1 /*
2 * CoDel - The Controlled-Delay Active Queue Management algorithm
3 *
4 * Copyright (C) 2013 Ermal Luçi <[email protected]>
5 * Copyright (C) 2011-2012 Kathleen Nichols <[email protected]>
6 * Copyright (C) 2011-2012 Van Jacobson <[email protected]>
7 * Copyright (C) 2012 Michael D. Taht <[email protected]>
8 * Copyright (C) 2012 Eric Dumazet <[email protected]>
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 ifnet * ifp,struct pf_altq * a)92 codel_add_altq(struct ifnet *ifp, struct pf_altq *a)
93 {
94 struct codel_if *cif;
95 struct codel_opts *opts;
96
97 if (ifp == NULL)
98 return (EINVAL);
99 if (!ALTQ_IS_READY(&ifp->if_snd))
100 return (ENODEV);
101
102 opts = &a->pq_u.codel_opts;
103
104 cif = malloc(sizeof(struct codel_if), M_DEVBUF, M_NOWAIT | M_ZERO);
105 if (cif == NULL)
106 return (ENOMEM);
107 cif->cif_bandwidth = a->ifbandwidth;
108 cif->cif_ifq = &ifp->if_snd;
109
110 cif->cl_q = malloc(sizeof(class_queue_t), M_DEVBUF, M_NOWAIT | M_ZERO);
111 if (cif->cl_q == NULL) {
112 free(cif, M_DEVBUF);
113 return (ENOMEM);
114 }
115
116 if (a->qlimit == 0)
117 a->qlimit = 50; /* use default. */
118 qlimit(cif->cl_q) = a->qlimit;
119 qtype(cif->cl_q) = Q_CODEL;
120 qlen(cif->cl_q) = 0;
121 qsize(cif->cl_q) = 0;
122
123 if (opts->target == 0)
124 opts->target = 5;
125 if (opts->interval == 0)
126 opts->interval = 100;
127 cif->codel.params.target = machclk_freq * opts->target / 1000;
128 cif->codel.params.interval = machclk_freq * opts->interval / 1000;
129 cif->codel.params.ecn = opts->ecn;
130 cif->codel.stats.maxpacket = 256;
131
132 cif->cl_stats.qlength = qlen(cif->cl_q);
133 cif->cl_stats.qlimit = qlimit(cif->cl_q);
134
135 /* keep the state in pf_altq */
136 a->altq_disc = cif;
137
138 return (0);
139 }
140
141 int
codel_remove_altq(struct pf_altq * a)142 codel_remove_altq(struct pf_altq *a)
143 {
144 struct codel_if *cif;
145
146 if ((cif = a->altq_disc) == NULL)
147 return (EINVAL);
148 a->altq_disc = NULL;
149
150 if (cif->cl_q)
151 free(cif->cl_q, M_DEVBUF);
152 free(cif, M_DEVBUF);
153
154 return (0);
155 }
156
157 int
codel_getqstats(struct pf_altq * a,void * ubuf,int * nbytes,int version)158 codel_getqstats(struct pf_altq *a, void *ubuf, int *nbytes, int version)
159 {
160 struct codel_if *cif;
161 struct codel_ifstats stats;
162 int error = 0;
163
164 if ((cif = altq_lookup(a->ifname, ALTQT_CODEL)) == NULL)
165 return (EBADF);
166
167 if (*nbytes < sizeof(stats))
168 return (EINVAL);
169
170 stats = cif->cl_stats;
171 stats.stats = cif->codel.stats;
172
173 if ((error = copyout((caddr_t)&stats, ubuf, sizeof(stats))) != 0)
174 return (error);
175 *nbytes = sizeof(stats);
176
177 return (0);
178 }
179
180 static int
codel_request(struct ifaltq * ifq,int req,void * arg)181 codel_request(struct ifaltq *ifq, int req, void *arg)
182 {
183 struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
184 struct mbuf *m;
185
186 IFQ_LOCK_ASSERT(ifq);
187
188 switch (req) {
189 case ALTRQ_PURGE:
190 if (!ALTQ_IS_ENABLED(cif->cif_ifq))
191 break;
192
193 if (qempty(cif->cl_q))
194 break;
195
196 while ((m = _getq(cif->cl_q)) != NULL) {
197 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
198 m_freem(m);
199 IFQ_DEC_LEN(cif->cif_ifq);
200 }
201 cif->cif_ifq->ifq_len = 0;
202 break;
203 }
204
205 return (0);
206 }
207
208 static int
codel_enqueue(struct ifaltq * ifq,struct mbuf * m,struct altq_pktattr * pktattr)209 codel_enqueue(struct ifaltq *ifq, struct mbuf *m, struct altq_pktattr *pktattr)
210 {
211
212 struct codel_if *cif = (struct codel_if *) ifq->altq_disc;
213
214 IFQ_LOCK_ASSERT(ifq);
215
216 /* grab class set by classifier */
217 if ((m->m_flags & M_PKTHDR) == 0) {
