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 * $FreeBSD$
41 */
42 #include "opt_altq.h"
43 #include "opt_inet.h"
44 #include "opt_inet6.h"
45
46 #ifdef ALTQ_CODEL /* CoDel is enabled by ALTQ_CODEL option in opt_altq.h */
47
48 #include <sys/param.h>
49 #include <sys/malloc.h>
50 #include <sys/mbuf.h>
51 #include <sys/socket.h>
52 #include <sys/systm.h>
53
54 #include <net/if.h>
55 #include <net/if_var.h>
56 #include <netinet/in.h>
57
58 #include <netpfil/pf/pf.h>
59 #include <netpfil/pf/pf_altq.h>
60 #include <net/altq/if_altq.h>
61 #include <net/altq/altq.h>
62 #include <net/altq/altq_codel.h>
63
64 static int codel_should_drop(struct codel *, class_queue_t *,
65 struct mbuf *, u_int64_t);
66 static void codel_Newton_step(struct codel_vars *);
67 static u_int64_t codel_control_law(u_int64_t t, u_int64_t, u_int32_t);
68
69 #define codel_time_after(a, b) ((int64_t)(a) - (int64_t)(b) > 0)
70 #define codel_time_after_eq(a, b) ((int64_t)(a) - (int64_t)(b) >= 0)
71 #define codel_time_before(a, b) ((int64_t)(a) - (int64_t)(b) < 0)
72 #define codel_time_before_eq(a, b) ((int64_t)(a) - (int64_t)(b) <= 0)
73
74 static int codel_request(struct ifaltq *, int, void *);
75
76 static int codel_enqueue(struct ifaltq *, struct mbuf *, struct altq_pktattr *);
77 static struct mbuf *codel_dequeue(struct ifaltq *, int);
78
79 int
codel_pfattach(struct pf_altq * a)80 codel_pfattach(struct pf_altq *a)
81 {
82 struct ifnet *ifp;
83
84 if ((ifp = ifunit(a->ifname)) == NULL || a->altq_disc == NULL)
85 return (EINVAL);
86
87 return (altq_attach(&ifp->if_snd, ALTQT_CODEL, a->altq_disc,
88 codel_enqueue, codel_dequeue, codel_request, NULL, NULL));
89 }
90
91 int
codel_add_altq(struct pf_altq * a)92 codel_add_altq(struct pf_altq *a)
93 {
94 struct codel_if *cif;
95 struct ifnet *ifp;
96 struct codel_opts *opts;
97
98 if ((ifp = ifunit(a->ifname)) == NULL)
99 return (EINVAL);
100 if (!ALTQ_IS_READY(&ifp->if_snd))
101 return (ENODEV);
102
103 opts = &a->pq_u.codel_opts;
104
105 cif = malloc(sizeof(struct codel_if), M_DEVBUF, M_NOWAIT | M_ZERO);
106 if (cif == NULL)
107 return (ENOMEM);
108 cif->cif_bandwidth = a->ifbandwidth;
109 cif->cif_ifq = &ifp->if_snd;
110
111 cif->cl_q = malloc(sizeof(class_queue_t), M_DEVBUF, M_NOWAIT | M_ZERO);
112 if (cif->cl_q == NULL) {
113 free(cif, M_DEVBUF);
114 return (ENOMEM);
115 }
116
117 if (a->qlimit == 0)
118 a->qlimit = 50; /* use default. */
119 qlimit(cif->cl_q) = a->qlimit;
120 qtype(cif->cl_q) = Q_CODEL;
121 qlen(cif->cl_q) = 0;
122 qsize(cif->cl_q) = 0;
123
124 if (opts->target == 0)
125 opts->target = 5;
126 if (opts->interval == 0)
127 opts->interval = 100;
128 cif->codel.params.target = machclk_freq * opts->target / 1000;
129 cif->codel.params.interval = machclk_freq * opts->interval / 1000;
130 cif->codel.params.ecn = opts->ecn;
131 cif->codel.stats.maxpacket = 256;
132
133 cif->cl_stats.qlength = qlen(cif->cl_q);
134 cif->cl_stats.qlimit = qlimit(cif->cl_q);
135
136 /* keep the state in pf_altq */
137 a->altq_disc = cif;
138
139 return (0);
140 }
141
142 int
