1 /*
2 * CoDel - The Controlled-Delay Active Queue Management algorithm
3 *
4 * Copyright (C) 2013 Ermal Luçi <eri@FreeBSD.org>
5 * Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com>
6 * Copyright (C) 2011-2012 Van Jacobson <van@pollere.net>
7 * Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net>
8 * Copyright (C) 2012 Eric Dumazet <edumazet@google.com>
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions, and the following disclaimer,
15 * without modification.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. The names of the authors may not be used to endorse or promote products
20 * derived from this software without specific prior written permission.
21 *
22 * Alternatively, provided that this notice is retained in full, this
23 * software may be distributed under the terms of the GNU General
24 * Public License ("GPL") version 2, in which case the provisions of the
25 * GPL apply INSTEAD OF those given above.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
30 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
31 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
32 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
33 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
37 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
38 * DAMAGE.
39 */
40 #include "opt_altq.h"
41 #include "opt_inet.h"
42 #include "opt_inet6.h"
43
44 #ifdef ALTQ_CODEL /* CoDel is enabled by ALTQ_CODEL option in opt_altq.h */
45
46 #include <sys/param.h>
47 #include <sys/malloc.h>
48 #include <sys/mbuf.h>
49 #include <sys/socket.h>
50 #include <sys/systm.h>
51
52 #include <net/if.h>
53 #include <net/if_var.h>
54 #include <net/if_private.h>
55 #include <netinet/in.h>
56
57 #include <netpfil/pf/pf.h>
58 #include <netpfil/pf/pf_altq.h>
59 #include <net/altq/if_altq.h>
60 #include <net/altq/altq.h>
61 #include <net/altq/altq_codel.h>
62
63 static int codel_should_drop(struct codel *, class_queue_t *,
64 struct mbuf *, u_int64_t);
65 static void codel_Newton_step(struct codel_vars *);
66 static u_int64_t codel_control_law(u_int64_t t, u_int64_t, u_int32_t);
67
68 #define codel_time_after(a, b) ((int64_t)(a) - (int64_t)(b) > 0)
69 #define codel_time_after_eq(a, b) ((int64_t)(a) - (int64_t)(b) >= 0)
70 #define codel_time_before(a, b) ((int64_t)(a) - (int64_t)(b) < 0)
71 #define codel_time_before_eq(a, b) ((int64_t)(a) - (int64_t)(b) <= 0)
72
73 static int codel_request(struct ifaltq *, int, void *);
74
75 static int codel_enqueue(struct ifaltq *, struct mbuf *, struct altq_pktattr *);
76 static struct mbuf *codel_dequeue(struct ifaltq *, int);
77
78 int
codel_pfattach(struct pf_altq * a)79 codel_pfattach(struct pf_altq *a)
80 {
81 struct ifnet *ifp;
82
83 if ((ifp = ifunit(a->ifname)) == NULL || a->altq_disc == NULL)
84 return (EINVAL);
85
86 return (altq_attach(&ifp->if_snd, ALTQT_CODEL, a->altq_disc,
87 codel_enqueue, codel_dequeue, codel_request));
88 }
89
90 int
codel_add_altq(struct ifnet * ifp,struct pf_altq * a)91 codel_add_altq(struct ifnet *ifp, struct pf_altq *a)
92 {
93 struct codel_if *cif;
94 struct codel_opts *opts;
95
96 if (ifp == NULL)
97 return (EINVAL);
98 if (!ALTQ_IS_READY(&ifp->if_snd))
99 return (ENODEV);
100
101 opts = &a->pq_u.codel_opts;
102
103 cif = malloc(sizeof(struct codel_if), M_DEVBUF, M_NOWAIT | M_ZERO);
104 if (cif == NULL)
105 return (ENOMEM);
106 cif->cif_bandwidth = a->ifbandwidth;
