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0545a303 | 1 | /* |
2 | * net/sched/sch_qfq.c Quick Fair Queueing Scheduler. | |
3 | * | |
4 | * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * version 2 as published by the Free Software Foundation. | |
9 | */ | |
10 | ||
11 | #include <linux/module.h> | |
12 | #include <linux/init.h> | |
13 | #include <linux/bitops.h> | |
14 | #include <linux/errno.h> | |
15 | #include <linux/netdevice.h> | |
16 | #include <linux/pkt_sched.h> | |
17 | #include <net/sch_generic.h> | |
18 | #include <net/pkt_sched.h> | |
19 | #include <net/pkt_cls.h> | |
20 | ||
21 | ||
22 | /* Quick Fair Queueing | |
23 | =================== | |
24 | ||
25 | Sources: | |
26 | ||
27 | Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient | |
28 | Packet Scheduling with Tight Bandwidth Distribution Guarantees." | |
29 | ||
30 | See also: | |
31 | http://retis.sssup.it/~fabio/linux/qfq/ | |
32 | */ | |
33 | ||
34 | /* | |
35 | ||
36 | Virtual time computations. | |
37 | ||
38 | S, F and V are all computed in fixed point arithmetic with | |
39 | FRAC_BITS decimal bits. | |
40 | ||
41 | QFQ_MAX_INDEX is the maximum index allowed for a group. We need | |
42 | one bit per index. | |
43 | QFQ_MAX_WSHIFT is the maximum power of two supported as a weight. | |
44 | ||
45 | The layout of the bits is as below: | |
46 | ||
47 | [ MTU_SHIFT ][ FRAC_BITS ] | |
48 | [ MAX_INDEX ][ MIN_SLOT_SHIFT ] | |
49 | ^.__grp->index = 0 | |
50 | *.__grp->slot_shift | |
51 | ||
52 | where MIN_SLOT_SHIFT is derived by difference from the others. | |
53 | ||
54 | The max group index corresponds to Lmax/w_min, where | |
55 | Lmax=1<<MTU_SHIFT, w_min = 1 . | |
56 | From this, and knowing how many groups (MAX_INDEX) we want, | |
57 | we can derive the shift corresponding to each group. | |
58 | ||
59 | Because we often need to compute | |
60 | F = S + len/w_i and V = V + len/wsum | |
61 | instead of storing w_i store the value | |
62 | inv_w = (1<<FRAC_BITS)/w_i | |
63 | so we can do F = S + len * inv_w * wsum. | |
64 | We use W_TOT in the formulas so we can easily move between | |
65 | static and adaptive weight sum. | |
66 | ||
67 | The per-scheduler-instance data contain all the data structures | |
68 | for the scheduler: bitmaps and bucket lists. | |
69 | ||
70 | */ | |
71 | ||
72 | /* | |
73 | * Maximum number of consecutive slots occupied by backlogged classes | |
74 | * inside a group. | |
75 | */ | |
76 | #define QFQ_MAX_SLOTS 32 | |
77 | ||
78 | /* | |
79 | * Shifts used for class<->group mapping. We allow class weights that are | |
80 | * in the range [1, 2^MAX_WSHIFT], and we try to map each class i to the | |
81 | * group with the smallest index that can support the L_i / r_i configured | |
82 | * for the class. | |
83 | * | |
84 | * grp->index is the index of the group; and grp->slot_shift | |
85 | * is the shift for the corresponding (scaled) sigma_i. | |
86 | */ | |
87 | #define QFQ_MAX_INDEX 19 | |
88 | #define QFQ_MAX_WSHIFT 16 | |
89 | ||
90 | #define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT) | |
91 | #define QFQ_MAX_WSUM (2*QFQ_MAX_WEIGHT) | |
92 | ||
93 | #define FRAC_BITS 30 /* fixed point arithmetic */ | |
94 | #define ONE_FP (1UL << FRAC_BITS) | |
95 | #define IWSUM (ONE_FP/QFQ_MAX_WSUM) | |
96 | ||
97 | #define QFQ_MTU_SHIFT 11 | |
98 | #define QFQ_MIN_SLOT_SHIFT (FRAC_BITS + QFQ_MTU_SHIFT - QFQ_MAX_INDEX) | |
99 | ||
100 | /* | |
101 | * Possible group states. These values are used as indexes for the bitmaps | |
102 | * array of struct qfq_queue. | |
103 | */ | |
104 | enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE }; | |
105 | ||
106 | struct qfq_group; | |
107 | ||
108 | struct qfq_class { | |
109 | struct Qdisc_class_common common; | |
110 | ||
111 | unsigned int refcnt; | |
112 | unsigned int filter_cnt; | |
113 | ||
114 | struct gnet_stats_basic_packed bstats; | |
115 | struct gnet_stats_queue qstats; | |
116 | struct gnet_stats_rate_est rate_est; | |
117 | struct Qdisc *qdisc; | |
118 | ||
119 | struct hlist_node next; /* Link for the slot list. */ | |
120 | u64 S, F; /* flow timestamps (exact) */ | |
121 | ||
122 | /* group we belong to. In principle we would need the index, | |
123 | * which is log_2(lmax/weight), but we never reference it | |
124 | * directly, only the group. | |
125 | */ | |
126 | struct qfq_group *grp; | |
127 | ||
128 | /* these are copied from the flowset. */ | |
129 | u32 inv_w; /* ONE_FP/weight */ | |
130 | u32 lmax; /* Max packet size for this flow. */ | |
131 | }; | |
132 | ||
133 | struct qfq_group { | |
134 | u64 S, F; /* group timestamps (approx). */ | |
