Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * net/sched/sch_tbf.c Token Bucket Filter queue. | |
3 | * | |
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. | |
8 | * | |
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 | |
12 | * | |
13 | */ | |
14 | ||
1da177e4 | 15 | #include <linux/module.h> |
1da177e4 LT |
16 | #include <linux/types.h> |
17 | #include <linux/kernel.h> | |
1da177e4 | 18 | #include <linux/string.h> |
1da177e4 | 19 | #include <linux/errno.h> |
1da177e4 | 20 | #include <linux/skbuff.h> |
0ba48053 | 21 | #include <net/netlink.h> |
1da177e4 LT |
22 | #include <net/pkt_sched.h> |
23 | ||
24 | ||
25 | /* Simple Token Bucket Filter. | |
26 | ======================================= | |
27 | ||
28 | SOURCE. | |
29 | ------- | |
30 | ||
31 | None. | |
32 | ||
33 | Description. | |
34 | ------------ | |
35 | ||
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). | |
39 | ||
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: | |
43 | ||
44 | s_i+....+s_k <= B + R*(t_k - t_i) | |
45 | ||
46 | Algorithm. | |
47 | ---------- | |
48 | ||
49 | Let N(t_i) be B/R initially and N(t) grow continuously with time as: | |
50 | ||
51 | N(t+delta) = min{B/R, N(t) + delta} | |
52 | ||
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: | |
56 | ||
57 | N(t_* + 0) = N(t_* - 0) - S/R. | |
58 | ||
59 | ||
60 | ||
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. | |
65 | ||
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. | |
68 | ||
69 | When TBF works in reshaping mode, latency is estimated as: | |
70 | ||
71 | lat = max ((L-B)/R, (L-M)/P) | |
72 | ||
73 | ||
74 | NOTES. | |
75 | ------ | |
76 | ||
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. | |
83 | ||
84 | ||
85 | This means, that with depth B, the maximal rate is | |
86 | ||
87 | R_crit = B*HZ | |
88 | ||
89 | F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes. | |
90 | ||
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 :-) | |
94 | ||
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. | |
98 | */ | |
99 | ||
100 | struct tbf_sched_data | |
101 | { | |
102 | /* Parameters */ | |
103 | u32 limit; /* Maximal length of backlog: bytes */ | |
104 | u32 buffer; /* Token bucket depth/rate: MUST BE >= MTU/B */ | |
105 | u32 mtu; | |
106 | u32 max_size; | |
107 | struct qdisc_rate_table *R_tab; | |
108 | struct qdisc_rate_table *P_tab; | |
109 | ||
110 | /* Variables */ | |
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 */ | |
1da177e4 | 114 | struct Qdisc *qdisc; /* Inner qdisc, default - bfifo queue */ |
f7f593e3 | 115 | struct qdisc_watchdog watchdog; /* Watchdog timer */ |
1da177e4 LT |
116 | }; |
117 | ||
118 | #define L2T(q,L) ((q)->R_tab->data[(L)>>(q)->R_tab->rate.cell_log]) | |
119 | #define L2T_P(q,L) ((q)->P_tab->data[(L)>>(q)->P_tab->rate.cell_log]) | |
120 | ||
121 | static int tbf_enqueue(struct sk_buff *skb, struct Qdisc* sch) | |
122 | { | |
123 | struct tbf_sched_data *q = qdisc_priv(sch); | |
