1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * net/sched/sch_qfq.c Quick Fair Queueing Plus Scheduler. |
4 | * |
5 | * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente. |
6 | * Copyright (c) 2012 Paolo Valente. |
7 | */ |
8 | |
9 | #include <linux/module.h> |
10 | #include <linux/init.h> |
11 | #include <linux/bitops.h> |
12 | #include <linux/errno.h> |
13 | #include <linux/netdevice.h> |
14 | #include <linux/pkt_sched.h> |
15 | #include <net/sch_generic.h> |
16 | #include <net/pkt_sched.h> |
17 | #include <net/pkt_cls.h> |
18 | |
19 | |
20 | /* Quick Fair Queueing Plus |
21 | ======================== |
22 | |
23 | Sources: |
24 | |
25 | [1] Paolo Valente, |
26 | "Reducing the Execution Time of Fair-Queueing Schedulers." |
27 | http://algo.ing.unimo.it/people/paolo/agg-sched/agg-sched.pdf |
28 | |
29 | Sources for QFQ: |
30 | |
31 | [2] Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient |
32 | Packet Scheduling with Tight Bandwidth Distribution Guarantees." |
33 | |
34 | See also: |
35 | http://retis.sssup.it/~fabio/linux/qfq/ |
36 | */ |
37 | |
38 | /* |
39 | |
40 | QFQ+ divides classes into aggregates of at most MAX_AGG_CLASSES |
41 | classes. Each aggregate is timestamped with a virtual start time S |
42 | and a virtual finish time F, and scheduled according to its |
43 | timestamps. S and F are computed as a function of a system virtual |
44 | time function V. The classes within each aggregate are instead |
45 | scheduled with DRR. |
46 | |
47 | To speed up operations, QFQ+ divides also aggregates into a limited |
48 | number of groups. Which group a class belongs to depends on the |
49 | ratio between the maximum packet length for the class and the weight |
50 | of the class. Groups have their own S and F. In the end, QFQ+ |
51 | schedules groups, then aggregates within groups, then classes within |
52 | aggregates. See [1] and [2] for a full description. |
53 | |
54 | Virtual time computations. |
55 | |
56 | S, F and V are all computed in fixed point arithmetic with |
57 | FRAC_BITS decimal bits. |
58 | |
59 | QFQ_MAX_INDEX is the maximum index allowed for a group. We need |
60 | one bit per index. |
61 | QFQ_MAX_WSHIFT is the maximum power of two supported as a weight. |
62 | |
63 | The layout of the bits is as below: |
64 | |
65 | [ MTU_SHIFT ][ FRAC_BITS ] |
66 | [ MAX_INDEX ][ MIN_SLOT_SHIFT ] |
67 | ^.__grp->index = 0 |
68 | *.__grp->slot_shift |
69 | |
70 | where MIN_SLOT_SHIFT is derived by difference from the others. |
71 | |
72 | The max group index corresponds to Lmax/w_min, where |
73 | Lmax=1<<MTU_SHIFT, w_min = 1 . |
74 | From this, and knowing how many groups (MAX_INDEX) we want, |
75 | we can derive the shift corresponding to each group. |
76 | |
77 | Because we often need to compute |
78 | F = S + len/w_i and V = V + len/wsum |
79 | instead of storing w_i store the value |
80 | inv_w = (1<<FRAC_BITS)/w_i |
81 | so we can do F = S + len * inv_w * wsum. |
82 | We use W_TOT in the formulas so we can easily move between |
83 | static and adaptive weight sum. |
84 | |
85 | The per-scheduler-instance data contain all the data structures |
86 | for the scheduler: bitmaps and bucket lists. |
87 | |
88 | */ |
89 | |
90 | /* |
91 | * Maximum number of consecutive slots occupied by backlogged classes |
92 | * inside a group. |
93 | */ |
94 | #define QFQ_MAX_SLOTS 32 |
95 | |
96 | /* |
97 | * Shifts used for aggregate<->group mapping. We allow class weights that are |
98 | * in the range [1, 2^MAX_WSHIFT], and we try to map each aggregate i to the |
99 | * group with the smallest index that can support the L_i / r_i configured |
100 | * for the classes in the aggregate. |
101 | * |
102 | * grp->index is the index of the group; and grp->slot_shift |
103 | * is the shift for the corresponding (scaled) sigma_i. |
104 | */ |
105 | #define QFQ_MAX_INDEX 24 |
106 | #define QFQ_MAX_WSHIFT 10 |
107 | |
108 | #define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT) /* see qfq_slot_insert */ |
109 | #define QFQ_MAX_WSUM (64*QFQ_MAX_WEIGHT) |
110 | |
111 | #define FRAC_BITS 30 /* fixed point arithmetic */ |
112 | #define ONE_FP (1UL << FRAC_BITS) |
113 | |
114 | #define QFQ_MTU_SHIFT 16 /* to support TSO/GSO */ |
115 | #define QFQ_MIN_LMAX 512 /* see qfq_slot_insert */ |
116 | #define QFQ_MAX_LMAX (1UL << QFQ_MTU_SHIFT) |
117 | |
118 | #define QFQ_MAX_AGG_CLASSES 8 /* max num classes per aggregate allowed */ |
119 | |
120 | /* |
121 | * Possible group states. These values are used as indexes for the bitmaps |
122 | * array of struct qfq_queue. |
123 | */ |
124 | enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE }; |
125 | |
126 | struct qfq_group; |
127 | |
128 | struct qfq_aggregate; |
129 | |
130 | struct qfq_class { |
131 | struct Qdisc_class_common common; |
132 | |
133 | struct gnet_stats_basic_sync bstats; |
134 | struct gnet_stats_queue qstats; |
135 | struct net_rate_estimator __rcu *rate_est; |
136 | struct Qdisc *qdisc; |
137 | struct list_head alist; /* Link for active-classes list. */ |
138 | struct qfq_aggregate *agg; /* Parent aggregate. */ |
139 | int deficit; /* DRR deficit counter. */ |
140 | }; |
141 | |
142 | struct qfq_aggregate { |
143 | struct hlist_node next; /* Link for the slot list. */ |
144 | u64 S, F; /* flow timestamps (exact) */ |
145 | |
146 | /* group we belong to. In principle we would need the index, |
147 | * which is log_2(lmax/weight), but we never reference it |
148 | * directly, only the group. |
149 | */ |
150 | struct qfq_group *grp; |
151 | |
152 | /* these are copied from the flowset. */ |
153 | u32 class_weight; /* Weight of each class in this aggregate. */ |
154 | /* Max pkt size for the classes in this aggregate, DRR quantum. */ |
155 | int lmax; |
156 | |
157 | u32 inv_w; /* ONE_FP/(sum of weights of classes in aggr.). */ |
158 | u32 budgetmax; /* Max budget for this aggregate. */ |
159 | u32 initial_budget, budget; /* Initial and current budget. */ |
160 | |
161 | int num_classes; /* Number of classes in this aggr. */ |
162 | struct list_head active; /* DRR queue of active classes. */ |
163 | |
164 | struct hlist_node nonfull_next; /* See nonfull_aggs in qfq_sched. */ |
165 | }; |
166 | |
167 | struct qfq_group { |
168 | u64 S, F; /* group timestamps (approx). */ |
169 | unsigned int slot_shift; /* Slot shift. */ |
170 | unsigned int index; /* Group index. */ |
171 | unsigned int front; /* Index of the front slot. */ |
172 | unsigned long full_slots; /* non-empty slots */ |
173 | |
174 | /* Array of RR lists of active aggregates. */ |
175 | struct hlist_head slots[QFQ_MAX_SLOTS]; |
176 | }; |
177 | |
178 | struct qfq_sched { |
179 | struct tcf_proto __rcu *filter_list; |
180 | struct tcf_block *block; |
181 | struct Qdisc_class_hash clhash; |
182 | |
