1 /* $KAME: altq_red.c,v 1.19 2004/04/17 10:54:49 kjc Exp $ */
2 /* $DragonFly: src/sys/net/altq/altq_red.c,v 1.4 2006/12/22 23:44:55 swildner Exp $ */
3
4 /*
5 * Copyright (C) 1997-2003
6 * Sony Computer Science Laboratories Inc. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY SONY CSL AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL SONY CSL OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 */
30 /*
31 * Copyright (c) 1990-1994 Regents of the University of California.
32 * All rights reserved.
33 *
34 * Redistribution and use in source and binary forms, with or without
35 * modification, are permitted provided that the following conditions
36 * are met:
37 * 1. Redistributions of source code must retain the above copyright
38 * notice, this list of conditions and the following disclaimer.
39 * 2. Redistributions in binary form must reproduce the above copyright
40 * notice, this list of conditions and the following disclaimer in the
41 * documentation and/or other materials provided with the distribution.
42 * 3. All advertising materials mentioning features or use of this software
43 * must display the following acknowledgement:
44 * This product includes software developed by the Computer Systems
45 * Engineering Group at Lawrence Berkeley Laboratory.
46 * 4. Neither the name of the University nor of the Laboratory may be used
47 * to endorse or promote products derived from this software without
48 * specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
60 * SUCH DAMAGE.
61 */
62
63 #include "opt_altq.h"
64 #include "opt_inet.h"
65 #include "opt_inet6.h"
66
67 #ifdef ALTQ_RED /* red is enabled by ALTQ_RED option in opt_altq.h */
68
69 #include <sys/param.h>
70 #include <sys/malloc.h>
71 #include <sys/mbuf.h>
72 #include <sys/socket.h>
73 #include <sys/systm.h>
74 #include <sys/errno.h>
75
76 #include <net/if.h>
77 #include <net/ifq_var.h>
78
79 #include <netinet/in.h>
80 #include <netinet/in_systm.h>
81 #include <netinet/ip.h>
82 #ifdef INET6
83 #include <netinet/ip6.h>
84 #endif
85
86 #include <net/pf/pfvar.h>
87 #include <net/altq/altq.h>
88 #include <net/altq/altq_red.h>
89
90 /*
91 * ALTQ/RED (Random Early Detection) implementation using 32-bit
92 * fixed-point calculation.
93 *
94 * written by kjc using the ns code as a reference.
95 * you can learn more about red and ns from Sally's home page at
96 * http://www-nrg.ee.lbl.gov/floyd/
97 *
98 * most of the red parameter values are fixed in this implementation
99 * to prevent fixed-point overflow/underflow.
100 * if you change the parameters, watch out for overflow/underflow!
101 *
102 * the parameters used are recommended values by Sally.
103 * the corresponding ns config looks:
104 * q_weight=0.00195
105 * minthresh=5 maxthresh=15 queue-size=60
106 * linterm=30
107 * dropmech=drop-tail
108 * bytes=false (can't be handled by 32-bit fixed-point)
109 * doubleq=false dqthresh=false
110 * wait=true
111 */
112 /*
113 * alternative red parameters for a slow link.
114 *
115 * assume the queue length becomes from zero to L and keeps L, it takes
116 * N packets for q_avg to reach 63% of L.
117 * when q_weight is 0.002, N is about 500 packets.
118 * for a slow link like dial-up, 500 packets takes more than 1 minute!
119 * when q_weight is 0.008, N is about 127 packets.
120 * when q_weight is 0.016, N is about 63 packets.
121 * bursts of 50 packets are allowed for 0.002, bursts of 25 packets
122 * are allowed for 0.016.
123 * see Sally's paper for more details.
