1 /* 2 * net/sched/sch_qfq.c Quick Fair Queueing Plus Scheduler. 3 * 4 * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente. 5 * Copyright (c) 2012 Paolo Valente. 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * version 2 as published by the Free Software Foundation. 10 */ 11 12 #include <linux/module.h> 13 #include <linux/init.h> 14 #include <linux/bitops.h> 15 #include <linux/errno.h> 16 #include <linux/netdevice.h> 17 #include <linux/pkt_sched.h> 18 #include <net/sch_generic.h> 19 #include <net/pkt_sched.h> 20 #include <net/pkt_cls.h> 21 22 23 /* Quick Fair Queueing Plus 24 ======================== 25 26 Sources: 27 28 [1] Paolo Valente, 29 "Reducing the Execution Time of Fair-Queueing Schedulers." 30 http://algo.ing.unimo.it/people/paolo/agg-sched/agg-sched.pdf 31 32 Sources for QFQ: 33 34 [2] Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient 35 Packet Scheduling with Tight Bandwidth Distribution Guarantees." 36 37 See also: 38 http://retis.sssup.it/~fabio/linux/qfq/ 39 */ 40 41 /* 42 43 QFQ+ divides classes into aggregates of at most MAX_AGG_CLASSES 44 classes. Each aggregate is timestamped with a virtual start time S 45 and a virtual finish time F, and scheduled according to its 46 timestamps. S and F are computed as a function of a system virtual 47 time function V. The classes within each aggregate are instead 48 scheduled with DRR. 49 50 To speed up operations, QFQ+ divides also aggregates into a limited 51 number of groups. Which group a class belongs to depends on the 52 ratio between the maximum packet length for the class and the weight 53 of the class. Groups have their own S and F. In the end, QFQ+ 54 schedules groups, then aggregates within groups, then classes within 55 aggregates. See [1] and [2] for a full description. 56 57 Virtual time computations. 58 59 S, F and V are all computed in fixed point arithmetic with 60 FRAC_BITS decimal bits. 61 62 QFQ_MAX_INDEX is the maximum index allowed for a group. We need 63 one bit per index. 64 QFQ_MAX_WSHIFT is the maximum power of two supported as a weight. 65 66 The layout of the bits is as below: 67 68 [ MTU_SHIFT ][ FRAC_BITS ] 69 [ MAX_INDEX ][ MIN_SLOT_SHIFT ] 70 ^.__grp->index = 0 71 *.__grp->slot_shift 72 73 where MIN_SLOT_SHIFT is derived by difference from the others. 74 75 The max group index corresponds to Lmax/w_min, where 76 Lmax=1<<MTU_SHIFT, w_min = 1 . 77 From this, and knowing how many groups (MAX_INDEX) we want, 78 we can derive the shift corresponding to each group. 79 80 Because we often need to compute 81 F = S + len/w_i and V = V + len/wsum 82 instead of storing w_i store the value 83 inv_w = (1<<FRAC_BITS)/w_i 84 so we can do F = S + len * inv_w * wsum. 85 We use W_TOT in the formulas so we can easily move between 86 static and adaptive weight sum. 87 88 The per-scheduler-instance data contain all the data structures 89 for the scheduler: bitmaps and bucket lists. 90 91 */ 92 93 /* 94 * Maximum number of consecutive slots occupied by backlogged classes 95 * inside a group. 96 */ 97 #define QFQ_MAX_SLOTS 32 98 99 /* 100 * Shifts used for aggregate<->group mapping. We allow class weights that are 101 * in the range [1, 2^MAX_WSHIFT], and we try to map each aggregate i to the 102 * group with the smallest index that can support the L_i / r_i configured 103 * for the classes in the aggregate. 104 * 105 * grp->index is the index of the group; and grp->slot_shift 106 * is the shift for the corresponding (scaled) sigma_i. 107 */ 108 #define QFQ_MAX_INDEX 24 109 #define QFQ_MAX_WSHIFT 10 110 111 #define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT) /* see qfq_slot_insert */ 112 #define QFQ_MAX_WSUM (64*QFQ_MAX_WEIGHT) 113 114 #define FRAC_BITS 30 /* fixed point arithmetic */ 115 #define ONE_FP (1UL << FRAC_BITS) 116 117 #define QFQ_MTU_SHIFT 16 /* to support TSO/GSO */ 118 #define QFQ_MIN_LMAX 512 /* see qfq_slot_insert */ 119 120 #define QFQ_MAX_AGG_CLASSES 8 /* max num classes per aggregate allowed */ 121 122 /* 123 * Possible group states. These values are used as indexes for the bitmaps 124 * array of struct qfq_queue. 125 */ 126 enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE }; 127 128 struct qfq_group; 129 130 struct qfq_aggregate; 131 132 struct qfq_class { 133 struct Qdisc_class_common common; 134 135 unsigned int refcnt; 136 unsigned int filter_cnt; 137 138 struct gnet_stats_basic_packed bstats; 139 struct gnet_stats_queue qstats; 140 struct net_rate_estimator __rcu *rate_est; 141 struct Qdisc *qdisc; 142 struct list_head alist; /* Link for active-classes list. */ 143 struct qfq_aggregate *agg; /* Parent aggregate. */ 144 int deficit; /* DRR deficit counter. */ 145 }; 146 147 struct qfq_aggregate { 148 struct hlist_node next; /* Link for the slot list. */ 149 u64 S, F; /* flow timestamps (exact) */ 150 151 /* group we belong to. In principle we would need the index, 152 * which is log_2(lmax/weight), but we never reference it 153 * directly, only the group. 154 */ 155 struct qfq_group *grp; 156 157 /* these are copied from the flowset. */ 158 u32 class_weight; /* Weight of each class in this aggregate. */ 159 /* Max pkt size for the classes in this aggregate, DRR quantum. */ 160 int lmax; 161 162 u32 inv_w; /* ONE_FP/(sum of weights of classes in aggr.). */ 163 u32 budgetmax; /* Max budget for this aggregate. */ 164 u32 initial_budget, budget; /* Initial and current budget. */ 165 166 int num_classes; /* Number of classes in this aggr. */ 167 struct list_head active; /* DRR queue of active classes. */ 168 169 struct hlist_node nonfull_next; /* See nonfull_aggs in qfq_sched. */ 170 }; 171 172 struct qfq_group { 173 u64 S, F; /* group timestamps (approx). */ 174 unsigned int slot_shift; /* Slot shift. */ 175 unsigned int index; /* Group index. */ 176 unsigned int front; /* Index of the front slot. */ 177 unsigned long full_slots; /* non-empty slots */ 178 179 /* Array of RR lists of active