codel_remove_altq(struct pf_altq * a)143 codel_remove_altq(struct pf_altq *a)
144 {
145 struct codel_if *cif;
146
147 if ((cif = a->altq_disc) == NULL)
148 return (EINVAL);
149 a->altq_disc = NULL;
150
151 if (cif->cl_q)
152 free(cif->cl_q, M_DEVBUF);
153 free(cif, M_DEVBUF);
154
155 return (0);
156 }
157
158 int
codel_getqstats(struct pf_altq * a,void * ubuf,int * nbytes)159 codel_getqstats(struct pf_altq *a, void *ubuf, int *nbytes)
160 {
161 struct codel_if *cif;
162 struct codel_ifstats stats;
163 int error = 0;
164
165 if ((cif = altq_lookup(a->ifname, ALTQT_CODEL)) == NULL)
166 return (EBADF);
167
168 if (*nbytes < sizeof(stats))
169 return (EINVAL);
170
171 stats = cif->cl_stats;
172 stats.stats = cif->codel.stats;
173
174 if ((error = copyout((caddr_t)&stats, ubuf, sizeof(stats))) != 0)
175 return (error);
176 *nbytes = sizeof(stats);
177
178 return (0);
179 }
180
181 static int
codel_request(struct ifaltq * ifq,int req,void * arg)182 codel_request(struct ifaltq *ifq, int req, void *arg)
183 {
184 struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
185 struct mbuf *m;
186
187 IFQ_LOCK_ASSERT(ifq);
188
189 switch (req) {
190 case ALTRQ_PURGE:
191 if (!ALTQ_IS_ENABLED(cif->cif_ifq))
192 break;
193
194 if (qempty(cif->cl_q))
195 break;
196
197 while ((m = _getq(cif->cl_q)) != NULL) {
198 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
199 m_freem(m);
200 IFQ_DEC_LEN(cif->cif_ifq);
201 }
202 cif->cif_ifq->ifq_len = 0;
203 break;
204 }
205
206 return (0);
207 }
208
209 static int
codel_enqueue(struct ifaltq * ifq,struct mbuf * m,struct altq_pktattr * pktattr)210 codel_enqueue(struct ifaltq *ifq, struct mbuf *m, struct altq_pktattr *pktattr)
211 {
212
213 struct codel_if *cif = (struct codel_if *) ifq->altq_disc;
214
215 IFQ_LOCK_ASSERT(ifq);
216
217 /* grab class set by classifier */
218 if ((m->m_flags & M_PKTHDR) == 0) {
219 /* should not happen */
220 printf("altq: packet for %s does not have pkthdr\n",
221 ifq->altq_ifp->if_xname);
222 m_freem(m);
223 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
224 return (ENOBUFS);
225 }
226
227 if (codel_addq(&cif->codel, cif->cl_q, m)) {
228 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
229 return (ENOBUFS);
230 }
231 IFQ_INC_LEN(ifq);
232
233 return (0);
234 }
235
236 static struct mbuf *
codel_dequeue(struct ifaltq * ifq,int op)237 codel_dequeue(struct ifaltq *ifq, int op)
238 {
239 struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
240 struct mbuf *m;
241
242 IFQ_LOCK_ASSERT(ifq);
243
244 if (IFQ_IS_EMPTY(ifq))
245 return (NULL);
246
247 if (op == ALTDQ_POLL)
248 return (qhead(cif->cl_q));
249
250
251 m = codel_getq(&cif->codel, cif->cl_q);
252 if (m != NULL) {
253 IFQ_DEC_LEN(ifq);
254 PKTCNTR_ADD(&cif->cl_stats.cl_xmitcnt, m_pktlen(m));
255 return (m);
256 }
257
258 return (NULL);
259 }
260
261 struct codel *
codel_alloc(int target,int interval,int ecn)262 codel_alloc(int target, int interval, int ecn)
263 {
264 struct codel *c;
265
266 c = malloc(sizeof(*c), M_DEVBUF, M_NOWAIT | M_ZERO);
267 if (c != NULL) {
