2 * net/sched/sch_qfq.c Quick Fair Queueing Plus Scheduler.
4 * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente.
5 * Copyright (c) 2012 Paolo Valente.
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.
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>
23 /* Quick Fair Queueing Plus
24 ========================
29 "Reducing the Execution Time of Fair-Queueing Schedulers."
30 http://algo.ing.unimo.it/people/paolo/agg-sched/agg-sched.pdf
34 [2] Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient
35 Packet Scheduling with Tight Bandwidth Distribution Guarantees."
38 http://retis.sssup.it/~fabio/linux/qfq/
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
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.
57 Virtual time computations.
59 S, F and V are all computed in fixed point arithmetic with
60 FRAC_BITS decimal bits.
62 QFQ_MAX_INDEX is the maximum index allowed for a group. We need
64 QFQ_MAX_WSHIFT is the maximum power of two supported as a weight.
66 The layout of the bits is as below:
68 [ MTU_SHIFT ][ FRAC_BITS ]
69 [ MAX_INDEX ][ MIN_SLOT_SHIFT ]
73 where MIN_SLOT_SHIFT is derived by difference from the others.
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.
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.
88 The per-scheduler-instance data contain all the data structures
89 for the scheduler: bitmaps and bucket lists.
94 * Maximum number of consecutive slots occupied by backlogged classes
97 #define QFQ_MAX_SLOTS 32
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.
105 * grp->index is the index of the group; and grp->slot_shift
106 * is the shift for the corresponding (scaled) sigma_i.
108 #define QFQ_MAX_INDEX 24
109 #define QFQ_MAX_WSHIFT 10
111 #define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT) /* see qfq_slot_insert */
112 #define QFQ_MAX_WSUM (64*QFQ_MAX_WEIGHT)
114 #define FRAC_BITS 30 /* fixed point arithmetic */
115 #define ONE_FP (1UL << FRAC_BITS)
117 #define QFQ_MTU_SHIFT 16 /* to support TSO/GSO */
118 #define QFQ_MIN_LMAX 512 /* see qfq_slot_insert */
120 #define QFQ_MAX_AGG_CLASSES 8 /* max num classes per aggregate allowed */
123 * Possible group states. These values are used as indexes for the bitmaps
124 * array of struct qfq_queue.
126 enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE };
130 struct qfq_aggregate;
133 struct Qdisc_class_common common;
136 unsigned int filter_cnt;
138 struct gnet_stats_basic_packed bstats;
139 struct gnet_stats_queue qstats;
140 struct gnet_stats_rate_est rate_est;
142 struct list_head alist; /* Link for active-classes list. */
143 struct qfq_aggregate *agg; /* Parent aggregate. */
144 int deficit; /* DRR deficit counter. */
147 struct qfq_aggregate {
148 struct hlist_node next; /* Link for the slot list. */
149 u64 S, F; /* flow timestamps (exact) */
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.
155 struct qfq_group *grp;
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. */
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. */
166 int num_classes; /* Number of classes in this aggr. */
167 struct list_head active; /* DRR queue of active classes. */
169 struct hlist_node nonfull_next; /* See nonfull_aggs in qfq_sched. */
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 */
179 /* Array of RR lists of active aggregates. */
180 struct hlist_head slots[QFQ_MAX_SLOTS];
184 struct tcf_proto *filter_list;
185 struct Qdisc_class_hash clhash;
187 u64 oldV, V; /* Precise virtual times. */
188 struct qfq_aggregate *in_serv_agg; /* Aggregate being served. */
189 u32 num_active_agg; /* Num. of active aggregates */
190 u32 wsum; /* weight sum */
191 u32 iwsum; /* inverse weight sum */
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. */
197 u32 max_agg_classes; /* Max number of classes per aggr. */
198 struct hlist_head nonfull_aggs; /* Aggs with room for more classes. */
202 * Possible reasons why the timestamps of an aggregate are updated
203 * enqueue: the aggregate switches from idle to active and must scheduled
205 * requeue: the aggregate finishes its budget, so it stops being served and
206 * must be rescheduled for service
208 enum update_reason {enqueue, requeue};
210 static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid)
212 struct qfq_sched *q = qdisc_priv(sch);
213 struct Qdisc_class_common *clc;
215 clc = qdisc_class_find(&q->clhash, classid);
218 return container_of(clc, struct qfq_class, common);
221 static void qfq_purge_queue(struct qfq_class *cl)
223 unsigned int len = cl->qdisc->q.qlen;
225 qdisc_reset(cl->qdisc);
226 qdisc_tree_decrease_qlen(cl->qdisc, len);
229 static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = {
230 [TCA_QFQ_WEIGHT] = { .type = NLA_U32 },
231 [TCA_QFQ_LMAX] = { .type = NLA_U32 },
235 * Calculate a flow index, given its weight and maximum packet length.
236 * index = log_2(maxlen/weight) but we need to apply the scaling.
237 * This is used only once at flow creation.