183 | u64 oldV, V; /* Precise virtual times. */ |
184 | struct qfq_aggregate *in_serv_agg; /* Aggregate being served. */ |
185 | u32 wsum; /* weight sum */ |
186 | u32 iwsum; /* inverse weight sum */ |
187 | |
188 | unsigned long bitmaps[QFQ_MAX_STATE]; /* Group bitmaps. */ |
189 | struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */ |
190 | u32 min_slot_shift; /* Index of the group-0 bit in the bitmaps. */ |
191 | |
192 | u32 max_agg_classes; /* Max number of classes per aggr. */ |
193 | struct hlist_head nonfull_aggs; /* Aggs with room for more classes. */ |
194 | }; |
195 | |
196 | /* |
197 | * Possible reasons why the timestamps of an aggregate are updated |
198 | * enqueue: the aggregate switches from idle to active and must scheduled |
199 | * for service |
200 | * requeue: the aggregate finishes its budget, so it stops being served and |
201 | * must be rescheduled for service |
202 | */ |
203 | enum update_reason {enqueue, requeue}; |
204 | |
205 | static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid) |
206 | { |
207 | struct qfq_sched *q = qdisc_priv(sch); |
208 | struct Qdisc_class_common *clc; |
209 | |
210 | clc = qdisc_class_find(hash: &q->clhash, id: classid); |
211 | if (clc == NULL) |
212 | return NULL; |
213 | return container_of(clc, struct qfq_class, common); |
214 | } |
215 | |
216 | static const struct netlink_range_validation lmax_range = { |
217 | .min = QFQ_MIN_LMAX, |
218 | .max = QFQ_MAX_LMAX, |
219 | }; |
220 | |
221 | static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = { |
222 | [TCA_QFQ_WEIGHT] = NLA_POLICY_RANGE(NLA_U32, 1, QFQ_MAX_WEIGHT), |
223 | [TCA_QFQ_LMAX] = NLA_POLICY_FULL_RANGE(NLA_U32, &lmax_range), |
224 | }; |
225 | |
226 | /* |
227 | * Calculate a flow index, given its weight and maximum packet length. |
228 | * index = log_2(maxlen/weight) but we need to apply the scaling. |
229 | * This is used only once at flow creation. |
230 | */ |
231 | static int qfq_calc_index(u32 inv_w, unsigned int maxlen, u32 min_slot_shift) |
232 | { |
233 | u64 slot_size = (u64)maxlen * inv_w; |
234 | unsigned long size_map; |
235 | int index = 0; |
236 | |
237 | size_map = slot_size >> min_slot_shift; |
238 | if (!size_map) |
239 | goto out; |
240 | |
241 | index = __fls(word: size_map) + 1; /* basically a log_2 */ |
242 | index -= !(slot_size - (1ULL << (index + min_slot_shift - 1))); |
243 | |
244 | if (index < 0) |
245 | index = 0; |
246 | out: |
247 | pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n" , |
248 | (unsigned long) ONE_FP/inv_w, maxlen, index); |
249 | |
250 | return index; |
251 | } |
252 | |
253 | static void qfq_deactivate_agg(struct qfq_sched *, struct qfq_aggregate *); |
254 | static void qfq_activate_agg(struct qfq_sched *, struct qfq_aggregate *, |
255 | enum update_reason); |
256 | |
257 | static void qfq_init_agg(struct qfq_sched *q, struct qfq_aggregate *agg, |
258 | u32 lmax, u32 weight) |
259 | { |
260 | INIT_LIST_HEAD(list: &agg->active); |
261 | hlist_add_head(n: &agg->nonfull_next, h: &q->nonfull_aggs); |
262 | |
263 | agg->lmax = lmax; |
264 | agg->class_weight = weight; |
265 | } |
266 | |
267 | static struct qfq_aggregate *qfq_find_agg(struct qfq_sched *q, |
268 | u32 lmax, u32 weight) |
269 | { |
270 | struct qfq_aggregate *agg; |
271 | |
272 | hlist_for_each_entry(agg, &q->nonfull_aggs, nonfull_next) |
273 | if (agg->lmax == lmax && agg->class_weight == weight) |
274 | return agg; |
275 | |
276 | return NULL; |
277 | } |
278 | |
279 | |
280 | /* Update aggregate as a function of the new number of classes. */ |
281 | static void qfq_update_agg(struct qfq_sched *q, struct qfq_aggregate *agg, |
282 | int new_num_classes) |
283 | { |
284 | u32 new_agg_weight; |
285 | |
286 | if (new_num_classes == q->max_agg_classes) |
287 | hlist_del_init(n: &agg->nonfull_next); |
288 | |
289 | if (agg->num_classes > new_num_classes && |
290 | new_num_classes == q->max_agg_classes - 1) /* agg no more full */ |
291 | hlist_add_head(n: &agg->nonfull_next, h: &q->nonfull_aggs); |
292 | |
293 | /* The next assignment may let |
294 | * agg->initial_budget > agg->budgetmax |
295 | * hold, we will take it into account in charge_actual_service(). |
296 | */ |
297 | agg->budgetmax = new_num_classes * agg->lmax; |
298 | new_agg_weight = agg->class_weight * new_num_classes; |
299 | agg->inv_w = ONE_FP/new_agg_weight; |
300 | |
301 | if (agg->grp == NULL) { |
302 | int i = qfq_calc_index(inv_w: agg->inv_w, maxlen: agg->budgetmax, |
303 | min_slot_shift: q->min_slot_shift); |
304 | agg->grp = &q->groups[i]; |
305 | } |
306 | |
307 | q->wsum += |
308 | (int) agg->class_weight * (new_num_classes - agg->num_classes); |
309 | q->iwsum = ONE_FP / q->wsum; |
310 | |
311 | agg->num_classes = new_num_classes; |
312 | } |
313 | |
314 | /* Add class to aggregate. */ |
315 | static void qfq_add_to_agg(struct qfq_sched *q, |
316 | struct qfq_aggregate *agg, |
317 | struct qfq_class *cl) |
318 | { |
319 | cl->agg = agg; |
320 | |
321 | qfq_update_agg(q, agg, new_num_classes: agg->num_classes+1); |
322 | if (cl->qdisc->q.qlen > 0) { /* adding an active class */ |
323 | list_add_tail(new: &cl->alist, head: &agg->active); |
324 | if (list_first_entry(&agg->active, struct qfq_class, alist) == |
325 | cl && q->in_serv_agg != agg) /* agg was inactive */ |
326 | qfq_activate_agg(q, agg, enqueue); /* schedule agg */ |
327 | } |
328 | } |
329 | |
330 | static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *); |
331 | |
332 | static void qfq_destroy_agg(struct qfq_sched *q, struct qfq_aggregate *agg) |
333 | { |
334 | hlist_del_init(n: &agg->nonfull_next); |
335 | q->wsum -= agg->class_weight; |
336 | if (q->wsum != 0) |
337 | q->iwsum = ONE_FP / q->wsum; |
338 | |
339 | if (q->in_serv_agg == agg) |
340 | q->in_serv_agg = qfq_choose_next_agg(q); |
341 | kfree(objp: agg); |
342 | } |
343 | |
344 | /* Deschedule class from within its parent aggregate. */ |
345 | static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl) |
346 | { |
347 | struct qfq_aggregate *agg = cl->agg; |
348 | |
349 | |
350 | list_del(entry: &cl->alist); /* remove from RR queue of the aggregate */ |
351 | if (list_empty(head: &agg->active)) /* agg is now inactive */ |
352 | qfq_deactivate_agg(q, agg); |
353 | } |
354 | |
355 | /* Remove class from its parent aggregate. */ |
356 | static void qfq_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl) |
357 | { |
358 | struct qfq_aggregate *agg = cl->agg; |
359 | |
360 | cl->agg = NULL; |
361 | if (agg->num_classes == 1) { /* agg being emptied, destroy it */ |
362 | qfq_destroy_agg(q, agg); |
363 | return; |
364 | } |
365 | qfq_update_agg(q, agg, new_num_classes: agg->num_classes-1); |
366 | } |
367 | |
368 | /* Deschedule class and remove it from its parent aggregate. */ |