135 | unsigned int slot_shift; /* Slot shift. */ | |
136 | unsigned int index; /* Group index. */ | |
137 | unsigned int front; /* Index of the front slot. */ | |
138 | unsigned long full_slots; /* non-empty slots */ | |
139 | ||
140 | /* Array of RR lists of active classes. */ | |
141 | struct hlist_head slots[QFQ_MAX_SLOTS]; | |
142 | }; | |
143 | ||
144 | struct qfq_sched { | |
145 | struct tcf_proto *filter_list; | |
146 | struct Qdisc_class_hash clhash; | |
147 | ||
148 | u64 V; /* Precise virtual time. */ | |
149 | u32 wsum; /* weight sum */ | |
150 | ||
151 | unsigned long bitmaps[QFQ_MAX_STATE]; /* Group bitmaps. */ | |
152 | struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */ | |
153 | }; | |
154 | ||
155 | static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid) | |
156 | { | |
157 | struct qfq_sched *q = qdisc_priv(sch); | |
158 | struct Qdisc_class_common *clc; | |
159 | ||
160 | clc = qdisc_class_find(&q->clhash, classid); | |
161 | if (clc == NULL) | |
162 | return NULL; | |
163 | return container_of(clc, struct qfq_class, common); | |
164 | } | |
165 | ||
166 | static void qfq_purge_queue(struct qfq_class *cl) | |
167 | { | |
168 | unsigned int len = cl->qdisc->q.qlen; | |
169 | ||
170 | qdisc_reset(cl->qdisc); | |
171 | qdisc_tree_decrease_qlen(cl->qdisc, len); | |
172 | } | |
173 | ||
174 | static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = { | |
175 | [TCA_QFQ_WEIGHT] = { .type = NLA_U32 }, | |
176 | [TCA_QFQ_LMAX] = { .type = NLA_U32 }, | |
177 | }; | |
178 | ||
179 | /* | |
180 | * Calculate a flow index, given its weight and maximum packet length. | |
181 | * index = log_2(maxlen/weight) but we need to apply the scaling. | |
182 | * This is used only once at flow creation. | |
183 | */ | |
184 | static int qfq_calc_index(u32 inv_w, unsigned int maxlen) | |
185 | { | |
186 | u64 slot_size = (u64)maxlen * inv_w; | |
187 | unsigned long size_map; | |
188 | int index = 0; | |
189 | ||
190 | size_map = slot_size >> QFQ_MIN_SLOT_SHIFT; | |
191 | if (!size_map) | |
192 | goto out; | |
193 | ||
194 | index = __fls(size_map) + 1; /* basically a log_2 */ | |
195 | index -= !(slot_size - (1ULL << (index + QFQ_MIN_SLOT_SHIFT - 1))); | |
196 | ||
197 | if (index < 0) | |
198 | index = 0; | |
199 | out: | |
200 | pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n", | |
201 | (unsigned long) ONE_FP/inv_w, maxlen, index); | |
202 | ||
203 | return index; | |
204 | } | |
205 | ||
206 | static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, | |
207 | struct nlattr **tca, unsigned long *arg) | |
208 | { | |
209 | struct qfq_sched *q = qdisc_priv(sch); | |
210 | struct qfq_class *cl = (struct qfq_class *)*arg; | |
211 | struct nlattr *tb[TCA_QFQ_MAX + 1]; | |
212 | u32 weight, lmax, inv_w; | |
213 | int i, err; | |
214 | ||
215 | if (tca[TCA_OPTIONS] == NULL) { | |
216 | pr_notice("qfq: no options\n"); | |
217 | return -EINVAL; | |
218 | } | |
219 | ||
220 | err = nla_parse_nested(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS], qfq_policy); | |
221 | if (err < 0) | |
222 | return err; | |
223 | ||
224 | if (tb[TCA_QFQ_WEIGHT]) { | |
225 | weight = nla_get_u32(tb[TCA_QFQ_WEIGHT]); | |
226 | if (!weight || weight > (1UL << QFQ_MAX_WSHIFT)) { | |
227 | pr_notice("qfq: invalid weight %u\n", weight); | |
228 | return -EINVAL; | |
229 | } | |
230 | } else | |
231 | weight = 1; | |
232 | ||
233 | inv_w = ONE_FP / weight; | |
234 | weight = ONE_FP / inv_w; | |
235 | if (q->wsum + weight > QFQ_MAX_WSUM) { | |
236 | pr_notice("qfq: total weight out of range (%u + %u)\n", | |
237 | weight, q->wsum); | |
238 | return -EINVAL; | |
239 | } | |
240 | ||
241 | if (tb[TCA_QFQ_LMAX]) { | |
242 | lmax = nla_get_u32(tb[TCA_QFQ_LMAX]); | |
243 | if (!lmax || lmax > (1UL << QFQ_MTU_SHIFT)) { | |
244 | pr_notice("qfq: invalid max length %u\n", lmax); | |
245 | return -EINVAL; | |
246 | } | |
247 | } else | |
248 | lmax = 1UL << QFQ_MTU_SHIFT; | |
249 | ||
250 | if (cl != NULL) { | |
251 | if (tca[TCA_RATE]) { | |
252 | err = gen_replace_estimator(&cl->bstats, &cl->rate_est, | |
253 | qdisc_root_sleeping_lock(sch), | |
254 | tca[TCA_RATE]); | |
255 | if (err) | |
256 | return err; | |
257 | } | |
258 | ||
259 | sch_tree_lock(sch); | |
260 | if (tb[TCA_QFQ_WEIGHT]) { | |
261 | q->wsum = weight - ONE_FP / cl->inv_w; | |
262 | cl->inv_w = inv_w; | |
263 | } | |
264 | sch_tree_unlock(sch); | |
265 | ||
266 | return 0; | |
267 | } | |
268 | ||
269 | cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL); | |
270 | if (cl == NULL) | |
271 | return -ENOBUFS; | |
272 | ||
273 | cl->refcnt = 1; | |
274 | cl->common.classid = classid; | |
275 | cl->lmax = lmax; | |