124 */
125 /* normal red parameters */
126 #define W_WEIGHT 512 /* inverse of weight of EWMA (511/512) */
127 /* q_weight = 0.00195 */
128
129 /* red parameters for a slow link */
130 #define W_WEIGHT_1 128 /* inverse of weight of EWMA (127/128) */
131 /* q_weight = 0.0078125 */
132
133 /* red parameters for a very slow link (e.g., dialup) */
134 #define W_WEIGHT_2 64 /* inverse of weight of EWMA (63/64) */
135 /* q_weight = 0.015625 */
136
137 /* fixed-point uses 12-bit decimal places */
138 #define FP_SHIFT 12 /* fixed-point shift */
139
140 /* red parameters for drop probability */
141 #define INV_P_MAX 10 /* inverse of max drop probability */
142 #define TH_MIN 5 /* min threshold */
143 #define TH_MAX 15 /* max threshold */
144
145 #define RED_LIMIT 60 /* default max queue lenght */
146 #define RED_STATS /* collect statistics */
147
148 /*
149 * our default policy for forced-drop is drop-tail.
150 * (in altq-1.1.2 or earlier, the default was random-drop.
151 * but it makes more sense to punish the cause of the surge.)
152 * to switch to the random-drop policy, define "RED_RANDOM_DROP".
153 */
154
155 /* default red parameter values */
156 static int default_th_min = TH_MIN;
157 static int default_th_max = TH_MAX;
158 static int default_inv_pmax = INV_P_MAX;
159
160 /*
161 * red support routines
162 */
163 red_t *
red_alloc(int weight,int inv_pmax,int th_min,int th_max,int flags,int pkttime)164 red_alloc(int weight, int inv_pmax, int th_min, int th_max, int flags, int pkttime)
165 {
166 red_t *rp;
167 int w, i;
168 int npkts_per_sec;
169
170 rp = kmalloc(sizeof(*rp), M_ALTQ, M_WAITOK | M_ZERO);
171 rp->red_avg = 0;
172 rp->red_idle = 1;
173
174 if (weight == 0)
175 rp->red_weight = W_WEIGHT;
176 else
177 rp->red_weight = weight;
178 if (inv_pmax == 0)
179 rp->red_inv_pmax = default_inv_pmax;
180 else
181 rp->red_inv_pmax = inv_pmax;
182 if (th_min == 0)
183 rp->red_thmin = default_th_min;
184 else
185 rp->red_thmin = th_min;
186 if (th_max == 0)
187 rp->red_thmax = default_th_max;
188 else
189 rp->red_thmax = th_max;
190
191 rp->red_flags = flags;
192
193 if (pkttime == 0)
194 /* default packet time: 1000 bytes / 10Mbps * 8 * 1000000 */
195 rp->red_pkttime = 800;
196 else
197 rp->red_pkttime = pkttime;
198
199 if (weight == 0) {
200 /* when the link is very slow, adjust red parameters */
201 npkts_per_sec = 1000000 / rp->red_pkttime;
202 if (npkts_per_sec < 50) {
203 /* up to about 400Kbps */
204 rp->red_weight = W_WEIGHT_2;
205 } else if (npkts_per_sec < 300) {
206 /* up to about 2.4Mbps */
207 rp->red_weight = W_WEIGHT_1;
208 }
209 }
210
211 /* calculate wshift. weight must be power of 2 */
212 w = rp->red_weight;
213 for (i = 0; w > 1; i++)
214 w = w >> 1;
215 rp->red_wshift = i;
216 w = 1 << rp->red_wshift;
217 if (w != rp->red_weight) {
218 kprintf("invalid weight value %d for red! use %d\n",
219 rp->red_weight, w);
220 rp->red_weight = w;
221 }
222
223 /*
224 * thmin_s and thmax_s are scaled versions of th_min and th_max
225 * to be compared with avg.