369 | static void qfq_deact_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl) |
370 | { |
371 | if (cl->qdisc->q.qlen > 0) /* class is active */ |
372 | qfq_deactivate_class(q, cl); |
373 | |
374 | qfq_rm_from_agg(q, cl); |
375 | } |
376 | |
377 | /* Move class to a new aggregate, matching the new class weight and/or lmax */ |
378 | static int qfq_change_agg(struct Qdisc *sch, struct qfq_class *cl, u32 weight, |
379 | u32 lmax) |
380 | { |
381 | struct qfq_sched *q = qdisc_priv(sch); |
382 | struct qfq_aggregate *new_agg; |
383 | |
384 | /* 'lmax' can range from [QFQ_MIN_LMAX, pktlen + stab overhead] */ |
385 | if (lmax > QFQ_MAX_LMAX) |
386 | return -EINVAL; |
387 | |
388 | new_agg = qfq_find_agg(q, lmax, weight); |
389 | if (new_agg == NULL) { /* create new aggregate */ |
390 | new_agg = kzalloc(size: sizeof(*new_agg), GFP_ATOMIC); |
391 | if (new_agg == NULL) |
392 | return -ENOBUFS; |
393 | qfq_init_agg(q, agg: new_agg, lmax, weight); |
394 | } |
395 | qfq_deact_rm_from_agg(q, cl); |
396 | qfq_add_to_agg(q, agg: new_agg, cl); |
397 | |
398 | return 0; |
399 | } |
400 | |
401 | static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, |
402 | struct nlattr **tca, unsigned long *arg, |
403 | struct netlink_ext_ack *extack) |
404 | { |
405 | struct qfq_sched *q = qdisc_priv(sch); |
406 | struct qfq_class *cl = (struct qfq_class *)*arg; |
407 | bool existing = false; |
408 | struct nlattr *tb[TCA_QFQ_MAX + 1]; |
409 | struct qfq_aggregate *new_agg = NULL; |
410 | u32 weight, lmax, inv_w; |
411 | int err; |
412 | int delta_w; |
413 | |
414 | if (NL_REQ_ATTR_CHECK(extack, NULL, tca, TCA_OPTIONS)) { |
415 | NL_SET_ERR_MSG_MOD(extack, "missing options" ); |
416 | return -EINVAL; |
417 | } |
418 | |
419 | err = nla_parse_nested_deprecated(tb, TCA_QFQ_MAX, nla: tca[TCA_OPTIONS], |
420 | policy: qfq_policy, extack); |
421 | if (err < 0) |
422 | return err; |
423 | |
424 | if (tb[TCA_QFQ_WEIGHT]) |
425 | weight = nla_get_u32(nla: tb[TCA_QFQ_WEIGHT]); |
426 | else |
427 | weight = 1; |
428 | |
429 | if (tb[TCA_QFQ_LMAX]) { |
430 | lmax = nla_get_u32(nla: tb[TCA_QFQ_LMAX]); |
431 | } else { |
432 | /* MTU size is user controlled */ |
433 | lmax = psched_mtu(dev: qdisc_dev(qdisc: sch)); |
434 | if (lmax < QFQ_MIN_LMAX || lmax > QFQ_MAX_LMAX) { |
435 | NL_SET_ERR_MSG_MOD(extack, |
436 | "MTU size out of bounds for qfq" ); |
437 | return -EINVAL; |
438 | } |
439 | } |
440 | |
441 | inv_w = ONE_FP / weight; |
442 | weight = ONE_FP / inv_w; |
443 | |
444 | if (cl != NULL && |
445 | lmax == cl->agg->lmax && |
446 | weight == cl->agg->class_weight) |
447 | return 0; /* nothing to change */ |
448 | |
449 | delta_w = weight - (cl ? cl->agg->class_weight : 0); |
450 | |
451 | if (q->wsum + delta_w > QFQ_MAX_WSUM) { |
452 | NL_SET_ERR_MSG_FMT_MOD(extack, |
453 | "total weight out of range (%d + %u)\n" , |
454 | delta_w, q->wsum); |
455 | return -EINVAL; |
456 | } |
457 | |
458 | if (cl != NULL) { /* modify existing class */ |
459 | if (tca[TCA_RATE]) { |
460 | err = gen_replace_estimator(bstats: &cl->bstats, NULL, |
461 | ptr: &cl->rate_est, |
462 | NULL, |
463 | running: true, |
464 | opt: tca[TCA_RATE]); |
465 | if (err) |
466 | return err; |
467 | } |
468 | existing = true; |
469 | goto set_change_agg; |
470 | } |
471 | |
472 | /* create and init new class */ |
473 | cl = kzalloc(size: sizeof(struct qfq_class), GFP_KERNEL); |
474 | if (cl == NULL) |
475 | return -ENOBUFS; |
476 | |
477 | gnet_stats_basic_sync_init(b: &cl->bstats); |
478 | cl->common.classid = classid; |
479 | cl->deficit = lmax; |
480 | |
481 | cl->qdisc = qdisc_create_dflt(dev_queue: sch->dev_queue, ops: &pfifo_qdisc_ops, |
482 | parentid: classid, NULL); |
483 | if (cl->qdisc == NULL) |
484 | cl->qdisc = &noop_qdisc; |
485 | |
486 | if (tca[TCA_RATE]) { |
487 | err = gen_new_estimator(bstats: &cl->bstats, NULL, |
488 | rate_est: &cl->rate_est, |
489 | NULL, |
490 | running: true, |
491 | opt: tca[TCA_RATE]); |
492 | if (err) |
493 | goto destroy_class; |
494 | } |
495 | |
496 | if (cl->qdisc != &noop_qdisc) |
497 | qdisc_hash_add(q: cl->qdisc, invisible: true); |
498 | |
499 | set_change_agg: |
500 | sch_tree_lock(q: sch); |
501 | new_agg = qfq_find_agg(q, lmax, weight); |
502 | if (new_agg == NULL) { /* create new aggregate */ |
503 | sch_tree_unlock(q: sch); |
504 | new_agg = kzalloc(size: sizeof(*new_agg), GFP_KERNEL); |
505 | if (new_agg == NULL) { |
506 | err = -ENOBUFS; |
507 | gen_kill_estimator(ptr: &cl->rate_est); |
508 | goto destroy_class; |
509 | } |
510 | sch_tree_lock(q: sch); |
511 | qfq_init_agg(q, agg: new_agg, lmax, weight); |
512 | } |
513 | if (existing) |
514 | qfq_deact_rm_from_agg(q, cl); |
515 | else |
516 | qdisc_class_hash_insert(&q->clhash, &cl->common); |
517 | qfq_add_to_agg(q, agg: new_agg, cl); |
518 | sch_tree_unlock(q: sch); |
519 | qdisc_class_hash_grow(sch, &q->clhash); |
520 | |
521 | *arg = (unsigned long)cl; |
522 | return 0; |
523 | |
524 | destroy_class: |
525 | qdisc_put(qdisc: cl->qdisc); |
526 | kfree(objp: cl); |
527 | return err; |
528 | } |
529 | |
530 | static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl) |
531 | { |
532 | struct qfq_sched *q = qdisc_priv(sch); |
533 | |
534 | qfq_rm_from_agg(q, cl); |
535 | gen_kill_estimator(ptr: &cl->rate_est); |
536 | qdisc_put(qdisc: cl->qdisc); |
537 | kfree(objp: cl); |
538 | } |
539 | |
540 | static int qfq_delete_class(struct Qdisc *sch, unsigned long arg, |
541 | struct netlink_ext_ack *extack) |
542 | { |
543 | struct qfq_sched *q = qdisc_priv(sch); |
544 | struct qfq_class *cl = (struct qfq_class *)arg; |
545 | |
546 | if (qdisc_class_in_use(cl: &cl->common)) { |
547 | NL_SET_ERR_MSG_MOD(extack, "QFQ class in use" ); |
548 | return -EBUSY; |
549 | } |
550 | |
551 | sch_tree_lock(q: sch); |
552 | |
553 | qdisc_purge_queue(sch: cl->qdisc); |
554 | qdisc_class_hash_remove(&q->clhash, &cl->common); |
555 | |
556 | sch_tree_unlock(q: sch); |
557 | |
558 | qfq_destroy_class(sch, cl); |
559 | return 0; |
560 | } |
561 | |
562 | static unsigned long qfq_search_class(struct Qdisc *sch, u32 classid) |
563 | { |
564 | return (unsigned long)qfq_find_class(sch, classid); |
565 | } |
566 | |
567 | static struct tcf_block *qfq_tcf_block(struct Qdisc *sch, unsigned long cl, |
568 | struct netlink_ext_ack *extack) |
569 | { |
570 | struct qfq_sched *q = qdisc_priv(sch); |
571 | |
572 | if (cl) |
573 | return NULL; |
574 | |
575 | return q->block; |
576 | } |
577 | |
578 | static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent, |
579 | u32 classid) |
580 | { |
581 | struct qfq_class *cl = qfq_find_class(sch, classid); |
582 | |
583 | if (cl) |
584 | qdisc_class_get(cl: &cl->common); |
585 | |
586 | return (unsigned long)cl; |
587 | } |
588 | |
589 | static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg) |
590 | { |
