blob: 7b0325459e718c6c0fb8d259ef7e10ecc6353130 [file] [log] [blame]
stephen hemminger0545a302011-04-04 05:30:58 +00001/*
2 * net/sched/sch_qfq.c Quick Fair Queueing Scheduler.
3 *
4 * Copyright (c) 2009 Fabio Checconi, Luigi Rizzo, and Paolo Valente.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * version 2 as published by the Free Software Foundation.
9 */
10
11#include <linux/module.h>
12#include <linux/init.h>
13#include <linux/bitops.h>
14#include <linux/errno.h>
15#include <linux/netdevice.h>
16#include <linux/pkt_sched.h>
17#include <net/sch_generic.h>
18#include <net/pkt_sched.h>
19#include <net/pkt_cls.h>
20
21
22/* Quick Fair Queueing
23 ===================
24
25 Sources:
26
27 Fabio Checconi, Luigi Rizzo, and Paolo Valente: "QFQ: Efficient
28 Packet Scheduling with Tight Bandwidth Distribution Guarantees."
29
30 See also:
31 http://retis.sssup.it/~fabio/linux/qfq/
32 */
33
34/*
35
36 Virtual time computations.
37
38 S, F and V are all computed in fixed point arithmetic with
39 FRAC_BITS decimal bits.
40
41 QFQ_MAX_INDEX is the maximum index allowed for a group. We need
42 one bit per index.
43 QFQ_MAX_WSHIFT is the maximum power of two supported as a weight.
44
45 The layout of the bits is as below:
46
47 [ MTU_SHIFT ][ FRAC_BITS ]
48 [ MAX_INDEX ][ MIN_SLOT_SHIFT ]
49 ^.__grp->index = 0
50 *.__grp->slot_shift
51
52 where MIN_SLOT_SHIFT is derived by difference from the others.
53
54 The max group index corresponds to Lmax/w_min, where
55 Lmax=1<<MTU_SHIFT, w_min = 1 .
56 From this, and knowing how many groups (MAX_INDEX) we want,
57 we can derive the shift corresponding to each group.
58
59 Because we often need to compute
60 F = S + len/w_i and V = V + len/wsum
61 instead of storing w_i store the value
62 inv_w = (1<<FRAC_BITS)/w_i
63 so we can do F = S + len * inv_w * wsum.
64 We use W_TOT in the formulas so we can easily move between
65 static and adaptive weight sum.
66
67 The per-scheduler-instance data contain all the data structures
68 for the scheduler: bitmaps and bucket lists.
69
70 */
71
72/*
73 * Maximum number of consecutive slots occupied by backlogged classes
74 * inside a group.
75 */
76#define QFQ_MAX_SLOTS 32
77
78/*
79 * Shifts used for class<->group mapping. We allow class weights that are
80 * in the range [1, 2^MAX_WSHIFT], and we try to map each class i to the
81 * group with the smallest index that can support the L_i / r_i configured
82 * for the class.
83 *
84 * grp->index is the index of the group; and grp->slot_shift
85 * is the shift for the corresponding (scaled) sigma_i.
86 */
87#define QFQ_MAX_INDEX 19
88#define QFQ_MAX_WSHIFT 16
89
90#define QFQ_MAX_WEIGHT (1<<QFQ_MAX_WSHIFT)
91#define QFQ_MAX_WSUM (2*QFQ_MAX_WEIGHT)
92
93#define FRAC_BITS 30 /* fixed point arithmetic */
94#define ONE_FP (1UL << FRAC_BITS)
95#define IWSUM (ONE_FP/QFQ_MAX_WSUM)
96
97#define QFQ_MTU_SHIFT 11
98#define QFQ_MIN_SLOT_SHIFT (FRAC_BITS + QFQ_MTU_SHIFT - QFQ_MAX_INDEX)
99
100/*
101 * Possible group states. These values are used as indexes for the bitmaps
102 * array of struct qfq_queue.
103 */
104enum qfq_state { ER, IR, EB, IB, QFQ_MAX_STATE };
105
106struct qfq_group;
107
108struct qfq_class {
109 struct Qdisc_class_common common;
110
111 unsigned int refcnt;
112 unsigned int filter_cnt;
113
114 struct gnet_stats_basic_packed bstats;
115 struct gnet_stats_queue qstats;
116 struct gnet_stats_rate_est rate_est;
117 struct Qdisc *qdisc;
118
119 struct hlist_node next; /* Link for the slot list. */
120 u64 S, F; /* flow timestamps (exact) */
121
122 /* group we belong to. In principle we would need the index,
123 * which is log_2(lmax/weight), but we never reference it
124 * directly, only the group.