239 static int qfq_calc_index(u32 inv_w, unsigned int maxlen, u32 min_slot_shift)
241 u64 slot_size = (u64)maxlen * inv_w;
242 unsigned long size_map;
245 size_map = slot_size >> min_slot_shift;
249 index = __fls(size_map) + 1; /* basically a log_2 */
250 index -= !(slot_size - (1ULL << (index + min_slot_shift - 1)));
255 pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n",
256 (unsigned long) ONE_FP/inv_w, maxlen, index);
261 static void qfq_deactivate_agg(struct qfq_sched *, struct qfq_aggregate *);
262 static void qfq_activate_agg(struct qfq_sched *, struct qfq_aggregate *,
265 static void qfq_init_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
266 u32 lmax, u32 weight)
268 INIT_LIST_HEAD(&agg->active);
269 hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);
272 agg->class_weight = weight;
275 static struct qfq_aggregate *qfq_find_agg(struct qfq_sched *q,
276 u32 lmax, u32 weight)
278 struct qfq_aggregate *agg;
280 hlist_for_each_entry(agg, &q->nonfull_aggs, nonfull_next)
281 if (agg->lmax == lmax && agg->class_weight == weight)
288 /* Update aggregate as a function of the new number of classes. */
289 static void qfq_update_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
294 if (new_num_classes == q->max_agg_classes)
295 hlist_del_init(&agg->nonfull_next);
297 if (agg->num_classes > new_num_classes &&
298 new_num_classes == q->max_agg_classes - 1) /* agg no more full */
299 hlist_add_head(&agg->nonfull_next, &q->nonfull_aggs);
301 /* The next assignment may let
302 * agg->initial_budget > agg->budgetmax
303 * hold, we will take it into account in charge_actual_service().
305 agg->budgetmax = new_num_classes * agg->lmax;
306 new_agg_weight = agg->class_weight * new_num_classes;
307 agg->inv_w = ONE_FP/new_agg_weight;
309 if (agg->grp == NULL) {
310 int i = qfq_calc_index(agg->inv_w, agg->budgetmax,
312 agg->grp = &q->groups[i];
316 (int) agg->class_weight * (new_num_classes - agg->num_classes);
317 q->iwsum = ONE_FP / q->wsum;
319 agg->num_classes = new_num_classes;
322 /* Add class to aggregate. */
323 static void qfq_add_to_agg(struct qfq_sched *q,
324 struct qfq_aggregate *agg,
325 struct qfq_class *cl)
329 qfq_update_agg(q, agg, agg->num_classes+1);
330 if (cl->qdisc->q.qlen > 0) { /* adding an active class */
331 list_add_tail(&cl->alist, &agg->active);
332 if (list_first_entry(&agg->active, struct qfq_class, alist) ==
333 cl && q->in_serv_agg != agg) /* agg was inactive */
334 qfq_activate_agg(q, agg, enqueue); /* schedule agg */
338 static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *);
340 static void qfq_destroy_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
342 if (!hlist_unhashed(&agg->nonfull_next))
343 hlist_del_init(&agg->nonfull_next);
344 q->wsum -= agg->class_weight;
346 q->iwsum = ONE_FP / q->wsum;
348 if (q->in_serv_agg == agg)
349 q->in_serv_agg = qfq_choose_next_agg(q);
353 /* Deschedule class from within its parent aggregate. */
354 static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
356 struct qfq_aggregate *agg = cl->agg;
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);
364 /* Remove class from its parent aggregate. */
365 static void qfq_rm_from_agg(struct qfq_sched *q, struct qfq_class *cl)
367 struct qfq_aggregate *agg = cl->agg;
370 if (agg->num_classes == 1) { /* agg being emptied, destroy it */
371 qfq_destroy_agg(q, agg);
374 qfq_update_agg(q, agg, agg->num_classes-1);
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)
380 if (cl->qdisc->q.qlen > 0) /* class is active */
381 qfq_deactivate_class(q, cl);
383 qfq_rm_from_agg(q, cl);
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,
390 struct qfq_sched *q = qdisc_priv(sch);
391 struct qfq_aggregate *new_agg = qfq_find_agg(q, lmax, weight);
393 if (new_agg == NULL) { /* create new aggregate */
394 new_agg = kzalloc(sizeof(*new_agg), GFP_ATOMIC);
397 qfq_init_agg(q, new_agg, lmax, weight);
399 qfq_deact_rm_from_agg(q, cl);
400 qfq_add_to_agg(q, new_agg, cl);
405 static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
406 struct nlattr **tca, unsigned long *arg)
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;
417 if (tca[TCA_OPTIONS] == NULL) {
418 pr_notice("qfq: no options\n");
422 err = nla_parse_nested(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS], qfq_policy);
426 if (tb[TCA_QFQ_WEIGHT]) {
427 weight = nla_get_u32(tb[TCA_QFQ_WEIGHT]);
428 if (!weight || weight > (1UL << QFQ_MAX_WSHIFT)) {
429 pr_notice("qfq: invalid weight %u\n", weight);
435 if (tb[TCA_QFQ_LMAX]) {
436 lmax = nla_get_u32(tb[TCA_QFQ_LMAX]);
437 if (lmax < QFQ_MIN_LMAX || lmax > (1UL << QFQ_MTU_SHIFT)) {
438 pr_notice("qfq: invalid max length %u\n", lmax);
442 lmax = psched_mtu(qdisc_dev(sch));
444 inv_w = ONE_FP / weight;
445 weight = ONE_FP / inv_w;
448 lmax == cl->agg->lmax &&
449 weight == cl->agg->class_weight)
450 return 0; /* nothing to change */
452 delta_w = weight - (cl ? cl->agg->class_weight : 0);
454 if (q->wsum + delta_w > QFQ_MAX_WSUM) {
455 pr_notice("qfq: total weight out of range (%d + %u)\n",