107 cif->cif_ifq = &ifp->if_snd;
108
109 cif->cl_q = malloc(sizeof(class_queue_t), M_DEVBUF, M_NOWAIT | M_ZERO);
110 if (cif->cl_q == NULL) {
111 free(cif, M_DEVBUF);
112 return (ENOMEM);
113 }
114
115 if (a->qlimit == 0)
116 a->qlimit = 50; /* use default. */
117 qlimit(cif->cl_q) = a->qlimit;
118 qtype(cif->cl_q) = Q_CODEL;
119 qlen(cif->cl_q) = 0;
120 qsize(cif->cl_q) = 0;
121
122 if (opts->target == 0)
123 opts->target = 5;
124 if (opts->interval == 0)
125 opts->interval = 100;
126 cif->codel.params.target = machclk_freq * opts->target / 1000;
127 cif->codel.params.interval = machclk_freq * opts->interval / 1000;
128 cif->codel.params.ecn = opts->ecn;
129 cif->codel.stats.maxpacket = 256;
130
131 cif->cl_stats.qlength = qlen(cif->cl_q);
132 cif->cl_stats.qlimit = qlimit(cif->cl_q);
133
134 /* keep the state in pf_altq */
135 a->altq_disc = cif;
136
137 return (0);
138 }
139
140 int
codel_remove_altq(struct pf_altq * a)141 codel_remove_altq(struct pf_altq *a)
142 {
143 struct codel_if *cif;
144
145 if ((cif = a->altq_disc) == NULL)
146 return (EINVAL);
147 a->altq_disc = NULL;
148
149 if (cif->cl_q)
150 free(cif->cl_q, M_DEVBUF);
151 free(cif, M_DEVBUF);
152
153 return (0);
154 }
155
156 int
codel_getqstats(struct pf_altq * a,void * ubuf,int * nbytes,int version)157 codel_getqstats(struct pf_altq *a, void *ubuf, int *nbytes, int version)
158 {
159 struct codel_if *cif;
160 struct codel_ifstats stats;
161 int error = 0;
162
163 if ((cif = altq_lookup(a->ifname, ALTQT_CODEL)) == NULL)
164 return (EBADF);
165
166 if (*nbytes < sizeof(stats))
167 return (EINVAL);
168
169 stats = cif->cl_stats;
170 stats.stats = cif->codel.stats;
171
172 if ((error = copyout((caddr_t)&stats, ubuf, sizeof(stats))) != 0)
173 return (error);
174 *nbytes = sizeof(stats);
175
176 return (0);
177 }
178
179 static int
codel_request(struct ifaltq * ifq,int req,void * arg)180 codel_request(struct ifaltq *ifq, int req, void *arg)
181 {
182 struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
183 struct mbuf *m;
184
185 IFQ_LOCK_ASSERT(ifq);
186
187 switch (req) {
188 case ALTRQ_PURGE:
189 if (!ALTQ_IS_ENABLED(cif->cif_ifq))
190 break;
191
192 if (qempty(cif->cl_q))
193 break;
194
195 while ((m = _getq(cif->cl_q)) != NULL) {
196 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
197 m_freem(m);
198 IFQ_DEC_LEN(cif->cif_ifq);
199 }
200 cif->cif_ifq->ifq_len = 0;
201 break;
202 }
203
204 return (0);
205 }
206
207 static int
codel_enqueue(struct ifaltq * ifq,struct mbuf * m,struct altq_pktattr * pktattr)208 codel_enqueue(struct ifaltq *ifq, struct mbuf *m, struct altq_pktattr *pktattr)
209 {
210
211 struct codel_if *cif = (struct codel_if *) ifq->altq_disc;
212
213 IFQ_LOCK_ASSERT(ifq);
214
215 /* grab class set by classifier */
216 if ((m->m_flags & M_PKTHDR) == 0) {
217 /* should not happen */
218 printf("altq: packet for %s does not have pkthdr\n",
219 ifq->altq_ifp->if_xname);
220 m_freem(m);
221 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
222 return (ENOBUFS);
223 }
224
225 if (codel_addq(&cif->codel, cif->cl_q, m)) {
226 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
227 return (ENOBUFS);
228 }
229 IFQ_INC_LEN(ifq);
230
231 return (0);
232 }
233
234 static struct mbuf *
codel_dequeue(struct ifaltq * ifq,int op)235 codel_dequeue(struct ifaltq *ifq, int op)
236 {
237 struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
238 struct mbuf *m;
239
