2 * net/sched/sch_tbf.c Token Bucket Filter queue.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
10 * Dmitry Torokhov <dtor@mail.ru> - allow attaching inner qdiscs -
11 * original idea by Martin Devera
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/string.h>
19 #include <linux/errno.h>
20 #include <linux/skbuff.h>
21 #include <net/netlink.h>
22 #include <net/pkt_sched.h>
25 /* Simple Token Bucket Filter.
26 =======================================
36 A data flow obeys TBF with rate R and depth B, if for any
37 time interval t_i...t_f the number of transmitted bits
38 does not exceed B + R*(t_f-t_i).
40 Packetized version of this definition:
41 The sequence of packets of sizes s_i served at moments t_i
42 obeys TBF, if for any i<=k:
44 s_i+....+s_k <= B + R*(t_k - t_i)
49 Let N(t_i) be B/R initially and N(t) grow continuously with time as:
51 N(t+delta) = min{B/R, N(t) + delta}
53 If the first packet in queue has length S, it may be
54 transmitted only at the time t_* when S/R <= N(t_*),
55 and in this case N(t) jumps:
57 N(t_* + 0) = N(t_* - 0) - S/R.
61 Actually, QoS requires two TBF to be applied to a data stream.
62 One of them controls steady state burst size, another
63 one with rate P (peak rate) and depth M (equal to link MTU)
64 limits bursts at a smaller time scale.
66 It is easy to see that P>R, and B>M. If P is infinity, this double
67 TBF is equivalent to a single one.
69 When TBF works in reshaping mode, latency is estimated as:
71 lat = max ((L-B)/R, (L-M)/P)
77 If TBF throttles, it starts a watchdog timer, which will wake it up
78 when it is ready to transmit.
79 Note that the minimal timer resolution is 1/HZ.
80 If no new packets arrive during this period,
81 or if the device is not awaken by EOI for some previous packet,
82 TBF can stop its activity for 1/HZ.
85 This means, that with depth B, the maximal rate is
89 F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes.
91 Note that the peak rate TBF is much more tough: with MTU 1500
92 P_crit = 150Kbytes/sec. So, if you need greater peak
93 rates, use alpha with HZ=1000 :-)
95 With classful TBF, limit is just kept for backwards compatibility.
96 It is passed to the default bfifo qdisc - if the inner qdisc is
97 changed the limit is not effective anymore.
100 struct tbf_sched_data
103 u32 limit; /* Maximal length of backlog: bytes */
104 u32 buffer; /* Token bucket depth/rate: MUST BE >= MTU/B */
107 struct qdisc_rate_table *R_tab;
108 struct qdisc_rate_table *P_tab;
111 long tokens; /* Current number of B tokens */
112 long ptokens; /* Current number of P tokens */
113 psched_time_t t_c; /* Time check-point */
114 struct Qdisc *qdisc; /* Inner qdisc, default - bfifo queue */
115 struct qdisc_watchdog watchdog; /* Watchdog timer */
118 #define L2T(q,L) qdisc_l2t((q)->R_tab,L)
119 #define L2T_P(q,L) qdisc_l2t((q)->P_tab,L)
121 static int tbf_enqueue(struct sk_buff *skb, struct Qdisc* sch)
123 struct tbf_sched_data *q = qdisc_priv(sch);
126 if (skb->len > q->max_size) {
128 #ifdef CONFIG_NET_CLS_ACT
129 if (sch->reshape_fail == NULL || sch->reshape_fail(skb, sch))
133 return NET_XMIT_DROP;
136 if ((ret = q->qdisc->enqueue(skb, q->qdisc)) != 0) {
142 sch->bstats.bytes += skb->len;
143 sch->bstats.packets++;
147 static int tbf_requeue(struct sk_buff *skb, struct Qdisc* sch)
149 struct tbf_sched_data *q = qdisc_priv(sch);
152 if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) {
154 sch->qstats.requeues++;
160 static unsigned int tbf_drop(struct Qdisc* sch)
162 struct tbf_sched_data *q = qdisc_priv(sch);
163 unsigned int len = 0;
165 if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
172 static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
174 struct tbf_sched_data *q = qdisc_priv(sch);
177 skb = q->qdisc->dequeue(q->qdisc);
183 unsigned int len = skb->len;
185 now = psched_get_time();
186 toks = psched_tdiff_bounded(now, q->t_c, q->buffer);
189 ptoks = toks + q->ptokens;
190 if (ptoks > (long)q->mtu)
192 ptoks -= L2T_P(q, len);
195 if (toks > (long)q->buffer)
199 if ((toks|ptoks) >= 0) {
204 sch->flags &= ~TCQ_F_THROTTLED;
208 qdisc_watchdog_schedule(&q->watchdog,
209 now + max_t(long, -toks, -ptoks));
211 /* Maybe we have a shorter packet in the queue,
212 which can be sent now. It sounds cool,
213 but, however, this is wrong in principle.