591 | struct qfq_class *cl = (struct qfq_class *)arg; |
592 | |
593 | qdisc_class_put(cl: &cl->common); |
594 | } |
595 | |
596 | static int qfq_graft_class(struct Qdisc *sch, unsigned long arg, |
597 | struct Qdisc *new, struct Qdisc **old, |
598 | struct netlink_ext_ack *extack) |
599 | { |
600 | struct qfq_class *cl = (struct qfq_class *)arg; |
601 | |
602 | if (new == NULL) { |
603 | new = qdisc_create_dflt(dev_queue: sch->dev_queue, ops: &pfifo_qdisc_ops, |
604 | parentid: cl->common.classid, NULL); |
605 | if (new == NULL) |
606 | new = &noop_qdisc; |
607 | } |
608 | |
609 | *old = qdisc_replace(sch, new, pold: &cl->qdisc); |
610 | return 0; |
611 | } |
612 | |
613 | static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg) |
614 | { |
615 | struct qfq_class *cl = (struct qfq_class *)arg; |
616 | |
617 | return cl->qdisc; |
618 | } |
619 | |
620 | static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, |
621 | struct sk_buff *skb, struct tcmsg *tcm) |
622 | { |
623 | struct qfq_class *cl = (struct qfq_class *)arg; |
624 | struct nlattr *nest; |
625 | |
626 | tcm->tcm_parent = TC_H_ROOT; |
627 | tcm->tcm_handle = cl->common.classid; |
628 | tcm->tcm_info = cl->qdisc->handle; |
629 | |
630 | nest = nla_nest_start_noflag(skb, attrtype: TCA_OPTIONS); |
631 | if (nest == NULL) |
632 | goto nla_put_failure; |
633 | if (nla_put_u32(skb, attrtype: TCA_QFQ_WEIGHT, value: cl->agg->class_weight) || |
634 | nla_put_u32(skb, attrtype: TCA_QFQ_LMAX, value: cl->agg->lmax)) |
635 | goto nla_put_failure; |
636 | return nla_nest_end(skb, start: nest); |
637 | |
638 | nla_put_failure: |
639 | nla_nest_cancel(skb, start: nest); |
640 | return -EMSGSIZE; |
641 | } |
642 | |
643 | static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg, |
644 | struct gnet_dump *d) |
645 | { |
646 | struct qfq_class *cl = (struct qfq_class *)arg; |
647 | struct tc_qfq_stats xstats; |
648 | |
649 | memset(&xstats, 0, sizeof(xstats)); |
650 | |
651 | xstats.weight = cl->agg->class_weight; |
652 | xstats.lmax = cl->agg->lmax; |
653 | |
654 | if (gnet_stats_copy_basic(d, NULL, b: &cl->bstats, running: true) < 0 || |
655 | gnet_stats_copy_rate_est(d, ptr: &cl->rate_est) < 0 || |
656 | qdisc_qstats_copy(d, sch: cl->qdisc) < 0) |
657 | return -1; |
658 | |
659 | return gnet_stats_copy_app(d, st: &xstats, len: sizeof(xstats)); |
660 | } |
661 | |
662 | static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg) |
663 | { |
664 | struct qfq_sched *q = qdisc_priv(sch); |
665 | struct qfq_class *cl; |
666 | unsigned int i; |
667 | |
668 | if (arg->stop) |
669 | return; |
670 | |
671 | for (i = 0; i < q->clhash.hashsize; i++) { |
672 | hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { |
673 | if (!tc_qdisc_stats_dump(sch, cl: (unsigned long)cl, arg)) |
674 | return; |
675 | } |
676 | } |
677 | } |
678 | |
679 | static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch, |
680 | int *qerr) |
681 | { |
682 | struct qfq_sched *q = qdisc_priv(sch); |
683 | struct qfq_class *cl; |
684 | struct tcf_result res; |
685 | struct tcf_proto *fl; |
686 | int result; |
687 | |
688 | if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) { |
689 | pr_debug("qfq_classify: found %d\n" , skb->priority); |
690 | cl = qfq_find_class(sch, classid: skb->priority); |
691 | if (cl != NULL) |
692 | return cl; |
693 | } |
694 | |
695 | *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; |
696 | fl = rcu_dereference_bh(q->filter_list); |
697 | result = tcf_classify(skb, NULL, tp: fl, res: &res, compat_mode: false); |
698 | if (result >= 0) { |
699 | #ifdef CONFIG_NET_CLS_ACT |
700 | switch (result) { |
701 | case TC_ACT_QUEUED: |
702 | case TC_ACT_STOLEN: |
703 | case TC_ACT_TRAP: |
704 | *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; |
705 | fallthrough; |
706 | case TC_ACT_SHOT: |
707 | return NULL; |
708 | } |
709 | #endif |
710 | cl = (struct qfq_class *)res.class; |
711 | if (cl == NULL) |
712 | cl = qfq_find_class(sch, classid: res.classid); |
713 | return cl; |
714 | } |
715 | |
716 | return NULL; |
717 | } |
718 | |
719 | /* Generic comparison function, handling wraparound. */ |
720 | static inline int qfq_gt(u64 a, u64 b) |
721 | { |
722 | return (s64)(a - b) > 0; |
723 | } |
724 | |
725 | /* Round a precise timestamp to its slotted value. */ |
726 | static inline u64 qfq_round_down(u64 ts, unsigned int shift) |
727 | { |
728 | return ts & ~((1ULL << shift) - 1); |
729 | } |
730 | |
731 | /* return the pointer to the group with lowest index in the bitmap */ |
732 | static inline struct qfq_group *qfq_ffs(struct qfq_sched *q, |
733 | unsigned long bitmap) |
734 | { |
735 | int index = __ffs(bitmap); |
736 | return &q->groups[index]; |
737 | } |
738 | /* Calculate a mask to mimic what would be ffs_from(). */ |
739 | static inline unsigned long mask_from(unsigned long bitmap, int from) |
740 | { |
741 | return bitmap & ~((1UL << from) - 1); |
742 | } |
743 | |
744 | /* |
745 | * The state computation relies on ER=0, IR=1, EB=2, IB=3 |
746 | * First compute eligibility comparing grp->S, q->V, |
747 | * then check if someone is blocking us and possibly add EB |
748 | */ |
749 | static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp) |
750 | { |
751 | /* if S > V we are not eligible */ |
752 | unsigned int state = qfq_gt(a: grp->S, b: q->V); |
753 | unsigned long mask = mask_from(bitmap: q->bitmaps[ER], from: grp->index); |
754 | struct qfq_group *next; |
755 | |
756 | if (mask) { |
757 | next = qfq_ffs(q, bitmap: mask); |
758 | if (qfq_gt(a: grp->F, b: next->F)) |
759 | state |= EB; |
760 | } |
761 | |
762 | return state; |
763 | } |
764 | |
765 | |
766 | /* |
767 | * In principle |
768 | * q->bitmaps[dst] |= q->bitmaps[src] & mask; |
769 | * q->bitmaps[src] &= ~mask; |
770 | * but we should make sure that src != dst |
771 | */ |
772 | static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask, |
773 | int src, int dst) |
774 | { |
775 | q->bitmaps[dst] |= q->bitmaps[src] & mask; |
776 | q->bitmaps[src] &= ~mask; |
777 | } |
778 | |
779 | static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F) |
780 | { |
781 | unsigned long mask = mask_from(bitmap: q->bitmaps[ER], from: index + 1); |
782 | struct qfq_group *next; |
783 | |
784 | if (mask) { |
785 | next = qfq_ffs(q, bitmap: mask); |
786 | if (!qfq_gt(a: next->F, b: old_F)) |
787 | return; |
788 | } |
789 | |
790 | mask = (1UL << index) - 1; |
791 | qfq_move_groups(q, mask, src: EB, dst: ER); |
792 | qfq_move_groups(q, mask, src: IB, dst: IR); |
793 | } |
794 | |
795 | /* |
796 | * perhaps |
797 | * |
798 | old_V ^= q->V; |
799 | old_V >>= q->min_slot_shift; |
800 | if (old_V) { |
801 | ... |
802 | } |
803 | * |
804 | */ |
805 | static void qfq_make_eligible(struct qfq_sched *q) |
806 | { |
807 | unsigned long vslot = q->V >> q->min_slot_shift; |