125 */
126 struct qfq_group *grp;
127
128 /* these are copied from the flowset. */
129 u32 inv_w; /* ONE_FP/weight */
130 u32 lmax; /* Max packet size for this flow. */
131};
132
133struct qfq_group {
134 u64 S, F; /* group timestamps (approx). */
135 unsigned int slot_shift; /* Slot shift. */
136 unsigned int index; /* Group index. */
137 unsigned int front; /* Index of the front slot. */
138 unsigned long full_slots; /* non-empty slots */
139
140 /* Array of RR lists of active classes. */
141 struct hlist_head slots[QFQ_MAX_SLOTS];
142};
143
144struct qfq_sched {
145 struct tcf_proto *filter_list;
146 struct Qdisc_class_hash clhash;
147
148 u64 V; /* Precise virtual time. */
149 u32 wsum; /* weight sum */
150
151 unsigned long bitmaps[QFQ_MAX_STATE]; /* Group bitmaps. */
152 struct qfq_group groups[QFQ_MAX_INDEX + 1]; /* The groups. */
153};
154
155static struct qfq_class *qfq_find_class(struct Qdisc *sch, u32 classid)
156{
157 struct qfq_sched *q = qdisc_priv(sch);
158 struct Qdisc_class_common *clc;
159
160 clc = qdisc_class_find(&q->clhash, classid);
161 if (clc == NULL)
162 return NULL;
163 return container_of(clc, struct qfq_class, common);
164}
165
166static void qfq_purge_queue(struct qfq_class *cl)
167{
168 unsigned int len = cl->qdisc->q.qlen;
169
170 qdisc_reset(cl->qdisc);
171 qdisc_tree_decrease_qlen(cl->qdisc, len);
172}
173
174static const struct nla_policy qfq_policy[TCA_QFQ_MAX + 1] = {
175 [TCA_QFQ_WEIGHT] = { .type = NLA_U32 },
176 [TCA_QFQ_LMAX] = { .type = NLA_U32 },
177};
178
179/*
180 * Calculate a flow index, given its weight and maximum packet length.
181 * index = log_2(maxlen/weight) but we need to apply the scaling.
182 * This is used only once at flow creation.
183 */
184static int qfq_calc_index(u32 inv_w, unsigned int maxlen)
185{
186 u64 slot_size = (u64)maxlen * inv_w;
187 unsigned long size_map;
188 int index = 0;
189
190 size_map = slot_size >> QFQ_MIN_SLOT_SHIFT;
191 if (!size_map)
192 goto out;
193
194 index = __fls(size_map) + 1; /* basically a log_2 */
195 index -= !(slot_size - (1ULL << (index + QFQ_MIN_SLOT_SHIFT - 1)));
196
197 if (index < 0)
198 index = 0;
199out:
200 pr_debug("qfq calc_index: W = %lu, L = %u, I = %d\n",
201 (unsigned long) ONE_FP/inv_w, maxlen, index);
202
203 return index;
204}
205
206static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
207 struct nlattr **tca, unsigned long *arg)
208{
209 struct qfq_sched *q = qdisc_priv(sch);
210 struct qfq_class *cl = (struct qfq_class *)*arg;
211 struct nlattr *tb[TCA_QFQ_MAX + 1];
212 u32 weight, lmax, inv_w;
213 int i, err;
214
215 if (tca[TCA_OPTIONS] == NULL) {
216 pr_notice("qfq: no options\n");
217 return -EINVAL;
218 }
219
220 err = nla_parse_nested(tb, TCA_QFQ_MAX, tca[TCA_OPTIONS], qfq_policy);
221 if (err < 0)
222 return err;
223
224 if (tb[TCA_QFQ_WEIGHT]) {
225 weight = nla_get_u32(tb[TCA_QFQ_WEIGHT]);
226 if (!weight || weight > (1UL << QFQ_MAX_WSHIFT)) {
227 pr_notice("qfq: invalid weight %u\n", weight);
228 return -EINVAL;
229 }
230 } else
231 weight = 1;
232
233 inv_w = ONE_FP / weight;
234 weight = ONE_FP / inv_w;
235 if (q->wsum + weight > QFQ_MAX_WSUM) {
236 pr_notice("qfq: total weight out of range (%u + %u)\n",
237 weight, q->wsum);
238 return -EINVAL;
239 }
240
241 if (tb[TCA_QFQ_LMAX]) {
242 lmax = nla_get_u32(tb[TCA_QFQ_LMAX]);
243 if (!lmax || lmax > (1UL << QFQ_MTU_SHIFT)) {
244 pr_notice("qfq: invalid max length %u\n", lmax);
245 return -EINVAL;
246 }
247 } else
248 lmax = 1UL << QFQ_MTU_SHIFT;
249
250 if (cl != NULL) {
251 if (tca[TCA_RATE]) {
252 err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
253 qdisc_root_sleeping_lock(sch),
254 tca[TCA_RATE]);
255 if (err)
256 return err;
257 }
258
259 sch_tree_lock(sch);
260 if (tb[TCA_QFQ_WEIGHT]) {
261 q->wsum = weight - ONE_FP / cl->inv_w;
262 cl->inv_w = inv_w;
263 }
264 sch_tree_unlock(sch);
265
266 return 0;
267 }
268
269 cl = kzalloc(sizeof(struct qfq_class), GFP_KERNEL);
270 if (cl == NULL)
271 return -ENOBUFS;
272
273 cl->refcnt = 1;
274 cl->common.classid = classid;
275 cl->lmax = lmax;
276 cl->inv_w = inv_w;
