Merge tag 'rproc-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc...
[linux.git] / net / sched / sch_sfb.c
blobd2835f1168e1dcef44044df8c4505bfc03a5d0cb
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * net/sched/sch_sfb.c Stochastic Fair Blue
5 * Copyright (c) 2008-2011 Juliusz Chroboczek <jch@pps.jussieu.fr>
6 * Copyright (c) 2011 Eric Dumazet <eric.dumazet@gmail.com>
8 * W. Feng, D. Kandlur, D. Saha, K. Shin. Blue:
9 * A New Class of Active Queue Management Algorithms.
10 * U. Michigan CSE-TR-387-99, April 1999.
12 * http://www.thefengs.com/wuchang/blue/CSE-TR-387-99.pdf
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/errno.h>
19 #include <linux/skbuff.h>
20 #include <linux/random.h>
21 #include <linux/siphash.h>
22 #include <net/ip.h>
23 #include <net/pkt_sched.h>
24 #include <net/pkt_cls.h>
25 #include <net/inet_ecn.h>
28 * SFB uses two B[l][n] : L x N arrays of bins (L levels, N bins per level)
29 * This implementation uses L = 8 and N = 16
30 * This permits us to split one 32bit hash (provided per packet by rxhash or
31 * external classifier) into 8 subhashes of 4 bits.
33 #define SFB_BUCKET_SHIFT 4
34 #define SFB_NUMBUCKETS (1 << SFB_BUCKET_SHIFT) /* N bins per Level */
35 #define SFB_BUCKET_MASK (SFB_NUMBUCKETS - 1)
36 #define SFB_LEVELS (32 / SFB_BUCKET_SHIFT) /* L */
38 /* SFB algo uses a virtual queue, named "bin" */
39 struct sfb_bucket {
40 u16 qlen; /* length of virtual queue */
41 u16 p_mark; /* marking probability */
44 /* We use a double buffering right before hash change
45 * (Section 4.4 of SFB reference : moving hash functions)
47 struct sfb_bins {
48 siphash_key_t perturbation; /* siphash key */
49 struct sfb_bucket bins[SFB_LEVELS][SFB_NUMBUCKETS];
52 struct sfb_sched_data {
53 struct Qdisc *qdisc;
54 struct tcf_proto __rcu *filter_list;
55 struct tcf_block *block;
56 unsigned long rehash_interval;
57 unsigned long warmup_time; /* double buffering warmup time in jiffies */
58 u32 max;
59 u32 bin_size; /* maximum queue length per bin */
60 u32 increment; /* d1 */
61 u32 decrement; /* d2 */
62 u32 limit; /* HARD maximal queue length */
63 u32 penalty_rate;
64 u32 penalty_burst;
65 u32 tokens_avail;
66 unsigned long rehash_time;
67 unsigned long token_time;
69 u8 slot; /* current active bins (0 or 1) */
70 bool double_buffering;
71 struct sfb_bins bins[2];
73 struct {
74 u32 earlydrop;
75 u32 penaltydrop;
76 u32 bucketdrop;
77 u32 queuedrop;
78 u32 childdrop; /* drops in child qdisc */
79 u32 marked; /* ECN mark */
80 } stats;
84 * Each queued skb might be hashed on one or two bins
85 * We store in skb_cb the two hash values.
86 * (A zero value means double buffering was not used)
88 struct sfb_skb_cb {
89 u32 hashes[2];
92 static inline struct sfb_skb_cb *sfb_skb_cb(const struct sk_buff *skb)
94 qdisc_cb_private_validate(skb, sizeof(struct sfb_skb_cb));
95 return (struct sfb_skb_cb *)qdisc_skb_cb(skb)->data;
99 * If using 'internal' SFB flow classifier, hash comes from skb rxhash
100 * If using external classifier, hash comes from the classid.