460 if (cl != NULL) { /* modify existing class */
462 err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
463 qdisc_root_sleeping_lock(sch),
472 /* create and init new class */
473 cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL);
478 cl->common.classid = classid;
481 cl->qdisc = qdisc_create_dflt(sch->dev_queue,
482 &pfifo_qdisc_ops, classid);
483 if (cl->qdisc == NULL)
484 cl->qdisc = &noop_qdisc;
487 err = gen_new_estimator(&cl->bstats, &cl->rate_est,
488 qdisc_root_sleeping_lock(sch),
495 qdisc_class_hash_insert(&q->clhash, &cl->common);
496 sch_tree_unlock(sch);
498 qdisc_class_hash_grow(sch, &q->clhash);
502 new_agg = qfq_find_agg(q, lmax, weight);
503 if (new_agg == NULL) { /* create new aggregate */
504 sch_tree_unlock(sch);
505 new_agg = kzalloc(sizeof(*new_agg), GFP_KERNEL);
506 if (new_agg == NULL) {
508 gen_kill_estimator(&cl->bstats, &cl->rate_est);
512 qfq_init_agg(q, new_agg, lmax, weight);
515 qfq_deact_rm_from_agg(q, cl);
516 qfq_add_to_agg(q, new_agg, cl);
517 sch_tree_unlock(sch);
519 *arg = (unsigned long)cl;
523 qdisc_destroy(cl->qdisc);
528 static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl)
530 struct qfq_sched *q = qdisc_priv(sch);
532 qfq_rm_from_agg(q, cl);
533 gen_kill_estimator(&cl->bstats, &cl->rate_est);
534 qdisc_destroy(cl->qdisc);
538 static int qfq_delete_class(struct Qdisc *sch, unsigned long arg)
540 struct qfq_sched *q = qdisc_priv(sch);
541 struct qfq_class *cl = (struct qfq_class *)arg;
543 if (cl->filter_cnt > 0)
549 qdisc_class_hash_remove(&q->clhash, &cl->common);
551 BUG_ON(--cl->refcnt == 0);
553 * This shouldn't happen: we "hold" one cops->get() when called
554 * from tc_ctl_tclass; the destroy method is done from cops->put().
557 sch_tree_unlock(sch);
561 static unsigned long qfq_get_class(struct Qdisc *sch, u32 classid)
563 struct qfq_class *cl = qfq_find_class(sch, classid);
568 return (unsigned long)cl;
571 static void qfq_put_class(struct Qdisc *sch, unsigned long arg)
573 struct qfq_class *cl = (struct qfq_class *)arg;
575 if (--cl->refcnt == 0)
576 qfq_destroy_class(sch, cl);
579 static struct tcf_proto **qfq_tcf_chain(struct Qdisc *sch, unsigned long cl)
581 struct qfq_sched *q = qdisc_priv(sch);
586 return &q->filter_list;
589 static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent,
592 struct qfq_class *cl = qfq_find_class(sch, classid);
597 return (unsigned long)cl;
600 static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg)
602 struct qfq_class *cl = (struct qfq_class *)arg;
607 static int qfq_graft_class(struct Qdisc *sch, unsigned long arg,
608 struct Qdisc *new, struct Qdisc **old)
610 struct qfq_class *cl = (struct qfq_class *)arg;
613 new = qdisc_create_dflt(sch->dev_queue,
614 &pfifo_qdisc_ops, cl->common.classid);
623 sch_tree_unlock(sch);
627 static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg)
629 struct qfq_class *cl = (struct qfq_class *)arg;
634 static int qfq_dump_class(struct Qdisc *sch, unsigned long arg,
635 struct sk_buff *skb, struct tcmsg *tcm)
637 struct qfq_class *cl = (struct qfq_class *)arg;
640 tcm->tcm_parent = TC_H_ROOT;
641 tcm->tcm_handle = cl->common.classid;
642 tcm->tcm_info = cl->qdisc->handle;
644 nest = nla_nest_start(skb, TCA_OPTIONS);
646 goto nla_put_failure;
647 if (nla_put_u32(skb, TCA_QFQ_WEIGHT, cl->agg->class_weight) ||
648 nla_put_u32(skb, TCA_QFQ_LMAX, cl->agg->lmax))
649 goto nla_put_failure;
650 return nla_nest_end(skb, nest);
653 nla_nest_cancel(skb, nest);
657 static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg,
660 struct qfq_class *cl = (struct qfq_class *)arg;
661 struct tc_qfq_stats xstats;
663 memset(&xstats, 0, sizeof(xstats));
664 cl->qdisc->qstats.qlen = cl->qdisc->q.qlen;
666 xstats.weight = cl->agg->class_weight;
667 xstats.lmax = cl->agg->lmax;
669 if (gnet_stats_copy_basic(d, &cl->bstats) < 0 ||
670 gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
671 gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0)
674 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
677 static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
679 struct qfq_sched *q = qdisc_priv(sch);
680 struct qfq_class *cl;
686 for (i = 0; i < q->clhash.hashsize; i++) {
687 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
688 if (arg->count < arg->skip) {
692 if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
701 static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch,
704 struct qfq_sched *q = qdisc_priv(sch);
705 struct qfq_class *cl;
706 struct tcf_result res;
709 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
710 pr_debug("qfq_classify: found %d\n", skb->priority);
711 cl = qfq_find_class(sch, skb->priority);
716 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
717 result = tc_classify(skb, q->filter_list, &res);
719 #ifdef CONFIG_NET_CLS_ACT
723 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
728 cl = (struct qfq_class *)res.class;
730 cl = qfq_find_class(sch, res.classid);
737 /* Generic comparison function, handling wraparound. */