277 i = qfq_calc_index(cl->inv_w, cl->lmax);
278
279 cl->grp = &q->groups[i];
280 q->wsum += weight;
281
282 cl->qdisc = qdisc_create_dflt(sch->dev_queue,
283 &pfifo_qdisc_ops, classid);
284 if (cl->qdisc == NULL)
285 cl->qdisc = &noop_qdisc;
286
287 if (tca[TCA_RATE]) {
288 err = gen_new_estimator(&cl->bstats, &cl->rate_est,
289 qdisc_root_sleeping_lock(sch),
290 tca[TCA_RATE]);
291 if (err) {
292 qdisc_destroy(cl->qdisc);
293 kfree(cl);
294 return err;
295 }
296 }
297
298 sch_tree_lock(sch);
299 qdisc_class_hash_insert(&q->clhash, &cl->common);
300 sch_tree_unlock(sch);
301
302 qdisc_class_hash_grow(sch, &q->clhash);
303
304 *arg = (unsigned long)cl;
305 return 0;
306}
307
308static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl)
309{
310 struct qfq_sched *q = qdisc_priv(sch);
311
312 if (cl->inv_w) {
313 q->wsum -= ONE_FP / cl->inv_w;
314 cl->inv_w = 0;
315 }
316
317 gen_kill_estimator(&cl->bstats, &cl->rate_est);
318 qdisc_destroy(cl->qdisc);
319 kfree(cl);
320}
321
322static int qfq_delete_class(struct Qdisc *sch, unsigned long arg)
323{
324 struct qfq_sched *q = qdisc_priv(sch);
325 struct qfq_class *cl = (struct qfq_class *)arg;
326
327 if (cl->filter_cnt > 0)
328 return -EBUSY;
329
330 sch_tree_lock(sch);
331
332 qfq_purge_queue(cl);
333 qdisc_class_hash_remove(&q->clhash, &cl->common);
334
335 BUG_ON(--cl->refcnt == 0);
336 /*
337 * This shouldn't happen: we "hold" one cops->get() when called
338 * from tc_ctl_tclass; the destroy method is done from cops->put().
339 */
340
341 sch_tree_unlock(sch);
342 return 0;
343}
344
345static unsigned long qfq_get_class(struct Qdisc *sch, u32 classid)
346{
347 struct qfq_class *cl = qfq_find_class(sch, classid);
348
349 if (cl != NULL)
350 cl->refcnt++;
351
352 return (unsigned long)cl;
353}
354
355static void qfq_put_class(struct Qdisc *sch, unsigned long arg)
356{
357 struct qfq_class *cl = (struct qfq_class *)arg;
358
359 if (--cl->refcnt == 0)
360 qfq_destroy_class(sch, cl);
361}
362
363static struct tcf_proto **qfq_tcf_chain(struct Qdisc *sch, unsigned long cl)
364{
365 struct qfq_sched *q = qdisc_priv(sch);
366
367 if (cl)
368 return NULL;
369
370 return &q->filter_list;
371}
372
373static unsigned long qfq_bind_tcf(struct Qdisc *sch, unsigned long parent,
374 u32 classid)
375{
376 struct qfq_class *cl = qfq_find_class(sch, classid);
377
378 if (cl != NULL)
379 cl->filter_cnt++;
380
381 return (unsigned long)cl;
382}
383
384static void qfq_unbind_tcf(struct Qdisc *sch, unsigned long arg)
385{
386 struct qfq_class *cl = (struct qfq_class *)arg;
387
388 cl->filter_cnt--;
389}
390
391static int qfq_graft_class(struct Qdisc *sch, unsigned long arg,
392 struct Qdisc *new, struct Qdisc **old)
393{
394 struct qfq_class *cl = (struct qfq_class *)arg;
395
396 if (new == NULL) {
397 new = qdisc_create_dflt(sch->dev_queue,
398 &pfifo_qdisc_ops, cl->common.classid);
399 if (new == NULL)
400 new = &noop_qdisc;
401 }
402
403 sch_tree_lock(sch);
404 qfq_purge_queue(cl);
405 *old = cl->qdisc;
406 cl->qdisc = new;
407 sch_tree_unlock(sch);
408 return 0;
409}
410
411static struct Qdisc *qfq_class_leaf(struct Qdisc *sch, unsigned long arg)
412{
413 struct qfq_class *cl = (struct qfq_class *)arg;
414
415 return cl->qdisc;
416}
417
418static int qfq_dump_class(struct Qdisc *sch, unsigned long arg,
419 struct sk_buff *skb, struct tcmsg *tcm)
420{
421 struct qfq_class *cl = (struct qfq_class *)arg;
422 struct nlattr *nest;
423
424 tcm->tcm_parent = TC_H_ROOT;
425 tcm->tcm_handle = cl->common.classid;
426 tcm->tcm_info = cl->qdisc->handle;
427
428 nest = nla_nest_start(skb, TCA_OPTIONS);
429 if (nest == NULL)
430 goto nla_put_failure;
431 NLA_PUT_U32(skb, TCA_QFQ_WEIGHT, ONE_FP/cl->inv_w);
432 NLA_PUT_U32(skb, TCA_QFQ_LMAX, cl->lmax);
433 return nla_nest_end(skb, nest);
434
435nla_put_failure:
436 nla_nest_cancel(skb, nest);
437 return -EMSGSIZE;
438}
439
440static int qfq_dump_class_stats(struct Qdisc *sch, unsigned long arg,
441 struct gnet_dump *d)
442{
443 struct qfq_class *cl = (struct qfq_class *)arg;
444 struct tc_qfq_stats xstats;
445