276 | cl->inv_w = inv_w; | |
277 | i = qfq_calc_index(cl->inv_w, cl->lmax); | |
278 | ||
279 | cl->grp = &q->groups[i]; | |
280 | q->wsum += weight; | |
281 | ||
282 | cl->qdisc = qdisc_create_dflt(sch->dev_queue, | |
283 | &pfifo_qdisc_ops, classid); | |
284 | if (cl->qdisc == NULL) | |
285 | cl->qdisc = &noop_qdisc; | |
286 | ||
287 | if (tca[TCA_RATE]) { | |
288 | err = gen_new_estimator(&cl->bstats, &cl->rate_est, | |
289 | qdisc_root_sleeping_lock(sch), | |
290 | tca[TCA_RATE]); | |
291 | if (err) { | |
292 | qdisc_destroy(cl->qdisc); | |
293 | kfree(cl); | |
294 | return err; | |
295 | } | |
296 | } | |
297 | ||
298 | sch_tree_lock(sch); | |
299 | qdisc_class_hash_insert(&q->clhash, &cl->common); | |
300 | sch_tree_unlock(sch); | |
301 | ||
302 | qdisc_class_hash_grow(sch, &q->clhash); | |
303 | ||
304 | *arg = (unsigned long)cl; | |
305 | return 0; | |
306 | } | |
307 | ||
308 | static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl) | |
309 | { | |
310 | struct qfq_sched *q = qdisc_priv(sch); | |
311 | ||
312 | if (cl->inv_w) { | |
313 | q->wsum -= ONE_FP / cl->inv_w; | |
314 | cl->inv_w = 0; | |
315 | } | |
316 | ||
317 | gen_kill_estimator(&cl->bstats, &cl->rate_est); | |
318 | qdisc_destroy(cl->qdisc); | |
319 | kfree(cl); | |
320 | } | |
321 | ||
322 | static int qfq_delete_class(struct Qdisc *sch, unsigned long arg) | |
323 | { | |
324 | struct qfq_sched *q = qdisc_priv(sch); | |
325 | struct qfq_class *cl = (struct qfq_class *)arg; | |
326 | ||
327 | if (cl->filter_cnt > 0) | |
328 | return -EBUSY; | |
329 | ||
330 | sch_tree_lock(sch); | |
331 | ||
332 | qfq_purge_queue(cl); | |
333 | qdisc_class_hash_remove(&q->clhash, &cl->common); | |
334 | ||
335 | BUG_ON(--cl->refcnt == 0); | |
336 | /* | |
337 | * This shouldn't happen: we "hold" one cops->get() when called | |
338 | * from tc_ctl_tclass; the destroy method is done from cops->put(). | |
339 | */ | |
340 | ||
341 | sch_tree_unlock(sch); | |
342 | return 0; | |
343 | } | |
344 | ||
345 | static unsigned long qfq_get_class(struct Qdisc *sch, u32 classid) | |
346 | { | |
347 | struct qfq_class *cl = qfq_find_class(sch, classid); | |
348 | ||
349 | if (cl != NULL) | |
350 | cl->refcnt++; | |
351 | ||
352 | return (unsigned long)cl; | |
353 | } | |
354 | ||
355 | static void qfq_put_class(struct Qdisc *sch, unsigned long arg) | |
356 | { | |
357 | struct qfq_class *cl = (struct qfq_class *)arg; | |
358 | ||
359 | if (--cl->refcnt == 0) | |
360 | qfq_destroy_class(sch, cl); | |
361 | } | |
362 | ||
363 | static struct tcf_proto **qfq_tcf_chain(struct Qdisc *sch, unsigned long cl) | |
364 | { | |
365 | struct qfq_sched *q = qdisc_priv(sch); | |
366 | ||
367 | if (cl) | |
368 | return NULL; | |
369 | ||
370 | return &q->filter_list; | |
371 | } | |
372 | ||
373 | static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent, | |
374 | u32 classid) | |
375 | { | |
376 | struct qfq_class *cl = qfq_find_class(sch, classid); | |
377 | ||
378 | if (cl != NULL) | |
379 | cl->filter_cnt++; | |
380 | ||
381 | return (unsigned long)cl; | |
382 | } | |
383 | ||
384 | static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg) | |
385 | { | |
386 | struct qfq_class *cl = (struct qfq_class *)arg; | |
387 | ||
388 | cl->filter_cnt--; | |
389 | } | |
390 | ||
391 | static int qfq_graft_class(struct Qdisc *sch, unsigned long arg, | |
392 | struct Qdisc *new, struct Qdisc **old) | |
393 | { | |
394 | struct qfq_class *cl = (struct qfq_class *)arg; | |
395 | ||
396 | if (new == NULL) { | |
397 | new = qdisc_create_dflt(sch->dev_queue, | |
398 | &pfifo_qdisc_ops, cl->common.classid); | |
399 | if (new == NULL) | |
400 | new = &noop_qdisc; | |
401 | } | |
402 | ||
403 | sch_tree_lock(sch); | |
404 | qfq_purge_queue(cl); | |
405 | *old = cl->qdisc; | |
406 | cl->qdisc = new; | |
407 | sch_tree_unlock(sch); | |
408 | return 0; | |
409 | } | |
410 | ||
411 | static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg) | |
412 | { | |
413 | struct qfq_class *cl = (struct qfq_class *)arg; | |
414 | ||
415 | return cl->qdisc; | |
416 | } | |
417 | ||
418 | static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, | |
419 | struct sk_buff *skb, struct tcmsg *tcm) | |
420 | { | |
421 | struct qfq_class *cl = (struct qfq_class *)arg; | |
422 | struct nlattr *nest; | |
423 | ||
424 | tcm->tcm_parent = TC_H_ROOT; | |
425 | tcm->tcm_handle = cl->common.classid; | |
426 | tcm->tcm_info = cl->qdisc->handle; | |
427 | ||
428 | nest = nla_nest_start(skb, TCA_OPTIONS); | |
429 | if (nest == NULL) | |
430 | goto nla_put_failure; | |
431 | NLA_PUT_U32(skb, TCA_QFQ_WEIGHT, ONE_FP/cl->inv_w); | |
432 | NLA_PUT_U32(skb, TCA_QFQ_LMAX, cl->lmax); | |