124 | int ret; | |
125 | ||
126 | if (skb->len > q->max_size) { | |
127 | sch->qstats.drops++; | |
128 | #ifdef CONFIG_NET_CLS_POLICE | |
129 | if (sch->reshape_fail == NULL || sch->reshape_fail(skb, sch)) | |
130 | #endif | |
131 | kfree_skb(skb); | |
132 | ||
133 | return NET_XMIT_DROP; | |
134 | } | |
135 | ||
136 | if ((ret = q->qdisc->enqueue(skb, q->qdisc)) != 0) { | |
137 | sch->qstats.drops++; | |
138 | return ret; | |
139 | } | |
140 | ||
141 | sch->q.qlen++; | |
142 | sch->bstats.bytes += skb->len; | |
143 | sch->bstats.packets++; | |
144 | return 0; | |
145 | } | |
146 | ||
147 | static int tbf_requeue(struct sk_buff *skb, struct Qdisc* sch) | |
148 | { | |
149 | struct tbf_sched_data *q = qdisc_priv(sch); | |
150 | int ret; | |
151 | ||
152 | if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) { | |
153 | sch->q.qlen++; | |
154 | sch->qstats.requeues++; | |
155 | } | |
156 | ||
157 | return ret; | |
158 | } | |
159 | ||
160 | static unsigned int tbf_drop(struct Qdisc* sch) | |
161 | { | |
162 | struct tbf_sched_data *q = qdisc_priv(sch); | |
6d037a26 | 163 | unsigned int len = 0; |
1da177e4 | 164 | |
6d037a26 | 165 | if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) { |
1da177e4 LT |
166 | sch->q.qlen--; |
167 | sch->qstats.drops++; | |
168 | } | |
169 | return len; | |
170 | } | |
171 | ||
1da177e4 LT |
172 | static struct sk_buff *tbf_dequeue(struct Qdisc* sch) |
173 | { | |
174 | struct tbf_sched_data *q = qdisc_priv(sch); | |
175 | struct sk_buff *skb; | |
176 | ||
177 | skb = q->qdisc->dequeue(q->qdisc); | |
178 | ||
179 | if (skb) { | |
180 | psched_time_t now; | |
f7f593e3 | 181 | long toks; |
1da177e4 LT |
182 | long ptoks = 0; |
183 | unsigned int len = skb->len; | |
184 | ||
3bebcda2 | 185 | now = psched_get_time(); |
03cc45c0 | 186 | toks = psched_tdiff_bounded(now, q->t_c, q->buffer); |
1da177e4 LT |
187 | |
188 | if (q->P_tab) { | |
189 | ptoks = toks + q->ptokens; | |
190 | if (ptoks > (long)q->mtu) | |
191 | ptoks = q->mtu; | |
192 | ptoks -= L2T_P(q, len); | |
193 | } | |
194 | toks += q->tokens; | |
195 | if (toks > (long)q->buffer) | |
196 | toks = q->buffer; | |
197 | toks -= L2T(q, len); | |
198 | ||
199 | if ((toks|ptoks) >= 0) { | |
200 | q->t_c = now; | |
201 | q->tokens = toks; | |
202 | q->ptokens = ptoks; | |
203 | sch->q.qlen--; | |
204 | sch->flags &= ~TCQ_F_THROTTLED; | |
205 | return skb; | |
206 | } | |
207 | ||
f7f593e3 PM |
208 | qdisc_watchdog_schedule(&q->watchdog, |
209 | now + max_t(long, -toks, -ptoks)); | |
1da177e4 LT |
210 | |
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. | |
215 | ||
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) | |
220 | */ | |
221 | ||
222 | if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) { | |
223 | /* When requeue fails skb is dropped */ | |
e488eafc | 224 | qdisc_tree_decrease_qlen(q->qdisc, 1); |
1da177e4 LT |
225 | sch->qstats.drops++; |
226 | } | |
227 | ||
1da177e4 LT |