446 memset(&xstats, 0, sizeof(xstats));
447 cl->qdisc->qstats.qlen = cl->qdisc->q.qlen;
448
449 xstats.weight = ONE_FP/cl->inv_w;
450 xstats.lmax = cl->lmax;
451
452 if (gnet_stats_copy_basic(d, &cl->bstats) < 0 ||
453 gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
454 gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0)
455 return -1;
456
457 return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
458}
459
460static void qfq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
461{
462 struct qfq_sched *q = qdisc_priv(sch);
463 struct qfq_class *cl;
464 struct hlist_node *n;
465 unsigned int i;
466
467 if (arg->stop)
468 return;
469
470 for (i = 0; i < q->clhash.hashsize; i++) {
471 hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode) {
472 if (arg->count < arg->skip) {
473 arg->count++;
474 continue;
475 }
476 if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
477 arg->stop = 1;
478 return;
479 }
480 arg->count++;
481 }
482 }
483}
484
485static struct qfq_class *qfq_classify(struct sk_buff *skb, struct Qdisc *sch,
486 int *qerr)
487{
488 struct qfq_sched *q = qdisc_priv(sch);
489 struct qfq_class *cl;
490 struct tcf_result res;
491 int result;
492
493 if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
494 pr_debug("qfq_classify: found %d\n", skb->priority);
495 cl = qfq_find_class(sch, skb->priority);
496 if (cl != NULL)
497 return cl;
498 }
499
500 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
501 result = tc_classify(skb, q->filter_list, &res);
502 if (result >= 0) {
503#ifdef CONFIG_NET_CLS_ACT
504 switch (result) {
505 case TC_ACT_QUEUED:
506 case TC_ACT_STOLEN:
507 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
508 case TC_ACT_SHOT:
509 return NULL;
510 }
511#endif
512 cl = (struct qfq_class *)res.class;
513 if (cl == NULL)
514 cl = qfq_find_class(sch, res.classid);
515 return cl;
516 }
517
518 return NULL;
519}
520
521/* Generic comparison function, handling wraparound. */
522static inline int qfq_gt(u64 a, u64 b)
523{
524 return (s64)(a - b) > 0;
525}
526
527/* Round a precise timestamp to its slotted value. */
528static inline u64 qfq_round_down(u64 ts, unsigned int shift)
529{
530 return ts & ~((1ULL << shift) - 1);
531}
532
533/* return the pointer to the group with lowest index in the bitmap */
534static inline struct qfq_group *qfq_ffs(struct qfq_sched *q,
535 unsigned long bitmap)
536{
537 int index = __ffs(bitmap);
538 return &q->groups[index];
539}
540/* Calculate a mask to mimic what would be ffs_from(). */
541static inline unsigned long mask_from(unsigned long bitmap, int from)
542{
543 return bitmap & ~((1UL << from) - 1);
544}
545
546/*
547 * The state computation relies on ER=0, IR=1, EB=2, IB=3
548 * First compute eligibility comparing grp->S, q->V,
549 * then check if someone is blocking us and possibly add EB
550 */
551static int qfq_calc_state(struct qfq_sched *q, const struct qfq_group *grp)
552{
553 /* if S > V we are not eligible */
554 unsigned int state = qfq_gt(grp->S, q->V);
555 unsigned long mask = mask_from(q->bitmaps[ER], grp->index);
556 struct qfq_group *next;
557
558 if (mask) {
559 next = qfq_ffs(q, mask);
560 if (qfq_gt(grp->F, next->F))
561 state |= EB;
562 }
563
564 return state;
565}
566
567
568/*
569 * In principle
570 * q->bitmaps[dst] |= q->bitmaps[src] & mask;
571 * q->bitmaps[src] &= ~mask;
572 * but we should make sure that src != dst
573 */
574static inline void qfq_move_groups(struct qfq_sched *q, unsigned long mask,
575 int src, int dst)
576{
577 q->bitmaps[dst] |= q->bitmaps[src] & mask;
578 q->bitmaps[src] &= ~mask;
579}
580
581static void qfq_unblock_groups(struct qfq_sched *q, int index, u64 old_F)
582{
583 unsigned long mask = mask_from(q->bitmaps[ER], index + 1);
584 struct qfq_group *next;
585
586 if (mask) {
587 next = qfq_ffs(q, mask);
588 if (!qfq_gt(next->F, old_F))
589 return;
590 }
591
592 mask = (1UL << index) - 1;
593 qfq_move_groups(q, mask, EB, ER);
594 qfq_move_groups(q, mask, IB, IR);
595}
596
597/*
598 * perhaps
599 *
600 old_V ^= q->V;
601 old_V >>= QFQ_MIN_SLOT_SHIFT;
602 if (old_V) {
603 ...
