cc_cubic.c (b8d60729deefa0bd13e6a395fcab4928e6e10445) cc_cubic.c (a9696510f5caef4a7c525fcf4359597798829350)
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2008-2010 Lawrence Stewart <lstewart@freebsd.org>
5 * Copyright (c) 2010 The FreeBSD Foundation
6 * All rights reserved.
7 *
8 * This software was developed by Lawrence Stewart while studying at the Centre

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65#include <net/route.h>
66#include <net/route/nhop.h>
67
68#include <netinet/in_pcb.h>
69#include <netinet/tcp.h>
70#include <netinet/tcp_seq.h>
71#include <netinet/tcp_timer.h>
72#include <netinet/tcp_var.h>
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2008-2010 Lawrence Stewart <lstewart@freebsd.org>
5 * Copyright (c) 2010 The FreeBSD Foundation
6 * All rights reserved.
7 *
8 * This software was developed by Lawrence Stewart while studying at the Centre

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65#include <net/route.h>
66#include <net/route/nhop.h>
67
68#include <netinet/in_pcb.h>
69#include <netinet/tcp.h>
70#include <netinet/tcp_seq.h>
71#include <netinet/tcp_timer.h>
72#include <netinet/tcp_var.h>
73#include <netinet/tcp_log_buf.h>
74#include <netinet/tcp_hpts.h>
73#include <netinet/cc/cc.h>
74#include <netinet/cc/cc_cubic.h>
75#include <netinet/cc/cc_module.h>
76
77static void cubic_ack_received(struct cc_var *ccv, uint16_t type);
78static void cubic_cb_destroy(struct cc_var *ccv);
79static int cubic_cb_init(struct cc_var *ccv, void *ptr);
80static void cubic_cong_signal(struct cc_var *ccv, uint32_t type);
81static void cubic_conn_init(struct cc_var *ccv);
82static int cubic_mod_init(void);
83static void cubic_post_recovery(struct cc_var *ccv);
84static void cubic_record_rtt(struct cc_var *ccv);
85static void cubic_ssthresh_update(struct cc_var *ccv, uint32_t maxseg);
86static void cubic_after_idle(struct cc_var *ccv);
87static size_t cubic_data_sz(void);
75#include <netinet/cc/cc.h>
76#include <netinet/cc/cc_cubic.h>
77#include <netinet/cc/cc_module.h>
78
79static void cubic_ack_received(struct cc_var *ccv, uint16_t type);
80static void cubic_cb_destroy(struct cc_var *ccv);
81static int cubic_cb_init(struct cc_var *ccv, void *ptr);
82static void cubic_cong_signal(struct cc_var *ccv, uint32_t type);
83static void cubic_conn_init(struct cc_var *ccv);
84static int cubic_mod_init(void);
85static void cubic_post_recovery(struct cc_var *ccv);
86static void cubic_record_rtt(struct cc_var *ccv);
87static void cubic_ssthresh_update(struct cc_var *ccv, uint32_t maxseg);
88static void cubic_after_idle(struct cc_var *ccv);
89static size_t cubic_data_sz(void);
90static void cubic_newround(struct cc_var *ccv, uint32_t round_cnt);
91static void cubic_rttsample(struct cc_var *ccv, uint32_t usec_rtt,
92 uint32_t rxtcnt, uint32_t fas);
88
93
89struct cubic {
90 /* Cubic K in fixed point form with CUBIC_SHIFT worth of precision. */
91 int64_t K;
92 /* Sum of RTT samples across an epoch in ticks. */
93 int64_t sum_rtt_ticks;
94 /* cwnd at the most recent congestion event. */
95 unsigned long max_cwnd;
96 /* cwnd at the previous congestion event. */
97 unsigned long prev_max_cwnd;
98 /* A copy of prev_max_cwnd. Used for CC_RTO_ERR */
99 unsigned long prev_max_cwnd_cp;
100 /* various flags */
101 uint32_t flags;
102#define CUBICFLAG_CONG_EVENT 0x00000001 /* congestion experienced */
103#define CUBICFLAG_IN_SLOWSTART 0x00000002 /* in slow start */
104#define CUBICFLAG_IN_APPLIMIT 0x00000004 /* application limited */
105#define CUBICFLAG_RTO_EVENT 0x00000008 /* RTO experienced */
106 /* Minimum observed rtt in ticks. */
107 int min_rtt_ticks;
108 /* Mean observed rtt between congestion epochs. */
109 int mean_rtt_ticks;
110 /* ACKs since last congestion event. */
111 int epoch_ack_count;
112 /* Timestamp (in ticks) of arriving in congestion avoidance from last
113 * congestion event.
