_log_hystart_event(ccv, nreno, 8, nreno->css_baseline_minrtt);
586 nreno->css_baseline_minrtt = 0xffffffff;
587 }
588 if (nreno->newreno_flags & CC_NEWRENO_HYSTART_ENABLED)
589 newreno_log_hystart_event(ccv, nreno, 5, usec_rtt);
590 }
591
592 SYSCTL_DECL(_net_inet_tcp_cc_newreno);
593 SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, newreno,
594 CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
595 "New Reno related settings");
596
597 SYSCTL_PROC(_net_inet_tcp_cc_newreno, OID_AUTO, beta,
598 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
599 &VNET_NAME(newreno_beta), 3, &newreno_beta_handler, "IU",
600 "New Reno beta, specified as number between 1 and 100");
601
602 SYSCTL_PROC(_net_inet_tcp_cc_newreno, OID_AUTO, beta_ecn,
603 CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
604 &VNET_NAME(newreno_beta_ecn), 3, &newreno_beta_handler, "IU",
605 "New Reno beta ecn, specified as number between 1 and 100");
606
607 DECLARE_CC_MODULE(newreno, &newreno_cc_algo);
608 MODULE_VERSION(newreno, 2);
609