240 IFQ_LOCK_ASSERT(ifq);
241
242 if (IFQ_IS_EMPTY(ifq))
243 return (NULL);
244
245 if (op == ALTDQ_POLL)
246 return (qhead(cif->cl_q));
247
248 m = codel_getq(&cif->codel, cif->cl_q);
249 if (m != NULL) {
250 IFQ_DEC_LEN(ifq);
251 PKTCNTR_ADD(&cif->cl_stats.cl_xmitcnt, m_pktlen(m));
252 return (m);
253 }
254
255 return (NULL);
256 }
257
258 struct codel *
codel_alloc(int target,int interval,int ecn)259 codel_alloc(int target, int interval, int ecn)
260 {
261 struct codel *c;
262
263 c = malloc(sizeof(*c), M_DEVBUF, M_NOWAIT | M_ZERO);
264 if (c != NULL) {
265 c->params.target = machclk_freq * target / 1000;
266 c->params.interval = machclk_freq * interval / 1000;
267 c->params.ecn = ecn;
268 c->stats.maxpacket = 256;
269 }
270
271 return (c);
272 }
273
274 void
codel_destroy(struct codel * c)275 codel_destroy(struct codel *c)
276 {
277
278 free(c, M_DEVBUF);
279 }
280
281 #define MTAG_CODEL 1438031249
282 int
codel_addq(struct codel * c,class_queue_t * q,struct mbuf * m)283 codel_addq(struct codel *c, class_queue_t *q, struct mbuf *m)
284 {
285 struct m_tag *mtag;
286 uint64_t *enqueue_time;
287
288 if (qlen(q) < qlimit(q)) {
289 mtag = m_tag_locate(m, MTAG_CODEL, 0, NULL);
290 if (mtag == NULL) {
291 mtag = m_tag_alloc(MTAG_CODEL, 0, sizeof(uint64_t),
292 M_NOWAIT);
293 if (mtag != NULL)
294 m_tag_prepend(m, mtag);
295 }
296 if (mtag == NULL) {
297 m_freem(m);
298 return (-1);
299 }
300 enqueue_time = (uint64_t *)(mtag + 1);
301 *enqueue_time = read_machclk();
302 _addq(q, m);
303 return (0);
304 }
305 c->drop_overlimit++;
306 m_freem(m);
307
308 return (-1);
309 }
310
311 static int
codel_should_drop(struct codel * c,class_queue_t * q,struct mbuf * m,u_int64_t now)312 codel_should_drop(struct codel *c, class_queue_t *q, struct mbuf *m,
313 u_int64_t now)
314 {
315 struct m_tag *mtag;
316 uint64_t *enqueue_time;
317
318 if (m == NULL) {
319 c->vars.first_above_time = 0;
320 return (0);
321 }
322
323 mtag = m_tag_locate(m, MTAG_CODEL, 0, NULL);
324 if (mtag == NULL) {
325 /* Only one warning per second. */
326 if (ppsratecheck(&c->last_log, &c->last_pps, 1))
327 printf("%s: could not found the packet mtag!\n",
328 __func__);
329 c->vars.first_above_time = 0;
330 return (0);
331 }
332 enqueue_time = (uint64_t *)(mtag + 1);
333 c->vars.ldelay = now - *enqueue_time;
334 c->stats.maxpacket = MAX(c->stats.maxpacket, m_pktlen(m));
335
336 if (codel_time_before(c->vars.ldelay, c->params.target) ||
337 qsize(q) <= c->stats.maxpacket) {
338 /* went below - stay below for at least interval */
339 c->vars.first_above_time = 0;
340 return (0);
341 }
342 if (c->vars.first_above_time == 0) {
343 /* just went above from below. If we stay above
344 * for at least interval we'll say it's ok to drop
345 */
346 c->vars.first_above_time = now + c->params.interval;
347 return (0);
348 }
349 if (codel_time_after(now, c->vars.first_above_time))
350 return (1);
351
352 return (0);
353 }
354
355 /*
356 * Run a Newton method step:
357 * new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2)
358 *
359 * Here, invsqrt is a fixed point number (< 1.0), 32bit mantissa, aka Q0.32
360 */
361 static void
codel_Newton_step(struct codel_vars * vars)362 codel_Newton_step(struct codel_vars *vars)
363 {
364 uint32_t invsqrt, invsqrt2;
365 uint64_t val;
366
367 /* sizeof_in_bits(rec_inv_sqrt) */
368 #define REC_INV_SQRT_BITS (8 * sizeof(u_int16_t))