604 }
605 *
606 */
607static void qfq_make_eligible(struct qfq_sched *q, u64 old_V)
608{
609 unsigned long vslot = q->V >> QFQ_MIN_SLOT_SHIFT;
610 unsigned long old_vslot = old_V >> QFQ_MIN_SLOT_SHIFT;
611
612 if (vslot != old_vslot) {
613 unsigned long mask = (1UL << fls(vslot ^ old_vslot)) - 1;
614 qfq_move_groups(q, mask, IR, ER);
615 qfq_move_groups(q, mask, IB, EB);
616 }
617}
618
619
620/*
621 * XXX we should make sure that slot becomes less than 32.
622 * This is guaranteed by the input values.
623 * roundedS is always cl->S rounded on grp->slot_shift bits.
624 */
625static void qfq_slot_insert(struct qfq_group *grp, struct qfq_class *cl,
626 u64 roundedS)
627{
628 u64 slot = (roundedS - grp->S) >> grp->slot_shift;
629 unsigned int i = (grp->front + slot) % QFQ_MAX_SLOTS;
630
631 hlist_add_head(&cl->next, &grp->slots[i]);
632 __set_bit(slot, &grp->full_slots);
633}
634
635/* Maybe introduce hlist_first_entry?? */
636static struct qfq_class *qfq_slot_head(struct qfq_group *grp)
637{
638 return hlist_entry(grp->slots[grp->front].first,
639 struct qfq_class, next);
640}
641
642/*
643 * remove the entry from the slot
644 */
645static void qfq_front_slot_remove(struct qfq_group *grp)
646{
647 struct qfq_class *cl = qfq_slot_head(grp);
648
649 BUG_ON(!cl);
650 hlist_del(&cl->next);
651 if (hlist_empty(&grp->slots[grp->front]))
652 __clear_bit(0, &grp->full_slots);
653}
654
655/*
656 * Returns the first full queue in a group. As a side effect,
657 * adjust the bucket list so the first non-empty bucket is at
658 * position 0 in full_slots.
659 */
660static struct qfq_class *qfq_slot_scan(struct qfq_group *grp)
661{
662 unsigned int i;
663
664 pr_debug("qfq slot_scan: grp %u full %#lx\n",
665 grp->index, grp->full_slots);
666
667 if (grp->full_slots == 0)
668 return NULL;
669
670 i = __ffs(grp->full_slots); /* zero based */
671 if (i > 0) {
672 grp->front = (grp->front + i) % QFQ_MAX_SLOTS;
673 grp->full_slots >>= i;
674 }
675
676 return qfq_slot_head(grp);
677}
678
679/*
680 * adjust the bucket list. When the start time of a group decreases,
681 * we move the index down (modulo QFQ_MAX_SLOTS) so we don't need to
682 * move the objects. The mask of occupied slots must be shifted
683 * because we use ffs() to find the first non-empty slot.
684 * This covers decreases in the group's start time, but what about
685 * increases of the start time ?
686 * Here too we should make sure that i is less than 32
687 */
688static void qfq_slot_rotate(struct qfq_group *grp, u64 roundedS)
689{
690 unsigned int i = (grp->S - roundedS) >> grp->slot_shift;
691
692 grp->full_slots <<= i;
693 grp->front = (grp->front - i) % QFQ_MAX_SLOTS;
694}
695
696static void qfq_update_eligible(struct qfq_sched *q, u64 old_V)
697{
698 struct qfq_group *grp;
699 unsigned long ineligible;
700
701 ineligible = q->bitmaps[IR] | q->bitmaps[IB];
702 if (ineligible) {
703 if (!q->bitmaps[ER]) {
704 grp = qfq_ffs(q, ineligible);
705 if (qfq_gt(grp->S, q->V))
706 q->V = grp->S;
707 }
708 qfq_make_eligible(q, old_V);
709 }
710}
711
712/* What is length of next packet in queue (0 if queue is empty) */
713static unsigned int qdisc_peek_len(struct Qdisc *sch)
714{
715 struct sk_buff *skb;
716
717 skb = sch->ops->peek(sch);
718 return skb ? qdisc_pkt_len(skb) : 0;
719}
720
721/*
722 * Updates the class, returns true if also the group needs to be updated.