228 | sch->qstats.overlimits++; |
229 | } | |
230 | return NULL; | |
231 | } | |
232 | ||
233 | static void tbf_reset(struct Qdisc* sch) | |
234 | { | |
235 | struct tbf_sched_data *q = qdisc_priv(sch); | |
236 | ||
237 | qdisc_reset(q->qdisc); | |
238 | sch->q.qlen = 0; | |
3bebcda2 | 239 | q->t_c = psched_get_time(); |
1da177e4 LT |
240 | q->tokens = q->buffer; |
241 | q->ptokens = q->mtu; | |
f7f593e3 | 242 | qdisc_watchdog_cancel(&q->watchdog); |
1da177e4 LT |
243 | } |
244 | ||
9f9afec4 | 245 | static struct Qdisc *tbf_create_dflt_qdisc(struct Qdisc *sch, u32 limit) |
1da177e4 | 246 | { |
9f9afec4 | 247 | struct Qdisc *q; |
10297b99 | 248 | struct rtattr *rta; |
1da177e4 LT |
249 | int ret; |
250 | ||
9f9afec4 PM |
251 | q = qdisc_create_dflt(sch->dev, &bfifo_qdisc_ops, |
252 | TC_H_MAKE(sch->handle, 1)); | |
1da177e4 LT |
253 | if (q) { |
254 | rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL); | |
255 | if (rta) { | |
256 | rta->rta_type = RTM_NEWQDISC; | |
10297b99 | 257 | rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt)); |
1da177e4 LT |
258 | ((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit; |
259 | ||
260 | ret = q->ops->change(q, rta); | |
261 | kfree(rta); | |
262 | ||
263 | if (ret == 0) | |
264 | return q; | |
265 | } | |
266 | qdisc_destroy(q); | |
267 | } | |
268 | ||
269 | return NULL; | |
270 | } | |
271 | ||
272 | static int tbf_change(struct Qdisc* sch, struct rtattr *opt) | |
273 | { | |
274 | int err = -EINVAL; | |
275 | struct tbf_sched_data *q = qdisc_priv(sch); | |
276 | struct rtattr *tb[TCA_TBF_PTAB]; | |
277 | struct tc_tbf_qopt *qopt; | |
278 | struct qdisc_rate_table *rtab = NULL; | |
279 | struct qdisc_rate_table *ptab = NULL; | |
280 | struct Qdisc *child = NULL; | |
281 | int max_size,n; | |
282 | ||
283 | if (rtattr_parse_nested(tb, TCA_TBF_PTAB, opt) || | |
284 | tb[TCA_TBF_PARMS-1] == NULL || | |
285 | RTA_PAYLOAD(tb[TCA_TBF_PARMS-1]) < sizeof(*qopt)) | |
286 | goto done; | |
287 | ||
288 | qopt = RTA_DATA(tb[TCA_TBF_PARMS-1]); | |
289 | rtab = qdisc_get_rtab(&qopt->rate, tb[TCA_TBF_RTAB-1]); | |
290 | if (rtab == NULL) | |
291 | goto done; | |
292 | ||
293 | if (qopt->peakrate.rate) { | |
294 | if (qopt->peakrate.rate > qopt->rate.rate) | |
295 | ptab = qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB-1]); | |
296 | if (ptab == NULL) | |
297 | goto done; | |
298 | } | |
299 | ||
300 | for (n = 0; n < 256; n++) | |
301 | if (rtab->data[n] > qopt->buffer) break; | |
302 | max_size = (n << qopt->rate.cell_log)-1; | |
303 | if (ptab) { | |
304 | int size; | |
305 | ||
306 | for (n = 0; n < 256; n++) | |
307 | if (ptab->data[n] > qopt->mtu) break; | |
308 | size = (n << qopt->peakrate.cell_log)-1; | |
309 | if (size < max_size) max_size = size; | |
310 | } | |
311 | if (max_size < 0) | |
312 | goto done; | |
313 | ||
053cfed7 | 314 | if (qopt->limit > 0) { |
9f9afec4 | 315 | if ((child = tbf_create_dflt_qdisc(sch, qopt->limit)) == NULL) |
1da177e4 LT |