808 | unsigned long old_vslot = q->oldV >> q->min_slot_shift; |
809 | |
810 | if (vslot != old_vslot) { |
811 | unsigned long mask; |
812 | int last_flip_pos = fls(x: vslot ^ old_vslot); |
813 | |
814 | if (last_flip_pos > 31) /* higher than the number of groups */ |
815 | mask = ~0UL; /* make all groups eligible */ |
816 | else |
817 | mask = (1UL << last_flip_pos) - 1; |
818 | |
819 | qfq_move_groups(q, mask, src: IR, dst: ER); |
820 | qfq_move_groups(q, mask, src: IB, dst: EB); |
821 | } |
822 | } |
823 | |
824 | /* |
825 | * The index of the slot in which the input aggregate agg is to be |
826 | * inserted must not be higher than QFQ_MAX_SLOTS-2. There is a '-2' |
827 | * and not a '-1' because the start time of the group may be moved |
828 | * backward by one slot after the aggregate has been inserted, and |
829 | * this would cause non-empty slots to be right-shifted by one |
830 | * position. |
831 | * |
832 | * QFQ+ fully satisfies this bound to the slot index if the parameters |
833 | * of the classes are not changed dynamically, and if QFQ+ never |
834 | * happens to postpone the service of agg unjustly, i.e., it never |
835 | * happens that the aggregate becomes backlogged and eligible, or just |
836 | * eligible, while an aggregate with a higher approximated finish time |
837 | * is being served. In particular, in this case QFQ+ guarantees that |
838 | * the timestamps of agg are low enough that the slot index is never |
839 | * higher than 2. Unfortunately, QFQ+ cannot provide the same |
840 | * guarantee if it happens to unjustly postpone the service of agg, or |
841 | * if the parameters of some class are changed. |
842 | * |
843 | * As for the first event, i.e., an out-of-order service, the |
844 | * upper bound to the slot index guaranteed by QFQ+ grows to |
845 | * 2 + |
846 | * QFQ_MAX_AGG_CLASSES * ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) * |
847 | * (current_max_weight/current_wsum) <= 2 + 8 * 128 * 1. |
848 | * |
849 | * The following function deals with this problem by backward-shifting |
850 | * the timestamps of agg, if needed, so as to guarantee that the slot |
851 | * index is never higher than QFQ_MAX_SLOTS-2. This backward-shift may |
852 | * cause the service of other aggregates to be postponed, yet the |
853 | * worst-case guarantees of these aggregates are not violated. In |
854 | * fact, in case of no out-of-order service, the timestamps of agg |
855 | * would have been even lower than they are after the backward shift, |
856 | * because QFQ+ would have guaranteed a maximum value equal to 2 for |
857 | * the slot index, and 2 < QFQ_MAX_SLOTS-2. Hence the aggregates whose |
858 | * service is postponed because of the backward-shift would have |
859 | * however waited for the service of agg before being served. |
860 | * |
861 | * The other event that may cause the slot index to be higher than 2 |
862 | * for agg is a recent change of the parameters of some class. If the |
863 | * weight of a class is increased or the lmax (max_pkt_size) of the |
864 | * class is decreased, then a new aggregate with smaller slot size |
865 | * than the original parent aggregate of the class may happen to be |
866 | * activated. The activation of this aggregate should be properly |
867 | * delayed to when the service of the class has finished in the ideal |
868 | * system tracked by QFQ+. If the activation of the aggregate is not |
869 | * delayed to this reference time instant, then this aggregate may be |
870 | * unjustly served before other aggregates waiting for service. This |
871 | * may cause the above bound to the slot index to be violated for some |
872 | * of these unlucky aggregates. |
873 | * |
874 | * Instead of delaying the activation of the new aggregate, which is |
875 | * quite complex, the above-discussed capping of the slot index is |
876 | * used to handle also the consequences of a change of the parameters |
877 | * of a class. |
878 | */ |
879 | static void qfq_slot_insert(struct qfq_group *grp, struct qfq_aggregate *agg, |
880 | u64 roundedS) |
881 | { |
882 | u64 slot = (roundedS - grp->S) >> grp->slot_shift; |
883 | unsigned int i; /* slot index in the bucket list */ |
884 | |
885 | if (unlikely(slot > QFQ_MAX_SLOTS - 2)) { |
886 | u64 deltaS = roundedS - grp->S - |
887 | ((u64)(QFQ_MAX_SLOTS - 2)<<grp->slot_shift); |
888 | agg->S -= deltaS; |
889 | agg->F -= deltaS; |
890 | slot = QFQ_MAX_SLOTS - 2; |
891 | } |
892 | |
893 | i = (grp->front + slot) % QFQ_MAX_SLOTS; |
894 | |
895 | hlist_add_head(n: &agg->next, h: &grp->slots[i]); |
896 | __set_bit(slot, &grp->full_slots); |
897 | } |
898 | |
899 | /* Maybe introduce hlist_first_entry?? */ |
900 | static struct qfq_aggregate *qfq_slot_head(struct qfq_group *grp) |
901 | { |
902 | return hlist_entry(grp->slots[grp->front].first, |
903 | struct qfq_aggregate, next); |
904 | } |
905 | |
906 | /* |
907 | * remove the entry from the slot |
908 | */ |
909 | static void qfq_front_slot_remove(struct qfq_group *grp) |
910 | { |
911 | struct qfq_aggregate *agg = qfq_slot_head(grp); |
912 | |
913 | BUG_ON(!agg); |
914 | hlist_del(n: &agg->next); |
915 | if (hlist_empty(h: &grp->slots[grp->front])) |
916 | __clear_bit(0, &grp->full_slots); |
917 | } |
918 | |
919 | /* |
920 | * Returns the first aggregate in the first non-empty bucket of the |
921 | * group. As a side effect, adjusts the bucket list so the first |
922 | * non-empty bucket is at position 0 in full_slots. |
923 | */ |
924 | static struct qfq_aggregate *qfq_slot_scan(struct qfq_group *grp) |
925 | { |
926 | unsigned int i; |
927 | |
928 | pr_debug("qfq slot_scan: grp %u full %#lx\n" , |
929 | grp->index, grp->full_slots); |
930 | |
931 | if (grp->full_slots == 0) |
932 | return NULL; |
933 | |
934 | i = __ffs(grp->full_slots); /* zero based */ |
935 | if (i > 0) { |
936 | grp->front = (grp->front + i) % QFQ_MAX_SLOTS; |
937 | grp->full_slots >>= i; |
938 | } |
939 | |
940 | return qfq_slot_head(grp); |
941 | } |
942 | |
943 | /* |
944 | * adjust the bucket list. When the start time of a group decreases, |
945 | * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to |
946 | * move the objects. The mask of occupied slots must be shifted |
947 | * because we use ffs() to find the first non-empty slot. |
948 | * This covers decreases in the group's start time, but what about |
949 | * increases of the start time ? |
950 | * Here too we should make sure that i is less than 32 |
951 | */ |
952 | static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS) |
953 | { |
954 | unsigned int i = (grp->S - roundedS) >> grp->slot_shift; |
955 | |
956 | grp->full_slots <<= i; |
957 | grp->front = (grp->front - i) % QFQ_MAX_SLOTS; |
958 | } |
959 | |
960 | static void qfq_update_eligible(struct qfq_sched *q) |
