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