738 static inline int qfq_gt(u64 a, u64 b)
740 return (s64)(a - b) > 0;
743 /* Round a precise timestamp to its slotted value. */
744 static inline u64 qfq_round_down(u64 ts, unsigned int shift)
746 return ts & ~((1ULL << shift) - 1);
749 /* return the pointer to the group with lowest index in the bitmap */
750 static inline struct qfq_group *qfq_ffs(struct qfq_sched *q,
751 unsigned long bitmap)
753 int index = __ffs(bitmap);
754 return &q->groups[index];
756 /* Calculate a mask to mimic what would be ffs_from(). */
757 static inline unsigned long mask_from(unsigned long bitmap, int from)
759 return bitmap & ~((1UL << from) - 1);
763 * The state computation relies on ER=0, IR=1, EB=2, IB=3
764 * First compute eligibility comparing grp->S, q->V,
765 * then check if someone is blocking us and possibly add EB
767 static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp)
769 /* if S > V we are not eligible */
770 unsigned int state = qfq_gt(grp->S, q->V);
771 unsigned long mask = mask_from(q->bitmaps[ER], grp->index);
772 struct qfq_group *next;
775 next = qfq_ffs(q, mask);
776 if (qfq_gt(grp->F, next->F))
786 * q->bitmaps[dst] |= q->bitmaps[src] & mask;
787 * q->bitmaps[src] &= ~mask;
788 * but we should make sure that src != dst
790 static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask,
793 q->bitmaps[dst] |= q->bitmaps[src] & mask;
794 q->bitmaps[src] &= ~mask;
797 static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F)
799 unsigned long mask = mask_from(q->bitmaps[ER], index + 1);
800 struct qfq_group *next;
803 next = qfq_ffs(q, mask);
804 if (!qfq_gt(next->F, old_F))
808 mask = (1UL << index) - 1;
809 qfq_move_groups(q, mask, EB, ER);
810 qfq_move_groups(q, mask, IB, IR);
817 old_V >>= q->min_slot_shift;
823 static void qfq_make_eligible(struct qfq_sched *q)
825 unsigned long vslot = q->V >> q->min_slot_shift;
826 unsigned long old_vslot = q->oldV >> q->min_slot_shift;
828 if (vslot != old_vslot) {
829 unsigned long mask = (1ULL << fls(vslot ^ old_vslot)) - 1;
830 qfq_move_groups(q, mask, IR, ER);
831 qfq_move_groups(q, mask, IB, EB);
836 * The index of the slot in which the input aggregate agg is to be
837 * inserted must not be higher than QFQ_MAX_SLOTS-2. There is a '-2'
838 * and not a '-1' because the start time of the group may be moved
839 * backward by one slot after the aggregate has been inserted, and
840 * this would cause non-empty slots to be right-shifted by one
843 * QFQ+ fully satisfies this bound to the slot index if the parameters
844 * of the classes are not changed dynamically, and if QFQ+ never
845 * happens to postpone the service of agg unjustly, i.e., it never
846 * happens that the aggregate becomes backlogged and eligible, or just
847 * eligible, while an aggregate with a higher approximated finish time
848 * is being served. In particular, in this case QFQ+ guarantees that
849 * the timestamps of agg are low enough that the slot index is never
850 * higher than 2. Unfortunately, QFQ+ cannot provide the same
851 * guarantee if it happens to unjustly postpone the service of agg, or
852 * if the parameters of some class are changed.
854 * As for the first event, i.e., an out-of-order service, the
855 * upper bound to the slot index guaranteed by QFQ+ grows to
857 * QFQ_MAX_AGG_CLASSES * ((1<<QFQ_MTU_SHIFT)/QFQ_MIN_LMAX) *
858 * (current_max_weight/current_wsum) <= 2 + 8 * 128 * 1.
860 * The following function deals with this problem by backward-shifting
861 * the timestamps of agg, if needed, so as to guarantee that the slot
862 * index is never higher than QFQ_MAX_SLOTS-2. This backward-shift may
863 * cause the service of other aggregates to be postponed, yet the
864 * worst-case guarantees of these aggregates are not violated. In
865 * fact, in case of no out-of-order service, the timestamps of agg
866 * would have been even lower than they are after the backward shift,
867 * because QFQ+ would have guaranteed a maximum value equal to 2 for
868 * the slot index, and 2 < QFQ_MAX_SLOTS-2. Hence the aggregates whose
869 * service is postponed because of the backward-shift would have
870 * however waited for the service of agg before being served.
872 * The other event that may cause the slot index to be higher than 2
873 * for agg is a recent change of the parameters of some class. If the
874 * weight of a class is increased or the lmax (max_pkt_size) of the
875 * class is decreased, then a new aggregate with smaller slot size
876 * than the original parent aggregate of the class may happen to be
877 * activated. The activation of this aggregate should be properly
878 * delayed to when the service of the class has finished in the ideal
879 * system tracked by QFQ+. If the activation of the aggregate is not
880 * delayed to this reference time instant, then this aggregate may be
881 * unjustly served before other aggregates waiting for service. This
882 * may cause the above bound to the slot index to be violated for some
883 * of these unlucky aggregates.
