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"); |