723 */
724static bool qfq_update_class(struct qfq_group *grp, struct qfq_class *cl)
725{
726 unsigned int len = qdisc_peek_len(cl->qdisc);
727
728 cl->S = cl->F;
729 if (!len)
730 qfq_front_slot_remove(grp); /* queue is empty */
731 else {
732 u64 roundedS;
733
734 cl->F = cl->S + (u64)len * cl->inv_w;
735 roundedS = qfq_round_down(cl->S, grp->slot_shift);
736 if (roundedS == grp->S)
737 return false;
738
739 qfq_front_slot_remove(grp);
740 qfq_slot_insert(grp, cl, roundedS);
741 }
742
743 return true;
744}
745
746static struct sk_buff *qfq_dequeue(struct Qdisc *sch)
747{
748 struct qfq_sched *q = qdisc_priv(sch);
749 struct qfq_group *grp;
750 struct qfq_class *cl;
751 struct sk_buff *skb;
752 unsigned int len;
753 u64 old_V;
754
755 if (!q->bitmaps[ER])
756 return NULL;
757
758 grp = qfq_ffs(q, q->bitmaps[ER]);
759
760 cl = qfq_slot_head(grp);
761 skb = qdisc_dequeue_peeked(cl->qdisc);
762 if (!skb) {
763 WARN_ONCE(1, "qfq_dequeue: non-workconserving leaf\n");
764 return NULL;
765 }
766
767 sch->q.qlen--;
768 qdisc_bstats_update(sch, skb);
769
770 old_V = q->V;
771 len = qdisc_pkt_len(skb);
772 q->V += (u64)len * IWSUM;
773 pr_debug("qfq dequeue: len %u F %lld now %lld\n",
774 len, (unsigned long long) cl->F, (unsigned long long) q->V);
775
776 if (qfq_update_class(grp, cl)) {
777 u64 old_F = grp->F;
778
779 cl = qfq_slot_scan(grp);
780 if (!cl)
781 __clear_bit(grp->index, &q->bitmaps[ER]);
782 else {
783 u64 roundedS = qfq_round_down(cl->S, grp->slot_shift);
784 unsigned int s;
785
786 if (grp->S == roundedS)
787 goto skip_unblock;
788 grp->S = roundedS;
789 grp->F = roundedS + (2ULL << grp->slot_shift);
790 __clear_bit(grp->index, &q->bitmaps[ER]);
791 s = qfq_calc_state(q, grp);
792 __set_bit(grp->index, &q->bitmaps[s]);
793 }
794
795 qfq_unblock_groups(q, grp->index, old_F);
796 }
797
798skip_unblock:
799 qfq_update_eligible(q, old_V);
800
801 return skb;
802}
803
804/*
805 * Assign a reasonable start time for a new flow k in group i.
806 * Admissible values for \hat(F) are multiples of \sigma_i
807 * no greater than V+\sigma_i . Larger values mean that
808 * we had a wraparound so we consider the timestamp to be stale.
809 *
810 * If F is not stale and F >= V then we set S = F.
811 * Otherwise we should assign S = V, but this may violate
812 * the ordering in ER. So, if we have groups in ER, set S to
813 * the F_j of the first group j which would be blocking us.
814 * We are guaranteed not to move S backward because
815 * otherwise our group i would still be blocked.
816 */
817static void qfq_update_start(struct qfq_sched *q, struct qfq_class *cl)
818{
819 unsigned long mask;
Eric Dumazet6bafcac2012-01-02 05:47:57 +0000820 u64 limit, roundedF;
stephen hemminger0545a302011-04-04 05:30:58 +0000821 int slot_shift = cl->grp->slot_shift;
822
823 roundedF = qfq_round_down(cl->F, slot_shift);
Eric Dumazet6bafcac2012-01-02 05:47:57 +0000824 limit = qfq_round_down(q->V, slot_shift) + (1ULL << slot_shift);
stephen hemminger0545a302011-04-04 05:30:58 +0000825
826 if (!qfq_gt(cl->F, q->V) || qfq_gt(roundedF, limit)) {
827 /* timestamp was stale */
828 mask = mask_from(q->bitmaps[ER], cl->grp->index);
829 if (mask) {
830 struct qfq_group *next = qfq_ffs(q, mask);
831 if (qfq_gt(roundedF, next->F)) {
832 cl->S = next->F;
833 return;
834 }
835 }
836 cl->S = q->V;
837 } else /* timestamp is not stale */
838 cl->S = cl->F;
839}
840
841static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
842{
843 struct qfq_sched *q = qdisc_priv(sch);
844 struct qfq_group *grp;
845 struct qfq_class *cl;
846 int err;
847 u64 roundedS;
848 int s;
849
850 cl = qfq_classify(skb, sch, &err);
851 if (cl == NULL) {
852 if (err & __NET_XMIT_BYPASS)
853 sch->qstats.drops++;
854 kfree_skb(skb);
855 return err;
856 }
857 pr_debug("qfq_enqueue: cl = %x\n", cl->common.classid);
858
859 err = qdisc_enqueue(skb, cl->qdisc);
860 if (unlikely(err != NET_XMIT_SUCCESS)) {
861 pr_debug("qfq_enqueue: enqueue failed %d\n", err);
862 if (net_xmit_drop_count(err)) {
863 cl->qstats.drops++;
864 sch->qstats.drops++;
865 }
866 return err;
867 }
868
869 bstats_update(&cl->bstats, skb);
870 ++sch->q.qlen;
871
872 /* If the new skb is not the head of queue, then done here. */
873 if (cl->qdisc->q.qlen != 1)
874 return err;
875
876 /* If reach this point, queue q was idle */
877 grp = cl->grp;
878 qfq_update_start(q, cl);
879
880 /* compute new finish time and rounded start. */
881 cl->F = cl->S + (u64)qdisc_pkt_len(skb) * cl->inv_w;
882 roundedS = qfq_round_down(cl->S, grp->slot_shift);
883
884 /*
885 * insert cl in the correct bucket.