885 * Instead of delaying the activation of the new aggregate, which is
886 * quite complex, the above-discussed capping of the slot index is
887 * used to handle also the consequences of a change of the parameters
890 static void qfq_slot_insert(struct qfq_group *grp, struct qfq_aggregate *agg,
893 u64 slot = (roundedS - grp->S) >> grp->slot_shift;
894 unsigned int i; /* slot index in the bucket list */
896 if (unlikely(slot > QFQ_MAX_SLOTS - 2)) {
897 u64 deltaS = roundedS - grp->S -
898 ((u64)(QFQ_MAX_SLOTS - 2)<<grp->slot_shift);
901 slot = QFQ_MAX_SLOTS - 2;
904 i = (grp->front + slot) % QFQ_MAX_SLOTS;
906 hlist_add_head(&agg->next, &grp->slots[i]);
907 __set_bit(slot, &grp->full_slots);
910 /* Maybe introduce hlist_first_entry?? */
911 static struct qfq_aggregate *qfq_slot_head(struct qfq_group *grp)
913 return hlist_entry(grp->slots[grp->front].first,
914 struct qfq_aggregate, next);
918 * remove the entry from the slot
920 static void qfq_front_slot_remove(struct qfq_group *grp)
922 struct qfq_aggregate *agg = qfq_slot_head(grp);
925 hlist_del(&agg->next);
926 if (hlist_empty(&grp->slots[grp->front]))
927 __clear_bit(0, &grp->full_slots);
931 * Returns the first aggregate in the first non-empty bucket of the
932 * group. As a side effect, adjusts the bucket list so the first
933 * non-empty bucket is at position 0 in full_slots.
935 static struct qfq_aggregate *qfq_slot_scan(struct qfq_group *grp)
939 pr_debug("qfq slot_scan: grp %u full %#lx\n",
940 grp->index, grp->full_slots);
942 if (grp->full_slots == 0)
945 i = __ffs(grp->full_slots); /* zero based */
947 grp->front = (grp->front + i) % QFQ_MAX_SLOTS;
948 grp->full_slots >>= i;
951 return qfq_slot_head(grp);
955 * adjust the bucket list. When the start time of a group decreases,
956 * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to
957 * move the objects. The mask of occupied slots must be shifted
958 * because we use ffs() to find the first non-empty slot.
959 * This covers decreases in the group's start time, but what about
960 * increases of the start time ?
961 * Here too we should make sure that i is less than 32
963 static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS)
965 unsigned int i = (grp->S - roundedS) >> grp->slot_shift;
967 grp->full_slots <<= i;
968 grp->front = (grp->front - i) % QFQ_MAX_SLOTS;
971 static void qfq_update_eligible(struct qfq_sched *q)
973 struct qfq_group *grp;
974 unsigned long ineligible;
976 ineligible = q->bitmaps[IR] | q->bitmaps[IB];
978 if (!q->bitmaps[ER]) {
979 grp = qfq_ffs(q, ineligible);
980 if (qfq_gt(grp->S, q->V))
983 qfq_make_eligible(q);
987 /* Dequeue head packet of the head class in the DRR queue of the aggregate. */
988 static void agg_dequeue(struct qfq_aggregate *agg,
989 struct qfq_class *cl, unsigned int len)
991 qdisc_dequeue_peeked(cl->qdisc);
993 cl->deficit -= (int) len;
995 if (cl->qdisc->q.qlen == 0) /* no more packets, remove from list */
996 list_del(&cl->alist);
997 else if (cl->deficit < qdisc_pkt_len(cl->qdisc->ops->peek(cl->qdisc))) {
998 cl->deficit += agg->lmax;
999 list_move_tail(&cl->alist, &agg->active);
1003 static inline struct sk_buff *qfq_peek_skb(struct qfq_aggregate *agg,
1004 struct qfq_class **cl,
1007 struct sk_buff *skb;
1009 *cl = list_first_entry(&agg->active, struct qfq_class, alist);
1010 skb = (*cl)->qdisc->ops->peek((*cl)->qdisc);
1012 WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n");
1014 *len = qdisc_pkt_len(skb);
1019 /* Update F according to the actual service received by the aggregate. */
1020 static inline void charge_actual_service(struct qfq_aggregate *agg)
1022 /* Compute the service received by the aggregate, taking into
1023 * account that, after decreasing the number of classes in
1024 * agg, it may happen that
1025 * agg->initial_budget - agg->budget > agg->bugdetmax
1027 u32 service_received = min(agg->budgetmax,
1028 agg->initial_budget - agg->budget);
1030 agg->F = agg->S + (u64)service_received * agg->inv_w;
1033 static inline void qfq_update_agg_ts(struct qfq_sched *q,
1034 struct qfq_aggregate *agg,
1035 enum update_reason reason);
1037 static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg);
1039 static struct sk_buff *qfq_dequeue(struct Qdisc *sch)
1041 struct qfq_sched *q = qdisc_priv(sch);
1042 struct qfq_aggregate *in_serv_agg = q->in_serv_agg;
1043 struct qfq_class *cl;
1044 struct sk_buff *skb = NULL;
1045 /* next-packet len, 0 means no more active classes in in-service agg */
1046 unsigned int len = 0;
1048 if (in_serv_agg == NULL)
1051 if (!list_empty(&in_serv_agg->active))
1052 skb = qfq_peek_skb(in_serv_agg, &cl, &len);
1055 * If there are no active classes in the in-service aggregate,
1056 * or if the aggregate has not enough budget to serve its next
1057 * class, then choose the next aggregate to serve.
1059 if (len == 0 || in_serv_agg->budget < len) {
1060 charge_actual_service(in_serv_agg);
1062 /* recharge the budget of the aggregate */
1063 in_serv_agg->initial_budget = in_serv_agg->budget =
1064 in_serv_agg->budgetmax;
1066 if (!list_empty(&in_serv_agg->active)) {
1068 * Still active: reschedule for
1069 * service. Possible optimization: if no other
1070 * aggregate is active, then there is no point
1071 * in rescheduling this aggregate, and we can
1072 * just keep it as the in-service one. This
1073 * should be however a corner case, and to
1074 * handle it, we would need to maintain an
1075 * extra num_active_aggs field.