218 /* should not happen */
219 printf("altq: packet for %s does not have pkthdr\n",
220 ifq->altq_ifp->if_xname);
221 m_freem(m);
222 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
223 return (ENOBUFS);
224 }
225
226 if (codel_addq(&cif->codel, cif->cl_q, m)) {
227 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
228 return (ENOBUFS);
229 }
230 IFQ_INC_LEN(ifq);
231
232 return (0);
233 }
234
235 static struct mbuf *
codel_dequeue(struct ifaltq * ifq,int op)236 codel_dequeue(struct ifaltq *ifq, int op)
237 {
238 struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
239 struct mbuf *m;
240
241 IFQ_LOCK_ASSERT(ifq);
242
243 if (IFQ_IS_EMPTY(ifq))
244 return (NULL);
245
246 if (op == ALTDQ_POLL)
247 return (qhead(cif->cl_q));
248
249 m = codel_getq(&cif->codel, cif->cl_q);
250 if (m != NULL) {
251 IFQ_DEC_LEN(ifq);
252 PKTCNTR_ADD(&cif->cl_stats.cl_xmitcnt, m_pktlen(m));
253 return (m);
254 }
255
256 return (NULL);
257 }
258
259 struct codel *
codel_alloc(int target,int interval,int ecn)260 codel_alloc(int target, int interval, int ecn)
261 {
262 struct codel *c;
263
264 c = malloc(sizeof(*c), M_DEVBUF, M_NOWAIT | M_ZERO);
265 if (c != NULL) {
266 c->params.target = machclk_freq * target / 1000;
267 c->params.interval = machclk_freq * interval / 1000;
268 c->params.ecn = ecn;
269 c->stats.maxpacket = 256;
270 }
271
272 return (c);
273 }
274
275 void
codel_destroy(struct codel * c)276 codel_destroy(struct codel *c)
277 {
278
279 free(c, M_DEVBUF);
280 }
281
282 #define MTAG_CODEL 1438031249
283 int
codel_addq(struct codel * c,class_queue_t * q,struct mbuf * m)284 codel_addq(struct codel *c, class_queue_t *q, struct mbuf *m)
285 {
286 struct m_tag *mtag;
287 uint64_t *enqueue_time;
288
289 if (qlen(q) < qlimit(q)) {
290 mtag = m_tag_locate(m, MTAG_CODEL, 0, NULL);
291 if (mtag == NULL)
292 mtag = m_tag_alloc(MTAG_CODEL, 0, sizeof(uint64_t),
293 M_NOWAIT);
294 if (mtag == NULL) {
295 m_freem(m);
296 return (-1);
297 }
298 enqueue_time = (uint64_t *)(mtag + 1);
299 *enqueue_time = read_machclk();
300 m_tag_prepend(m, mtag);
301 _addq(q, m);
302 return (0);
303 }
304 c->drop_overlimit++;
305 m_freem(m);
306
307 return (-1);
308 }
309
310 static int
codel_should_drop(struct codel * c,class_queue_t * q,struct mbuf * m,u_int64_t now)311 codel_should_drop(struct codel *c, class_queue_t *q, struct mbuf *m,
312 u_int64_t now)
313 {
314 struct m_tag *mtag;
315 uint64_t *enqueue_time;
316
317 if (m == NULL) {
318 c->vars.first_above_time = 0;
319 return (0);
320 }
321
322 mtag = m_tag_locate(m, MTAG_CODEL, 0, NULL);
323 if (mtag == NULL) {
324 /* Only one warning per second. */
325 if (ppsratecheck(&c->last_log, &c->last_pps, 1))
326 printf("%s: could not found the packet mtag!\n",
327 __func__);
328 c->vars.first_above_time = 0;
329 return (0);
330 }
331 enqueue_time = (uint64_t *)(mtag + 1);
332 c->vars.ldelay = now - *enqueue_time;
333 c->stats.maxpacket = MAX(c->stats.maxpacket, m_pktlen(m));
334
335 if (codel_time_before(c->vars.ldelay, c->params.target) ||
336 qsize(q) <= c->stats.maxpacket) {
337 /* went below - stay below for at least interval */
338 c->vars.first_above_time = 0;
339 return (0);
340 }
341 if (c->vars.first_above_time == 0) {
342 /* just went above from below. If we stay above
343 * for at least interval we'll say it's ok to drop
344 */
345 c->vars.first_above_time = now + c->params.interval;
346 return (0);
347 }
348 if (codel_time_after(now, c->vars.first_above_time))
349 return (1);
350
351 return (0);
352 }
353
354 /*
355 * Run a Newton method step:
356 * new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2)
357 *
358 * Here, invsqrt is a fixed point number (< 1.0), 32bit mantissa, aka Q0.32