226 */
227 rp->red_thmin_s = rp->red_thmin << (rp->red_wshift + FP_SHIFT);
228 rp->red_thmax_s = rp->red_thmax << (rp->red_wshift + FP_SHIFT);
229
230 /*
231 * precompute probability denominator
232 * probd = (2 * (TH_MAX-TH_MIN) / pmax) in fixed-point
233 */
234 rp->red_probd = (2 * (rp->red_thmax - rp->red_thmin)
235 * rp->red_inv_pmax) << FP_SHIFT;
236
237 /* allocate weight table */
238 rp->red_wtab = wtab_alloc(rp->red_weight);
239
240 microtime(&rp->red_last);
241 return (rp);
242 }
243
244 void
red_destroy(red_t * rp)245 red_destroy(red_t *rp)
246 {
247 wtab_destroy(rp->red_wtab);
248 kfree(rp, M_ALTQ);
249 }
250
251 void
red_getstats(red_t * rp,struct redstats * sp)252 red_getstats(red_t *rp, struct redstats *sp)
253 {
254 sp->q_avg = rp->red_avg >> rp->red_wshift;
255 sp->xmit_cnt = rp->red_stats.xmit_cnt;
256 sp->drop_cnt = rp->red_stats.drop_cnt;
257 sp->drop_forced = rp->red_stats.drop_forced;
258 sp->drop_unforced = rp->red_stats.drop_unforced;
259 sp->marked_packets = rp->red_stats.marked_packets;
260 }
261
262 int
red_addq(red_t * rp,class_queue_t * q,struct mbuf * m,struct altq_pktattr * pktattr)263 red_addq(red_t *rp, class_queue_t *q, struct mbuf *m, struct altq_pktattr *pktattr)
264 {
265 int avg, droptype;
266 int n;
267
268 avg = rp->red_avg;
269
270 /*
271 * if we were idle, we pretend that n packets arrived during
272 * the idle period.
273 */
274 if (rp->red_idle) {
275 struct timeval now;
276 int t;
277
278 rp->red_idle = 0;
279 microtime(&now);
280 t = (now.tv_sec - rp->red_last.tv_sec);
281 if (t > 60) {
282 /*
283 * being idle for more than 1 minute, set avg to zero.
284 * this prevents t from overflow.
285 */
286 avg = 0;
287 } else {
288 t = t * 1000000 + (now.tv_usec - rp->red_last.tv_usec);
289 n = t / rp->red_pkttime - 1;
290
291 /* the following line does (avg = (1 - Wq)^n * avg) */
292 if (n > 0)
293 avg = (avg >> FP_SHIFT) *
294 pow_w(rp->red_wtab, n);
295 }
296 }
297
298 /* run estimator. (note: avg is scaled by WEIGHT in fixed-point) */
299 avg += (qlen(q) << FP_SHIFT) - (avg >> rp->red_wshift);
300 rp->red_avg = avg; /* save the new value */
301
302 /*
303 * red_count keeps a tally of arriving traffic that has not
304 * been dropped.
305 */
306 rp->red_count++;
307
308 /* see if we drop early */
309 droptype = DTYPE_NODROP;
310 if (avg >= rp->red_thmin_s && qlen(q) > 1) {
311 if (avg >= rp->red_thmax_s) {
312 /* avg >= th_max: forced drop */
313 droptype = DTYPE_FORCED;
314 } else if (rp->red_old == 0) {
315 /* first exceeds th_min */
316 rp->red_count = 1;
317 rp->red_old = 1;
318 } else if (drop_early((avg - rp->red_thmin_s) >> rp->red_wshift,
319 rp->red_probd, rp->red_count)) {
320 /* mark or drop by red */
321 if ((rp->red_flags & REDF_ECN) &&
322 mark_ecn(m, pktattr, rp->red_flags)) {
323 /* successfully marked. do not drop. */
324 rp->red_count = 0;
325 #ifdef RED_STATS
326 rp->red_stats.marked_packets++;
327 #endif
328 } else {
329 /* unforced drop by red */
330 droptype = DTYPE_EARLY;
331 }
332 }
333 } else {
334 /* avg < th_min */
335 rp->red_old = 0;
336 }
337
338 /*
339 * if the queue length hits the hard limit, it's a forced drop.