114 */
115 int t_last_cong;
116 /* Timestamp (in ticks) of a previous congestion event. Used for
117 * CC_RTO_ERR.
118 */
119 int t_last_cong_prev;
120};
121
122struct cc_algo cubic_cc_algo = {
123 .name = "cubic",
124 .ack_received = cubic_ack_received,
125 .cb_destroy = cubic_cb_destroy,
126 .cb_init = cubic_cb_init,
127 .cong_signal = cubic_cong_signal,
128 .conn_init = cubic_conn_init,
129 .mod_init = cubic_mod_init,
130 .post_recovery = cubic_post_recovery,
131 .after_idle = cubic_after_idle,
94struct cc_algo cubic_cc_algo = {
95 .name = "cubic",
96 .ack_received = cubic_ack_received,
97 .cb_destroy = cubic_cb_destroy,
98 .cb_init = cubic_cb_init,
99 .cong_signal = cubic_cong_signal,
100 .conn_init = cubic_conn_init,
101 .mod_init = cubic_mod_init,
102 .post_recovery = cubic_post_recovery,
103 .after_idle = cubic_after_idle,
132 .cc_data_sz = cubic_data_sz
104 .cc_data_sz = cubic_data_sz,
105 .rttsample = cubic_rttsample,
106 .newround = cubic_newround
133};
134
135static void
107};
108
109static void
110cubic_log_hystart_event(struct cc_var *ccv, struct cubic *cubicd, uint8_t mod, uint32_t flex1)
111{
112 /*
113 * Types of logs (mod value)
114 * 1 - rtt_thresh in flex1, checking to see if RTT is to great.
115 * 2 - rtt is too great, rtt_thresh in flex1.
116 * 3 - CSS is active incr in flex1
117 * 4 - A new round is beginning flex1 is round count
118 * 5 - A new RTT measurement flex1 is the new measurement.
119 * 6 - We enter CA ssthresh is also in flex1.
120 * 7 - Socket option to change hystart executed opt.val in flex1.
121 * 8 - Back out of CSS into SS, flex1 is the css_baseline_minrtt
122 * 9 - We enter CA, via an ECN mark.
123 * 10 - We enter CA, via a loss.
124 * 11 - We have slipped out of SS into CA via cwnd growth.
125 * 12 - After idle has re-enabled hystart++
126 */
127 struct tcpcb *tp;
128
129 if (hystart_bblogs == 0)
130 return;
131 tp = ccv->ccvc.tcp;
132 if (tp->t_logstate != TCP_LOG_STATE_OFF) {
133 union tcp_log_stackspecific log;
134 struct timeval tv;
135
136 memset(&log, 0, sizeof(log));
137 log.u_bbr.flex1 = flex1;
138 log.u_bbr.flex2 = cubicd->css_current_round_minrtt;
139 log.u_bbr.flex3 = cubicd->css_lastround_minrtt;
140 log.u_bbr.flex4 = cubicd->css_rttsample_count;
141 log.u_bbr.flex5 = cubicd->css_entered_at_round;
142 log.u_bbr.flex6 = cubicd->css_baseline_minrtt;
143 /* We only need bottom 16 bits of flags */
144 log.u_bbr.flex7 = cubicd->flags & 0x0000ffff;
145 log.u_bbr.flex8 = mod;
146 log.u_bbr.epoch = cubicd->css_current_round;
147 log.u_bbr.timeStamp = tcp_get_usecs(&tv);
148 log.u_bbr.lt_epoch = cubicd->css_fas_at_css_entry;
149 log.u_bbr.pkts_out = cubicd->css_last_fas;
150 log.u_bbr.delivered = cubicd->css_lowrtt_fas;
151 log.u_bbr.pkt_epoch = ccv->flags;
152 TCP_LOG_EVENTP(tp, NULL,
153 &tp->t_inpcb->inp_socket->so_rcv,
154 &tp->t_inpcb->inp_socket->so_snd,
155 TCP_HYSTART, 0,
156 0, &log, false, &tv);
157 }
158}
159
160static void
161cubic_does_slow_start(struct cc_var *ccv, struct cubic *cubicd)
162{
163 /*
164 * In slow-start with ABC enabled and no RTO in sight?