aggregates. */ 180 struct hlist_head slots[QFQ_MAX_SLOTS]; 181 }; 182 183 struct qfq_sched { 184 struct tcf_proto __rcu *filter_list; 185 struct tcf_block *block; 186 struct Qdisc_class_hash clhash; 187 188 u64 oldV, V; /* Precise virtual times. */ 189 struct qfq_aggregate *in_serv_agg; /* Aggregate being served. */ 190 u32 wsum; /* weight sum */ 191 u32 iwsum; /* inverse weight sum */ 192 193 unsigned long bitmaps[QFQ_MAX_STATE]; /* Group bitmaps. */ 194 struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */ 195 u32 min_slot_shift; /* Index of the group-0 bit in the bitmaps. */ 196 197 u32 max_agg_classes; /* Max number of classes per aggr. */ 198 struct hlist_head nonfull_aggs; /* Aggs with room for more classes. */ 199 }; 200 201 /* 202 * Possible reasons why the timestamps of an aggregate are updated 203 * enqueue: the aggregate switches from idle to active and must scheduled 204 * for service 205 * requeue: the aggregate finishes its budget, so it stops being served and 206 * must be rescheduled for service 207 */ 208 enum update_reason {enqueue, requeue}; 209 210 static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid) 211 { 212 struct qfq_sched *q = qdisc_priv(sch); 213 struct Qdisc_class_common *clc; 214 215 clc = qdisc_class_find(&q->clhash, classid); 216 if (clc == NULL) 217 return NULL; 218 return container_of(clc, struct qfq_class, common); 219 } 220 221 static void qfq_purge_queue(struct qfq_class *cl) 222 { 223 unsigned int len = cl->qdisc->q.qlen; 224 unsigned int backlog = cl->qdisc->qstats.backlog; 225 226 qdisc_reset(cl->qdisc); 227 qdisc_tree_reduce_backlog(cl->qdisc, len, backlog); 228 } 229 230 static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = { 231 [TCA_QFQ_WEIGHT] = { .type = NLA_U32 }, 232 [TCA_QFQ_LMAX] = { .type = NLA_U32 }, 233 }; 234 235 /* 236 * Calculate a flow index, given its weight and maximum packet length. 237 * index = log_2(maxlen/weight) but we need to apply the scaling. 238 * This is used only once at flow creation. 239 */ 240 static int qfq_calc_index(u32 inv_w, unsigned int maxlen, u32 min_slot_shift) 241 { 242 u64 slot_size = (u64)maxlen * inv_w; 243 unsigned long size_map; 244 int index = 0; 245 246 size_map = slot_size >> min_slot_shift; 247 if (!size_map) 248 goto out; 249 250 index = __fls(size_map) + 1; /* basically a log_2 */ 251 index -= !(slot_size - (1ULL << (index + min_slot_shift - 1))); 252 253 if (index < 0) 254 index = 0; 255 out: 256 pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n", 257 (unsigned long) ONE_FP/inv_w, maxlen, index); 258 259 return index; 260 } 261 262 static void qfq_deactivate_agg(struct qfq_sched *, struct qfq_aggregate *); 263 static void qfq_activate_agg(struct qfq_sched *, struct qfq_aggregate *, 264 enum update_reason); 265 266 static void qfq_init_agg(struct qfq_sched *q, struct qfq_aggregate *agg, 267 u32 lmax, u32 weight) 268 { 269 INIT_LIST_HEAD(&agg->active); 270 hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs); 271 272 agg->lmax = lmax; 273 agg->class_weight = weight; 274 } 275 276 static struct qfq_aggregate *qfq_find_agg(struct qfq_sched *q, 277 u32 lmax, u32 weight) 278 { 279 struct qfq_aggregate *agg; 280 281 hlist_for_each_entry(agg, &q->nonfull_aggs, nonfull_next) 282 if (agg->lmax == lmax && agg->class_weight == weight) 283 return agg; 284 285 return NULL; 286 } 287 288 289 /* Update aggregate as a function of the new number of classes. */ 290 static void qfq_update_agg(struct qfq_sched *q, struct qfq_aggregate *agg, 291 int new_num_classes) 292 { 293 u32 new_agg_weight; 294 295 if (new_num_classes == q->max_agg_classes) 296 hlist_del_init(&agg->nonfull_next); 297 298 if (agg->num_classes > new_num_classes && 299 new_num_classes == q->max_agg_classes - 1) /* agg no more full */ 300 hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs); 301 302 /* The next assignment may let 303 * agg->initial_budget > agg->budgetmax 304 * hold, we will take it into account in charge_actual_service(). 305 */ 306 agg->budgetmax = new_num_classes * agg->lmax; 307 new_agg_weight = agg->class_weight * new_num_classes; 308 agg->inv_w = ONE_FP/new_agg_weight; 309 310 if (agg->grp == NULL) { 311 int i = qfq_calc_index(agg->inv_w, agg->budgetmax, 312 q->min_slot_shift); 313 agg->grp = &q->groups[i]; 314 } 315 316 q->wsum += 317 (int) agg->class_weight * (new_num_classes - agg->num_classes); 318 q->iwsum = ONE_FP / q->wsum; 319 320 agg->num_classes = new_num_classes; 321 } 322 323 /* Add class to aggregate. */ 324 static void qfq_add_to_agg(struct qfq_sched *q, 325 struct qfq_aggregate *agg, 326 struct qfq_class *cl) 327 { 328 cl->agg = agg; 329 330 qfq_update_agg(q, agg, agg->num_classes+1); 331 if (cl->qdisc->q.qlen > 0) { /* adding an active class */ 332 list_add_tail(&cl->alist, &agg->active); 333 if (list_first_entry(&agg->active, struct qfq_class, alist) == 334 cl && q->in_serv_agg != agg) /* agg was inactive */ 335 qfq_activate_agg(q, agg, enqueue); /* schedule agg */ 336 } 337 } 338 339 static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *); 340 341 static void qfq_destroy_agg(struct qfq_sched *q, struct qfq_aggregate *agg) 342 { 343 hlist_del_init(&agg->nonfull_next); 344 q->wsum -= agg->class_weight; 345 if (q->wsum != 0) 346 q->iwsum = ONE_FP / q->wsum; 347 348 if (q->in_serv_agg == agg) 349 q->in_serv_agg = qfq_choose_next_agg(q); 350 kfree(agg); 351 } 352 353 /* Deschedule class from within its parent aggregate. */ 354 static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl) 355 { 356 struct qfq_aggregate *agg = cl->agg; 357 358 359 list_del(&cl->alist); /* remove from RR queue of the aggregate */ 360 if (list_empty(&agg->active)) /* agg is now inactive */ 361 qfq_deactivate_agg(q, agg); 362 } 363 364 /* Remove class from its parent aggregate. */ 365 static void qfq_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl) 366 { 367 struct qfq_aggregate *agg = cl->agg; 368 369 