433 | return nla_nest_end(skb, nest); | |
434 | ||
435 | nla_put_failure: | |
436 | nla_nest_cancel(skb, nest); | |
437 | return -EMSGSIZE; | |
438 | } | |
439 | ||
440 | static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg, | |
441 | struct gnet_dump *d) | |
442 | { | |
443 | struct qfq_class *cl = (struct qfq_class *)arg; | |
444 | struct tc_qfq_stats xstats; | |
445 | ||
446 | memset(&xstats, 0, sizeof(xstats)); | |
447 | cl->qdisc->qstats.qlen = cl->qdisc->q.qlen; | |
448 | ||
449 | xstats.weight = ONE_FP/cl->inv_w; | |
450 | xstats.lmax = cl->lmax; | |
451 | ||
452 | if (gnet_stats_copy_basic(d, &cl->bstats) < 0 || | |
453 | gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 || | |
454 | gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0) | |
455 | return -1; | |
456 | ||
457 | return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); | |
458 | } | |
459 | ||
460 | static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg) | |
461 | { | |
462 | struct qfq_sched *q = qdisc_priv(sch); | |
463 | struct qfq_class *cl; | |
464 | struct hlist_node *n; | |
465 | unsigned int i; | |
466 | ||
467 | if (arg->stop) | |
468 | return; | |
469 | ||
470 | for (i = 0; i < q->clhash.hashsize; i++) { | |
471 | hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) { | |
472 | if (arg->count < arg->skip) { | |
473 | arg->count++; | |
474 | continue; | |
475 | } | |
476 | if (arg->fn(sch, (unsigned long)cl, arg) < 0) { | |
477 | arg->stop = 1; | |
478 | return; | |
479 | } | |
480 | arg->count++; | |
481 | } | |
482 | } | |
483 | } | |
484 | ||
485 | static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch, | |
486 | int *qerr) | |
487 | { | |
488 | struct qfq_sched *q = qdisc_priv(sch); | |
489 | struct qfq_class *cl; | |
490 | struct tcf_result res; | |
491 | int result; | |
492 | ||
493 | if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) { | |
494 | pr_debug("qfq_classify: found %d\n", skb->priority); | |
495 | cl = qfq_find_class(sch, skb->priority); | |
496 | if (cl != NULL) | |
497 | return cl; | |
498 | } | |
499 | ||
500 | *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; | |
501 | result = tc_classify(skb, q->filter_list, &res); | |
502 | if (result >= 0) { | |
503 | #ifdef CONFIG_NET_CLS_ACT | |
504 | switch (result) { | |
505 | case TC_ACT_QUEUED: | |
506 | case TC_ACT_STOLEN: | |
507 | *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; | |
508 | case TC_ACT_SHOT: | |
509 | return NULL; | |
510 | } | |
511 | #endif | |
512 | cl = (struct qfq_class *)res.class; | |
513 | if (cl == NULL) | |
514 | cl = qfq_find_class(sch, res.classid); | |
515 | return cl; | |
516 | } | |
517 | ||
518 | return NULL; | |
519 | } | |
520 | ||
521 | /* Generic comparison function, handling wraparound. */ | |
522 | static inline int qfq_gt(u64 a, u64 b) | |
523 | { | |
524 | return (s64)(a - b) > 0; | |
525 | } | |
526 | ||
527 | /* Round a precise timestamp to its slotted value. */ | |
528 | static inline u64 qfq_round_down(u64 ts, unsigned int shift) | |
529 | { | |
530 | return ts & ~((1ULL << shift) - 1); | |
531 | } | |
532 | ||
533 | /* return the pointer to the group with lowest index in the bitmap */ | |
534 | static inline struct qfq_group *qfq_ffs(struct qfq_sched *q, | |
535 | unsigned long bitmap) | |
536 | { | |
537 | int index = __ffs(bitmap); | |
538 | return &q->groups[index]; | |
539 | } | |
540 | /* Calculate a mask to mimic what would be ffs_from(). */ | |
541 | static inline unsigned long mask_from(unsigned long bitmap, int from) | |
542 | { | |
543 | return bitmap & ~((1UL << from) - 1); | |
544 | } | |
545 | ||
546 | /* | |
547 | * The state computation relies on ER=0, IR=1, EB=2, IB=3 | |
548 | * First compute eligibility comparing grp->S, q->V, | |
549 | * then check if someone is blocking us and possibly add EB | |
550 | */ | |
551 | static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp) | |
552 | { | |
553 | /* if S > V we are not eligible */ | |
554 | unsigned int state = qfq_gt(grp->S, q->V); | |
555 | unsigned long mask = mask_from(q->bitmaps[ER], grp->index); | |
556 | struct qfq_group *next; | |
557 | ||
558 | if (mask) { | |
559 | next = qfq_ffs(q, mask); | |
560 | if (qfq_gt(grp->F, next->F)) | |
561 | state |= EB; | |
562 | } | |
563 | ||
564 | return state; | |
565 | } | |
566 | ||
567 | ||
568 | /* | |
569 | * In principle | |
570 | * q->bitmaps[dst] |= q->bitmaps[src] & mask; | |
571 | * q->bitmaps[src] &= ~mask; | |
572 | * but we should make sure that src != dst | |
573 | */ | |
574 | static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask, | |
575 | int src, int dst) | |