1077 qfq_update_agg_ts(q, in_serv_agg, requeue);
1078 qfq_schedule_agg(q, in_serv_agg);
1079 } else if (sch->q.qlen == 0) { /* no aggregate to serve */
1080 q->in_serv_agg = NULL;
1085 * If we get here, there are other aggregates queued:
1086 * choose the new aggregate to serve.
1088 in_serv_agg = q->in_serv_agg = qfq_choose_next_agg(q);
1089 skb = qfq_peek_skb(in_serv_agg, &cl, &len);
1095 qdisc_bstats_update(sch, skb);
1097 agg_dequeue(in_serv_agg, cl, len);
1098 /* If lmax is lowered, through qfq_change_class, for a class
1099 * owning pending packets with larger size than the new value
1100 * of lmax, then the following condition may hold.
1102 if (unlikely(in_serv_agg->budget < len))
1103 in_serv_agg->budget = 0;
1105 in_serv_agg->budget -= len;
1107 q->V += (u64)len * q->iwsum;
1108 pr_debug("qfq dequeue: len %u F %lld now %lld\n",
1109 len, (unsigned long long) in_serv_agg->F,
1110 (unsigned long long) q->V);
1115 static struct qfq_aggregate *qfq_choose_next_agg(struct qfq_sched *q)
1117 struct qfq_group *grp;
1118 struct qfq_aggregate *agg, *new_front_agg;
1121 qfq_update_eligible(q);
1124 if (!q->bitmaps[ER])
1127 grp = qfq_ffs(q, q->bitmaps[ER]);
1130 agg = qfq_slot_head(grp);
1132 /* agg starts to be served, remove it from schedule */
1133 qfq_front_slot_remove(grp);
1135 new_front_agg = qfq_slot_scan(grp);
1137 if (new_front_agg == NULL) /* group is now inactive, remove from ER */
1138 __clear_bit(grp->index, &q->bitmaps[ER]);
1140 u64 roundedS = qfq_round_down(new_front_agg->S,
1144 if (grp->S == roundedS)
1147 grp->F = roundedS + (2ULL << grp->slot_shift);
1148 __clear_bit(grp->index, &q->bitmaps[ER]);
1149 s = qfq_calc_state(q, grp);
1150 __set_bit(grp->index, &q->bitmaps[s]);
1153 qfq_unblock_groups(q, grp->index, old_F);
1159 * Assign a reasonable start time for a new aggregate in group i.
1160 * Admissible values for \hat(F) are multiples of \sigma_i
1161 * no greater than V+\sigma_i . Larger values mean that
1162 * we had a wraparound so we consider the timestamp to be stale.
1164 * If F is not stale and F >= V then we set S = F.
1165 * Otherwise we should assign S = V, but this may violate
1166 * the ordering in EB (see [2]). So, if we have groups in ER,
1167 * set S to the F_j of the first group j which would be blocking us.
1168 * We are guaranteed not to move S backward because
1169 * otherwise our group i would still be blocked.
1171 static void qfq_update_start(struct qfq_sched *q, struct qfq_aggregate *agg)
1174 u64 limit, roundedF;
1175 int slot_shift = agg->grp->slot_shift;
1177 roundedF = qfq_round_down(agg->F, slot_shift);
1178 limit = qfq_round_down(q->V, slot_shift) + (1ULL << slot_shift);
1180 if (!qfq_gt(agg->F, q->V) || qfq_gt(roundedF, limit)) {
1181 /* timestamp was stale */
1182 mask = mask_from(q->bitmaps[ER], agg->grp->index);
1184 struct qfq_group *next = qfq_ffs(q, mask);
1185 if (qfq_gt(roundedF, next->F)) {
1186 if (qfq_gt(limit, next->F))
1188 else /* preserve timestamp correctness */
1194 } else /* timestamp is not stale */
1199 * Update the timestamps of agg before scheduling/rescheduling it for
1200 * service. In particular, assign to agg->F its maximum possible
1201 * value, i.e., the virtual finish time with which the aggregate
1202 * should be labeled if it used all its budget once in service.