165 * (Must not use abc_l_var > 1 if slow starting after
166 * an RTO. On RTO, snd_nxt = snd_una, so the
167 * snd_nxt == snd_max check is sufficient to
168 * handle this).
169 *
170 * XXXLAS: Find a way to signal SS after RTO that
171 * doesn't rely on tcpcb vars.
172 */
173 u_int cw = CCV(ccv, snd_cwnd);
174 u_int incr = CCV(ccv, t_maxseg);
175 uint16_t abc_val;
176
177 cubicd->flags |= CUBICFLAG_IN_SLOWSTART;
178 if (ccv->flags & CCF_USE_LOCAL_ABC)
179 abc_val = ccv->labc;
180 else
181 abc_val = V_tcp_abc_l_var;
182 if ((ccv->flags & CCF_HYSTART_ALLOWED) &&
183 (cubicd->flags & CUBICFLAG_HYSTART_ENABLED) &&
184 ((cubicd->flags & CUBICFLAG_HYSTART_IN_CSS) == 0)) {
185 /*
186 * Hystart is allowed and still enabled and we are not yet
187 * in CSS. Lets check to see if we can make a decision on
188 * if we need to go into CSS.
189 */
190 if ((cubicd->css_rttsample_count >= hystart_n_rttsamples) &&
191 (cubicd->css_current_round_minrtt != 0xffffffff) &&
192 (cubicd->css_lastround_minrtt != 0xffffffff)) {
193 uint32_t rtt_thresh;
194
195 /* Clamp (minrtt_thresh, lastround/8, maxrtt_thresh) */
196 rtt_thresh = (cubicd->css_lastround_minrtt >> 3);
197 if (rtt_thresh < hystart_minrtt_thresh)
198 rtt_thresh = hystart_minrtt_thresh;
199 if (rtt_thresh > hystart_maxrtt_thresh)
200 rtt_thresh = hystart_maxrtt_thresh;
201 cubic_log_hystart_event(ccv, cubicd, 1, rtt_thresh);
202
203 if (cubicd->css_current_round_minrtt >= (cubicd->css_lastround_minrtt + rtt_thresh)) {
204 /* Enter CSS */
205 cubicd->flags |= CUBICFLAG_HYSTART_IN_CSS;
206 cubicd->css_fas_at_css_entry = cubicd->css_lowrtt_fas;
207 /*
208 * The draft (v4) calls for us to set baseline to css_current_round_min
209 * but that can cause an oscillation. We probably shoudl be using
210 * css_lastround_minrtt, but the authors insist that will cause
211 * issues on exiting early. We will leave the draft version for now
212 * but I suspect this is incorrect.
