2 * CoDel - The Controlled-Delay Active Queue Management algorithm
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>
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
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.
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.
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
44 #include "opt_inet6.h"
46 #ifdef ALTQ_CODEL /* CoDel is enabled by ALTQ_CODEL option in opt_altq.h */
48 #include <sys/param.h>
49 #include <sys/malloc.h>
51 #include <sys/socket.h>
52 #include <sys/systm.h>
55 #include <net/if_var.h>
56 #include <netinet/in.h>
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>
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);
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)
74 static int codel_request(struct ifaltq *, int, void *);
76 static int codel_enqueue(struct ifaltq *, struct mbuf *, struct altq_pktattr *);
77 static struct mbuf *codel_dequeue(struct ifaltq *, int);
80 codel_pfattach(struct pf_altq *a)
84 if ((ifp = ifunit(a->ifname)) == NULL || a->altq_disc == NULL)
87 return (altq_attach(&ifp->if_snd, ALTQT_CODEL, a->altq_disc,
88 codel_enqueue, codel_dequeue, codel_request, NULL, NULL));
92 codel_add_altq(struct pf_altq *a)
96 struct codel_opts *opts;
98 if ((ifp = ifunit(a->ifname)) == NULL)
100 if (!ALTQ_IS_READY(&ifp->if_snd))
103 opts = &a->pq_u.codel_opts;
105 cif = malloc(sizeof(struct codel_if), M_DEVBUF, M_NOWAIT | M_ZERO);
108 cif->cif_bandwidth = a->ifbandwidth;
109 cif->cif_ifq = &ifp->if_snd;
111 cif->cl_q = malloc(sizeof(class_queue_t), M_DEVBUF, M_NOWAIT | M_ZERO);
112 if (cif->cl_q == NULL) {
118 a->qlimit = 50; /* use default. */
119 qlimit(cif->cl_q) = a->qlimit;
120 qtype(cif->cl_q) = Q_CODEL;
122 qsize(cif->cl_q) = 0;
124 if (opts->target == 0)
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;
133 cif->cl_stats.qlength = qlen(cif->cl_q);
134 cif->cl_stats.qlimit = qlimit(cif->cl_q);
136 /* keep the state in pf_altq */
143 codel_remove_altq(struct pf_altq *a)
145 struct codel_if *cif;
147 if ((cif = a->altq_disc) == NULL)
152 free(cif->cl_q, M_DEVBUF);
159 codel_getqstats(struct pf_altq *a, void *ubuf, int *nbytes, int version)
161 struct codel_if *cif;
162 struct codel_ifstats stats;
165 if ((cif = altq_lookup(a->ifname, ALTQT_CODEL)) == NULL)
168 if (*nbytes < sizeof(stats))
171 stats = cif->cl_stats;
172 stats.stats = cif->codel.stats;
174 if ((error = copyout((caddr_t)&stats, ubuf, sizeof(stats))) != 0)
176 *nbytes = sizeof(stats);
182 codel_request(struct ifaltq *ifq, int req, void *arg)
184 struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
187 IFQ_LOCK_ASSERT(ifq);
191 if (!ALTQ_IS_ENABLED(cif->cif_ifq))
194 if (qempty(cif->cl_q))
197 while ((m = _getq(cif->cl_q)) != NULL) {
198 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
200 IFQ_DEC_LEN(cif->cif_ifq);
202 cif->cif_ifq->ifq_len = 0;
210 codel_enqueue(struct ifaltq *ifq, struct mbuf *m, struct altq_pktattr *pktattr)
213 struct codel_if *cif = (struct codel_if *) ifq->altq_disc;
215 IFQ_LOCK_ASSERT(ifq);
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);
223 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
227 if (codel_addq(&cif->codel, cif->cl_q, m)) {
228 PKTCNTR_ADD(&cif->cl_stats.cl_dropcnt, m_pktlen(m));
237 codel_dequeue(struct ifaltq *ifq, int op)
239 struct codel_if *cif = (struct codel_if *)ifq->altq_disc;
242 IFQ_LOCK_ASSERT(ifq);
244 if (IFQ_IS_EMPTY(ifq))
247 if (op == ALTDQ_POLL)
248 return (qhead(cif->cl_q));
251 m = codel_getq(&cif->codel, cif->cl_q);
254 PKTCNTR_ADD(&cif->cl_stats.cl_xmitcnt, m_pktlen(m));
262 codel_alloc(int target, int interval, int ecn)
266 c = malloc(sizeof(*c), M_DEVBUF, M_NOWAIT | M_ZERO);
268 c->params.target = machclk_freq * target / 1000;
269 c->params.interval = machclk_freq * interval / 1000;
271 c->stats.maxpacket = 256;
278 codel_destroy(struct codel *c)
284 #define MTAG_CODEL 1438031249
286 codel_addq(struct codel *c, class_queue_t *q, struct mbuf *m)
289 uint64_t *enqueue_time;
291 if (qlen(q) < qlimit(q)) {
292 mtag = m_tag_locate(m, MTAG_CODEL, 0, NULL);
294 mtag = m_tag_alloc(MTAG_CODEL, 0, sizeof(uint64_t),
300 enqueue_time = (uint64_t *)(mtag + 1);
301 *enqueue_time = read_machclk();
302 m_tag_prepend(m, mtag);
313 codel_should_drop(struct codel *c, class_queue_t *q, struct mbuf *m,
317 uint64_t *enqueue_time;
320 c->vars.first_above_time = 0;
324 mtag = m_tag_locate(m, MTAG_CODEL, 0, 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",
330 c->vars.first_above_time = 0;
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));
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;
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
347 c->vars.first_above_time = now + c->params.interval;
350 if (codel_time_after(now, c->vars.first_above_time))
357 * Run a Newton method step:
358 * new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2)
360 * Here, invsqrt is a fixed point number (< 1.0), 32bit mantissa, aka Q0.32
363 codel_Newton_step(struct codel_vars *vars)
365 uint32_t invsqrt, invsqrt2;
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)
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);
379 vars->rec_inv_sqrt = val >> REC_INV_SQRT_SHIFT;
383 codel_control_law(u_int64_t t, u_int64_t interval, u_int32_t rec_inv_sqrt)
386 return (t + (u_int32_t)(((u_int64_t)interval *
387 (rec_inv_sqrt << REC_INV_SQRT_SHIFT)) >> 32));
391 codel_getq(struct codel *c, class_queue_t *q)
397 if ((m = _getq(q)) == NULL) {
398 c->vars.dropping = 0;
402 now = read_machclk();
403 drop = codel_should_drop(c, q, m, now);
404 if (c->vars.dropping) {
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.
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
422 codel_Newton_step(&c->vars);
424 PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
427 if (!codel_should_drop(c, q, m, now))
428 /* leave dropping state */
429 c->vars.dropping = 0;
431 /* and schedule the next drop */
433 codel_control_law(c->vars.drop_next,
435 c->vars.rec_inv_sqrt);
440 PKTCNTR_ADD(&c->stats.drop_cnt, m_pktlen(m));
444 drop = codel_should_drop(c, q, m, now);
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.
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.
458 codel_Newton_step(&c->vars);
461 c->vars.rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;
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);
472 codel_getstats(struct codel *c, struct codel_stats *s)
477 #endif /* ALTQ_CODEL */