886 * If cl->S >= grp->S we don't need to adjust the
887 * bucket list and simply go to the insertion phase.
888 * Otherwise grp->S is decreasing, we must make room
889 * in the bucket list, and also recompute the group state.
890 * Finally, if there were no flows in this group and nobody
891 * was in ER make sure to adjust V.
892 */
893 if (grp->full_slots) {
894 if (!qfq_gt(grp->S, cl->S))
895 goto skip_update;
896
897 /* create a slot for this cl->S */
898 qfq_slot_rotate(grp, roundedS);
899 /* group was surely ineligible, remove */
900 __clear_bit(grp->index, &q->bitmaps[IR]);
901 __clear_bit(grp->index, &q->bitmaps[IB]);
902 } else if (!q->bitmaps[ER] && qfq_gt(roundedS, q->V))
903 q->V = roundedS;
904
905 grp->S = roundedS;
906 grp->F = roundedS + (2ULL << grp->slot_shift);
907 s = qfq_calc_state(q, grp);
908 __set_bit(grp->index, &q->bitmaps[s]);
909
910 pr_debug("qfq enqueue: new state %d %#lx S %lld F %lld V %lld\n",
911 s, q->bitmaps[s],
912 (unsigned long long) cl->S,
913 (unsigned long long) cl->F,
914 (unsigned long long) q->V);
915
916skip_update:
917 qfq_slot_insert(grp, cl, roundedS);
918
919 return err;
920}
921
922
923static void qfq_slot_remove(struct qfq_sched *q, struct qfq_group *grp,
924 struct qfq_class *cl)
925{
926 unsigned int i, offset;
927 u64 roundedS;
928
929 roundedS = qfq_round_down(cl->S, grp->slot_shift);
930 offset = (roundedS - grp->S) >> grp->slot_shift;
931 i = (grp->front + offset) % QFQ_MAX_SLOTS;
932
933 hlist_del(&cl->next);
934 if (hlist_empty(&grp->slots[i]))
935 __clear_bit(offset, &grp->full_slots);
936}
937
938/*
939 * called to forcibly destroy a queue.
940 * If the queue is not in the front bucket, or if it has
941 * other queues in the front bucket, we can simply remove
942 * the queue with no other side effects.
943 * Otherwise we must propagate the event up.
944 */
945static void qfq_deactivate_class(struct qfq_sched *q, struct qfq_class *cl)
946{
947 struct qfq_group *grp = cl->grp;
948 unsigned long mask;
949 u64 roundedS;
950 int s;
951
952 cl->F = cl->S;
953 qfq_slot_remove(q, grp, cl);
954
955 if (!grp->full_slots) {
956 __clear_bit(grp->index, &q->bitmaps[IR]);
957 __clear_bit(grp->index, &q->bitmaps[EB]);
958 __clear_bit(grp->index, &q->bitmaps[IB]);
959
960 if (test_bit(grp->index, &q->bitmaps[ER]) &&
961 !(q->bitmaps[ER] & ~((1UL << grp->index) - 1))) {
962 mask = q->bitmaps[ER] & ((1UL << grp->index) - 1);
963 if (mask)
964 mask = ~((1UL << __fls(mask)) - 1);
965 else
966 mask = ~0UL;
967 qfq_move_groups(q, mask, EB, ER);
968 qfq_move_groups(q, mask, IB, IR);
969 }
970 __clear_bit(grp->index, &q->bitmaps[ER]);
971 } else if (hlist_empty(&grp->slots[grp->front])) {
972 cl = qfq_slot_scan(grp);
973 roundedS = qfq_round_down(cl->S, grp->slot_shift);
974 if (grp->S != roundedS) {
975 __clear_bit(grp->index, &q->bitmaps[ER]);
976 __clear_bit(grp->index, &q->bitmaps[IR]);
977 __clear_bit(grp->index, &q->bitmaps[EB]);
978 __clear_bit(grp->index, &q->bitmaps[IB]);
979 grp->S = roundedS;
980 grp->F = roundedS + (2ULL << grp->slot_shift);
981 s = qfq_calc_state(q, grp);
982 __set_bit(grp->index, &q->bitmaps[s]);
983 }
984 }
985
986 qfq_update_eligible(q, q->V);
987}
988
989static void qfq_qlen_notify(struct Qdisc *sch, unsigned long arg)
990{
991 struct qfq_sched *q = qdisc_priv(sch);
992 struct qfq_class *cl = (struct qfq_class *)arg;
993
994 if (cl->qdisc->q.qlen == 0)
995 qfq_deactivate_class(q, cl);
996}
997
998static unsigned int qfq_drop(struct Qdisc *sch)