1205 qfq_update_agg_ts(struct qfq_sched *q,
1206 struct qfq_aggregate *agg, enum update_reason reason)
1208 if (reason != requeue)
1209 qfq_update_start(q, agg);
1210 else /* just charge agg for the service received */
1213 agg->F = agg->S + (u64)agg->budgetmax * agg->inv_w;
1216 static void qfq_schedule_agg(struct qfq_sched *, struct qfq_aggregate *);
1218 static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
1220 struct qfq_sched *q = qdisc_priv(sch);
1221 struct qfq_class *cl;
1222 struct qfq_aggregate *agg;
1225 cl = qfq_classify(skb, sch, &err);
1227 if (err & __NET_XMIT_BYPASS)
1228 sch->qstats.drops++;
1232 pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid);
1234 if (unlikely(cl->agg->lmax < qdisc_pkt_len(skb))) {
1235 pr_debug("qfq: increasing maxpkt from %u to %u for class %u",
1236 cl->agg->lmax, qdisc_pkt_len(skb), cl->common.classid);
1237 err = qfq_change_agg(sch, cl, cl->agg->class_weight,
1238 qdisc_pkt_len(skb));
1243 err = qdisc_enqueue(skb, cl->qdisc);
1244 if (unlikely(err != NET_XMIT_SUCCESS)) {
1245 pr_debug("qfq_enqueue: enqueue failed %d\n", err);
1246 if (net_xmit_drop_count(err)) {
1248 sch->qstats.drops++;
1253 bstats_update(&cl->bstats, skb);
1257 /* if the queue was not empty, then done here */
1258 if (cl->qdisc->q.qlen != 1) {
1259 if (unlikely(skb == cl->qdisc->ops->peek(cl->qdisc)) &&
1260 list_first_entry(&agg->active, struct qfq_class, alist)
1261 == cl && cl->deficit < qdisc_pkt_len(skb))
1262 list_move_tail(&cl->alist, &agg->active);
1267 /* schedule class for service within the aggregate */
1268 cl->deficit = agg->lmax;
1269 list_add_tail(&cl->alist, &agg->active);
1271 if (list_first_entry(&agg->active, struct qfq_class, alist) != cl ||
1272 q->in_serv_agg == agg)
1273 return err; /* non-empty or in service, nothing else to do */
1275 qfq_activate_agg(q, agg, enqueue);
1281 * Schedule aggregate according to its timestamps.
1283 static void qfq_schedule_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
1285 struct qfq_group *grp = agg->grp;
1289 roundedS = qfq_round_down(agg->S, grp->slot_shift);
1292 * Insert agg in the correct bucket.
1293 * If agg->S >= grp->S we don't need to adjust the
1294 * bucket list and simply go to the insertion phase.
1295 * Otherwise grp->S is decreasing, we must make room
1296 * in the bucket list, and also recompute the group state.
1297 * Finally, if there were no flows in this group and nobody
1298 * was in ER make sure to adjust V.
1300 if (grp->full_slots) {
1301 if (!qfq_gt(grp->S, agg->S))
1304 /* create a slot for this agg->S */
1305 qfq_slot_rotate(grp, roundedS);
1306 /* group was surely ineligible, remove */
1307 __clear_bit(grp->index, &q->bitmaps[IR]);
1308 __clear_bit(grp->index, &q->bitmaps[IB]);
1309 } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V) &&
1310 q->in_serv_agg == NULL)
1314 grp->F = roundedS + (2ULL << grp->slot_shift);
1315 s = qfq_calc_state(q, grp);
1316 __set_bit(grp->index, &q->bitmaps[s]);
1318 pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n",
1320 (unsigned long long) agg->S,
1321 (unsigned long long) agg->F,
1322 (unsigned long long) q->V);
1325 qfq_slot_insert(grp, agg, roundedS);
1329 /* Update agg ts and schedule agg for service */
1330 static void qfq_activate_agg(struct qfq_sched *q, struct qfq_aggregate *agg,
1331 enum update_reason reason)
1333 agg->initial_budget = agg->budget = agg->budgetmax; /* recharge budg. */
1335 qfq_update_agg_ts(q, agg, reason);
1336 if (q->in_serv_agg == NULL) { /* no aggr. in service or scheduled */
1337 q->in_serv_agg = agg; /* start serving this aggregate */
1338 /* update V: to be in service, agg must be eligible */
1339 q->oldV = q->V = agg->S;
1340 } else if (agg != q->in_serv_agg)
1341 qfq_schedule_agg(q, agg);
1344 static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp,
1345 struct qfq_aggregate *agg)
1347 unsigned int i, offset;
1350 roundedS = qfq_round_down(agg->S, grp->slot_shift);
1351 offset = (roundedS - grp->S) >> grp->slot_shift;
1353 i = (grp->front + offset) % QFQ_MAX_SLOTS;
1355 hlist_del(&agg->next);
1356 if (hlist_empty(&grp->slots[i]))
1357 __clear_bit(offset, &grp->full_slots);
1361 * Called to forcibly deschedule an aggregate. If the aggregate is
1362 * not in the front bucket, or if the latter has other aggregates in
1363 * the front bucket, we can simply remove the aggregate with no other
1365 * Otherwise we must propagate the event up.