576 | { | |
577 | q->bitmaps[dst] |= q->bitmaps[src] & mask; | |
578 | q->bitmaps[src] &= ~mask; | |
579 | } | |
580 | ||
581 | static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F) | |
582 | { | |
583 | unsigned long mask = mask_from(q->bitmaps[ER], index + 1); | |
584 | struct qfq_group *next; | |
585 | ||
586 | if (mask) { | |
587 | next = qfq_ffs(q, mask); | |
588 | if (!qfq_gt(next->F, old_F)) | |
589 | return; | |
590 | } | |
591 | ||
592 | mask = (1UL << index) - 1; | |
593 | qfq_move_groups(q, mask, EB, ER); | |
594 | qfq_move_groups(q, mask, IB, IR); | |
595 | } | |
596 | ||
597 | /* | |
598 | * perhaps | |
599 | * | |
600 | old_V ^= q->V; | |
601 | old_V >>= QFQ_MIN_SLOT_SHIFT; | |
602 | if (old_V) { | |
603 | ... | |
604 | } | |
605 | * | |
606 | */ | |
607 | static void qfq_make_eligible(struct qfq_sched *q, u64 old_V) | |
608 | { | |
609 | unsigned long vslot = q->V >> QFQ_MIN_SLOT_SHIFT; | |
610 | unsigned long old_vslot = old_V >> QFQ_MIN_SLOT_SHIFT; | |
611 | ||
612 | if (vslot != old_vslot) { | |
613 | unsigned long mask = (1UL << fls(vslot ^ old_vslot)) - 1; | |
614 | qfq_move_groups(q, mask, IR, ER); | |
615 | qfq_move_groups(q, mask, IB, EB); | |
616 | } | |
617 | } | |
618 | ||
619 | ||
620 | /* | |
621 | * XXX we should make sure that slot becomes less than 32. | |
622 | * This is guaranteed by the input values. | |
623 | * roundedS is always cl->S rounded on grp->slot_shift bits. | |
624 | */ | |
625 | static void qfq_slot_insert(struct qfq_group *grp, struct qfq_class *cl, | |
626 | u64 roundedS) | |
627 | { | |
628 | u64 slot = (roundedS - grp->S) >> grp->slot_shift; | |
629 | unsigned int i = (grp->front + slot) % QFQ_MAX_SLOTS; | |
630 | ||
631 | hlist_add_head(&cl->next, &grp->slots[i]); | |
632 | __set_bit(slot, &grp->full_slots); | |
633 | } | |
634 | ||
635 | /* Maybe introduce hlist_first_entry?? */ | |
636 | static struct qfq_class *qfq_slot_head(struct qfq_group *grp) | |
637 | { | |
638 | return hlist_entry(grp->slots[grp->front].first, | |
639 | struct qfq_class, next); | |
640 | } | |
641 | ||
642 | /* | |
643 | * remove the entry from the slot | |
644 | */ | |
645 | static void qfq_front_slot_remove(struct qfq_group *grp) | |
646 | { | |
647 | struct qfq_class *cl = qfq_slot_head(grp); | |
648 | ||
649 | BUG_ON(!cl); | |
650 | hlist_del(&cl->next); | |
651 | if (hlist_empty(&grp->slots[grp->front])) | |
652 | __clear_bit(0, &grp->full_slots); | |
653 | } | |
654 | ||
655 | /* | |
656 | * Returns the first full queue in a group. As a side effect, | |
657 | * adjust the bucket list so the first non-empty bucket is at | |
658 | * position 0 in full_slots. | |
659 | */ | |
660 | static struct qfq_class *qfq_slot_scan(struct qfq_group *grp) | |
661 | { | |
662 | unsigned int i; | |
663 | ||
664 | pr_debug("qfq slot_scan: grp %u full %#lx\n", | |
665 | grp->index, grp->full_slots); | |
666 | ||
667 | if (grp->full_slots == 0) | |
668 | return NULL; | |
669 | ||
670 | i = __ffs(grp->full_slots); /* zero based */ | |
671 | if (i > 0) { | |
672 | grp->front = (grp->front + i) % QFQ_MAX_SLOTS; | |
673 | grp->full_slots >>= i; | |
674 | } | |
675 | ||
676 | return qfq_slot_head(grp); | |
677 | } | |
678 | ||
679 | /* | |
680 | * adjust the bucket list. When the start time of a group decreases, | |
681 | * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to | |
682 | * move the objects. The mask of occupied slots must be shifted | |
683 | * because we use ffs() to find the first non-empty slot. | |
684 | * This covers decreases in the group's start time, but what about | |
685 | * increases of the start time ? | |
686 | * Here too we should make sure that i is less than 32 | |
687 | */ | |
688 | static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS) | |
689 | { | |
690 | unsigned int i = (grp->S - roundedS) >> grp->slot_shift; | |
691 | ||
692 | grp->full_slots <<= i; | |
693 | grp->front = (grp->front - i) % QFQ_MAX_SLOTS; | |
694 | } | |
695 | ||
696 | static void qfq_update_eligible(struct qfq_sched *q, u64 old_V) | |
697 | { | |
698 | struct qfq_group *grp; | |
699 | unsigned long ineligible; | |
700 | ||
701 | ineligible = q->bitmaps[IR] | q->bitmaps[IB]; | |
702 | if (ineligible) { | |
703 | if (!q->bitmaps[ER]) { | |
704 | grp = qfq_ffs(q, ineligible); | |
705 | if (qfq_gt(grp->S, q->V)) | |
706 | q->V = grp->S; | |
707 | } | |
708 | qfq_make_eligible(q, old_V); | |
709 | } | |
710 | } | |
711 | ||
712 | /* What is length of next packet in queue (0 if queue is empty) */ | |
713 | static unsigned int qdisc_peek_len(struct Qdisc *sch) | |
714 | { | |
715 | struct sk_buff *skb; | |
716 | ||