999{
1000 struct qfq_sched *q = qdisc_priv(sch);
1001 struct qfq_group *grp;
1002 unsigned int i, j, len;
1003
1004 for (i = 0; i <= QFQ_MAX_INDEX; i++) {
1005 grp = &q->groups[i];
1006 for (j = 0; j < QFQ_MAX_SLOTS; j++) {
1007 struct qfq_class *cl;
1008 struct hlist_node *n;
1009
1010 hlist_for_each_entry(cl, n, &grp->slots[j], next) {
1011
1012 if (!cl->qdisc->ops->drop)
1013 continue;
1014
1015 len = cl->qdisc->ops->drop(cl->qdisc);
1016 if (len > 0) {
1017 sch->q.qlen--;
1018 if (!cl->qdisc->q.qlen)
1019 qfq_deactivate_class(q, cl);
1020
1021 return len;
1022 }
1023 }
1024 }
1025 }
1026
1027 return 0;
1028}
1029
1030static int qfq_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
1031{
1032 struct qfq_sched *q = qdisc_priv(sch);
1033 struct qfq_group *grp;
1034 int i, j, err;
1035
1036 err = qdisc_class_hash_init(&q->clhash);
1037 if (err < 0)
1038 return err;
1039
1040 for (i = 0; i <= QFQ_MAX_INDEX; i++) {
1041 grp = &q->groups[i];
1042 grp->index = i;
1043 grp->slot_shift = QFQ_MTU_SHIFT + FRAC_BITS
1044 - (QFQ_MAX_INDEX - i);
1045 for (j = 0; j < QFQ_MAX_SLOTS; j++)
1046 INIT_HLIST_HEAD(&grp->slots[j]);
1047 }
1048
1049 return 0;
1050}
1051
1052static void qfq_reset_qdisc(struct Qdisc *sch)
1053{
1054 struct qfq_sched *q = qdisc_priv(sch);
1055 struct qfq_group *grp;
1056 struct qfq_class *cl;
1057 struct hlist_node *n, *tmp;
1058 unsigned int i, j;
1059
1060 for (i = 0; i <= QFQ_MAX_INDEX; i++) {
1061 grp = &q->groups[i];
1062 for (j = 0; j < QFQ_MAX_SLOTS; j++) {
1063 hlist_for_each_entry_safe(cl, n, tmp,
1064 &grp->slots[j], next) {
1065 qfq_deactivate_class(q, cl);
1066 }
1067 }
1068 }
1069
1070 for (i = 0; i < q->clhash.hashsize; i++) {
1071 hlist_for_each_entry(cl, n, &q->clhash.hash[i], common.hnode)
1072 qdisc_reset(cl->qdisc);
1073 }
1074 sch->q.qlen = 0;
1075}
1076
1077static void qfq_destroy_qdisc(struct Qdisc *sch)
1078{
1079 struct qfq_sched *q = qdisc_priv(sch);
1080 struct qfq_class *cl;
1081 struct hlist_node *n, *next;
1082 unsigned int i;
1083
1084 tcf_destroy_chain(&q->filter_list);
1085
1086 for (i = 0; i < q->clhash.hashsize; i++) {
1087 hlist_for_each_entry_safe(cl, n, next, &q->clhash.hash[i],
1088 common.hnode) {
1089 qfq_destroy_class(sch, cl);
1090 }
1091 }
1092 qdisc_class_hash_destroy(&q->clhash);
1093}
1094
1095static const struct Qdisc_class_ops qfq_class_ops = {
1096 .change = qfq_change_class,
1097 .delete = qfq_delete_class,
1098 .get = qfq_get_class,
1099 .put = qfq_put_class,
1100 .tcf_chain = qfq_tcf_chain,
1101 .bind_tcf = qfq_bind_tcf,
1102 .unbind_tcf = qfq_unbind_tcf,
1103 .graft = qfq_graft_class,
1104 .leaf = qfq_class_leaf,
1105 .qlen_notify = qfq_qlen_notify,
1106 .dump = qfq_dump_class,
1107 .dump_stats = qfq_dump_class_stats,
1108 .walk = qfq_walk,
1109};
1110
1111static struct Qdisc_ops qfq_qdisc_ops __read_mostly = {
1112 .cl_ops = &qfq_class_ops,
1113 .id = "qfq",
1114 .priv_size = sizeof(struct qfq_sched),
1115 .enqueue = qfq_enqueue,
1116 .dequeue = qfq_dequeue,
1117 .peek = qdisc_peek_dequeued,
1118 .drop = qfq_drop,
1119 .init = qfq_init_qdisc,
1120 .reset = qfq_reset_qdisc,
1121 .destroy = qfq_destroy_qdisc,
1122 .owner = THIS_MODULE,
1123};
1124
1125static int __init qfq_init(void)
1126{
1127 return register_qdisc(&qfq_qdisc_ops);
1128}
1129
1130static void __exit qfq_exit(void)
1131{
1132 unregister_qdisc(&qfq_qdisc_ops);
1133}
1134
1135module_init(qfq_init);
1136module_exit(qfq_exit);
1137MODULE_LICENSE("GPL");