961 | { |
962 | struct qfq_group *grp; |
963 | unsigned long ineligible; |
964 | |
965 | ineligible = q->bitmaps[IR] | q->bitmaps[IB]; |
966 | if (ineligible) { |
967 | if (!q->bitmaps[ER]) { |
968 | grp = qfq_ffs(q, bitmap: ineligible); |
969 | if (qfq_gt(a: grp->S, b: q->V)) |
970 | q->V = grp->S; |
971 | } |
972 | qfq_make_eligible(q); |
973 | } |
974 | } |
975 | |
976 | /* Dequeue head packet of the head class in the DRR queue of the aggregate. */ |
977 | static struct sk_buff *agg_dequeue(struct qfq_aggregate *agg, |
978 | struct qfq_class *cl, unsigned int len) |
979 | { |
980 | struct sk_buff *skb = qdisc_dequeue_peeked(sch: cl->qdisc); |
981 | |
982 | if (!skb) |
983 | return NULL; |
984 | |
985 | cl->deficit -= (int) len; |
986 | |
987 | if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */ |
988 | list_del(entry: &cl->alist); |
989 | else if (cl->deficit < qdisc_pkt_len(skb: cl->qdisc->ops->peek(cl->qdisc))) { |
990 | cl->deficit += agg->lmax; |
991 | list_move_tail(list: &cl->alist, head: &agg->active); |
992 | } |
993 | |
994 | return skb; |
995 | } |
996 | |
997 | static inline struct sk_buff *qfq_peek_skb(struct qfq_aggregate *agg, |
998 | struct qfq_class **cl, |
999 | unsigned int *len) |
1000 | { |
1001 | struct sk_buff *skb; |
1002 | |
1003 | *cl = list_first_entry(&agg->active, struct qfq_class, alist); |
1004 | skb = (*cl)->qdisc->ops->peek((*cl)->qdisc); |
1005 | if (skb == NULL) |
1006 | qdisc_warn_nonwc(txt: "qfq_dequeue" , qdisc: (*cl)->qdisc); |
1007 | else |
1008 | *len = qdisc_pkt_len(skb); |
1009 | |
1010 | return skb; |
1011 | } |
1012 | |
1013 | /* Update F according to the actual service received by the aggregate. */ |
1014 | static inline void charge_actual_service(struct qfq_aggregate *agg) |
1015 | { |
1016 | /* Compute the service received by the aggregate, taking into |
1017 | * account that, after decreasing the number of classes in |
1018 | * agg, it may happen that |
1019 | * agg->initial_budget - agg->budget > agg->bugdetmax |
1020 | */ |
1021 | u32 service_received = min(agg->budgetmax, |
1022 | agg->initial_budget - agg->budget); |
1023 | |
1024 | agg->F = agg->S + (u64)service_received * agg->inv_w; |
1025 | } |
1026 | |
1027 | /* Assign a reasonable start time for a new aggregate in group i. |
1028 | * Admissible values for \hat(F) are multiples of \sigma_i |
1029 | * no greater than V+\sigma_i . Larger values mean that |
1030 | * we had a wraparound so we consider the timestamp to be stale. |
1031 | * |
1032 | * If F is not stale and F >= V then we set S = F. |
1033 | * Otherwise we should assign S = V, but this may violate |
1034 | * the ordering in EB (see [2]). So, if we have groups in ER, |
1035 | * set S to the F_j of the first group j which would be blocking us. |
1036 | * We are guaranteed not to move S backward because |
1037 | * otherwise our group i would still be blocked. |
1038 | */ |
1039 | static void qfq_update_start(struct qfq_sched *q, struct qfq_aggregate *agg) |
1040 | { |
1041 | unsigned long mask; |
1042 | u64 limit, roundedF; |
1043 | int slot_shift = agg->grp->slot_shift; |
1044 | |
1045 | roundedF = qfq_round_down(ts: agg->F, shift: slot_shift); |
1046 | limit = qfq_round_down(ts: q->V, shift: slot_shift) + (1ULL << slot_shift); |
1047 | |
1048 | if (!qfq_gt(a: agg->F, b: q->V) || qfq_gt(a: roundedF, b: limit)) { |
1049 | /* timestamp was stale */ |
1050 | mask = mask_from(bitmap: q->bitmaps[ER], from: agg->grp->index); |
1051 | if (mask) { |
1052 | struct qfq_group *next = qfq_ffs(q, bitmap: mask); |
1053 | if (qfq_gt(a: roundedF, b: next->F)) { |
1054 | if (qfq_gt(a: limit, b: next->F)) |
1055 | agg->S = next->F; |
1056 | else /* preserve timestamp correctness */ |
1057 | agg->S = limit; |
1058 | return; |
1059 | } |
1060 | } |
1061 | agg->S = q->V; |
1062 | } else /* timestamp is not stale */ |
1063 | agg->S = agg->F; |
1064 | } |
1065 | |
1066 | /* Update the timestamps of agg before scheduling/rescheduling it for |
1067 | * service. In particular, assign to agg->F its maximum possible |
1068 | * value, i.e., the virtual finish time with which the aggregate |
1069 | * should be labeled if it used all its budget once in service. |
1070 | */ |
1071 | static inline void |
1072 | qfq_update_agg_ts(struct qfq_sched *q, |
1073 | struct qfq_aggregate *agg, enum update_reason reason) |
1074 | { |
1075 | if (reason != requeue) |
1076 | qfq_update_start(q, agg); |
1077 | else /* just charge agg for the service received */ |
1078 | agg->S = agg->F; |
1079 | |
1080 | agg->F = agg->S + (u64)agg->budgetmax * agg->inv_w; |
1081 | } |
1082 | |
1083 | static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg); |
1084 | |
1085 | static struct sk_buff *qfq_dequeue(struct Qdisc *sch) |
1086 | { |
1087 | struct qfq_sched *q = qdisc_priv(sch); |
1088 | struct qfq_aggregate *in_serv_agg = q->in_serv_agg; |
1089 | struct qfq_class *cl; |
1090 | struct sk_buff *skb = NULL; |
1091 | /* next-packet len, 0 means no more active classes in in-service agg */ |
1092 | unsigned int len = 0; |
1093 | |
1094 | if (in_serv_agg == NULL) |
1095 | return NULL; |
1096 | |
1097 | if (!list_empty(head: &in_serv_agg->active)) |
1098 | skb = qfq_peek_skb(agg: in_serv_agg, cl: &cl, len: &len); |
1099 | |
1100 | /* |
1101 | * If there are no active classes in the in-service aggregate, |
1102 | * or if the aggregate has not enough budget to serve its next |
1103 | * class, then choose the next aggregate to serve. |
1104 | */ |
1105 | if (len == 0 || in_serv_agg->budget < len) { |
1106 | charge_actual_service(agg: in_serv_agg); |
1107 | |
1108 | /* recharge the budget of the aggregate */ |
1109 | in_serv_agg->initial_budget = in_serv_agg->budget = |
1110 | in_serv_agg->budgetmax; |
1111 | |
1112 | if (!list_empty(head: &in_serv_agg->active)) { |
1113 | /* |
1114 | * Still active: reschedule for |
1115 | * service. Possible optimization: if no other |
1116 | * aggregate is active, then there is no point |
1117 | * in rescheduling this aggregate, and we can |
1118 | * just keep it as the in-service one. This |
1119 | * should be however a corner case, and to |
1120 | * handle it, we would need to maintain an |
1121 | * extra num_active_aggs field. |
1122 | */ |
1123 | qfq_update_agg_ts(q, agg: in_serv_agg, reason: requeue); |
1124 | qfq_schedule_agg(q, agg: in_serv_agg); |
1125 | } else if (sch->q.qlen == 0) { /* no aggregate to serve */ |
1126 | q->in_serv_agg = NULL; |
1127 | return NULL; |
1128 | } |
1129 | |
1130 | /* |
1131 | * If we get here, there are other aggregates queued: |
1132 | * choose the new aggregate to serve. |
1133 | */ |
1134 | in_serv_agg = q->in_serv_agg = qfq_choose_next_agg(q); |
1135 | skb = qfq_peek_skb(agg: in_serv_agg, cl: &cl, len: &len); |
1136 | } |
1137 | if (!skb) |