717 | skb = sch->ops->peek(sch); | |
718 | return skb ? qdisc_pkt_len(skb) : 0; | |
719 | } | |
720 | ||
721 | /* | |
722 | * Updates the class, returns true if also the group needs to be updated. | |
723 | */ | |
724 | static bool qfq_update_class(struct qfq_group *grp, struct qfq_class *cl) | |
725 | { | |
726 | unsigned int len = qdisc_peek_len(cl->qdisc); | |
727 | ||
728 | cl->S = cl->F; | |
729 | if (!len) | |
730 | qfq_front_slot_remove(grp); /* queue is empty */ | |
731 | else { | |
732 | u64 roundedS; | |
733 | ||
734 | cl->F = cl->S + (u64)len * cl->inv_w; | |
735 | roundedS = qfq_round_down(cl->S, grp->slot_shift); | |
736 | if (roundedS == grp->S) | |
737 | return false; | |
738 | ||
739 | qfq_front_slot_remove(grp); | |
740 | qfq_slot_insert(grp, cl, roundedS); | |
741 | } | |
742 | ||
743 | return true; | |
744 | } | |
745 | ||
746 | static struct sk_buff *qfq_dequeue(struct Qdisc *sch) | |
747 | { | |
748 | struct qfq_sched *q = qdisc_priv(sch); | |
749 | struct qfq_group *grp; | |
750 | struct qfq_class *cl; | |
751 | struct sk_buff *skb; | |
752 | unsigned int len; | |
753 | u64 old_V; | |
754 | ||
755 | if (!q->bitmaps[ER]) | |
756 | return NULL; | |
757 | ||
758 | grp = qfq_ffs(q, q->bitmaps[ER]); | |
759 | ||
760 | cl = qfq_slot_head(grp); | |
761 | skb = qdisc_dequeue_peeked(cl->qdisc); | |
762 | if (!skb) { | |
763 | WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n"); | |
764 | return NULL; | |
765 | } | |
766 | ||
767 | sch->q.qlen--; | |
768 | qdisc_bstats_update(sch, skb); | |
769 | ||
770 | old_V = q->V; | |
771 | len = qdisc_pkt_len(skb); | |
772 | q->V += (u64)len * IWSUM; | |
773 | pr_debug("qfq dequeue: len %u F %lld now %lld\n", | |
774 | len, (unsigned long long) cl->F, (unsigned long long) q->V); | |
775 | ||
776 | if (qfq_update_class(grp, cl)) { | |
777 | u64 old_F = grp->F; | |
778 | ||
779 | cl = qfq_slot_scan(grp); | |
780 | if (!cl) | |
781 | __clear_bit(grp->index, &q->bitmaps[ER]); | |
782 | else { | |
783 | u64 roundedS = qfq_round_down(cl->S, grp->slot_shift); | |
784 | unsigned int s; | |
785 | ||
786 | if (grp->S == roundedS) | |
787 | goto skip_unblock; | |
788 | grp->S = roundedS; | |
789 | grp->F = roundedS + (2ULL << grp->slot_shift); | |
790 | __clear_bit(grp->index, &q->bitmaps[ER]); | |
791 | s = qfq_calc_state(q, grp); | |
792 | __set_bit(grp->index, &q->bitmaps[s]); | |
793 | } | |
794 | ||
795 | qfq_unblock_groups(q, grp->index, old_F); | |
796 | } | |
797 | ||
798 | skip_unblock: | |
799 | qfq_update_eligible(q, old_V); | |
800 | ||
801 | return skb; | |
802 | } | |
803 | ||
804 | /* | |
805 | * Assign a reasonable start time for a new flow k in group i. | |
806 | * Admissible values for \hat(F) are multiples of \sigma_i | |
807 | * no greater than V+\sigma_i . Larger values mean that | |
808 | * we had a wraparound so we consider the timestamp to be stale. | |
809 | * | |
810 | * If F is not stale and F >= V then we set S = F. | |
811 | * Otherwise we should assign S = V, but this may violate | |
812 | * the ordering in ER. So, if we have groups in ER, set S to | |
813 | * the F_j of the first group j which would be blocking us. | |
814 | * We are guaranteed not to move S backward because | |
815 | * otherwise our group i would still be blocked. | |
816 | */ | |
817 | static void qfq_update_start(struct qfq_sched *q, struct qfq_class *cl) | |
818 | { | |
819 | unsigned long mask; | |
820 | uint32_t limit, roundedF; | |
821 | int slot_shift = cl->grp->slot_shift; | |
822 | ||
823 | roundedF = qfq_round_down(cl->F, slot_shift); | |
824 | limit = qfq_round_down(q->V, slot_shift) + (1UL << slot_shift); | |
825 | ||
826 | if (!qfq_gt(cl->F, q->V) || qfq_gt(roundedF, limit)) { | |
827 | /* timestamp was stale */ | |
828 | mask = mask_from(q->bitmaps[ER], cl->grp->index); | |
829 | if (mask) { | |
830 | struct qfq_group *next = qfq_ffs(q, mask); | |
831 | if (qfq_gt(roundedF, next->F)) { | |
832 | cl->S = next->F; | |
833 | return; | |
834 | } | |
835 | } | |
836 | cl->S = q->V; | |
837 | } else /* timestamp is not stale */ | |
838 | cl->S = cl->F; | |
839 | } | |
840 | ||
841 | static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) | |
842 | { | |
843 | struct qfq_sched *q = qdisc_priv(sch); | |
844 | struct qfq_group *grp; | |
845 | struct qfq_class *cl; | |
846 | int err; | |
847 | u64 roundedS; | |
848 | int s; | |
849 | ||
850 | cl = qfq_classify(skb, sch, &err); | |
851 | if (cl == NULL) { | |
852 | if (err & __NET_XMIT_BYPASS) | |
853 | sch->qstats.drops++; | |
854 | kfree_skb(skb); | |
855 | return err; | |
856 | } | |
857 | pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid); | |
858 | ||