cl->agg = NULL; 370 if (agg->num_classes == 1) { /* agg being emptied, destroy it */ 371 qfq_destroy_agg(q, agg); 372 return; 373 } 374 qfq_update_agg(q, agg, agg->num_classes-1); 375 } 376 377 /* Deschedule class and remove it from its parent aggregate. */ 378 static void qfq_deact_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl) 379 { 380 if (cl->qdisc->q.qlen > 0) /* class is active */ 381 qfq_deactivate_class(q, cl); 382 383 qfq_rm_from_agg(q, cl); 384 } 385 386 /* Move class to a new aggregate, matching the new class weight and/or lmax */ 387 static int qfq_change_agg(struct Qdisc *sch, struct qfq_class *cl, u32 weight, 388 u32 lmax) 389 { 390 struct qfq_sched *q = qdisc_priv(sch); 391 struct qfq_aggregate *new_agg = qfq_find_agg(q, lmax, weight); 392 393 if (new_agg == NULL) { /* create new aggregate */ 394 new_agg = kzalloc(sizeof(*new_agg), GFP_ATOMIC); 395 if (new_agg == NULL) 396 return -ENOBUFS; 397 qfq_init_agg(q, new_agg, lmax, weight); 398 } 399 qfq_deact_rm_from_agg(q, cl); 400 qfq_add_to_agg(q, new_agg, cl); 401 402 return 0; 403 } 404 405 static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 406 struct nlattr **tca, unsigned long *arg) 407 { 408 struct qfq_sched *q = qdisc_priv(sch); 409 struct qfq_class *cl = (struct qfq_class *)*arg; 410 bool existing = false; 411 struct nlattr *tb[TCA_QFQ_MAX + 1]; 412 struct qfq_aggregate *new_agg = NULL; 413 u32 weight, lmax, inv_w; 414 int err; 415 int delta_w; 416 417 if (tca[TCA_OPTIONS] == NULL) { 418 pr_notice("qfq: no options\n"); 419 return -EINVAL; 420 } 421 422 err = nla_parse_nested(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS], qfq_policy, 423 NULL); 424 if (err < 0) 425 return err; 426 427 if (tb[TCA_QFQ_WEIGHT]) { 428 weight = nla_get_u32(tb[TCA_QFQ_WEIGHT]); 429 if (!weight || weight > (1UL << QFQ_MAX_WSHIFT)) { 430 pr_notice("qfq: invalid weight %u\n", weight); 431 return -EINVAL; 432 } 433 } else 434 weight = 1; 435 436 if (tb[TCA_QFQ_LMAX]) { 437 lmax = nla_get_u32(tb[TCA_QFQ_LMAX]); 438 if (lmax < QFQ_MIN_LMAX || lmax > (1UL << QFQ_MTU_SHIFT)) { 439 pr_notice("qfq: invalid max length %u\n", lmax); 440 return -EINVAL; 441 } 442 } else 443 lmax = psched_mtu(qdisc_dev(sch)); 444 445 inv_w = ONE_FP / weight; 446 weight = ONE_FP / inv_w; 447 448 if (cl != NULL && 449 lmax == cl->agg->lmax && 450 weight == cl->agg->class_weight) 451 return 0; /* nothing to change */ 452 453 delta_w = weight - (cl ? cl->agg->class_weight : 0); 454 455 if (q->wsum + delta_w > QFQ_MAX_WSUM) { 456 pr_notice("qfq: total weight out of range (%d + %u)\n", 457 delta_w, q->wsum); 458 return -EINVAL; 459 } 460 461 if (cl != NULL) { /* modify existing class */ 462 if (tca[TCA_RATE]) { 463 err = gen_replace_estimator(&cl->bstats, NULL, 464 &cl->rate_est, 465 NULL, 466 qdisc_root_sleeping_running(sch), 467 tca[TCA_RATE]); 468 if (err) 469 return err; 470 } 471 existing = true; 472 goto set_change_agg; 473 } 474 475 /* create and init new class */ 476 cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL); 477 if (cl == NULL) 478 return -ENOBUFS; 479 480 cl->refcnt = 1; 481 cl->common.classid = classid; 482 cl->deficit = lmax; 483 484 cl->qdisc = qdisc_create_dflt(sch->dev_queue, 485 &pfifo_qdisc_ops, classid); 486 if (cl->qdisc == NULL) 487 cl->qdisc = &noop_qdisc; 488 489 if (tca[TCA_RATE]) { 490 err = gen_new_estimator(&cl->bstats, NULL, 491 &cl->rate_est, 492 NULL, 493 qdisc_root_sleeping_running(sch), 494 tca[TCA_RATE]); 495 if (err) 496 goto destroy_class; 497 } 498 499 if (cl->qdisc != &noop_qdisc) 500 qdisc_hash_add(cl->qdisc, true); 501 sch_tree_lock(sch); 502 qdisc_class_hash_insert(&q->clhash, &cl->common); 503 sch_tree_unlock(sch); 504 505 qdisc_class_hash_grow(sch, &q->clhash); 506 507 set_change_agg: 508 sch_tree_lock(sch); 509 new_agg = qfq_find_agg(q, lmax, weight); 510 if (new_agg == NULL) { /* create new aggregate */ 511 sch_tree_unlock(sch); 512 new_agg = kzalloc(sizeof(*new_agg), GFP_KERNEL); 513 if (new_agg == NULL) { 514 err = -ENOBUFS; 515 gen_kill_estimator(&cl->rate_est); 516 goto destroy_class; 517 } 518 sch_tree_lock(sch); 519 qfq_init_agg(q, new_agg, lmax, weight); 520 } 521 if (existing) 522 qfq_deact_rm_from_agg(q, cl); 523 qfq_add_to_agg(q, new_agg, cl); 524 sch_tree_unlock(sch); 525 526 *arg = (unsigned long)cl; 527 return 0; 528 529 destroy_class: 530 qdisc_destroy(cl->qdisc); 531 kfree(cl); 532 return err; 533 } 534 535 static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl) 536 { 537 struct qfq_sched *q = qdisc_priv(sch); 538 539 qfq_rm_from_agg(q, cl); 540 gen_kill_estimator(&cl->rate_est); 541 qdisc_destroy(cl->qdisc); 542 kfree(cl); 543 } 544 545 static int qfq_delete_class(struct Qdisc *sch, unsigned long arg) 546 { 547 struct qfq_sched *q = qdisc_priv(sch); 548 struct qfq_class *cl = (struct qfq_class *)arg; 549 550 if (cl->filter_cnt > 0) 551 return -EBUSY; 552 553 sch_tree_lock(sch); 554 555 qfq_purge_queue(cl); 556 qdisc_class_hash_remove(&q->clhash, &cl->common); 557 558 BUG_ON(--cl->refcnt == 0); 559 /* 560 * This shouldn't happen: we "hold" one cops->get() when called 561 * from tc_ctl_tclass; the destroy method is done from cops->put(). 