213 */
214 cubicd->css_baseline_minrtt = cubicd->css_current_round_minrtt;
215 cubicd->css_entered_at_round = cubicd->css_current_round;
216 cubic_log_hystart_event(ccv, cubicd, 2, rtt_thresh);
217 }
218 }
219 }
220 if (CCV(ccv, snd_nxt) == CCV(ccv, snd_max))
221 incr = min(ccv->bytes_this_ack,
222 ccv->nsegs * abc_val *
223 CCV(ccv, t_maxseg));
224 else
225 incr = min(ccv->bytes_this_ack, CCV(ccv, t_maxseg));
226
227 /* Only if Hystart is enabled will the flag get set */
228 if (cubicd->flags & CUBICFLAG_HYSTART_IN_CSS) {
229 incr /= hystart_css_growth_div;
230 cubic_log_hystart_event(ccv, cubicd, 3, incr);
231 }
232 /* ABC is on by default, so incr equals 0 frequently. */
233 if (incr > 0)
234 CCV(ccv, snd_cwnd) = min((cw + incr),
235 TCP_MAXWIN << CCV(ccv, snd_scale));
236}
237
238static void
136cubic_ack_received(struct cc_var *ccv, uint16_t type)
137{
138 struct cubic *cubic_data;
139 unsigned long w_tf, w_cubic_next;
140 int ticks_since_cong;
141
142 cubic_data = ccv->cc_data;
143 cubic_record_rtt(ccv);
144
145 /*
146 * For a regular ACK and we're not in cong/fast recovery and
147 * we're cwnd limited, always recalculate cwnd.
148 */
149 if (type == CC_ACK && !IN_RECOVERY(CCV(ccv, t_flags)) &&
150 (ccv->flags & CCF_CWND_LIMITED)) {
151 /* Use the logic in NewReno ack_received() for slow start. */
152 if (CCV(ccv, snd_cwnd) <= CCV(ccv, snd_ssthresh) ||
153 cubic_data->min_rtt_ticks == TCPTV_SRTTBASE) {
239cubic_ack_received(struct cc_var *ccv, uint16_t type)
240{
241 struct cubic *cubic_data;
242 unsigned long w_tf, w_cubic_next;
243 int ticks_since_cong;
244
245 cubic_data = ccv->cc_data;
246 cubic_record_rtt(ccv);
247
248 /*
249 * For a regular ACK and we're not in cong/fast recovery and
250 * we're cwnd limited, always recalculate cwnd.
251 */
252 if (type == CC_ACK && !IN_RECOVERY(CCV(ccv, t_flags)) &&
253 (ccv->flags & CCF_CWND_LIMITED)) {
254 /* Use the logic in NewReno ack_received() for slow start. */
255 if (CCV(ccv, snd_cwnd) <= CCV(ccv, snd_ssthresh) ||
256 cubic_data->min_rtt_ticks == TCPTV_SRTTBASE) {
154 cubic_data->flags |= CUBICFLAG_IN_SLOWSTART;
155 newreno_cc_ack_received(ccv, type);
257 cubic_does_slow_start(ccv, cubic_data);
156 } else {
258 } else {
259 if (cubic_data->flags & CUBICFLAG_HYSTART_IN_CSS) {
260 /*
261 * We have slipped into CA with
262 * CSS active. Deactivate all.