340 */
341 if (droptype == DTYPE_NODROP && qlen(q) >= qlimit(q))
342 droptype = DTYPE_FORCED;
343
344 #ifdef RED_RANDOM_DROP
345 /* if successful or forced drop, enqueue this packet. */
346 if (droptype != DTYPE_EARLY)
347 _addq(q, m);
348 #else
349 /* if successful, enqueue this packet. */
350 if (droptype == DTYPE_NODROP)
351 _addq(q, m);
352 #endif
353 if (droptype != DTYPE_NODROP) {
354 if (droptype == DTYPE_EARLY) {
355 /* drop the incoming packet */
356 #ifdef RED_STATS
357 rp->red_stats.drop_unforced++;
358 #endif
359 } else {
360 /* forced drop, select a victim packet in the queue. */
361 #ifdef RED_RANDOM_DROP
362 m = _getq_random(q);
363 #endif
364 #ifdef RED_STATS
365 rp->red_stats.drop_forced++;
366 #endif
367 }
368 #ifdef RED_STATS
369 PKTCNTR_ADD(&rp->red_stats.drop_cnt, m_pktlen(m));
370 #endif
371 rp->red_count = 0;
372 m_freem(m);
373 return (-1);
374 }
375 /* successfully queued */
376 #ifdef RED_STATS
377 PKTCNTR_ADD(&rp->red_stats.xmit_cnt, m_pktlen(m));
378 #endif
379 return (0);
380 }
381
382 /*
383 * early-drop probability is calculated as follows:
384 * prob = p_max * (avg - th_min) / (th_max - th_min)
385 * prob_a = prob / (2 - count*prob)
386 * = (avg-th_min) / (2*(th_max-th_min)*inv_p_max - count*(avg-th_min))
387 * here prob_a increases as successive undrop count increases.
388 * (prob_a starts from prob/2, becomes prob when (count == (1 / prob)),
389 * becomes 1 when (count >= (2 / prob))).
390 */
391 int
drop_early(int fp_len,int fp_probd,int count)392 drop_early(int fp_len, int fp_probd, int count)
393 {
394 int d; /* denominator of drop-probability */
395
396 d = fp_probd - count * fp_len;
397 if (d <= 0) {
398 /* count exceeds the hard limit: drop or mark */
399 return (1);
400 }
401
402 /*
403 * now the range of d is [1..600] in fixed-point. (when
404 * th_max-th_min=10 and p_max=1/30)
405 * drop probability = (avg - TH_MIN) / d
406 */
407
408 if ((karc4random() % d) < fp_len) {
409 /* drop or mark */
410 return (1);
411 }
412 /* no drop/mark */
413 return (0);
414 }
415
416 /*
417 * try to mark CE bit to the packet.
418 * returns 1 if successfully marked, 0 otherwise.
419 */
420 int
mark_ecn(struct mbuf * m,struct altq_pktattr * pktattr,int flags)421 mark_ecn(struct mbuf *m, struct altq_pktattr *pktattr, int flags)
422 {
423 struct mbuf *m0;
424 void *hdr;
425 int af;
426
427 if (m->m_pkthdr.fw_flags & PF_MBUF_STRUCTURE) {
428 af = m->m_pkthdr.pf.ecn_af;
429 hdr = m->m_pkthdr.pf.hdr;
430 } else if (pktattr) {
431 af = pktattr->pattr_af;
432 hdr = pktattr->pattr_hdr;
433 } else {
434 return (0);
435 }
436
437 if (af != AF_INET && af != AF_INET6)
438 return (0);
439
440 /* verify that pattr_hdr is within the mbuf data */
441 for (m0 = m; m0 != NULL; m0 = m0->m_next) {
442 if (((caddr_t)hdr >= m0->m_data) &&
443 ((caddr_t)hdr < m0->m_data + m0->m_len))
444 break;
445 }
446 if (m0 == NULL) {
447 /* ick, tag info is stale */
448 return (0);
449 }
450
451 switch (af) {
452 case AF_INET:
453 if (flags & REDF_ECN4) {
454 struct ip *ip = hdr;
455 uint8_t otos;
456 int sum;
457
458 if ((ip->ip_tos & IPTOS_ECN_MASK) == IPTOS_ECN_NOTECT)
459 return (0); /* not-ECT */
460 if ((ip->ip_tos & IPTOS_ECN_MASK) == IPTOS_ECN_CE)