562 */ 563 564 sch_tree_unlock(sch); 565 return 0; 566 } 567 568 static unsigned long qfq_get_class(struct Qdisc *sch, u32 classid) 569 { 570 struct qfq_class *cl = qfq_find_class(sch, classid); 571 572 if (cl != NULL) 573 cl->refcnt++; 574 575 return (unsigned long)cl; 576 } 577 578 static void qfq_put_class(struct Qdisc *sch, unsigned long arg) 579 { 580 struct qfq_class *cl = (struct qfq_class *)arg; 581 582 if (--cl->refcnt == 0) 583 qfq_destroy_class(sch, cl); 584 } 585 586 static struct tcf_block *qfq_tcf_block(struct Qdisc *sch, unsigned long cl) 587 { 588 struct qfq_sched *q = qdisc_priv(sch); 589 590 if (cl) 591 return NULL; 592 593 return q->block; 594 } 595 596 static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent, 597 u32 classid) 598 { 599 struct qfq_class *cl = qfq_find_class(sch, classid); 600 601 if (cl != NULL) 602 cl->filter_cnt++; 603 604 return (unsigned long)cl; 605 } 606 607 static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg) 608 { 609 struct qfq_class *cl = (struct qfq_class *)arg; 610 611 cl->filter_cnt--; 612 } 613 614 static int qfq_graft_class(struct Qdisc *sch, unsigned long arg, 615 struct Qdisc *new, struct Qdisc **old) 616 { 617 struct qfq_class *cl = (struct qfq_class *)arg; 618 619 if (new == NULL) { 620 new = qdisc_create_dflt(sch->dev_queue, 621 &pfifo_qdisc_ops, cl->common.classid); 622 if (new == NULL) 623 new = &noop_qdisc; 624 } 625 626 *old = qdisc_replace(sch, new, &cl->qdisc); 627 return 0; 628 } 629 630 static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg) 631 { 632 struct qfq_class *cl = (struct qfq_class *)arg; 633 634 return cl->qdisc; 635 } 636 637 static int qfq_dump_class(struct Qdisc *sch, unsigned long arg, 638 struct sk_buff *skb, struct tcmsg *tcm) 639 { 640 struct qfq_class *cl = (struct qfq_class *)arg; 641 struct nlattr *nest; 642 643 tcm->tcm_parent = TC_H_ROOT; 644 tcm->tcm_handle = cl->common.classid; 645 tcm->tcm_info = cl->qdisc->handle; 646 647 nest = nla_nest_start(skb, TCA_OPTIONS); 648 if (nest == NULL) 649 goto nla_put_failure; 650 if (nla_put_u32(skb, TCA_QFQ_WEIGHT, cl->agg->class_weight) || 651 nla_put_u32(skb, TCA_QFQ_LMAX, cl->agg->lmax)) 652 goto nla_put_failure; 653 return nla_nest_end(skb, nest); 654 655 nla_put_failure: 656 nla_nest_cancel(skb, nest); 657 return -EMSGSIZE; 658 } 659 660 static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg, 661 struct gnet_dump *d) 662 { 663 struct qfq_class *cl = (struct qfq_class *)arg; 664 struct tc_qfq_stats xstats; 665 666 memset(&xstats, 0, sizeof(xstats)); 667 668 xstats.weight = cl->agg->class_weight; 669 xstats.lmax = cl->agg->lmax; 670 671 if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch), 672 d, NULL, &cl->bstats) < 0 || 673 gnet_stats_copy_rate_est(d, &cl->rate_est) < 0 || 674 gnet_stats_copy_queue(d, NULL, 675 &cl->qdisc->qstats, cl->qdisc->q.qlen) < 0) 676 return -1; 677 678 return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); 679 } 680 681 static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg) 682 { 683 struct qfq_sched *q = qdisc_priv(sch); 684 struct qfq_class *cl; 685 unsigned int i; 686 687 if (arg->stop) 688 return; 689 690 for (i = 0; i < q->clhash.hashsize; i++) { 691 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 692 if (arg->count < arg->skip) { 693 arg->count++; 694 continue; 695 } 696 if (arg->fn(sch, (unsigned long)cl, arg) < 0) { 697 arg->stop = 1; 698 return; 699 } 700 arg->count++; 701 } 702 } 703 } 704 705 static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch, 706 int *qerr) 707 { 708 struct qfq_sched *q = qdisc_priv(sch); 709 struct qfq_class *cl; 710 struct tcf_result res; 711 struct tcf_proto *fl; 712 int result; 713 714 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) { 715 pr_debug("qfq_classify: found %d\n", skb->priority); 716 cl = qfq_find_class(sch, skb->priority); 717 if (cl != NULL) 718 return cl; 719 } 720 721 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; 722 fl = rcu_dereference_bh(q->filter_list); 723 result = tcf_classify(skb, fl, &res, false); 724 if (result >= 0) { 725 #ifdef CONFIG_NET_CLS_ACT 726 switch (result) { 727 case TC_ACT_QUEUED: 728 case TC_ACT_STOLEN: 729 case TC_ACT_TRAP: 730 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; 731 case TC_ACT_SHOT: 732 return NULL; 733 } 734 #endif 735 cl = (struct qfq_class *)res.class; 736 if (cl == NULL) 737 cl = qfq_find_class(sch, res.classid); 738 return cl; 739 } 740 741 return NULL; 742 } 743 744 /* Generic comparison function, handling wraparound. */ 745 static inline int qfq_gt(u64 a, u64 b) 746 { 747 return (s64)(a - b) > 0; 748 } 749 750 /* Round a precise timestamp to its slotted value. */ 751 static inline u64 qfq_round_down(u64 ts, unsigned int shift) 752 { 753 return ts & ~((1ULL << shift) - 1); 754 } 755 756 /* return the pointer to the group with lowest index in the bitmap */ 757 static inline struct qfq_group *qfq_ffs(struct qfq_sched *q, 758 unsigned long bitmap) 759 { 760 int index = __ffs(bitmap); 761 return &q->groups[index]; 762 } 763 /* Calculate a mask to mimic what would be ffs_from(). */ 764 static inline unsigned long mask_from(unsigned long bitmap, int from) 765 { 766 return bitmap & ~((1UL << from) - 1); 767 } 768 769 /* 770 * The state computation relies on ER=0, IR=1, EB=2, IB=3 771 * First compute eligibility comparing grp->S, q->V, 772 * then check if someone is blocking us and possibly add EB 773 */ 774 static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp) 775 { 776 /* if S > V we are not eligible */ 777 unsigned int state = qfq_gt(grp->S, q->V); 778 unsigned long mask = mask_from(q->bitmaps[ER], grp->index); 779 struct qfq_group *next; 780 781 if (mask) { 782 next = qfq_ffs(q, mask); 783 if (qfq_gt(grp->F, next->F)) 784 state |= EB; 785 } 786 787 return state; 788 } 789 790 791 /* 792 * In principle 793 * q->bitmaps[dst] |= q->bitmaps[src] & mask; 794 * q->bitmaps[src] &= ~mask; 795 * but we should make sure that src != dst 796 */ 797 static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask, 798 int src, int dst) 799 { 800 q->bitmaps[dst] |= q->bitmaps[src] & mask; 801 q->bitmaps[src] &= ~mask; 802 } 803 804 static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F) 805 { 806 unsigned long mask = mask_from(q->bitmaps[ER], index + 1); 807 struct qfq_group *next; 808 809 if (mask) { 810 next = qfq_ffs(q, mask); 811 if (!qfq_gt(next->F, old_F)) 812 return; 813 } 814 815 mask = (1UL << index) - 1; 816 qfq_move_groups(q, mask, EB, ER); 817 qfq_move_groups(q, mask, IB, IR); 818 } 819 820 /* 821 * perhaps 822 * 823 old_V ^= q->V; 824 old_V >>= q->min_slot_shift; 825 if (old_V) { 826 ... 