263 */
264 /* Turn off the CSS flag */
265 cubic_data->flags &= ~CUBICFLAG_HYSTART_IN_CSS;
266 /* Disable use of CSS in the future except long idle */
267 cubic_data->flags &= ~CUBICFLAG_HYSTART_ENABLED;
268 cubic_log_hystart_event(ccv, cubic_data, 11, CCV(ccv, snd_ssthresh));
269 }
157 if ((cubic_data->flags & CUBICFLAG_RTO_EVENT) &&
158 (cubic_data->flags & CUBICFLAG_IN_SLOWSTART)) {
159 /* RFC8312 Section 4.7 */
160 cubic_data->flags &= ~(CUBICFLAG_RTO_EVENT |
161 CUBICFLAG_IN_SLOWSTART);
162 cubic_data->max_cwnd = CCV(ccv, snd_cwnd);
163 cubic_data->K = 0;
164 } else if (cubic_data->flags & (CUBICFLAG_IN_SLOWSTART |

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240cubic_after_idle(struct cc_var *ccv)
241{
242 struct cubic *cubic_data;
243
244 cubic_data = ccv->cc_data;
245
246 cubic_data->max_cwnd = ulmax(cubic_data->max_cwnd, CCV(ccv, snd_cwnd));
247 cubic_data->K = cubic_k(cubic_data->max_cwnd / CCV(ccv, t_maxseg));
270 if ((cubic_data->flags & CUBICFLAG_RTO_EVENT) &&
271 (cubic_data->flags & CUBICFLAG_IN_SLOWSTART)) {
272 /* RFC8312 Section 4.7 */
273 cubic_data->flags &= ~(CUBICFLAG_RTO_EVENT |
274 CUBICFLAG_IN_SLOWSTART);
275 cubic_data->max_cwnd = CCV(ccv, snd_cwnd);
276 cubic_data->K = 0;
277 } else if (cubic_data->flags & (CUBICFLAG_IN_SLOWSTART |

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353cubic_after_idle(struct cc_var *ccv)
354{
355 struct cubic *cubic_data;
356
357 cubic_data = ccv->cc_data;
358
359 cubic_data->max_cwnd = ulmax(cubic_data->max_cwnd, CCV(ccv, snd_cwnd));
360 cubic_data->K = cubic_k(cubic_data->max_cwnd / CCV(ccv, t_maxseg));
248
361 if ((cubic_data->flags & CUBICFLAG_HYSTART_ENABLED) == 0) {
362 /*
363 * Re-enable hystart if we have been idle.
364 */
365 cubic_data->flags &= ~CUBICFLAG_HYSTART_IN_CSS;
366 cubic_data->flags |= CUBICFLAG_HYSTART_ENABLED;
367 cubic_log_hystart_event(ccv, cubic_data, 12, CCV(ccv, snd_ssthresh));
368 }
249 newreno_cc_after_idle(ccv);
250 cubic_data->t_last_cong = ticks;
251}
252
253static void
254cubic_cb_destroy(struct cc_var *ccv)
255{
256 free(ccv->cc_data, M_CC_MEM);

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276 cubic_data = ptr;
277
278 /* Init some key variables with sensible defaults. */
279 cubic_data->t_last_cong = ticks;
280 cubic_data->min_rtt_ticks = TCPTV_SRTTBASE;
281 cubic_data->mean_rtt_ticks = 1;
282
283 ccv->cc_data = cubic_data;
369 newreno_cc_after_idle(ccv);
370 cubic_data->t_last_cong = ticks;
371}
372
373static void
374cubic_cb_destroy(struct cc_var *ccv)
375{
376 free(ccv->cc_data, M_CC_MEM);

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396 cubic_data = ptr;
397
398 /* Init some key variables with sensible defaults. */
399 cubic_data->t_last_cong = ticks;
400 cubic_data->min_rtt_ticks = TCPTV_SRTTBASE;
401 cubic_data->mean_rtt_ticks = 1;
402
403 ccv->cc_data = cubic_data;
404 cubic_data->flags = CUBICFLAG_HYSTART_ENABLED;
405 /* At init set both to infinity */
406 cubic_data->css_lastround_minrtt = 0xffffffff;
407 cubic_data->css_current_round_minrtt = 0xffffffff;
408 cubic_data->css_current_round = 0;
409 cubic_data->css_baseline_minrtt = 0xffffffff;
410 cubic_data->css_rttsample_count = 0;
411 cubic_data->css_entered_at_round = 0;
412 cubic_data->css_fas_at_css_entry = 0;
413 cubic_data->css_lowrtt_fas = 0;
414 cubic_data->css_last_fas = 0;
284
285 return (0);
286}
287
288/*
289 * Perform any necessary tasks before we enter congestion recovery.