102 static u32 sfb_hash(const struct sk_buff *skb, u32 slot)
104 return sfb_skb_cb(skb)->hashes[slot];
107 /* Probabilities are coded as Q0.16 fixed-point values,
108 * with 0xFFFF representing 65535/65536 (almost 1.0)
109 * Addition and subtraction are saturating in [0, 65535]
111 static u32 prob_plus(u32 p1, u32 p2)
113 u32 res = p1 + p2;
115 return min_t(u32, res, SFB_MAX_PROB);
118 static u32 prob_minus(u32 p1, u32 p2)
120 return p1 > p2 ? p1 - p2 : 0;
123 static void increment_one_qlen(u32 sfbhash, u32 slot, struct sfb_sched_data *q)
125 int i;
126 struct sfb_bucket *b = &q->bins[slot].bins[0][0];
128 for (i = 0; i < SFB_LEVELS; i++) {
129 u32 hash = sfbhash & SFB_BUCKET_MASK;
131 sfbhash >>= SFB_BUCKET_SHIFT;
132 if (b[hash].qlen < 0xFFFF)
133 b[hash].qlen++;
134 b += SFB_NUMBUCKETS; /* next level */
138 static void increment_qlen(const struct sfb_skb_cb *cb, struct sfb_sched_data *q)
140 u32 sfbhash;
142 sfbhash = cb->hashes[0];
143 if (sfbhash)
144 increment_one_qlen(sfbhash, 0, q);
146 sfbhash = cb->hashes[1];
147 if (sfbhash)
148 increment_one_qlen(sfbhash, 1, q);
151 static void decrement_one_qlen(u32 sfbhash, u32 slot,
152 struct sfb_sched_data *q)
154 int i;
155 struct sfb_bucket *b = &q->bins[slot].bins[0][0];
157 for (i = 0; i < SFB_LEVELS; i++) {
158 u32 hash = sfbhash & SFB_BUCKET_MASK;
160 sfbhash >>= SFB_BUCKET_SHIFT;
161 if (b[hash].qlen > 0)
162 b[hash].qlen--;
163 b += SFB_NUMBUCKETS; /* next level */
167 static void decrement_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
169 u32 sfbhash;
171 sfbhash = sfb_hash(skb, 0);
172 if (sfbhash)
173 decrement_one_qlen(sfbhash, 0, q);
175 sfbhash = sfb_hash(skb, 1);
176 if (sfbhash)
177 decrement_one_qlen(sfbhash, 1, q);
180 static void decrement_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
182 b->p_mark = prob_minus(b->p_mark, q->decrement);
185 static void increment_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
187 b->p_mark = prob_plus(b->p_mark, q->increment);
190 static void sfb_zero_all_buckets(struct sfb_sched_data *q)
192 memset(&q->bins, 0, sizeof(q->bins));
196 * compute max qlen, max p_mark, and avg p_mark
198 static u32 sfb_compute_qlen(u32 *prob_r, u32 *avgpm_r, const struct sfb_sched_data *q)
200 int i;
201 u32 qlen = 0, prob = 0, totalpm = 0;
202 const struct sfb_bucket *b = &q->bins[q->slot].bins[0][0];
204 for (i = 0; i < SFB_LEVELS * SFB_NUMBUCKETS; i++) {
205 if (qlen < b->qlen)
206 qlen = b->qlen;
207 totalpm += b->p_mark;
208 if (prob < b->p_mark)
209 prob = b->p_mark;
210 b++;
212 *prob_r = prob;
213 *avgpm_r = totalpm / (SFB_LEVELS * SFB_NUMBUCKETS);
214 return qlen;
218 static void sfb_init_perturbation(u32 slot, struct sfb_sched_data *q)
220 get_random_bytes(&q->bins[slot].perturbation,
221 sizeof(q->bins[slot].perturbation));
224 static void sfb_swap_slot(struct sfb_sched_data *q)
226 sfb_init_perturbation(q->slot, q);
227 q->slot ^= 1;
228 q->double_buffering = false;
231 /* Non elastic flows are allowed to use part of the bandwidth, expressed