316 | goto done; |
317 | } | |
318 | ||
319 | sch_tree_lock(sch); | |
5e50da01 PM |
320 | if (child) { |
321 | qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen); | |
053cfed7 | 322 | qdisc_destroy(xchg(&q->qdisc, child)); |
5e50da01 | 323 | } |
1da177e4 LT |
324 | q->limit = qopt->limit; |
325 | q->mtu = qopt->mtu; | |
326 | q->max_size = max_size; | |
327 | q->buffer = qopt->buffer; | |
328 | q->tokens = q->buffer; | |
329 | q->ptokens = q->mtu; | |
330 | rtab = xchg(&q->R_tab, rtab); | |
331 | ptab = xchg(&q->P_tab, ptab); | |
332 | sch_tree_unlock(sch); | |
333 | err = 0; | |
334 | done: | |
335 | if (rtab) | |
336 | qdisc_put_rtab(rtab); | |
337 | if (ptab) | |
338 | qdisc_put_rtab(ptab); | |
339 | return err; | |
340 | } | |
341 | ||
342 | static int tbf_init(struct Qdisc* sch, struct rtattr *opt) | |
343 | { | |
344 | struct tbf_sched_data *q = qdisc_priv(sch); | |
345 | ||
346 | if (opt == NULL) | |
347 | return -EINVAL; | |
348 | ||
3bebcda2 | 349 | q->t_c = psched_get_time(); |
f7f593e3 | 350 | qdisc_watchdog_init(&q->watchdog, sch); |
1da177e4 LT |
351 | q->qdisc = &noop_qdisc; |
352 | ||
353 | return tbf_change(sch, opt); | |
354 | } | |
355 | ||
356 | static void tbf_destroy(struct Qdisc *sch) | |
357 | { | |
358 | struct tbf_sched_data *q = qdisc_priv(sch); | |
359 | ||
f7f593e3 | 360 | qdisc_watchdog_cancel(&q->watchdog); |
1da177e4 LT |
361 | |
362 | if (q->P_tab) | |
363 | qdisc_put_rtab(q->P_tab); | |
364 | if (q->R_tab) | |
365 | qdisc_put_rtab(q->R_tab); | |
366 | ||
367 | qdisc_destroy(q->qdisc); | |
368 | } | |
369 | ||
370 | static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb) | |
371 | { | |
372 | struct tbf_sched_data *q = qdisc_priv(sch); | |
27a884dc | 373 | unsigned char *b = skb_tail_pointer(skb); |
1da177e4 LT |
374 | struct rtattr *rta; |
375 | struct tc_tbf_qopt opt; | |
376 | ||
377 | rta = (struct rtattr*)b; | |
378 | RTA_PUT(skb, TCA_OPTIONS, 0, NULL); | |
379 | ||
380 | opt.limit = q->limit; | |
381 | opt.rate = q->R_tab->rate; | |
382 | if (q->P_tab) | |
383 | opt.peakrate = q->P_tab->rate; | |
384 | else | |
385 | memset(&opt.peakrate, 0, sizeof(opt.peakrate)); | |
386 | opt.mtu = q->mtu; | |
387 | opt.buffer = q->buffer; | |
388 | RTA_PUT(skb, TCA_TBF_PARMS, sizeof(opt), &opt); | |
27a884dc | 389 | rta->rta_len = skb_tail_pointer(skb) - b; |
1da177e4 LT |
390 | |
391 | return skb->len; | |
392 | ||
393 | rtattr_failure: | |
dc5fc579 | 394 | nlmsg_trim(skb, b); |
1da177e4 LT |
395 | return -1; |
396 | } | |
397 | ||
398 | static int tbf_dump_class(struct Qdisc *sch, unsigned long cl, | |
399 | struct sk_buff *skb, struct tcmsg *tcm) | |
400 | { | |
401 | struct tbf_sched_data *q = qdisc_priv(sch); | |
402 | ||
403 | if (cl != 1) /* only one class */ | |
404 | return -ENOENT; | |
405 | ||
406 | tcm->tcm_handle |= TC_H_MIN(1); | |
407 | tcm->tcm_info = q->qdisc->handle; | |
408 | ||
409 | return 0; | |
410 | } | |
411 | ||