359 */
360 static void
codel_Newton_step(struct codel_vars * vars)361 codel_Newton_step(struct codel_vars *vars)
362 {
363 uint32_t invsqrt, invsqrt2;
364 uint64_t val;
365
366 /* sizeof_in_bits(rec_inv_sqrt) */
367 #define REC_INV_SQRT_BITS (8 * sizeof(u_int16_t))
368 /* needed shift to get a Q0.32 number from rec_inv_sqrt */
369 #define REC_INV_SQRT_SHIFT (32 - REC_INV_SQRT_BITS)
370
371 invsqrt = ((u_int32_t)vars->rec_inv_sqrt) << REC_INV_SQRT_SHIFT;
372 invsqrt2 = ((u_int64_t)invsqrt * invsqrt) >> 32;
373 val = (3LL << 32) - ((u_int64_t)vars->count * invsqrt2);
374 val >>= 2; /* avoid overflow in following multiply */
375 val = (val * invsqrt) >> (32 - 2 + 1);
376
377 vars->rec_inv_sqrt = val >> REC_INV_SQRT_SHIFT;
378 }
379
380 static u_int64_t
codel_control_law(u_int64_t t,u_int64_t interval,u_int32_t rec_inv_sqrt)381 codel_control_law(u_int64_t t, u_int64_t interval, u_int32_t rec_inv_sqrt)
382 {
383
384 return (t + (u_int32_t)(((u_int64_t)interval *
385 (rec_inv_sqrt << REC_INV_SQRT_SHIFT)) >> 32));
386 }
387
388 struct mbuf *
codel_getq(struct codel * c,class_queue_t * q)389 codel_getq(struct codel *c, class_queue_t *q)
390 {
391 struct mbuf *m;
392 u_int64_t now;
393 int drop;
394
395 if ((m = _getq(q)) == NULL) {
396 c->vars.dropping = 0;
397 return (m);
398 }
399
400 now = read_machclk();
401 drop = codel_should_drop(c, q, m, now);
402 if (c->vars.dropping) {
403 if (!drop) {
404 /* sojourn time below target - leave dropping state */
405 c->vars.dropping = 0;
406 } else if (codel_time_after_eq(now, c->vars.drop_next)) {
407 /* It's time for the next drop. Drop the current
408 * packet and dequeue the next. The dequeue might
409 * take us out of dropping state.
410 * If not, schedule the next drop.
411 * A large backlog might result in drop rates so high
412 * that the next drop should happen now,
413 * hence the while loop.
414 */
415 while (c->vars.dropping &&
416 codel_time_after_eq(now, c->vars.drop_next)) {
417 c->vars.count++; /* don't care of possible wrap
418 * since there is no more
419 * divide */
420 codel_Newton_step(&c->vars);
421 /* TODO ECN */
422 PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
423 m_freem(m);
424 m = _getq(q);
425 if (!codel_should_drop(c, q, m, now))
426 /* leave dropping state */
427 c->vars.dropping = 0;
428 else
429 /* and schedule the next drop */
430 c->vars.drop_next =
431 codel_control_law(c->vars.drop_next,
432 c->params.interval,
433 c->vars.rec_inv_sqrt);
434 }
435 }
436 } else if (drop) {
437 /* TODO ECN */
438 PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
439 m_freem(m);
440
441 m = _getq(q);
442 drop = codel_should_drop(c, q, m, now);
443
444 c->vars.dropping = 1;
445 /* if min went above target close to when we last went below it
446 * assume that the drop rate that controlled the queue on the
447 * last cycle is a good starting point to control it now.
448 */
449 if (codel_time_before(now - c->vars.drop_next,
450 16 * c->params.interval)) {
451 c->vars.count = (c->vars.count - c->vars.lastcount) | 1;
452 /* we dont care if rec_inv_sqrt approximation
453 * is not very precise :
454 * Next Newton steps will correct it quadratically.
455 */
456 codel_Newton_step(&c->vars);
457 } else {
458 c->vars.count = 1;
459 c->vars.rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
460 }
461 c->vars.lastcount = c->vars.count;
462 c->vars.drop_next = codel_control_law(now, c->params.interval,
463 c->vars.rec_inv_sqrt);
464 }
465
466 return (m);
467 }
468
469 void
codel_getstats(struct codel * c,struct codel_stats * s)470 codel_getstats(struct codel *c, struct codel_stats *s)
471 {
472 *s = c->stats;
473 }
474
475 #endif /* ALTQ_CODEL */
476