1138 | return NULL; |
1139 | |
1140 | sch->q.qlen--; |
1141 | |
1142 | skb = agg_dequeue(agg: in_serv_agg, cl, len); |
1143 | |
1144 | if (!skb) { |
1145 | sch->q.qlen++; |
1146 | return NULL; |
1147 | } |
1148 | |
1149 | qdisc_qstats_backlog_dec(sch, skb); |
1150 | qdisc_bstats_update(sch, skb); |
1151 | |
1152 | /* If lmax is lowered, through qfq_change_class, for a class |
1153 | * owning pending packets with larger size than the new value |
1154 | * of lmax, then the following condition may hold. |
1155 | */ |
1156 | if (unlikely(in_serv_agg->budget < len)) |
1157 | in_serv_agg->budget = 0; |
1158 | else |
1159 | in_serv_agg->budget -= len; |
1160 | |
1161 | q->V += (u64)len * q->iwsum; |
1162 | pr_debug("qfq dequeue: len %u F %lld now %lld\n" , |
1163 | len, (unsigned long long) in_serv_agg->F, |
1164 | (unsigned long long) q->V); |
1165 | |
1166 | return skb; |
1167 | } |
1168 | |
1169 | static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q) |
1170 | { |
1171 | struct qfq_group *grp; |
1172 | struct qfq_aggregate *agg, *new_front_agg; |
1173 | u64 old_F; |
1174 | |
1175 | qfq_update_eligible(q); |
1176 | q->oldV = q->V; |
1177 | |
1178 | if (!q->bitmaps[ER]) |
1179 | return NULL; |
1180 | |
1181 | grp = qfq_ffs(q, bitmap: q->bitmaps[ER]); |
1182 | old_F = grp->F; |
1183 | |
1184 | agg = qfq_slot_head(grp); |
1185 | |
1186 | /* agg starts to be served, remove it from schedule */ |
1187 | qfq_front_slot_remove(grp); |
1188 | |
1189 | new_front_agg = qfq_slot_scan(grp); |
1190 | |
1191 | if (new_front_agg == NULL) /* group is now inactive, remove from ER */ |
1192 | __clear_bit(grp->index, &q->bitmaps[ER]); |
1193 | else { |
1194 | u64 roundedS = qfq_round_down(ts: new_front_agg->S, |
1195 | shift: grp->slot_shift); |
1196 | unsigned int s; |
1197 | |
1198 | if (grp->S == roundedS) |
1199 | return agg; |
1200 | grp->S = roundedS; |
1201 | grp->F = roundedS + (2ULL << grp->slot_shift); |
1202 | __clear_bit(grp->index, &q->bitmaps[ER]); |
1203 | s = qfq_calc_state(q, grp); |
1204 | __set_bit(grp->index, &q->bitmaps[s]); |
1205 | } |
1206 | |
1207 | qfq_unblock_groups(q, index: grp->index, old_F); |
1208 | |
1209 | return agg; |
1210 | } |
1211 | |
1212 | static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, |
1213 | struct sk_buff **to_free) |
1214 | { |
1215 | unsigned int len = qdisc_pkt_len(skb), gso_segs; |
1216 | struct qfq_sched *q = qdisc_priv(sch); |
1217 | struct qfq_class *cl; |
1218 | struct qfq_aggregate *agg; |
1219 | int err = 0; |
1220 | bool first; |
1221 | |
1222 | cl = qfq_classify(skb, sch, qerr: &err); |
1223 | if (cl == NULL) { |
1224 | if (err & __NET_XMIT_BYPASS) |
1225 | qdisc_qstats_drop(sch); |
1226 | __qdisc_drop(skb, to_free); |
1227 | return err; |
1228 | } |
1229 | pr_debug("qfq_enqueue: cl = %x\n" , cl->common.classid); |
1230 | |
1231 | if (unlikely(cl->agg->lmax < len)) { |
1232 | pr_debug("qfq: increasing maxpkt from %u to %u for class %u" , |
1233 | cl->agg->lmax, len, cl->common.classid); |
1234 | err = qfq_change_agg(sch, cl, weight: cl->agg->class_weight, lmax: len); |
1235 | if (err) { |
1236 | cl->qstats.drops++; |
1237 | return qdisc_drop(skb, sch, to_free); |
1238 | } |
1239 | } |
1240 | |
1241 | gso_segs = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1; |
1242 | first = !cl->qdisc->q.qlen; |
1243 | err = qdisc_enqueue(skb, sch: cl->qdisc, to_free); |
1244 | if (unlikely(err != NET_XMIT_SUCCESS)) { |
1245 | pr_debug("qfq_enqueue: enqueue failed %d\n" , err); |
1246 | if (net_xmit_drop_count(err)) { |
1247 | cl->qstats.drops++; |
1248 | qdisc_qstats_drop(sch); |
1249 | } |
1250 | return err; |
1251 | } |
1252 | |
1253 | _bstats_update(bstats: &cl->bstats, bytes: len, packets: gso_segs); |
1254 | sch->qstats.backlog += len; |
1255 | ++sch->q.qlen; |
1256 | |
1257 | agg = cl->agg; |
1258 | /* if the queue was not empty, then done here */ |
1259 | if (!first) { |
1260 | if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) && |
1261 | list_first_entry(&agg->active, struct qfq_class, alist) |
1262 | == cl && cl->deficit < len) |
1263 | list_move_tail(list: &cl->alist, head: &agg->active); |
1264 | |
1265 | return err; |
1266 | } |
1267 | |
1268 | /* schedule class for service within the aggregate */ |
1269 | cl->deficit = agg->lmax; |
1270 | list_add_tail(new: &cl->alist, head: &agg->active); |
1271 | |
1272 | if (list_first_entry(&agg->active, struct qfq_class, alist) != cl || |
1273 | q->in_serv_agg == agg) |
1274 | return err; /* non-empty or in service, nothing else to do */ |
1275 | |
1276 | qfq_activate_agg(q, agg, enqueue); |
1277 | |
1278 | return err; |
1279 | } |
1280 | |
1281 | /* |
1282 | * Schedule aggregate according to its timestamps. |
1283 | */ |
1284 | static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg) |
1285 | { |
1286 | struct qfq_group *grp = agg->grp; |
1287 | u64 roundedS; |
1288 | int s; |
1289 | |
1290 | roundedS = qfq_round_down(ts: agg->S, shift: grp->slot_shift); |
1291 | |
1292 | /* |
1293 | * Insert agg in the correct bucket. |
1294 | * If agg->S >= grp->S we don't need to adjust the |
1295 | * bucket list and simply go to the insertion phase. |
1296 | * Otherwise grp->S is decreasing, we must make room |
1297 | * in the bucket list, and also recompute the group state. |
1298 | * Finally, if there were no flows in this group and nobody |
1299 | * was in ER make sure to adjust V. |
1300 | */ |
1301 | if (grp->full_slots) { |
1302 | if (!qfq_gt(a: grp->S, b: agg->S)) |
1303 | goto skip_update; |
1304 | |
1305 | /* create a slot for this agg->S */ |
1306 | qfq_slot_rotate(grp, roundedS); |
1307 | /* group was surely ineligible, remove */ |
1308 | __clear_bit(grp->index, &q->bitmaps[IR]); |
1309 | __clear_bit(grp->index, &q->bitmaps[IB]); |
1310 | } else if (!q->bitmaps[ER] && qfq_gt(a: roundedS, b: q->V) && |
1311 | q->in_serv_agg == NULL) |
1312 | q->V = roundedS; |
1313 | |
1314 | grp->S = roundedS; |
1315 | grp->F = roundedS + (2ULL << grp->slot_shift); |
1316 | s = qfq_calc_state(q, grp); |
1317 | __set_bit(grp->index, &q->bitmaps[s]); |
1318 | |
1319 | pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n" , |
1320 | s, q->bitmaps[s], |
1321 | (unsigned long long) agg->S, |
1322 | (unsigned long long) agg->F, |
1323 | (unsigned long long) q->V); |
1324 | |
1325 | skip_update: |
1326 | qfq_slot_insert(grp, agg, roundedS); |
1327 | } |
1328 | |
1329 | |
1330 | /* Update agg ts and schedule agg for service */ |
1331 | static void qfq_activate_agg(struct qfq_sched *q, struct qfq_aggregate *agg, |
1332 | enum update_reason reason) |
1333 | { |
1334 | agg->initial_budget = agg->budget = agg->budgetmax; /* recharge budg. */ |
1335 | |
1336 | qfq_update_agg_ts(q, agg, reason); |
1337 | if (q->in_serv_agg == NULL) { /* no aggr. in service or scheduled */ |