268 c->params.target = machclk_freq * target / 1000;
269 c->params.interval = machclk_freq * interval / 1000;
270 c->params.ecn = ecn;
271 c->stats.maxpacket = 256;
272 }
273
274 return (c);
275 }
276
277 void
codel_destroy(struct codel * c)278 codel_destroy(struct codel *c)
279 {
280
281 free(c, M_DEVBUF);
282 }
283
284 #define MTAG_CODEL 1438031249
285 int
codel_addq(struct codel * c,class_queue_t * q,struct mbuf * m)286 codel_addq(struct codel *c, class_queue_t *q, struct mbuf *m)
287 {
288 struct m_tag *mtag;
289 uint64_t *enqueue_time;
290
291 if (qlen(q) < qlimit(q)) {
292 mtag = m_tag_locate(m, MTAG_CODEL, 0, NULL);
293 if (mtag == NULL)
294 mtag = m_tag_alloc(MTAG_CODEL, 0, sizeof(uint64_t),
295 M_NOWAIT);
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 m_tag_prepend(m, mtag);
303 _addq(q, m);
304 return (0);
305 }
306 c->drop_overlimit++;
307 m_freem(m);
308
309 return (-1);
310 }
311
312 static int
codel_should_drop(struct codel * c,class_queue_t * q,struct mbuf * m,u_int64_t now)313 codel_should_drop(struct codel *c, class_queue_t *q, struct mbuf *m,
314 u_int64_t now)
315 {
316 struct m_tag *mtag;
317 uint64_t *enqueue_time;
318
319 if (m == NULL) {
320 c->vars.first_above_time = 0;
321 return (0);
322 }
323
324 mtag = m_tag_locate(m, MTAG_CODEL, 0, NULL);
325 if (mtag == NULL) {
326 /* Only one warning per second. */
327 if (ppsratecheck(&c->last_log, &c->last_pps, 1))
328 printf("%s: could not found the packet mtag!\n",
329 __func__);
330 c->vars.first_above_time = 0;
331 return (0);
332 }
333 enqueue_time = (uint64_t *)(mtag + 1);
334 c->vars.ldelay = now - *enqueue_time;
335 c->stats.maxpacket = MAX(c->stats.maxpacket, m_pktlen(m));
336
337 if (codel_time_before(c->vars.ldelay, c->params.target) ||
338 qsize(q) <= c->stats.maxpacket) {
339 /* went below - stay below for at least interval */
340 c->vars.first_above_time = 0;
341 return (0);
342 }
343 if (c->vars.first_above_time == 0) {
344 /* just went above from below. If we stay above
345 * for at least interval we'll say it's ok to drop
346 */
347 c->vars.first_above_time = now + c->params.interval;
348 return (0);
349 }
350 if (codel_time_after(now, c->vars.first_above_time))
351 return (1);
352
353 return (0);
354 }
355
356 /*
357 * Run a Newton method step:
358 * new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2)
359 *
360 * Here, invsqrt is a fixed point number (< 1.0), 32bit mantissa, aka Q0.32
361 */
362 static void
codel_Newton_step(struct codel_vars * vars)363 codel_Newton_step(struct codel_vars *vars)
364 {
365 uint32_t invsqrt, invsqrt2;
366 uint64_t val;
367
368 /* sizeof_in_bits(rec_inv_sqrt) */
369 #define REC_INV_SQRT_BITS (8 * sizeof(u_int16_t))
370 /* needed shift to get a Q0.32 number from rec_inv_sqrt */
371 #define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS)
372
373 invsqrt = ((u_int32_t)vars->rec_inv_sqrt) << REC_INV_SQRT_SHIFT;
374 invsqrt2 = ((u_int64_t)invsqrt * invsqrt) >> 32;
375 val = (3LL << 32) - ((u_int64_t)vars->count * invsqrt2);
376 val >>= 2; /* avoid overflow in following multiply */