461 return (1); /* already marked */
462
463 /*
464 * ecn-capable but not marked,
465 * mark CE and update checksum
466 */
467 otos = ip->ip_tos;
468 ip->ip_tos |= IPTOS_ECN_CE;
469 /*
470 * update checksum (from RFC1624)
471 * HC' = ~(~HC + ~m + m')
472 */
473 sum = ~ntohs(ip->ip_sum) & 0xffff;
474 sum += (~otos & 0xffff) + ip->ip_tos;
475 sum = (sum >> 16) + (sum & 0xffff);
476 sum += (sum >> 16); /* add carry */
477 ip->ip_sum = htons(~sum & 0xffff);
478 return (1);
479 }
480 break;
481 #ifdef INET6
482 case AF_INET6:
483 if (flags & REDF_ECN6) {
484 struct ip6_hdr *ip6 = hdr;
485 uint32_t flowlabel;
486
487 flowlabel = ntohl(ip6->ip6_flow);
488 if ((flowlabel >> 28) != 6)
489 return (0); /* version mismatch! */
490 if ((flowlabel & (IPTOS_ECN_MASK << 20)) ==
491 (IPTOS_ECN_NOTECT << 20))
492 return (0); /* not-ECT */
493 if ((flowlabel & (IPTOS_ECN_MASK << 20)) ==
494 (IPTOS_ECN_CE << 20))
495 return (1); /* already marked */
496 /*
497 * ecn-capable but not marked, mark CE
498 */
499 flowlabel |= (IPTOS_ECN_CE << 20);
500 ip6->ip6_flow = htonl(flowlabel);
501 return (1);
502 }
503 break;
504 #endif /* INET6 */
505 }
506
507 /* not marked */
508 return (0);
509 }
510
511 struct mbuf *
red_getq(red_t * rp,class_queue_t * q)512 red_getq(red_t *rp, class_queue_t *q)
513 {
514 struct mbuf *m;
515
516 if ((m = _getq(q)) == NULL) {
517 if (rp->red_idle == 0) {
518 rp->red_idle = 1;
519 microtime(&rp->red_last);
520 }
521 return NULL;
522 }
523
524 rp->red_idle = 0;
525 return (m);
526 }
527
528 /*
529 * helper routine to calibrate avg during idle.
530 * pow_w(wtab, n) returns (1 - Wq)^n in fixed-point
531 * here Wq = 1/weight and the code assumes Wq is close to zero.
532 *
533 * w_tab[n] holds ((1 - Wq)^(2^n)) in fixed-point.
534 */
535 static SLIST_HEAD(, wtab) wtab_list = SLIST_HEAD_INITIALIZER(&wtab_list);
536
537 struct wtab *
wtab_alloc(int weight)538 wtab_alloc(int weight)
539 {
540 struct wtab *w;
541 int i;
542
543 SLIST_FOREACH(w, &wtab_list, w_link) {
544 if (w->w_weight == weight) {
545 w->w_refcount++;
546 return (w);
547 }
548 }
549
550 w = kmalloc(sizeof(*w), M_ALTQ, M_WAITOK | M_ZERO);
551 w->w_weight = weight;
552 w->w_refcount = 1;
553 SLIST_INSERT_HEAD(&wtab_list, w, w_link);
554
555 /* initialize the weight table */
556 w->w_tab[0] = ((weight - 1) << FP_SHIFT) / weight;
557 for (i = 1; i < 32; i++) {
558 w->w_tab[i] = (w->w_tab[i-1] * w->w_tab[i-1]) >> FP_SHIFT;
559 if (w->w_tab[i] == 0 && w->w_param_max == 0)
560 w->w_param_max = 1 << i;
561 }
562
563 return (w);
564 }
565
566 int
wtab_destroy(struct wtab * w)567 wtab_destroy(struct wtab *w)
568 {
569 if (--w->w_refcount > 0)
570 return (0);
571
572 SLIST_REMOVE(&wtab_list, w, wtab, w_link);
573 kfree(w, M_ALTQ);
574
575 return (0);
576 }
577
578 int32_t
pow_w(struct wtab * w,int n)579 pow_w(struct wtab *w, int n)
580 {
581 int i, bit;
582 int32_t val;
583
584 if (n >= w->w_param_max)
585 return (0);
586
587 val = 1 << FP_SHIFT;
588 if (n <= 0)
589 return (val);
590
591 bit = 1;
592 i = 0;
593 while (n) {
594 if (n & bit) {
595 val = (val * w->w_tab[i]) >> FP_SHIFT;
596 n &= ~bit;
597 }
598 i++;
599 bit <<= 1;
600 }
601 return (val);
602 }
603
604 #endif /* ALTQ_RED */
605