1338 | q->in_serv_agg = agg; /* start serving this aggregate */ |
1339 | /* update V: to be in service, agg must be eligible */ |
1340 | q->oldV = q->V = agg->S; |
1341 | } else if (agg != q->in_serv_agg) |
1342 | qfq_schedule_agg(q, agg); |
1343 | } |
1344 | |
1345 | static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp, |
1346 | struct qfq_aggregate *agg) |
1347 | { |
1348 | unsigned int i, offset; |
1349 | u64 roundedS; |
1350 | |
1351 | roundedS = qfq_round_down(ts: agg->S, shift: grp->slot_shift); |
1352 | offset = (roundedS - grp->S) >> grp->slot_shift; |
1353 | |
1354 | i = (grp->front + offset) % QFQ_MAX_SLOTS; |
1355 | |
1356 | hlist_del(n: &agg->next); |
1357 | if (hlist_empty(h: &grp->slots[i])) |
1358 | __clear_bit(offset, &grp->full_slots); |
1359 | } |
1360 | |
1361 | /* |
1362 | * Called to forcibly deschedule an aggregate. If the aggregate is |
1363 | * not in the front bucket, or if the latter has other aggregates in |
1364 | * the front bucket, we can simply remove the aggregate with no other |
1365 | * side effects. |
1366 | * Otherwise we must propagate the event up. |
1367 | */ |
1368 | static void qfq_deactivate_agg(struct qfq_sched *q, struct qfq_aggregate *agg) |
1369 | { |
1370 | struct qfq_group *grp = agg->grp; |
1371 | unsigned long mask; |
1372 | u64 roundedS; |
1373 | int s; |
1374 | |
1375 | if (agg == q->in_serv_agg) { |
1376 | charge_actual_service(agg); |
1377 | q->in_serv_agg = qfq_choose_next_agg(q); |
1378 | return; |
1379 | } |
1380 | |
1381 | agg->F = agg->S; |
1382 | qfq_slot_remove(q, grp, agg); |
1383 | |
1384 | if (!grp->full_slots) { |
1385 | __clear_bit(grp->index, &q->bitmaps[IR]); |
1386 | __clear_bit(grp->index, &q->bitmaps[EB]); |
1387 | __clear_bit(grp->index, &q->bitmaps[IB]); |
1388 | |
1389 | if (test_bit(grp->index, &q->bitmaps[ER]) && |
1390 | !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) { |
1391 | mask = q->bitmaps[ER] & ((1UL << grp->index) - 1); |
1392 | if (mask) |
1393 | mask = ~((1UL << __fls(word: mask)) - 1); |
1394 | else |
1395 | mask = ~0UL; |
1396 | qfq_move_groups(q, mask, src: EB, dst: ER); |
1397 | qfq_move_groups(q, mask, src: IB, dst: IR); |
1398 | } |
1399 | __clear_bit(grp->index, &q->bitmaps[ER]); |
1400 | } else if (hlist_empty(h: &grp->slots[grp->front])) { |
1401 | agg = qfq_slot_scan(grp); |
1402 | roundedS = qfq_round_down(ts: agg->S, shift: grp->slot_shift); |
1403 | if (grp->S != roundedS) { |
1404 | __clear_bit(grp->index, &q->bitmaps[ER]); |
1405 | __clear_bit(grp->index, &q->bitmaps[IR]); |
1406 | __clear_bit(grp->index, &q->bitmaps[EB]); |
1407 | __clear_bit(grp->index, &q->bitmaps[IB]); |
1408 | grp->S = roundedS; |
1409 | grp->F = roundedS + (2ULL << grp->slot_shift); |
1410 | s = qfq_calc_state(q, grp); |
1411 | __set_bit(grp->index, &q->bitmaps[s]); |
1412 | } |
1413 | } |
1414 | } |
1415 | |
1416 | static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg) |
1417 | { |
1418 | struct qfq_sched *q = qdisc_priv(sch); |
1419 | struct qfq_class *cl = (struct qfq_class *)arg; |
1420 | |
1421 | qfq_deactivate_class(q, cl); |
1422 | } |
1423 | |
1424 | static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt, |
1425 | struct netlink_ext_ack *extack) |
1426 | { |
1427 | struct qfq_sched *q = qdisc_priv(sch); |
1428 | struct qfq_group *grp; |
1429 | int i, j, err; |
1430 | u32 max_cl_shift, maxbudg_shift, max_classes; |
1431 | |
1432 | err = tcf_block_get(p_block: &q->block, p_filter_chain: &q->filter_list, q: sch, extack); |
1433 | if (err) |
1434 | return err; |
1435 | |
1436 | err = qdisc_class_hash_init(&q->clhash); |
1437 | if (err < 0) |
1438 | return err; |
1439 | |
1440 | max_classes = min_t(u64, (u64)qdisc_dev(sch)->tx_queue_len + 1, |
1441 | QFQ_MAX_AGG_CLASSES); |
1442 | /* max_cl_shift = floor(log_2(max_classes)) */ |
1443 | max_cl_shift = __fls(word: max_classes); |
1444 | q->max_agg_classes = 1<<max_cl_shift; |
1445 | |
1446 | /* maxbudg_shift = log2(max_len * max_classes_per_agg) */ |
1447 | maxbudg_shift = QFQ_MTU_SHIFT + max_cl_shift; |
1448 | q->min_slot_shift = FRAC_BITS + maxbudg_shift - QFQ_MAX_INDEX; |
1449 | |
1450 | for (i = 0; i <= QFQ_MAX_INDEX; i++) { |
1451 | grp = &q->groups[i]; |
1452 | grp->index = i; |
1453 | grp->slot_shift = q->min_slot_shift + i; |
1454 | for (j = 0; j < QFQ_MAX_SLOTS; j++) |
1455 | INIT_HLIST_HEAD(&grp->slots[j]); |
1456 | } |
1457 | |
1458 | INIT_HLIST_HEAD(&q->nonfull_aggs); |
1459 | |
1460 | return 0; |
1461 | } |
1462 | |
1463 | static void qfq_reset_qdisc(struct Qdisc *sch) |
1464 | { |
1465 | struct qfq_sched *q = qdisc_priv(sch); |
1466 | struct qfq_class *cl; |
1467 | unsigned int i; |
1468 | |
1469 | for (i = 0; i < q->clhash.hashsize; i++) { |
1470 | hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { |
1471 | if (cl->qdisc->q.qlen > 0) |
1472 | qfq_deactivate_class(q, cl); |
1473 | |
1474 | qdisc_reset(qdisc: cl->qdisc); |
1475 | } |
1476 | } |
1477 | } |
1478 | |
1479 | static void qfq_destroy_qdisc(struct Qdisc *sch) |
1480 | { |
1481 | struct qfq_sched *q = qdisc_priv(sch); |
1482 | struct qfq_class *cl; |
1483 | struct hlist_node *next; |
1484 | unsigned int i; |
1485 | |
1486 | tcf_block_put(block: q->block); |
1487 | |
1488 | for (i = 0; i < q->clhash.hashsize; i++) { |
1489 | hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i], |
1490 | common.hnode) { |
1491 | qfq_destroy_class(sch, cl); |
1492 | } |
1493 | } |
1494 | qdisc_class_hash_destroy(&q->clhash); |
1495 | } |
1496 | |
1497 | static const struct Qdisc_class_ops qfq_class_ops = { |
1498 | .change = qfq_change_class, |
1499 | .delete = qfq_delete_class, |
1500 | .find = qfq_search_class, |
1501 | .tcf_block = qfq_tcf_block, |
1502 | .bind_tcf = qfq_bind_tcf, |
1503 | .unbind_tcf = qfq_unbind_tcf, |
1504 | .graft = qfq_graft_class, |
1505 | .leaf = qfq_class_leaf, |
1506 | .qlen_notify = qfq_qlen_notify, |
1507 | .dump = qfq_dump_class, |
1508 | .dump_stats = qfq_dump_class_stats, |
1509 | .walk = qfq_walk, |
1510 | }; |
1511 | |
1512 | static struct Qdisc_ops qfq_qdisc_ops __read_mostly = { |
1513 | .cl_ops = &qfq_class_ops, |
1514 | .id = "qfq" , |
1515 | .priv_size = sizeof(struct qfq_sched), |
1516 | .enqueue = qfq_enqueue, |
1517 | .dequeue = qfq_dequeue, |
1518 | .peek = qdisc_peek_dequeued, |
1519 | .init = qfq_init_qdisc, |
1520 | .reset = qfq_reset_qdisc, |
1521 | .destroy = qfq_destroy_qdisc, |
1522 | .owner = THIS_MODULE, |
1523 | }; |
1524 | |
1525 | static int __init qfq_init(void) |
1526 | { |
1527 | return register_qdisc(qops: &qfq_qdisc_ops); |
1528 | } |
1529 | |
1530 | static void __exit qfq_exit(void) |
1531 | { |
1532 | unregister_qdisc(qops: &qfq_qdisc_ops); |
1533 | } |
1534 | |
1535 | module_init(qfq_init); |
1536 | module_exit(qfq_exit); |
1537 | MODULE_LICENSE("GPL" ); |
1538 | |