232 * in "penalty_rate" packets per second, with "penalty_burst" burst
234 static bool sfb_rate_limit(struct sk_buff *skb, struct sfb_sched_data *q)
236 if (q->penalty_rate == 0 || q->penalty_burst == 0)
237 return true;
239 if (q->tokens_avail < 1) {
240 unsigned long age = min(10UL * HZ, jiffies - q->token_time);
242 q->tokens_avail = (age * q->penalty_rate) / HZ;
243 if (q->tokens_avail > q->penalty_burst)
244 q->tokens_avail = q->penalty_burst;
245 q->token_time = jiffies;
246 if (q->tokens_avail < 1)
247 return true;
250 q->tokens_avail--;
251 return false;
254 static bool sfb_classify(struct sk_buff *skb, struct tcf_proto *fl,
255 int *qerr, u32 *salt)
257 struct tcf_result res;
258 int result;
260 result = tcf_classify(skb, NULL, fl, &res, false);
261 if (result >= 0) {
262 #ifdef CONFIG_NET_CLS_ACT
263 switch (result) {
264 case TC_ACT_STOLEN:
265 case TC_ACT_QUEUED:
266 case TC_ACT_TRAP:
267 *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
268 fallthrough;
269 case TC_ACT_SHOT:
270 return false;
272 #endif
273 *salt = TC_H_MIN(res.classid);
274 return true;
276 return false;
279 static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch,
280 struct sk_buff **to_free)
283 enum skb_drop_reason reason = SKB_DROP_REASON_QDISC_OVERLIMIT;
284 struct sfb_sched_data *q = qdisc_priv(sch);
285 unsigned int len = qdisc_pkt_len(skb);
286 struct Qdisc *child = q->qdisc;
287 struct tcf_proto *fl;
288 struct sfb_skb_cb cb;
289 int i;
290 u32 p_min = ~0;
291 u32 minqlen = ~0;
292 u32 r, sfbhash;
293 u32 slot = q->slot;
294 int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
296 if (unlikely(sch->q.qlen >= q->limit)) {
297 qdisc_qstats_overlimit(sch);
298 q->stats.queuedrop++;
299 goto drop;
302 if (q->rehash_interval > 0) {
303 unsigned long limit = q->rehash_time + q->rehash_interval;
305 if (unlikely(time_after(jiffies, limit))) {
306 sfb_swap_slot(q);
307 q->rehash_time = jiffies;
308 } else if (unlikely(!q->double_buffering && q->warmup_time > 0 &&
309 time_after(jiffies, limit - q->warmup_time))) {
310 q->double_buffering = true;
314 fl = rcu_dereference_bh(q->filter_list);
315 if (fl) {
316 u32 salt;
318 /* If using external classifiers, get result and record it. */
319 if (!sfb_classify(skb, fl, &ret, &salt))
320 goto other_drop;
321 sfbhash = siphash_1u32(salt, &q->bins[slot].perturbation);
322 } else {
323 sfbhash = skb_get_hash_perturb(skb, &q->bins[slot].perturbation);
327 if (!sfbhash)
328 sfbhash = 1;
329 sfb_skb_cb(skb)->hashes[slot] = sfbhash;
331 for (i = 0; i < SFB_LEVELS; i++) {
332 u32 hash = sfbhash & SFB_BUCKET_MASK;
333 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
335 sfbhash >>= SFB_BUCKET_SHIFT;
336 if (b->qlen == 0)
337 decrement_prob(b, q);
338 else if (b->qlen >= q->bin_size)
339 increment_prob(b, q);
340 if (minqlen > b->qlen)
341 minqlen = b->qlen;
342 if (p_min > b->p_mark)
343 p_min = b->p_mark;
346 slot ^= 1;
347 sfb_skb_cb(skb)->hashes[slot] = 0;
349 if (unlikely(minqlen >= q->max)) {
350 qdisc_qstats_overlimit(sch);