859 | err = qdisc_enqueue(skb, cl->qdisc); | |
860 | if (unlikely(err != NET_XMIT_SUCCESS)) { | |
861 | pr_debug("qfq_enqueue: enqueue failed %d\n", err); | |
862 | if (net_xmit_drop_count(err)) { | |
863 | cl->qstats.drops++; | |
864 | sch->qstats.drops++; | |
865 | } | |
866 | return err; | |
867 | } | |
868 | ||
869 | bstats_update(&cl->bstats, skb); | |
870 | ++sch->q.qlen; | |
871 | ||
872 | /* If the new skb is not the head of queue, then done here. */ | |
873 | if (cl->qdisc->q.qlen != 1) | |
874 | return err; | |
875 | ||
876 | /* If reach this point, queue q was idle */ | |
877 | grp = cl->grp; | |
878 | qfq_update_start(q, cl); | |
879 | ||
880 | /* compute new finish time and rounded start. */ | |
881 | cl->F = cl->S + (u64)qdisc_pkt_len(skb) * cl->inv_w; | |
882 | roundedS = qfq_round_down(cl->S, grp->slot_shift); | |
883 | ||
884 | /* | |
885 | * insert cl in the correct bucket. | |
886 | * If cl->S >= grp->S we don't need to adjust the | |
887 | * bucket list and simply go to the insertion phase. | |
888 | * Otherwise grp->S is decreasing, we must make room | |
889 | * in the bucket list, and also recompute the group state. | |
890 | * Finally, if there were no flows in this group and nobody | |
891 | * was in ER make sure to adjust V. | |
892 | */ | |
893 | if (grp->full_slots) { | |
894 | if (!qfq_gt(grp->S, cl->S)) | |
895 | goto skip_update; | |
896 | ||
897 | /* create a slot for this cl->S */ | |
898 | qfq_slot_rotate(grp, roundedS); | |
899 | /* group was surely ineligible, remove */ | |
900 | __clear_bit(grp->index, &q->bitmaps[IR]); | |
901 | __clear_bit(grp->index, &q->bitmaps[IB]); | |
902 | } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V)) | |
903 | q->V = roundedS; | |
904 | ||
905 | grp->S = roundedS; | |
906 | grp->F = roundedS + (2ULL << grp->slot_shift); | |
907 | s = qfq_calc_state(q, grp); | |
908 | __set_bit(grp->index, &q->bitmaps[s]); | |
909 | ||
910 | pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n", | |
911 | s, q->bitmaps[s], | |
912 | (unsigned long long) cl->S, | |
913 | (unsigned long long) cl->F, | |
914 | (unsigned long long) q->V); | |
915 | ||
916 | skip_update: | |
917 | qfq_slot_insert(grp, cl, roundedS); | |
918 | ||
919 | return err; | |
920 | } | |
921 | ||
922 | ||
923 | static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp, | |
924 | struct qfq_class *cl) | |
925 | { | |
926 | unsigned int i, offset; | |
927 | u64 roundedS; | |
928 | ||
929 | roundedS = qfq_round_down(cl->S, grp->slot_shift); | |
930 | offset = (roundedS - grp->S) >> grp->slot_shift; | |
931 | i = (grp->front + offset) % QFQ_MAX_SLOTS; | |
932 | ||
933 | hlist_del(&cl->next); | |
934 | if (hlist_empty(&grp->slots[i])) | |
935 | __clear_bit(offset, &grp->full_slots); | |
936 | } | |
937 | ||
938 | /* | |
939 | * called to forcibly destroy a queue. | |
940 | * If the queue is not in the front bucket, or if it has | |
941 | * other queues in the front bucket, we can simply remove | |
942 | * the queue with no other side effects. | |
943 | * Otherwise we must propagate the event up. | |
944 | */ | |
945 | static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl) | |
946 | { | |
947 | struct qfq_group *grp = cl->grp; | |
948 | unsigned long mask; | |
949 | u64 roundedS; | |
950 | int s; | |
951 | ||
952 | cl->F = cl->S; | |
953 | qfq_slot_remove(q, grp, cl); | |
954 | ||
955 | if (!grp->full_slots) { | |
956 | __clear_bit(grp->index, &q->bitmaps[IR]); | |
957 | __clear_bit(grp->index, &q->bitmaps[EB]); | |
958 | __clear_bit(grp->index, &q->bitmaps[IB]); | |
959 | ||
960 | if (test_bit(grp->index, &q->bitmaps[ER]) && | |
961 | !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) { | |
962 | mask = q->bitmaps[ER] & ((1UL << grp->index) - 1); | |
963 | if (mask) | |
964 | mask = ~((1UL << __fls(mask)) - 1); | |
965 | else | |
966 | mask = ~0UL; | |
967 | qfq_move_groups(q, mask, EB, ER); | |
968 | qfq_move_groups(q, mask, IB, IR); | |
969 | } | |
970 | __clear_bit(grp->index, &q->bitmaps[ER]); | |
971 | } else if (hlist_empty(&grp->slots[grp->front])) { | |
972 | cl = qfq_slot_scan(grp); | |
973 | roundedS = qfq_round_down(cl->S, grp->slot_shift); | |
974 | if (grp->S != roundedS) { | |
975 | __clear_bit(grp->index, &q->bitmaps[ER]); | |
976 | __clear_bit(grp->index, &q->bitmaps[IR]); | |
977 | __clear_bit(grp->index, &q->bitmaps[EB]); | |
978 | __clear_bit(grp->index, &q->bitmaps[IB]); | |
979 | grp->S = roundedS; | |
980 | grp->F = roundedS + (2ULL << grp->slot_shift); | |
981 | s = qfq_calc_state(q, grp); | |
982 | __set_bit(grp->index, &q->bitmaps[s]); | |
983 | } | |
984 | } | |
985 | ||
986 | qfq_update_eligible(q, q->V); | |