827 } 828 * 829 */ 830 static void qfq_make_eligible(struct qfq_sched *q) 831 { 832 unsigned long vslot = q->V >> q->min_slot_shift; 833 unsigned long old_vslot = q->oldV >> q->min_slot_shift; 834 835 if (vslot != old_vslot) { 836 unsigned long mask; 837 int last_flip_pos = fls(vslot ^ old_vslot); 838 839 if (last_flip_pos > 31) /* higher than the number of groups */ 840 mask = ~0UL; /* make all groups eligible */ 841 else 842 mask = (1UL << last_flip_pos) - 1; 843 844 qfq_move_groups(q, mask, IR, ER); 845 qfq_move_groups(q, mask, IB, EB); 846 } 847 } 848 849 /* 850 * The index of the slot in which the input aggregate agg is to be 851 * inserted must not be higher than QFQ_MAX_SLOTS-2. There is a '-2' 852 * and not a '-1' because the start time of the group may be moved 853 * backward by one slot after the aggregate has been inserted, and 854 * this would cause non-empty slots to be right-shifted by one 855 * position. 856 * 857 * QFQ+ fully satisfies this bound to the slot index if the parameters 858 * of the classes are not changed dynamically, and if QFQ+ never 859 * happens to postpone the service of agg unjustly, i.e., it never 860 * happens that the aggregate becomes backlogged and eligible, or just 861 * eligible, while an aggregate with a higher approximated finish time 862 * is being served. In particular, in this case QFQ+ guarantees that 863 * the timestamps of agg are low enough that the slot index is never 864 * higher than 2. Unfortunately, QFQ+ cannot provide the same 865 * guarantee if it happens to unjustly postpone the service of agg, or 866 * if the parameters of some class are changed. 867 * 868 * As for the first event, i.e., an out-of-order service, the 869 * upper bound to the slot index guaranteed by QFQ+ grows to 870 * 2 + 871 * QFQ_MAX_AGG_CLASSES * ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) * 872 * (current_max_weight/current_wsum) <= 2 + 8 * 128 * 1. 873 * 874 * The following function deals with this problem by backward-shifting 875 * the timestamps of agg, if needed, so as to guarantee that the slot 876 * index is never higher than QFQ_MAX_SLOTS-2. This backward-shift may 877 * cause the service of other aggregates to be postponed, yet the 878 * worst-case guarantees of these aggregates are not violated. In 879 * fact, in case of no out-of-order service, the timestamps of agg 880 * would have been even lower than they are after the backward shift, 881 * because QFQ+ would have guaranteed a maximum value equal to 2 for 882 * the slot index, and 2 < QFQ_MAX_SLOTS-2. Hence the aggregates whose 883 * service is postponed because of the backward-shift would have 884 * however waited for the service of agg before being served. 885 * 886 * The other event that may cause the slot index to be higher than 2 887 * for agg is a recent change of the parameters of some class. If the 888 * weight of a class is increased or the lmax (max_pkt_size) of the 889 * class is decreased, then a new aggregate with smaller slot size 890 * than the original parent aggregate of the class may happen to be 891 * activated. The activation of this aggregate should be properly 892 * delayed to when the service of the class has finished in the ideal 893 * system tracked by QFQ+. If the activation of the aggregate is not 894 * delayed to this reference time instant, then this aggregate may be 895 * unjustly served before other aggregates waiting for service. This 896 * may cause the above bound to the slot index to be violated for some 897 * of these unlucky aggregates. 898 * 899 * Instead of delaying the activation of the new aggregate, which is 900 * quite complex, the above-discussed capping of the slot index is 901 * used to handle also the consequences of a change of the parameters 902 * of a class. 903 */ 904 static void qfq_slot_insert(struct qfq_group *grp, struct qfq_aggregate *agg, 905 u64 roundedS) 906 { 907 u64 slot = (roundedS - grp->S) >> grp->slot_shift; 908 unsigned int i; /* slot index in the bucket list */ 909 910 if (unlikely(slot > QFQ_MAX_SLOTS - 2)) { 911 u64 deltaS = roundedS - grp->S - 912 ((u64)(QFQ_MAX_SLOTS - 2)<<grp->slot_shift); 913 agg->S -= deltaS; 914 agg->F -= deltaS; 915 slot = QFQ_MAX_SLOTS - 2; 916 } 917 918 i = (grp->front + slot) % QFQ_MAX_SLOTS; 919 920 hlist_add_head(&agg->next, &grp->slots[i]); 921 __set_bit(slot, &grp->full_slots); 922 } 923 924 /* Maybe introduce hlist_first_entry?? */ 925 static struct qfq_aggregate *qfq_slot_head(struct qfq_group *grp) 926 { 927 return hlist_entry(grp->slots[grp->front].first, 928 struct qfq_aggregate, next); 929 } 930 931 /* 932 * remove the entry from the slot 933 */ 934 static void qfq_front_slot_remove(struct qfq_group *grp) 935 { 936 struct qfq_aggregate *agg = qfq_slot_head(grp); 937 938 BUG_ON(!agg); 939 hlist_del(&agg->next); 940 if (hlist_empty(&grp->slots[grp->front])) 941 __clear_bit(0, &grp->full_slots); 942 } 943 944 /* 945 * Returns the first aggregate in the first non-empty bucket of the 946 * group. As a side effect, adjusts the bucket list so the first 947 * non-empty bucket is at position 0 in full_slots. 948 */ 949 static struct qfq_aggregate *qfq_slot_scan(struct qfq_group *grp) 950 { 951 unsigned int i; 952 953 pr_debug("qfq slot_scan: grp %u full %#lx\n", 954 grp->index, grp->full_slots); 955 956 if (grp->full_slots == 0) 957 return NULL; 958 959 i = __ffs(grp->full_slots); /* zero based */ 960 if (i > 0) { 961 grp->front = (grp->front + i) % QFQ_MAX_SLOTS; 962 grp->full_slots >>= i; 963 } 964 965 return qfq_slot_head(grp); 966 } 967 968 /* 969 * adjust the bucket list. When the start time of a group decreases, 970 * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to 971 * move the objects. The mask of occupied slots must be shifted 972 * because we use ffs() to find the first non-empty slot. 973 * This covers decreases in the group's start time, but what about 974 * increases of the start time ? 