369 /* needed shift to get a Q0.32 number from rec_inv_sqrt */
370 #define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS)
371
372 invsqrt = ((u_int32_t)vars->rec_inv_sqrt) << REC_INV_SQRT_SHIFT;
373 invsqrt2 = ((u_int64_t)invsqrt * invsqrt) >> 32;
374 val = (3LL << 32) - ((u_int64_t)vars->count * invsqrt2);
375 val >>= 2; /* avoid overflow in following multiply */
376 val = (val * invsqrt) >> (32 - 2 + 1);
377
378 vars->rec_inv_sqrt = val >> REC_INV_SQRT_SHIFT;
379 }
380
381 static u_int64_t
codel_control_law(u_int64_t t,u_int64_t interval,u_int32_t rec_inv_sqrt)382 codel_control_law(u_int64_t t, u_int64_t interval, u_int32_t rec_inv_sqrt)
383 {
384
385 return (t + (u_int32_t)(((u_int64_t)interval *
386 (rec_inv_sqrt << REC_INV_SQRT_SHIFT)) >> 32));
387 }
388
389 struct mbuf *
codel_getq(struct codel * c,class_queue_t * q)390 codel_getq(struct codel *c, class_queue_t *q)
391 {
392 struct mbuf *m;
393 u_int64_t now;
394 int drop;
395
396 if ((m = _getq(q)) == NULL) {
397 c->vars.dropping = 0;
398 return (m);
399 }
400
401 now = read_machclk();
402 drop = codel_should_drop(c, q, m, now);
403 if (c->vars.dropping) {
404 if (!drop) {
405 /* sojourn time below target - leave dropping state */
406 c->vars.dropping = 0;
407 } else if (codel_time_after_eq(now, c->vars.drop_next)) {
408 /* It's time for the next drop. Drop the current
409 * packet and dequeue the next. The dequeue might
410 * take us out of dropping state.
411 * If not, schedule the next drop.
412 * A large backlog might result in drop rates so high
413 * that the next drop should happen now,
414 * hence the while loop.
415 */
416 while (c->vars.dropping &&
417 codel_time_after_eq(now, c->vars.drop_next)) {
418 c->vars.count++; /* don't care of possible wrap
419 * since there is no more
420 * divide */
421 codel_Newton_step(&c->vars);
422 /* TODO ECN */
423 PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
424 m_freem(m);
425 m = _getq(q);
426 if (!codel_should_drop(c, q, m, now))
427 /* leave dropping state */
428 c->vars.dropping = 0;
429 else
430 /* and schedule the next drop */
431 c->vars.drop_next =
432 codel_control_law(c->vars.drop_next,
433 c->params.interval,
434 c->vars.rec_inv_sqrt);
435 }
436 }
437 } else if (drop) {
438 /* TODO ECN */
439 PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
440 m_freem(m);
441
442 m = _getq(q);
443 drop = codel_should_drop(c, q, m, now);
444
445 c->vars.dropping = 1;
446 /* if min went above target close to when we last went below it
447 * assume that the drop rate that controlled the queue on the
448 * last cycle is a good starting point to control it now.
449 */
450 if (codel_time_before(now - c->vars.drop_next,
451 16 * c->params.interval)) {
452 c->vars.count = (c->vars.count - c->vars.lastcount) | 1;
453 /* we dont care if rec_inv_sqrt approximation
454 * is not very precise :
455 * Next Newton steps will correct it quadratically.
456 */
457 codel_Newton_step(&c->vars);
458 } else {
459 c->vars.count = 1;
460 c->vars.rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
461 }
462 c->vars.lastcount = c->vars.count;
463 c->vars.drop_next = codel_control_law(now, c->params.interval,
464 c->vars.rec_inv_sqrt);
465 }
466
467 return (m);
468 }
469
470 void
codel_getstats(struct codel * c,struct codel_stats * s)471 codel_getstats(struct codel *c, struct codel_stats *s)
472 {
473 *s = c->stats;
474 }
475
476 #endif /* ALTQ_CODEL */
477