214 We MUST NOT reorder packets under these circumstances.
216 Really, if we split the flow into independent
217 subflows, it would be a very good solution.
218 This is the main idea of all FQ algorithms
219 (cf. CSZ, HPFQ, HFSC)
222 if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
223 /* When requeue fails skb is dropped */
224 qdisc_tree_decrease_qlen(q->qdisc, 1);
228 sch->qstats.overlimits++;
233 static void tbf_reset(struct Qdisc* sch)
235 struct tbf_sched_data *q = qdisc_priv(sch);
237 qdisc_reset(q->qdisc);
239 q->t_c = psched_get_time();
240 q->tokens = q->buffer;
242 qdisc_watchdog_cancel(&q->watchdog);
245 static struct Qdisc *tbf_create_dflt_qdisc(struct Qdisc *sch, u32 limit)
251 q = qdisc_create_dflt(sch->dev, &bfifo_qdisc_ops,
252 TC_H_MAKE(sch->handle, 1));
254 nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)),
257 nla->nla_type = RTM_NEWQDISC;
258 nla->nla_len = nla_attr_size(sizeof(struct tc_fifo_qopt));
259 ((struct tc_fifo_qopt *)nla_data(nla))->limit = limit;
261 ret = q->ops->change(q, nla);
273 static int tbf_change(struct Qdisc* sch, struct nlattr *opt)
276 struct tbf_sched_data *q = qdisc_priv(sch);
277 struct nlattr *tb[TCA_TBF_PTAB + 1];
278 struct tc_tbf_qopt *qopt;
279 struct qdisc_rate_table *rtab = NULL;
280 struct qdisc_rate_table *ptab = NULL;
281 struct Qdisc *child = NULL;
284 err = nla_parse_nested(tb, TCA_TBF_PTAB, opt, NULL);
289 if (tb[TCA_TBF_PARMS] == NULL ||
290 nla_len(tb[TCA_TBF_PARMS]) < sizeof(*qopt))
293 qopt = nla_data(tb[TCA_TBF_PARMS]);
294 rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB]);
298 if (qopt->peakrate.rate) {
299 if (qopt->peakrate.rate > qopt->rate.rate)
300 ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB]);
305 for (n = 0; n < 256; n++)
306 if (rtab->data[n] > qopt->buffer) break;
307 max_size = (n << qopt->rate.cell_log)-1;
311 for (n = 0; n < 256; n++)
312 if (ptab->data[n] > qopt->mtu) break;
313 size = (n << qopt->peakrate.cell_log)-1;
314 if (size < max_size) max_size = size;
319 if (qopt->limit > 0) {
320 if ((child = tbf_create_dflt_qdisc(sch, qopt->limit)) == NULL)
326 qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
327 qdisc_destroy(xchg(&q->qdisc, child));
329 q->limit = qopt->limit;
331 q->max_size = max_size;
332 q->buffer = qopt->buffer;
333 q->tokens = q->buffer;
335 rtab = xchg(&q->R_tab, rtab);
336 ptab = xchg(&q->P_tab, ptab);
337 sch_tree_unlock(sch);
341 qdisc_put_rtab(rtab);
343 qdisc_put_rtab(ptab);
347 static int tbf_init(struct Qdisc* sch, struct nlattr *opt)
349 struct tbf_sched_data *q = qdisc_priv(sch);
354 q->t_c = psched_get_time();
355 qdisc_watchdog_init(&q->watchdog, sch);
356 q->qdisc = &noop_qdisc;