975 * Here too we should make sure that i is less than 32 976 */ 977 static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS) 978 { 979 unsigned int i = (grp->S - roundedS) >> grp->slot_shift; 980 981 grp->full_slots <<= i; 982 grp->front = (grp->front - i) % QFQ_MAX_SLOTS; 983 } 984 985 static void qfq_update_eligible(struct qfq_sched *q) 986 { 987 struct qfq_group *grp; 988 unsigned long ineligible; 989 990 ineligible = q->bitmaps[IR] | q->bitmaps[IB]; 991 if (ineligible) { 992 if (!q->bitmaps[ER]) { 993 grp = qfq_ffs(q, ineligible); 994 if (qfq_gt(grp->S, q->V)) 995 q->V = grp->S; 996 } 997 qfq_make_eligible(q); 998 } 999 } 1000 1001 /* Dequeue head packet of the head class in the DRR queue of the aggregate. */ 1002 static void agg_dequeue(struct qfq_aggregate *agg, 1003 struct qfq_class *cl, unsigned int len) 1004 { 1005 qdisc_dequeue_peeked(cl->qdisc); 1006 1007 cl->deficit -= (int) len; 1008 1009 if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */ 1010 list_del(&cl->alist); 1011 else if (cl->deficit < qdisc_pkt_len(cl->qdisc->ops->peek(cl->qdisc))) { 1012 cl->deficit += agg->lmax; 1013 list_move_tail(&cl->alist, &agg->active); 1014 } 1015 } 1016 1017 static inline struct sk_buff *qfq_peek_skb(struct qfq_aggregate *agg, 1018 struct qfq_class **cl, 1019 unsigned int *len) 1020 { 1021 struct sk_buff *skb; 1022 1023 *cl = list_first_entry(&agg->active, struct qfq_class, alist); 1024 skb = (*cl)->qdisc->ops->peek((*cl)->qdisc); 1025 if (skb == NULL) 1026 WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n"); 1027 else 1028 *len = qdisc_pkt_len(skb); 1029 1030 return skb; 1031 } 1032 1033 /* Update F according to the actual service received by the aggregate. */ 1034 static inline void charge_actual_service(struct qfq_aggregate *agg) 1035 { 1036 /* Compute the service received by the aggregate, taking into 1037 * account that, after decreasing the number of classes in 1038 * agg, it may happen that 1039 * agg->initial_budget - agg->budget > agg->bugdetmax 1040 */ 1041 u32 service_received = min(agg->budgetmax, 1042 agg->initial_budget - agg->budget); 1043 1044 agg->F = agg->S + (u64)service_received * agg->inv_w; 1045 } 1046 1047 /* Assign a reasonable start time for a new aggregate in group i. 1048 * Admissible values for \hat(F) are multiples of \sigma_i 1049 * no greater than V+\sigma_i . Larger values mean that 1050 * we had a wraparound so we consider the timestamp to be stale. 1051 * 1052 * If F is not stale and F >= V then we set S = F. 1053 * Otherwise we should assign S = V, but this may violate 1054 * the ordering in EB (see [2]). So, if we have groups in ER, 1055 * set S to the F_j of the first group j which would be blocking us. 1056 * We are guaranteed not to move S backward because 1057 * otherwise our group i would still be blocked. 1058 */ 1059 static void qfq_update_start(struct qfq_sched *q, struct qfq_aggregate *agg) 1060 { 1061 unsigned long mask; 1062 u64 limit, roundedF; 1063 int slot_shift = agg->grp->slot_shift; 1064 1065 roundedF = qfq_round_down(agg->F, slot_shift); 1066 limit = qfq_round_down(q->V, slot_shift) + (1ULL << slot_shift); 1067 1068 if (!qfq_gt(agg->F, q->V) || qfq_gt(roundedF, limit)) { 1069 /* timestamp was stale */ 1070 mask = mask_from(q->bitmaps[ER], agg->grp->index); 1071 if (mask) { 1072 struct qfq_group *next = qfq_ffs(q, mask); 1073 if (qfq_gt(roundedF, next->F)) { 1074 if (qfq_gt(limit, next->F)) 1075 agg->S = next->F; 1076 else /* preserve timestamp correctness */ 1077 agg->S = limit; 1078 return; 1079 } 1080 } 1081 agg->S = q->V; 1082 } else /* timestamp is not stale */ 1083 agg->S = agg->F; 1084 } 1085 1086 /* Update the timestamps of agg before scheduling/rescheduling it for 1087 * service. In particular, assign to agg->F its maximum possible 1088 * value, i.e., the virtual finish time with which the aggregate 1089 * should be labeled if it used all its budget once in service. 1090 */ 1091 static inline void 1092 qfq_update_agg_ts(struct qfq_sched *q, 1093 struct qfq_aggregate *agg, enum update_reason reason) 1094 { 1095 if (reason != requeue) 1096 qfq_update_start(q, agg); 1097 else /* just charge agg for the service received */ 1098 agg->S = agg->F; 1099 1100 agg->F = agg->S + (u64)agg->budgetmax * agg->inv_w; 1101 } 1102 1103 static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg); 1104 1105 static struct sk_buff *qfq_dequeue(struct Qdisc *sch) 1106 { 1107 struct qfq_sched *q = qdisc_priv(sch); 1108 struct qfq_aggregate *in_serv_agg = q->in_serv_agg; 1109 struct qfq_class *cl; 1110 struct sk_buff *skb = NULL; 1111 /* next-packet len, 0 means no more active classes in in-service agg */ 1112 unsigned int len = 0; 1113 1114 if (in_serv_agg == NULL) 1115 return NULL; 1116 1117 if (!list_empty(&in_serv_agg->active)) 1118 skb = qfq_peek_skb(in_serv_agg, &cl, &len); 1119 1120 /* 1121 * If there are no active classes in the in-service aggregate, 1122 * or if the aggregate has not enough budget to serve its next 1123 * class, then choose the next aggregate to serve. 1124 */ 1125 if (len == 0 || in_serv_agg->budget < len) { 1126 charge_actual_service(in_serv_agg); 1127 1128 /* recharge the budget of the aggregate */ 1129 in_serv_agg->initial_budget = in_serv_agg->budget = 1130 in_serv_agg->budgetmax; 1131 1132 if (!list_empty(&in_serv_agg->active)) { 1133 /* 1134 * Still active: reschedule for 1135 * service. Possible optimization: if no other 1136 * aggregate is active, then there is no point 1137 * in rescheduling this aggregate, and we can 1138 * just keep it as the in-service one. This 1139 * should be however a corner case, and to 1140 * handle it, we would need to maintain an 1141 * extra num_active_aggs field. 1142 */ 1143 qfq_update_agg_ts(q, in_serv_agg, requeue); 1144 qfq_schedule_agg(q, in_serv_agg); 1145 } else if (sch->q.qlen == 0) { /* no aggregate to serve */ 1146 q->in_serv_agg = NULL; 1147 return NULL; 1148 } 1149 1150 /* 1151 * If we get here, there are other aggregates queued: 1152 * choose the new aggregate to serve. 