290 */
291static void
292cubic_cong_signal(struct cc_var *ccv, uint32_t type)
293{
294 struct cubic *cubic_data;
295 u_int mss;
296
297 cubic_data = ccv->cc_data;
298 mss = tcp_maxseg(ccv->ccvc.tcp);
299
300 switch (type) {
301 case CC_NDUPACK:
415
416 return (0);
417}
418
419/*
420 * Perform any necessary tasks before we enter congestion recovery.
421 */
422static void
423cubic_cong_signal(struct cc_var *ccv, uint32_t type)
424{
425 struct cubic *cubic_data;
426 u_int mss;
427
428 cubic_data = ccv->cc_data;
429 mss = tcp_maxseg(ccv->ccvc.tcp);
430
431 switch (type) {
432 case CC_NDUPACK:
433 if (cubic_data->flags & CUBICFLAG_HYSTART_ENABLED) {
434 /* Make sure the flags are all off we had a loss */
435 cubic_data->flags &= ~CUBICFLAG_HYSTART_ENABLED;
436 cubic_data->flags &= ~CUBICFLAG_HYSTART_IN_CSS;
437 cubic_log_hystart_event(ccv, cubic_data, 10, CCV(ccv, snd_ssthresh));
438 }
302 if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
303 if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
304 cubic_ssthresh_update(ccv, mss);
305 cubic_data->flags |= CUBICFLAG_CONG_EVENT;
306 cubic_data->t_last_cong = ticks;
307 cubic_data->K = cubic_k(cubic_data->max_cwnd / mss);
308 }
309 ENTER_RECOVERY(CCV(ccv, t_flags));
310 }
311 break;
312
313 case CC_ECN:
439 if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
440 if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
441 cubic_ssthresh_update(ccv, mss);
442 cubic_data->flags |= CUBICFLAG_CONG_EVENT;
443 cubic_data->t_last_cong = ticks;
444 cubic_data->K = cubic_k(cubic_data->max_cwnd / mss);
445 }
446 ENTER_RECOVERY(CCV(ccv, t_flags));
447 }
448 break;
449
450 case CC_ECN:
451 if (cubic_data->flags & CUBICFLAG_HYSTART_ENABLED) {
452 /* Make sure the flags are all off we had a loss */
453 cubic_data->flags &= ~CUBICFLAG_HYSTART_ENABLED;
454 cubic_data->flags &= ~CUBICFLAG_HYSTART_IN_CSS;
455 cubic_log_hystart_event(ccv, cubic_data, 9, CCV(ccv, snd_ssthresh));
456 }
314 if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
315 cubic_ssthresh_update(ccv, mss);
316 cubic_data->flags |= CUBICFLAG_CONG_EVENT;
317 cubic_data->t_last_cong = ticks;
318 cubic_data->K = cubic_k(cubic_data->max_cwnd / mss);
319 CCV(ccv, snd_cwnd) = CCV(ccv, snd_ssthresh);
320 ENTER_CONGRECOVERY(CCV(ccv, t_flags));
321 }

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490 CUBIC_BETA) >> CUBIC_SHIFT;
491 } else {
492 ssthresh = ((uint64_t)cwnd *
493 CUBIC_BETA) >> CUBIC_SHIFT;
494 }
495 CCV(ccv, snd_ssthresh) = max(ssthresh, 2 * maxseg);
496}
497
457 if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
458 cubic_ssthresh_update(ccv, mss);
459 cubic_data->flags |= CUBICFLAG_CONG_EVENT;
460 cubic_data->t_last_cong = ticks;
461 cubic_data->K = cubic_k(cubic_data->max_cwnd / mss);
462 CCV(ccv, snd_cwnd) = CCV(ccv, snd_ssthresh);
463 ENTER_CONGRECOVERY(CCV(ccv, t_flags));
464 }

--- 168 unchanged lines hidden (view full) ---

633 CUBIC_BETA) >> CUBIC_SHIFT;
634 } else {
635 ssthresh = ((uint64_t)cwnd *
636 CUBIC_BETA) >> CUBIC_SHIFT;
637 }
638 CCV(ccv, snd_ssthresh) = max(ssthresh, 2 * maxseg);
639}
640
641static void
642cubic_rttsample(struct cc_var *ccv, uint32_t usec_rtt, uint32_t rxtcnt, uint32_t fas)
643{
644 struct cubic *cubicd;
645
646 cubicd = ccv->cc_data;
647 if (rxtcnt > 1) {
648 /*
649 * Only look at RTT's that are non-ambiguous.