1367 static void qfq_deactivate_agg(struct qfq_sched *q, struct qfq_aggregate *agg)
1369 struct qfq_group *grp = agg->grp;
1374 if (agg == q->in_serv_agg) {
1375 charge_actual_service(agg);
1376 q->in_serv_agg = qfq_choose_next_agg(q);
1381 qfq_slot_remove(q, grp, agg);
1383 if (!grp->full_slots) {
1384 __clear_bit(grp->index, &q->bitmaps[IR]);
1385 __clear_bit(grp->index, &q->bitmaps[EB]);
1386 __clear_bit(grp->index, &q->bitmaps[IB]);
1388 if (test_bit(grp->index, &q->bitmaps[ER]) &&
1389 !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) {
1390 mask = q->bitmaps[ER] & ((1UL << grp->index) - 1);
1392 mask = ~((1UL << __fls(mask)) - 1);
1395 qfq_move_groups(q, mask, EB, ER);
1396 qfq_move_groups(q, mask, IB, IR);
1398 __clear_bit(grp->index, &q->bitmaps[ER]);
1399 } else if (hlist_empty(&grp->slots[grp->front])) {
1400 agg = qfq_slot_scan(grp);
1401 roundedS = qfq_round_down(agg->S, grp->slot_shift);
1402 if (grp->S != roundedS) {
1403 __clear_bit(grp->index, &q->bitmaps[ER]);
1404 __clear_bit(grp->index, &q->bitmaps[IR]);
1405 __clear_bit(grp->index, &q->bitmaps[EB]);
1406 __clear_bit(grp->index, &q->bitmaps[IB]);
1408 grp->F = roundedS + (2ULL << grp->slot_shift);
1409 s = qfq_calc_state(q, grp);
1410 __set_bit(grp->index, &q->bitmaps[s]);
1415 static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg)
1417 struct qfq_sched *q = qdisc_priv(sch);
1418 struct qfq_class *cl = (struct qfq_class *)arg;
1420 if (cl->qdisc->q.qlen == 0)
1421 qfq_deactivate_class(q, cl);
1424 static unsigned int qfq_drop_from_slot(struct qfq_sched *q,
1425 struct hlist_head *slot)
1427 struct qfq_aggregate *agg;
1428 struct qfq_class *cl;
1431 hlist_for_each_entry(agg, slot, next) {
1432 list_for_each_entry(cl, &agg->active, alist) {
1434 if (!cl->qdisc->ops->drop)
1437 len = cl->qdisc->ops->drop(cl->qdisc);
1439 if (cl->qdisc->q.qlen == 0)
1440 qfq_deactivate_class(q, cl);
1449 static unsigned int qfq_drop(struct Qdisc *sch)
1451 struct qfq_sched *q = qdisc_priv(sch);
1452 struct qfq_group *grp;
1453 unsigned int i, j, len;
1455 for (i = 0; i <= QFQ_MAX_INDEX; i++) {
1456 grp = &q->groups[i];
1457 for (j = 0; j < QFQ_MAX_SLOTS; j++) {
1458 len = qfq_drop_from_slot(q, &grp->slots[j]);
1470 static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
1472 struct qfq_sched *q = qdisc_priv(sch);
1473 struct qfq_group *grp;
1475 u32 max_cl_shift, maxbudg_shift, max_classes;
1477 err = qdisc_class_hash_init(&q->clhash);
1481 if (qdisc_dev(sch)->tx_queue_len + 1 > QFQ_MAX_AGG_CLASSES)
1482 max_classes = QFQ_MAX_AGG_CLASSES;
1484 max_classes = qdisc_dev(sch)->tx_queue_len + 1;
1485 /* max_cl_shift = floor(log_2(max_classes)) */
1486 max_cl_shift = __fls(max_classes);
1487 q->max_agg_classes = 1<<max_cl_shift;
1489 /* maxbudg_shift = log2(max_len * max_classes_per_agg) */
1490 maxbudg_shift = QFQ_MTU_SHIFT + max_cl_shift;
1491 q->min_slot_shift = FRAC_BITS + maxbudg_shift - QFQ_MAX_INDEX;
1493 for (i = 0; i <= QFQ_MAX_INDEX; i++) {
1494 grp = &q->groups[i];
1496 grp->slot_shift = q->min_slot_shift + i;
1497 for (j = 0; j < QFQ_MAX_SLOTS; j++)
1498 INIT_HLIST_HEAD(&grp->slots[j]);
1501 INIT_HLIST_HEAD(&q->nonfull_aggs);
1506 static void qfq_reset_qdisc(struct Qdisc *sch)
1508 struct qfq_sched *q = qdisc_priv(sch);
1509 struct qfq_class *cl;
1512 for (i = 0; i < q->clhash.hashsize; i++) {
1513 hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
1514 if (cl->qdisc->q.qlen > 0)
1515 qfq_deactivate_class(q, cl);
1517 qdisc_reset(cl->qdisc);
1523 static void qfq_destroy_qdisc(struct Qdisc *sch)
1525 struct qfq_sched *q = qdisc_priv(sch);
1526 struct qfq_class *cl;
1527 struct hlist_node *next;
1530 tcf_destroy_chain(&q->filter_list);
1532 for (i = 0; i < q->clhash.hashsize; i++) {
1533 hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
1535 qfq_destroy_class(sch, cl);
1538 qdisc_class_hash_destroy(&q->clhash);
1541 static const struct Qdisc_class_ops qfq_class_ops = {
1542 .change = qfq_change_class,
1543 .delete = qfq_delete_class,
1544 .get = qfq_get_class,
1545 .put = qfq_put_class,
1546 .tcf_chain = qfq_tcf_chain,
1547 .bind_tcf = qfq_bind_tcf,
1548 .unbind_tcf = qfq_unbind_tcf,
1549 .graft = qfq_graft_class,
1550 .leaf = qfq_class_leaf,
1551 .qlen_notify = qfq_qlen_notify,
1552 .dump = qfq_dump_class,
1553 .dump_stats = qfq_dump_class_stats,
1557 static struct Qdisc_ops qfq_qdisc_ops __read_mostly = {
1558 .cl_ops = &qfq_class_ops,
1560 .priv_size = sizeof(struct qfq_sched),
1561 .enqueue = qfq_enqueue,
1562 .dequeue = qfq_dequeue,
1563 .peek = qdisc_peek_dequeued,
1565 .init = qfq_init_qdisc,
1566 .reset = qfq_reset_qdisc,
1567 .destroy = qfq_destroy_qdisc,
1568 .owner = THIS_MODULE,
1571 static int __init qfq_init(void)
1573 return register_qdisc(&qfq_qdisc_ops);
1576 static void __exit qfq_exit(void)
1578 unregister_qdisc(&qfq_qdisc_ops);
1581 module_init(qfq_init);
1582 module_exit(qfq_exit);
1583 MODULE_LICENSE("GPL");