412 | static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new, | |
413 | struct Qdisc **old) | |
414 | { | |
415 | struct tbf_sched_data *q = qdisc_priv(sch); | |
416 | ||
417 | if (new == NULL) | |
418 | new = &noop_qdisc; | |
419 | ||
420 | sch_tree_lock(sch); | |
421 | *old = xchg(&q->qdisc, new); | |
5e50da01 | 422 | qdisc_tree_decrease_qlen(*old, (*old)->q.qlen); |
1da177e4 | 423 | qdisc_reset(*old); |
1da177e4 LT |
424 | sch_tree_unlock(sch); |
425 | ||
426 | return 0; | |
427 | } | |
428 | ||
429 | static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg) | |
430 | { | |
431 | struct tbf_sched_data *q = qdisc_priv(sch); | |
432 | return q->qdisc; | |
433 | } | |
434 | ||
435 | static unsigned long tbf_get(struct Qdisc *sch, u32 classid) | |
436 | { | |
437 | return 1; | |
438 | } | |
439 | ||
440 | static void tbf_put(struct Qdisc *sch, unsigned long arg) | |
441 | { | |
442 | } | |
443 | ||
10297b99 | 444 | static int tbf_change_class(struct Qdisc *sch, u32 classid, u32 parentid, |
1da177e4 LT |
445 | struct rtattr **tca, unsigned long *arg) |
446 | { | |
447 | return -ENOSYS; | |
448 | } | |
449 | ||
450 | static int tbf_delete(struct Qdisc *sch, unsigned long arg) | |
451 | { | |
452 | return -ENOSYS; | |
453 | } | |
454 | ||
455 | static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker) | |
456 | { | |
457 | if (!walker->stop) { | |
458 | if (walker->count >= walker->skip) | |
459 | if (walker->fn(sch, 1, walker) < 0) { | |
460 | walker->stop = 1; | |
461 | return; | |
462 | } | |
463 | walker->count++; | |
464 | } | |
465 | } | |
466 | ||
467 | static struct tcf_proto **tbf_find_tcf(struct Qdisc *sch, unsigned long cl) | |
468 | { | |
469 | return NULL; | |
470 | } | |
471 | ||
472 | static struct Qdisc_class_ops tbf_class_ops = | |
473 | { | |
474 | .graft = tbf_graft, | |
475 | .leaf = tbf_leaf, | |
476 | .get = tbf_get, | |
477 | .put = tbf_put, | |
478 | .change = tbf_change_class, | |
479 | .delete = tbf_delete, | |
480 | .walk = tbf_walk, | |
481 | .tcf_chain = tbf_find_tcf, | |
482 | .dump = tbf_dump_class, | |
483 | }; | |
484 | ||
485 | static struct Qdisc_ops tbf_qdisc_ops = { | |
486 | .next = NULL, | |
487 | .cl_ops = &tbf_class_ops, | |
488 | .id = "tbf", | |
489 | .priv_size = sizeof(struct tbf_sched_data), | |
490 | .enqueue = tbf_enqueue, | |
491 | .dequeue = tbf_dequeue, | |
492 | .requeue = tbf_requeue, | |
493 | .drop = tbf_drop, | |
494 | .init = tbf_init, | |
495 | .reset = tbf_reset, | |
496 | .destroy = tbf_destroy, | |
497 | .change = tbf_change, | |
498 | .dump = tbf_dump, | |
499 | .owner = THIS_MODULE, | |
500 | }; | |
501 | ||
502 | static int __init tbf_module_init(void) | |
503 | { | |
504 | return register_qdisc(&tbf_qdisc_ops); | |
505 | } | |
506 | ||
507 | static void __exit tbf_module_exit(void) | |
508 | { | |
509 | unregister_qdisc(&tbf_qdisc_ops); | |
510 | } | |
511 | module_init(tbf_module_init) | |
512 | module_exit(tbf_module_exit) | |
513 | MODULE_LICENSE("GPL"); |