1153 */ 1154 in_serv_agg = q->in_serv_agg = qfq_choose_next_agg(q); 1155 skb = qfq_peek_skb(in_serv_agg, &cl, &len); 1156 } 1157 if (!skb) 1158 return NULL; 1159 1160 qdisc_qstats_backlog_dec(sch, skb); 1161 sch->q.qlen--; 1162 qdisc_bstats_update(sch, skb); 1163 1164 agg_dequeue(in_serv_agg, cl, len); 1165 /* If lmax is lowered, through qfq_change_class, for a class 1166 * owning pending packets with larger size than the new value 1167 * of lmax, then the following condition may hold. 1168 */ 1169 if (unlikely(in_serv_agg->budget < len)) 1170 in_serv_agg->budget = 0; 1171 else 1172 in_serv_agg->budget -= len; 1173 1174 q->V += (u64)len * q->iwsum; 1175 pr_debug("qfq dequeue: len %u F %lld now %lld\n", 1176 len, (unsigned long long) in_serv_agg->F, 1177 (unsigned long long) q->V); 1178 1179 return skb; 1180 } 1181 1182 static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q) 1183 { 1184 struct qfq_group *grp; 1185 struct qfq_aggregate *agg, *new_front_agg; 1186 u64 old_F; 1187 1188 qfq_update_eligible(q); 1189 q->oldV = q->V; 1190 1191 if (!q->bitmaps[ER]) 1192 return NULL; 1193 1194 grp = qfq_ffs(q, q->bitmaps[ER]); 1195 old_F = grp->F; 1196 1197 agg = qfq_slot_head(grp); 1198 1199 /* agg starts to be served, remove it from schedule */ 1200 qfq_front_slot_remove(grp); 1201 1202 new_front_agg = qfq_slot_scan(grp); 1203 1204 if (new_front_agg == NULL) /* group is now inactive, remove from ER */ 1205 __clear_bit(grp->index, &q->bitmaps[ER]); 1206 else { 1207 u64 roundedS = qfq_round_down(new_front_agg->S, 1208 grp->slot_shift); 1209 unsigned int s; 1210 1211 if (grp->S == roundedS) 1212 return agg; 1213 grp->S = roundedS; 1214 grp->F = roundedS + (2ULL << grp->slot_shift); 1215 __clear_bit(grp->index, &q->bitmaps[ER]); 1216 s = qfq_calc_state(q, grp); 1217 __set_bit(grp->index, &q->bitmaps[s]); 1218 } 1219 1220 qfq_unblock_groups(q, grp->index, old_F); 1221 1222 return agg; 1223 } 1224 1225 static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, 1226 struct sk_buff **to_free) 1227 { 1228 struct qfq_sched *q = qdisc_priv(sch); 1229 struct qfq_class *cl; 1230 struct qfq_aggregate *agg; 1231 int err = 0; 1232 1233 cl = qfq_classify(skb, sch, &err); 1234 if (cl == NULL) { 1235 if (err & __NET_XMIT_BYPASS) 1236 qdisc_qstats_drop(sch); 1237 kfree_skb(skb); 1238 return err; 1239 } 1240 pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid); 1241 1242 if (unlikely(cl->agg->lmax < qdisc_pkt_len(skb))) { 1243 pr_debug("qfq: increasing maxpkt from %u to %u for class %u", 1244 cl->agg->lmax, qdisc_pkt_len(skb), cl->common.classid); 1245 err = qfq_change_agg(sch, cl, cl->agg->class_weight, 1246 qdisc_pkt_len(skb)); 1247 if (err) { 1248 cl->qstats.drops++; 1249 return qdisc_drop(skb, sch, to_free); 1250 } 1251 } 1252 1253 err = qdisc_enqueue(skb, cl->qdisc, to_free); 1254 if (unlikely(err != NET_XMIT_SUCCESS)) { 1255 pr_debug("qfq_enqueue: enqueue failed %d\n", err); 1256 if (net_xmit_drop_count(err)) { 1257 cl->qstats.drops++; 1258 qdisc_qstats_drop(sch); 1259 } 1260 return err; 1261 } 1262 1263 bstats_update(&cl->bstats, skb); 1264 qdisc_qstats_backlog_inc(sch, skb); 1265 ++sch->q.qlen; 1266 1267 agg = cl->agg; 1268 /* if the queue was not empty, then done here */ 1269 if (cl->qdisc->q.qlen != 1) { 1270 if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) && 1271 list_first_entry(&agg->active, struct qfq_class, alist) 1272 == cl && cl->deficit < qdisc_pkt_len(skb)) 1273 list_move_tail(&cl->alist, &agg->active); 1274 1275 return err; 1276 } 1277 1278 /* schedule class for service within the aggregate */ 1279 cl->deficit = agg->lmax; 1280 list_add_tail(&cl->alist, &agg->active); 1281 1282 if (list_first_entry(&agg->active, struct qfq_class, alist) != cl || 1283 q->in_serv_agg == agg) 1284 return err; /* non-empty or in service, nothing else to do */ 1285 1286 qfq_activate_agg(q, agg, enqueue); 1287 1288 return err; 1289 } 1290 1291 /* 1292 * Schedule aggregate according to its timestamps. 1293 */ 1294 static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg) 1295 { 1296 struct qfq_group *grp = agg->grp; 1297 u64 roundedS; 1298 int s; 1299 1300 roundedS = qfq_round_down(agg->S, grp->slot_shift); 1301 1302 /* 1303 * Insert agg in the correct bucket. 1304 * If agg->S >= grp->S we don't need to adjust the 1305 * bucket list and simply go to the insertion phase. 1306 * Otherwise grp->S is decreasing, we must make room 1307 * in the bucket list, and also recompute the group state. 1308 * Finally, if there were no flows in this group and nobody 1309 * was in ER make sure to adjust V. 1310 */ 1311 if (grp->full_slots) { 1312 if (!qfq_gt(grp->S, agg->S)) 1313 goto skip_update; 1314 1315 /* create a slot for this agg->S */ 1316 qfq_slot_rotate(grp, roundedS); 1317 /* group was surely ineligible, remove */ 1318 __clear_bit(grp->index, &q->bitmaps[IR]); 1319 __clear_bit(grp->index, &q->bitmaps[IB]); 1320 } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V) && 1321 q->in_serv_agg == NULL) 1322 q->V = roundedS; 1323 1324 grp->S = roundedS; 1325 grp->F = roundedS + (2ULL << grp->slot_shift); 1326 s = qfq_calc_state(q, grp); 1327 __set_bit(grp->index, &q->bitmaps[s]); 1328 1329 pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n", 1330 s, q->bitmaps[s], 1331 (unsigned long long) agg->S, 1332 (unsigned long long) agg->F, 1333 (unsigned long long) q->V); 1334 1335 skip_update: 1336 qfq_slot_insert(grp, agg, roundedS); 1337 } 1338 1339 1340 /* Update agg ts and schedule agg for service */ 1341 static void qfq_activate_agg(struct qfq_sched *q, struct qfq_aggregate *agg, 1342 enum update_reason reason) 1343 { 1344 agg->initial_budget = agg->budget = agg->budgetmax; /* recharge budg. */ 1345 1346 qfq_update_agg_ts(q, agg, reason); 1347 if (q->in_serv_agg == NULL) { /* no aggr. in service or scheduled */ 1348 q->in_serv_agg = agg; /* start serving this aggregate */ 1349 /* update V: to be in service, agg must be eligible */ 1350 q->oldV = q->V = agg->S; 1351 } else if (agg != q->in_serv_agg) 1352 qfq_schedule_agg(q, agg); 1353 } 1354 1355 static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp, 1356 struct qfq_aggregate *agg) 1357 { 1358 unsigned int i, offset; 1359 u64 roundedS; 1360 1361 roundedS = qfq_round_down(agg->S, grp->slot_shift); 1362 offset = (roundedS - grp->S) >> grp->slot_shift; 1363 1364 i = (grp->front + offset) % QFQ_MAX_SLOTS; 1365 1366 hlist_del(&agg->next); 1367 if (hlist_empty(&grp->slots[i])) 1368 __clear_bit(offset, &grp->full_slots); 1369 } 1370 1371 /* 1372 * Called to forcibly deschedule an aggregate. If the aggregate is 1373 * not in the front bucket, or if the latter has other aggregates in 1374 * the front bucket, we can simply remove the aggregate with no other 1375 * side effects. 