377 val = (val * invsqrt) >> (32 - 2 + 1);
378
379 vars->rec_inv_sqrt = val >> REC_INV_SQRT_SHIFT;
380 }
381
382 static u_int64_t
codel_control_law(u_int64_t t,u_int64_t interval,u_int32_t rec_inv_sqrt)383 codel_control_law(u_int64_t t, u_int64_t interval, u_int32_t rec_inv_sqrt)
384 {
385
386 return (t + (u_int32_t)(((u_int64_t)interval *
387 (rec_inv_sqrt << REC_INV_SQRT_SHIFT)) >> 32));
388 }
389
390 struct mbuf *
codel_getq(struct codel * c,class_queue_t * q)391 codel_getq(struct codel *c, class_queue_t *q)
392 {
393 struct mbuf *m;
394 u_int64_t now;
395 int drop;
396
397 if ((m = _getq(q)) == NULL) {
398 c->vars.dropping = 0;
399 return (m);
400 }
401
402 now = read_machclk();
403 drop = codel_should_drop(c, q, m, now);
404 if (c->vars.dropping) {
405 if (!drop) {
406 /* sojourn time below target - leave dropping state */
407 c->vars.dropping = 0;
408 } else if (codel_time_after_eq(now, c->vars.drop_next)) {
409 /* It's time for the next drop. Drop the current
410 * packet and dequeue the next. The dequeue might
411 * take us out of dropping state.
412 * If not, schedule the next drop.
413 * A large backlog might result in drop rates so high
414 * that the next drop should happen now,
415 * hence the while loop.
416 */
417 while (c->vars.dropping &&
418 codel_time_after_eq(now, c->vars.drop_next)) {
419 c->vars.count++; /* don't care of possible wrap
420 * since there is no more
421 * divide */
422 codel_Newton_step(&c->vars);
423 /* TODO ECN */
424 PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
425 m_freem(m);
426 m = _getq(q);
427 if (!codel_should_drop(c, q, m, now))
428 /* leave dropping state */
429 c->vars.dropping = 0;
430 else
431 /* and schedule the next drop */
432 c->vars.drop_next =
433 codel_control_law(c->vars.drop_next,
434 c->params.interval,
435 c->vars.rec_inv_sqrt);
436 }
437 }
438 } else if (drop) {
439 /* TODO ECN */
440 PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
441 m_freem(m);
442
443 m = _getq(q);
444 drop = codel_should_drop(c, q, m, now);
445
446 c->vars.dropping = 1;
447 /* if min went above target close to when we last went below it
448 * assume that the drop rate that controlled the queue on the
449 * last cycle is a good starting point to control it now.
450 */
451 if (codel_time_before(now - c->vars.drop_next,
452 16 * c->params.interval)) {
453 c->vars.count = (c->vars.count - c->vars.lastcount) | 1;
454 /* we dont care if rec_inv_sqrt approximation
455 * is not very precise :
456 * Next Newton steps will correct it quadratically.
457 */
458 codel_Newton_step(&c->vars);
459 } else {
460 c->vars.count = 1;
461 c->vars.rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
462 }
463 c->vars.lastcount = c->vars.count;
464 c->vars.drop_next = codel_control_law(now, c->params.interval,
465 c->vars.rec_inv_sqrt);
466 }
467
468 return (m);
469 }
470
471 void
codel_getstats(struct codel * c,struct codel_stats * s)472 codel_getstats(struct codel *c, struct codel_stats *s)
473 {
474 *s = c->stats;
475 }
476
477 #endif /* ALTQ_CODEL */
478