351 q->stats.bucketdrop++;
352 goto drop;
355 if (unlikely(p_min >= SFB_MAX_PROB)) {
356 /* Inelastic flow */
357 if (q->double_buffering) {
358 sfbhash = skb_get_hash_perturb(skb,
359 &q->bins[slot].perturbation);
360 if (!sfbhash)
361 sfbhash = 1;
362 sfb_skb_cb(skb)->hashes[slot] = sfbhash;
364 for (i = 0; i < SFB_LEVELS; i++) {
365 u32 hash = sfbhash & SFB_BUCKET_MASK;
366 struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
368 sfbhash >>= SFB_BUCKET_SHIFT;
369 if (b->qlen == 0)
370 decrement_prob(b, q);
371 else if (b->qlen >= q->bin_size)
372 increment_prob(b, q);
375 if (sfb_rate_limit(skb, q)) {
376 qdisc_qstats_overlimit(sch);
377 q->stats.penaltydrop++;
378 goto drop;
380 goto enqueue;
383 r = get_random_u16() & SFB_MAX_PROB;
384 reason = SKB_DROP_REASON_QDISC_CONGESTED;
386 if (unlikely(r < p_min)) {
387 if (unlikely(p_min > SFB_MAX_PROB / 2)) {
388 /* If we're marking that many packets, then either
389 * this flow is unresponsive, or we're badly congested.
390 * In either case, we want to start dropping packets.
392 if (r < (p_min - SFB_MAX_PROB / 2) * 2) {
393 q->stats.earlydrop++;
394 goto drop;
397 if (INET_ECN_set_ce(skb)) {
398 q->stats.marked++;
399 } else {
400 q->stats.earlydrop++;
401 goto drop;
405 enqueue:
406 memcpy(&cb, sfb_skb_cb(skb), sizeof(cb));
407 ret = qdisc_enqueue(skb, child, to_free);
408 if (likely(ret == NET_XMIT_SUCCESS)) {
409 sch->qstats.backlog += len;
410 sch->q.qlen++;
411 increment_qlen(&cb, q);
412 } else if (net_xmit_drop_count(ret)) {
413 q->stats.childdrop++;
414 qdisc_qstats_drop(sch);
416 return ret;
418 drop:
419 qdisc_drop_reason(skb, sch, to_free, reason);
420 return NET_XMIT_CN;
421 other_drop:
422 if (ret & __NET_XMIT_BYPASS)
423 qdisc_qstats_drop(sch);
424 kfree_skb(skb);
425 return ret;
428 static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
430 struct sfb_sched_data *q = qdisc_priv(sch);
431 struct Qdisc *child = q->qdisc;
432 struct sk_buff *skb;
434 skb = child->dequeue(q->qdisc);
436 if (skb) {
437 qdisc_bstats_update(sch, skb);
438 qdisc_qstats_backlog_dec(sch, skb);
439 sch->q.qlen--;
440 decrement_qlen(skb, q);
443 return skb;
446 static struct sk_buff *sfb_peek(struct Qdisc *sch)
448 struct sfb_sched_data *q = qdisc_priv(sch);
449 struct Qdisc *child = q->qdisc;
451 return child->ops->peek(child);
454 /* No sfb_drop -- impossible since the child doesn't return the dropped skb. */
456 static void sfb_reset(struct Qdisc *sch)
458 struct sfb_sched_data *q = qdisc_priv(sch);
460 if (likely(q->qdisc))
461 qdisc_reset(q->qdisc);
462 q->slot = 0;
463 q->double_buffering = false;
464 sfb_zero_all_buckets(q);
465 sfb_init_perturbation(0, q);
468 static void sfb_destroy(struct Qdisc *sch)
470 struct sfb_sched_data *q = qdisc_priv(sch);
472 tcf_block_put(q->block);
473 qdisc_put(q->qdisc);
476 static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
477 [TCA_SFB_PARMS] = { .len = sizeof(struct tc_sfb_qopt) },
480 static const struct tc_sfb_qopt sfb_default_ops = {
481 .rehash_interval = 600 * MSEC_PER_SEC,