1376 * Otherwise we must propagate the event up. 1377 */ 1378 static void qfq_deactivate_agg(struct qfq_sched *q, struct qfq_aggregate *agg) 1379 { 1380 struct qfq_group *grp = agg->grp; 1381 unsigned long mask; 1382 u64 roundedS; 1383 int s; 1384 1385 if (agg == q->in_serv_agg) { 1386 charge_actual_service(agg); 1387 q->in_serv_agg = qfq_choose_next_agg(q); 1388 return; 1389 } 1390 1391 agg->F = agg->S; 1392 qfq_slot_remove(q, grp, agg); 1393 1394 if (!grp->full_slots) { 1395 __clear_bit(grp->index, &q->bitmaps[IR]); 1396 __clear_bit(grp->index, &q->bitmaps[EB]); 1397 __clear_bit(grp->index, &q->bitmaps[IB]); 1398 1399 if (test_bit(grp->index, &q->bitmaps[ER]) && 1400 !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) { 1401 mask = q->bitmaps[ER] & ((1UL << grp->index) - 1); 1402 if (mask) 1403 mask = ~((1UL << __fls(mask)) - 1); 1404 else 1405 mask = ~0UL; 1406 qfq_move_groups(q, mask, EB, ER); 1407 qfq_move_groups(q, mask, IB, IR); 1408 } 1409 __clear_bit(grp->index, &q->bitmaps[ER]); 1410 } else if (hlist_empty(&grp->slots[grp->front])) { 1411 agg = qfq_slot_scan(grp); 1412 roundedS = qfq_round_down(agg->S, grp->slot_shift); 1413 if (grp->S != roundedS) { 1414 __clear_bit(grp->index, &q->bitmaps[ER]); 1415 __clear_bit(grp->index, &q->bitmaps[IR]); 1416 __clear_bit(grp->index, &q->bitmaps[EB]); 1417 __clear_bit(grp->index, &q->bitmaps[IB]); 1418 grp->S = roundedS; 1419 grp->F = roundedS + (2ULL << grp->slot_shift); 1420 s = qfq_calc_state(q, grp); 1421 __set_bit(grp->index, &q->bitmaps[s]); 1422 } 1423 } 1424 } 1425 1426 static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg) 1427 { 1428 struct qfq_sched *q = qdisc_priv(sch); 1429 struct qfq_class *cl = (struct qfq_class *)arg; 1430 1431 if (cl->qdisc->q.qlen == 0) 1432 qfq_deactivate_class(q, cl); 1433 } 1434 1435 static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt) 1436 { 1437 struct qfq_sched *q = qdisc_priv(sch); 1438 struct qfq_group *grp; 1439 int i, j, err; 1440 u32 max_cl_shift, maxbudg_shift, max_classes; 1441 1442 err = tcf_block_get(&q->block, &q->filter_list); 1443 if (err) 1444 return err; 1445 1446 err = qdisc_class_hash_init(&q->clhash); 1447 if (err < 0) 1448 return err; 1449 1450 if (qdisc_dev(sch)->tx_queue_len + 1 > QFQ_MAX_AGG_CLASSES) 1451 max_classes = QFQ_MAX_AGG_CLASSES; 1452 else 1453 max_classes = qdisc_dev(sch)->tx_queue_len + 1; 1454 /* max_cl_shift = floor(log_2(max_classes)) */ 1455 max_cl_shift = __fls(max_classes); 1456 q->max_agg_classes = 1<<max_cl_shift; 1457 1458 /* maxbudg_shift = log2(max_len * max_classes_per_agg) */ 1459 maxbudg_shift = QFQ_MTU_SHIFT + max_cl_shift; 1460 q->min_slot_shift = FRAC_BITS + maxbudg_shift - QFQ_MAX_INDEX; 1461 1462 for (i = 0; i <= QFQ_MAX_INDEX; i++) { 1463 grp = &q->groups[i]; 1464 grp->index = i; 1465 grp->slot_shift = q->min_slot_shift + i; 1466 for (j = 0; j < QFQ_MAX_SLOTS; j++) 1467 INIT_HLIST_HEAD(&grp->slots[j]); 1468 } 1469 1470 INIT_HLIST_HEAD(&q->nonfull_aggs); 1471 1472 return 0; 1473 } 1474 1475 static void qfq_reset_qdisc(struct Qdisc *sch) 1476 { 1477 struct qfq_sched *q = qdisc_priv(sch); 1478 struct qfq_class *cl; 1479 unsigned int i; 1480 1481 for (i = 0; i < q->clhash.hashsize; i++) { 1482 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { 1483 if (cl->qdisc->q.qlen > 0) 1484 qfq_deactivate_class(q, cl); 1485 1486 qdisc_reset(cl->qdisc); 1487 } 1488 } 1489 sch->qstats.backlog = 0; 1490 sch->q.qlen = 0; 1491 } 1492 1493 static void qfq_destroy_qdisc(struct Qdisc *sch) 1494 { 1495 struct qfq_sched *q = qdisc_priv(sch); 1496 struct qfq_class *cl; 1497 struct hlist_node *next; 1498 unsigned int i; 1499 1500 tcf_block_put(q->block); 1501 1502 for (i = 0; i < q->clhash.hashsize; i++) { 1503 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i], 1504 common.hnode) { 1505 qfq_destroy_class(sch, cl); 1506 } 1507 } 1508 qdisc_class_hash_destroy(&q->clhash); 1509 } 1510 1511 static const struct Qdisc_class_ops qfq_class_ops = { 1512 .change = qfq_change_class, 1513 .delete = qfq_delete_class, 1514 .get = qfq_get_class, 1515 .put = qfq_put_class, 1516 .tcf_block = qfq_tcf_block, 1517 .bind_tcf = qfq_bind_tcf, 1518 .unbind_tcf = qfq_unbind_tcf, 1519 .graft = qfq_graft_class, 1520 .leaf = qfq_class_leaf, 1521 .qlen_notify = qfq_qlen_notify, 1522 .dump = qfq_dump_class, 1523 .dump_stats = qfq_dump_class_stats, 1524 .walk = qfq_walk, 1525 }; 1526 1527 static struct Qdisc_ops qfq_qdisc_ops __read_mostly = { 1528 .cl_ops = &qfq_class_ops, 1529 .id = "qfq", 1530 .priv_size = sizeof(struct qfq_sched), 1531 .enqueue = qfq_enqueue, 1532 .dequeue = qfq_dequeue, 1533 .peek = qdisc_peek_dequeued, 1534 .init = qfq_init_qdisc, 1535 .reset = qfq_reset_qdisc, 1536 .destroy = qfq_destroy_qdisc, 1537 .owner = THIS_MODULE, 1538 }; 1539 1540 static int __init qfq_init(void) 1541 { 1542 return register_qdisc(&qfq_qdisc_ops); 1543 } 1544 1545 static void __exit qfq_exit(void) 1546 { 1547 unregister_qdisc(&qfq_qdisc_ops); 1548 } 1549 1550 module_init(qfq_init); 1551 module_exit(qfq_exit); 1552 MODULE_LICENSE("GPL"); 1553