987 | } | |
988 | ||
989 | static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg) | |
990 | { | |
991 | struct qfq_sched *q = qdisc_priv(sch); | |
992 | struct qfq_class *cl = (struct qfq_class *)arg; | |
993 | ||
994 | if (cl->qdisc->q.qlen == 0) | |
995 | qfq_deactivate_class(q, cl); | |
996 | } | |
997 | ||
998 | static unsigned int qfq_drop(struct Qdisc *sch) | |
999 | { | |
1000 | struct qfq_sched *q = qdisc_priv(sch); | |
1001 | struct qfq_group *grp; | |
1002 | unsigned int i, j, len; | |
1003 | ||
1004 | for (i = 0; i <= QFQ_MAX_INDEX; i++) { | |
1005 | grp = &q->groups[i]; | |
1006 | for (j = 0; j < QFQ_MAX_SLOTS; j++) { | |
1007 | struct qfq_class *cl; | |
1008 | struct hlist_node *n; | |
1009 | ||
1010 | hlist_for_each_entry(cl, n, &grp->slots[j], next) { | |
1011 | ||
1012 | if (!cl->qdisc->ops->drop) | |
1013 | continue; | |
1014 | ||
1015 | len = cl->qdisc->ops->drop(cl->qdisc); | |
1016 | if (len > 0) { | |
1017 | sch->q.qlen--; | |
1018 | if (!cl->qdisc->q.qlen) | |
1019 | qfq_deactivate_class(q, cl); | |
1020 | ||
1021 | return len; | |
1022 | } | |
1023 | } | |
1024 | } | |
1025 | } | |
1026 | ||
1027 | return 0; | |
1028 | } | |
1029 | ||
1030 | static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt) | |
1031 | { | |
1032 | struct qfq_sched *q = qdisc_priv(sch); | |
1033 | struct qfq_group *grp; | |
1034 | int i, j, err; | |
1035 | ||
1036 | err = qdisc_class_hash_init(&q->clhash); | |
1037 | if (err < 0) | |
1038 | return err; | |
1039 | ||
1040 | for (i = 0; i <= QFQ_MAX_INDEX; i++) { | |
1041 | grp = &q->groups[i]; | |
1042 | grp->index = i; | |
1043 | grp->slot_shift = QFQ_MTU_SHIFT + FRAC_BITS | |
1044 | - (QFQ_MAX_INDEX - i); | |
1045 | for (j = 0; j < QFQ_MAX_SLOTS; j++) | |
1046 | INIT_HLIST_HEAD(&grp->slots[j]); | |
1047 | } | |
1048 | ||
1049 | return 0; | |
1050 | } | |
1051 | ||
1052 | static void qfq_reset_qdisc(struct Qdisc *sch) | |
1053 | { | |
1054 | struct qfq_sched *q = qdisc_priv(sch); | |
1055 | struct qfq_group *grp; | |
1056 | struct qfq_class *cl; | |
1057 | struct hlist_node *n, *tmp; | |
1058 | unsigned int i, j; | |
1059 | ||
1060 | for (i = 0; i <= QFQ_MAX_INDEX; i++) { | |
1061 | grp = &q->groups[i]; | |
1062 | for (j = 0; j < QFQ_MAX_SLOTS; j++) { | |
1063 | hlist_for_each_entry_safe(cl, n, tmp, | |
1064 | &grp->slots[j], next) { | |
1065 | qfq_deactivate_class(q, cl); | |
1066 | } | |
1067 | } | |
1068 | } | |
1069 | ||
1070 | for (i = 0; i < q->clhash.hashsize; i++) { | |
1071 | hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) | |
1072 | qdisc_reset(cl->qdisc); | |
1073 | } | |
1074 | sch->q.qlen = 0; | |
1075 | } | |
1076 | ||
1077 | static void qfq_destroy_qdisc(struct Qdisc *sch) | |
1078 | { | |
1079 | struct qfq_sched *q = qdisc_priv(sch); | |
1080 | struct qfq_class *cl; | |
1081 | struct hlist_node *n, *next; | |
1082 | unsigned int i; | |
1083 | ||
1084 | tcf_destroy_chain(&q->filter_list); | |
1085 | ||
1086 | for (i = 0; i < q->clhash.hashsize; i++) { | |
1087 | hlist_for_each_entry_safe(cl, n, next, &q->clhash.hash[i], | |
1088 | common.hnode) { | |
1089 | qfq_destroy_class(sch, cl); | |
1090 | } | |
1091 | } | |
1092 | qdisc_class_hash_destroy(&q->clhash); | |
1093 | } | |
1094 | ||
1095 | static const struct Qdisc_class_ops qfq_class_ops = { | |
1096 | .change = qfq_change_class, | |
1097 | .delete = qfq_delete_class, | |
1098 | .get = qfq_get_class, | |
1099 | .put = qfq_put_class, | |
1100 | .tcf_chain = qfq_tcf_chain, | |
1101 | .bind_tcf = qfq_bind_tcf, | |
1102 | .unbind_tcf = qfq_unbind_tcf, | |
1103 | .graft = qfq_graft_class, | |
1104 | .leaf = qfq_class_leaf, | |
1105 | .qlen_notify = qfq_qlen_notify, | |
1106 | .dump = qfq_dump_class, | |
1107 | .dump_stats = qfq_dump_class_stats, | |
1108 | .walk = qfq_walk, | |
1109 | }; | |
1110 | ||
1111 | static struct Qdisc_ops qfq_qdisc_ops __read_mostly = { | |
1112 | .cl_ops = &qfq_class_ops, | |
1113 | .id = "qfq", | |
1114 | .priv_size = sizeof(struct qfq_sched), | |
1115 | .enqueue = qfq_enqueue, | |
1116 | .dequeue = qfq_dequeue, | |
1117 | .peek = qdisc_peek_dequeued, | |
1118 | .drop = qfq_drop, | |
1119 | .init = qfq_init_qdisc, | |
1120 | .reset = qfq_reset_qdisc, | |
1121 | .destroy = qfq_destroy_qdisc, | |
1122 | .owner = THIS_MODULE, | |
1123 | }; | |
1124 | ||
1125 | static int __init qfq_init(void) | |
1126 | { | |
1127 | return register_qdisc(&qfq_qdisc_ops); | |
1128 | } | |
1129 | ||
1130 | static void __exit qfq_exit(void) | |
1131 | { | |
1132 | unregister_qdisc(&qfq_qdisc_ops); | |
1133 | } | |
1134 | ||
1135 | module_init(qfq_init); | |
1136 | module_exit(qfq_exit); | |
1137 | MODULE_LICENSE("GPL"); |