358 return tbf_change(sch, opt);
361 static void tbf_destroy(struct Qdisc *sch)
363 struct tbf_sched_data *q = qdisc_priv(sch);
365 qdisc_watchdog_cancel(&q->watchdog);
368 qdisc_put_rtab(q->P_tab);
370 qdisc_put_rtab(q->R_tab);
372 qdisc_destroy(q->qdisc);
375 static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb)
377 struct tbf_sched_data *q = qdisc_priv(sch);
378 unsigned char *b = skb_tail_pointer(skb);
380 struct tc_tbf_qopt opt;
382 nla = (struct nlattr*)b;
383 NLA_PUT(skb, TCA_OPTIONS, 0, NULL);
385 opt.limit = q->limit;
386 opt.rate = q->R_tab->rate;
388 opt.peakrate = q->P_tab->rate;
390 memset(&opt.peakrate, 0, sizeof(opt.peakrate));
392 opt.buffer = q->buffer;
393 NLA_PUT(skb, TCA_TBF_PARMS, sizeof(opt), &opt);
394 nla->nla_len = skb_tail_pointer(skb) - b;
403 static int tbf_dump_class(struct Qdisc *sch, unsigned long cl,
404 struct sk_buff *skb, struct tcmsg *tcm)
406 struct tbf_sched_data *q = qdisc_priv(sch);
408 if (cl != 1) /* only one class */
411 tcm->tcm_handle |= TC_H_MIN(1);
412 tcm->tcm_info = q->qdisc->handle;
417 static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
420 struct tbf_sched_data *q = qdisc_priv(sch);
426 *old = xchg(&q->qdisc, new);
427 qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
429 sch_tree_unlock(sch);
434 static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg)
436 struct tbf_sched_data *q = qdisc_priv(sch);
440 static unsigned long tbf_get(struct Qdisc *sch, u32 classid)
445 static void tbf_put(struct Qdisc *sch, unsigned long arg)
449 static int tbf_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
450 struct nlattr **tca, unsigned long *arg)
455 static int tbf_delete(struct Qdisc *sch, unsigned long arg)
460 static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker)
463 if (walker->count >= walker->skip)
464 if (walker->fn(sch, 1, walker) < 0) {
472 static struct tcf_proto **tbf_find_tcf(struct Qdisc *sch, unsigned long cl)
477 static const struct Qdisc_class_ops tbf_class_ops =
483 .change = tbf_change_class,
484 .delete = tbf_delete,
486 .tcf_chain = tbf_find_tcf,
487 .dump = tbf_dump_class,
490 static struct Qdisc_ops tbf_qdisc_ops __read_mostly = {
492 .cl_ops = &tbf_class_ops,
494 .priv_size = sizeof(struct tbf_sched_data),
495 .enqueue = tbf_enqueue,
496 .dequeue = tbf_dequeue,
497 .requeue = tbf_requeue,
501 .destroy = tbf_destroy,
502 .change = tbf_change,
504 .owner = THIS_MODULE,
507 static int __init tbf_module_init(void)
509 return register_qdisc(&tbf_qdisc_ops);
512 static void __exit tbf_module_exit(void)
514 unregister_qdisc(&tbf_qdisc_ops);
516 module_init(tbf_module_init)
517 module_exit(tbf_module_exit)
518 MODULE_LICENSE("GPL");