650 */
651 return;
652 }
653 cubicd->css_rttsample_count++;
654 cubicd->css_last_fas = fas;
655 if (cubicd->css_current_round_minrtt > usec_rtt) {
656 cubicd->css_current_round_minrtt = usec_rtt;
657 cubicd->css_lowrtt_fas = cubicd->css_last_fas;
658 }
659 if ((cubicd->css_rttsample_count >= hystart_n_rttsamples) &&
660 (cubicd->css_current_round_minrtt != 0xffffffff) &&
661 (cubicd->css_lastround_minrtt != 0xffffffff)) {
662 /*
663 * We were in CSS and the RTT is now less, we
664 * entered CSS erroneously.
665 */
666 cubicd->flags &= ~CUBICFLAG_HYSTART_IN_CSS;
667 cubic_log_hystart_event(ccv, cubicd, 8, cubicd->css_baseline_minrtt);
668 cubicd->css_baseline_minrtt = 0xffffffff;
669 }
670 if (cubicd->flags & CUBICFLAG_HYSTART_ENABLED)
671 cubic_log_hystart_event(ccv, cubicd, 5, usec_rtt);
672}
673
674static void
675cubic_newround(struct cc_var *ccv, uint32_t round_cnt)
676{
677 struct cubic *cubicd;
678
679 cubicd = ccv->cc_data;
680 /* We have entered a new round */
681 cubicd->css_lastround_minrtt = cubicd->css_current_round_minrtt;
682 cubicd->css_current_round_minrtt = 0xffffffff;
683 cubicd->css_rttsample_count = 0;
684 cubicd->css_current_round = round_cnt;
685 if ((cubicd->flags & CUBICFLAG_HYSTART_IN_CSS) &&
686 ((round_cnt - cubicd->css_entered_at_round) >= hystart_css_rounds)) {
687 /* Enter CA */
688 if (ccv->flags & CCF_HYSTART_CAN_SH_CWND) {
689 /*
690 * We engage more than snd_ssthresh, engage
691 * the brakes!! Though we will stay in SS to
692 * creep back up again, so lets leave CSS active
693 * and give us hystart_css_rounds more rounds.
694 */
695 if (ccv->flags & CCF_HYSTART_CONS_SSTH) {
696 CCV(ccv, snd_ssthresh) = ((cubicd->css_lowrtt_fas + cubicd->css_fas_at_css_entry) / 2);
697 } else {
698 CCV(ccv, snd_ssthresh) = cubicd->css_lowrtt_fas;
699 }
700 CCV(ccv, snd_cwnd) = cubicd->css_fas_at_css_entry;
701 cubicd->css_entered_at_round = round_cnt;
702 } else {
703 CCV(ccv, snd_ssthresh) = CCV(ccv, snd_cwnd);
704 /* Turn off the CSS flag */
705 cubicd->flags &= ~CUBICFLAG_HYSTART_IN_CSS;
706 /* Disable use of CSS in the future except long idle */
707 cubicd->flags &= ~CUBICFLAG_HYSTART_ENABLED;
708 }
709 cubic_log_hystart_event(ccv, cubicd, 6, CCV(ccv, snd_ssthresh));
710 }
711 if (cubicd->flags & CUBICFLAG_HYSTART_ENABLED)
712 cubic_log_hystart_event(ccv, cubicd, 4, round_cnt);
713}
714
498DECLARE_CC_MODULE(cubic, &cubic_cc_algo);
499MODULE_VERSION(cubic, 2);
715DECLARE_CC_MODULE(cubic, &cubic_cc_algo);
716MODULE_VERSION(cubic, 2);