482 .warmup_time = 60 * MSEC_PER_SEC,
483 .limit = 0,
484 .max = 25,
485 .bin_size = 20,
486 .increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
487 .decrement = (SFB_MAX_PROB + 3000) / 6000,
488 .penalty_rate = 10,
489 .penalty_burst = 20,
492 static int sfb_change(struct Qdisc *sch, struct nlattr *opt,
493 struct netlink_ext_ack *extack)
495 struct sfb_sched_data *q = qdisc_priv(sch);
496 struct Qdisc *child, *old;
497 struct nlattr *tb[TCA_SFB_MAX + 1];
498 const struct tc_sfb_qopt *ctl = &sfb_default_ops;
499 u32 limit;
500 int err;
502 if (opt) {
503 err = nla_parse_nested_deprecated(tb, TCA_SFB_MAX, opt,
504 sfb_policy, NULL);
505 if (err < 0)
506 return -EINVAL;
508 if (tb[TCA_SFB_PARMS] == NULL)
509 return -EINVAL;
511 ctl = nla_data(tb[TCA_SFB_PARMS]);
514 limit = ctl->limit;
515 if (limit == 0)
516 limit = qdisc_dev(sch)->tx_queue_len;
518 child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit, extack);
519 if (IS_ERR(child))
520 return PTR_ERR(child);
522 if (child != &noop_qdisc)
523 qdisc_hash_add(child, true);
524 sch_tree_lock(sch);
526 qdisc_purge_queue(q->qdisc);
527 old = q->qdisc;
528 q->qdisc = child;
530 q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
531 q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
532 q->rehash_time = jiffies;
533 q->limit = limit;
534 q->increment = ctl->increment;
535 q->decrement = ctl->decrement;
536 q->max = ctl->max;
537 q->bin_size = ctl->bin_size;
538 q->penalty_rate = ctl->penalty_rate;
539 q->penalty_burst = ctl->penalty_burst;
540 q->tokens_avail = ctl->penalty_burst;
541 q->token_time = jiffies;
543 q->slot = 0;
544 q->double_buffering = false;
545 sfb_zero_all_buckets(q);
546 sfb_init_perturbation(0, q);
547 sfb_init_perturbation(1, q);
549 sch_tree_unlock(sch);
550 qdisc_put(old);
552 return 0;
555 static int sfb_init(struct Qdisc *sch, struct nlattr *opt,
556 struct netlink_ext_ack *extack)
558 struct sfb_sched_data *q = qdisc_priv(sch);
559 int err;
561 err = tcf_block_get(&q->block, &q->filter_list, sch, extack);
562 if (err)
563 return err;
565 q->qdisc = &noop_qdisc;
566 return sfb_change(sch, opt, extack);
569 static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
571 struct sfb_sched_data *q = qdisc_priv(sch);
572 struct nlattr *opts;
573 struct tc_sfb_qopt opt = {
574 .rehash_interval = jiffies_to_msecs(q->rehash_interval),
575 .warmup_time = jiffies_to_msecs(q->warmup_time),
576 .limit = q->limit,
577 .max = q->max,
578 .bin_size = q->bin_size,
579 .increment = q->increment,
580 .decrement = q->decrement,
581 .penalty_rate = q->penalty_rate,
582 .penalty_burst = q->penalty_burst,
585 sch->qstats.backlog = q->qdisc->qstats.backlog;
586 opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
587 if (opts == NULL)
588 goto nla_put_failure;
589 if (nla_put(skb, TCA_SFB_PARMS, sizeof(opt), &opt))
590 goto nla_put_failure;
591 return nla_nest_end(skb, opts);
593 nla_put_failure:
594 nla_nest_cancel(skb, opts);
595 return -EMSGSIZE;
598 static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
600 struct sfb_sched_data *q = qdisc_priv(sch);
601 struct tc_sfb_xstats st = {
602 .earlydrop = q->stats.earlydrop,
603 .penaltydrop = q->stats.penaltydrop,
604 .bucketdrop = q->stats.bucketdrop,
605 .queuedrop = q->stats.queuedrop,
606 .childdrop = q->stats.childdrop,
607 .marked = q->stats.marked,
610 st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);
612 return gnet_stats_copy_app(d, &st, sizeof(st));
615 static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
616 struct sk_buff *skb, struct tcmsg *tcm)
618 return -ENOSYS;
621 static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
622 struct Qdisc **old, struct netlink_ext_ack *extack)
624 struct sfb_sched_data *q = qdisc_priv(sch);
626 if (new == NULL)
627 new = &noop_qdisc;
629 *old = qdisc_replace(sch, new, &q->qdisc);
630 return 0;
633 static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
635 struct sfb_sched_data *q = qdisc_priv(sch);
637 return q->qdisc;
640 static unsigned long sfb_find(struct Qdisc *sch, u32 classid)
642 return 1;
645 static void sfb_unbind(struct Qdisc *sch, unsigned long arg)
649 static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
650 struct nlattr **tca, unsigned long *arg,
651 struct netlink_ext_ack *extack)
653 return -ENOSYS;
656 static int sfb_delete(struct Qdisc *sch, unsigned long cl,
657 struct netlink_ext_ack *extack)
659 return -ENOSYS;
662 static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
664 if (!walker->stop) {
665 tc_qdisc_stats_dump(sch, 1, walker);
669 static struct tcf_block *sfb_tcf_block(struct Qdisc *sch, unsigned long cl,
670 struct netlink_ext_ack *extack)
672 struct sfb_sched_data *q = qdisc_priv(sch);
674 if (cl)
675 return NULL;
676 return q->block;
679 static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
680 u32 classid)
682 return 0;
686 static const struct Qdisc_class_ops sfb_class_ops = {
687 .graft = sfb_graft,
688 .leaf = sfb_leaf,
689 .find = sfb_find,
690 .change = sfb_change_class,
691 .delete = sfb_delete,
692 .walk = sfb_walk,
693 .tcf_block = sfb_tcf_block,
694 .bind_tcf = sfb_bind,
695 .unbind_tcf = sfb_unbind,
696 .dump = sfb_dump_class,
699 static struct Qdisc_ops sfb_qdisc_ops __read_mostly = {
700 .id = "sfb",
701 .priv_size = sizeof(struct sfb_sched_data),
702 .cl_ops = &sfb_class_ops,
703 .enqueue = sfb_enqueue,
704 .dequeue = sfb_dequeue,
705 .peek = sfb_peek,
706 .init = sfb_init,
707 .reset = sfb_reset,
708 .destroy = sfb_destroy,
709 .change = sfb_change,
710 .dump = sfb_dump,
711 .dump_stats = sfb_dump_stats,
712 .owner = THIS_MODULE,
714 MODULE_ALIAS_NET_SCH("sfb");
716 static int __init sfb_module_init(void)
718 return register_qdisc(&sfb_qdisc_ops);
721 static void __exit sfb_module_exit(void)
723 unregister_qdisc(&sfb_qdisc_ops);
726 module_init(sfb_module_init)
727 module_exit(sfb_module_exit)
729 MODULE_DESCRIPTION("Stochastic Fair Blue queue discipline");
730 MODULE_AUTHOR("Juliusz Chroboczek");
731 MODULE_AUTHOR("Eric Dumazet");
732 MODULE_LICENSE("GPL");