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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Scheduler topology setup/handling methods
4 */
5#include "sched.h"
6
7DEFINE_MUTEX(sched_domains_mutex);
8
9/* Protected by sched_domains_mutex: */
10cpumask_var_t sched_domains_tmpmask;
11cpumask_var_t sched_domains_tmpmask2;
12
13#ifdef CONFIG_SCHED_DEBUG
14
15static int __init sched_debug_setup(char *str)
16{
17 sched_debug_enabled = true;
18
19 return 0;
20}
21early_param("sched_debug", sched_debug_setup);
22
23static inline bool sched_debug(void)
24{
25 return sched_debug_enabled;
26}
27
28static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
29 struct cpumask *groupmask)
30{
31 struct sched_group *group = sd->groups;
32
33 cpumask_clear(groupmask);
34
35 printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
36
37 if (!(sd->flags & SD_LOAD_BALANCE)) {
38 printk("does not load-balance\n");
39 if (sd->parent)
40 printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain has parent");
41 return -1;
42 }
43
44 printk(KERN_CONT "span=%*pbl level=%s\n",
45 cpumask_pr_args(sched_domain_span(sd)), sd->name);
46
47 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
48 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
49 }
50 if (!cpumask_test_cpu(cpu, sched_group_span(group))) {
51 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
52 }
53
54 printk(KERN_DEBUG "%*s groups:", level + 1, "");
55 do {
56 if (!group) {
57 printk("\n");
58 printk(KERN_ERR "ERROR: group is NULL\n");
59 break;
60 }
61
62 if (!cpumask_weight(sched_group_span(group))) {
63 printk(KERN_CONT "\n");
64 printk(KERN_ERR "ERROR: empty group\n");
65 break;
66 }
67
68 if (!(sd->flags & SD_OVERLAP) &&
69 cpumask_intersects(groupmask, sched_group_span(group))) {
70 printk(KERN_CONT "\n");
71 printk(KERN_ERR "ERROR: repeated CPUs\n");
72 break;
73 }
74
75 cpumask_or(groupmask, groupmask, sched_group_span(group));
76
77 printk(KERN_CONT " %d:{ span=%*pbl",
78 group->sgc->id,
79 cpumask_pr_args(sched_group_span(group)));
80
81 if ((sd->flags & SD_OVERLAP) &&
82 !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
83 printk(KERN_CONT " mask=%*pbl",
84 cpumask_pr_args(group_balance_mask(group)));
85 }
86
87 if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
88 printk(KERN_CONT " cap=%lu", group->sgc->capacity);
89
90 if (group == sd->groups && sd->child &&
91 !cpumask_equal(sched_domain_span(sd->child),
92 sched_group_span(group))) {
93 printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
94 }
95
96 printk(KERN_CONT " }");
97
98 group = group->next;
99
100 if (group != sd->groups)
101 printk(KERN_CONT ",");
102
103 } while (group != sd->groups);
104 printk(KERN_CONT "\n");
105
106 if (!cpumask_equal(sched_domain_span(sd), groupmask))
107 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
108
109 if (sd->parent &&
110 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
111 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
112 return 0;
113}
114
115static void sched_domain_debug(struct sched_domain *sd, int cpu)
116{
117 int level = 0;
118
119 if (!sched_debug_enabled)
120 return;
121
122 if (!sd) {
123 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
124 return;
125 }
126
127 printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
128
129 for (;;) {
130 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
131 break;
132 level++;
133 sd = sd->parent;
134 if (!sd)
135 break;
136 }
137}
138#else /* !CONFIG_SCHED_DEBUG */
139
140# define sched_debug_enabled 0
141# define sched_domain_debug(sd, cpu) do { } while (0)
142static inline bool sched_debug(void)
143{
144 return false;
145}
146#endif /* CONFIG_SCHED_DEBUG */
147
148static int sd_degenerate(struct sched_domain *sd)
149{
150 if (cpumask_weight(sched_domain_span(sd)) == 1)
151 return 1;
152
153 /* Following flags need at least 2 groups */
154 if (sd->flags & (SD_LOAD_BALANCE |
155 SD_BALANCE_NEWIDLE |
156 SD_BALANCE_FORK |
157 SD_BALANCE_EXEC |
158 SD_SHARE_CPUCAPACITY |
159 SD_ASYM_CPUCAPACITY |
160 SD_SHARE_PKG_RESOURCES |
161 SD_SHARE_POWERDOMAIN)) {
162 if (sd->groups != sd->groups->next)
163 return 0;
164 }
165
166 /* Following flags don't use groups */
167 if (sd->flags & (SD_WAKE_AFFINE))
168 return 0;
169
170 return 1;
171}
172
173static int
174sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
175{
176 unsigned long cflags = sd->flags, pflags = parent->flags;
177
178 if (sd_degenerate(parent))
179 return 1;
180
181 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
182 return 0;
183
184 /* Flags needing groups don't count if only 1 group in parent */
185 if (parent->groups == parent->groups->next) {
186 pflags &= ~(SD_LOAD_BALANCE |
187 SD_BALANCE_NEWIDLE |
188 SD_BALANCE_FORK |
189 SD_BALANCE_EXEC |
190 SD_ASYM_CPUCAPACITY |
191 SD_SHARE_CPUCAPACITY |
192 SD_SHARE_PKG_RESOURCES |
193 SD_PREFER_SIBLING |
194 SD_SHARE_POWERDOMAIN);
195 if (nr_node_ids == 1)
196 pflags &= ~SD_SERIALIZE;
197 }
198 if (~cflags & pflags)
199 return 0;
200
201 return 1;
202}
203
204static void free_rootdomain(struct rcu_head *rcu)
205{
206 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
207
208 cpupri_cleanup(&rd->cpupri);
209 cpudl_cleanup(&rd->cpudl);
210 free_cpumask_var(rd->dlo_mask);
211 free_cpumask_var(rd->rto_mask);
212 free_cpumask_var(rd->online);
213 free_cpumask_var(rd->span);
214 kfree(rd);
215}
216
217void rq_attach_root(struct rq *rq, struct root_domain *rd)
218{
219 struct root_domain *old_rd = NULL;
220 unsigned long flags;
221
222 raw_spin_lock_irqsave(&rq->lock, flags);
223
224 if (rq->rd) {
225 old_rd = rq->rd;
226
227 if (cpumask_test_cpu(rq->cpu, old_rd->online))
228 set_rq_offline(rq);
229
230 cpumask_clear_cpu(rq->cpu, old_rd->span);
231
232 /*
233 * If we dont want to free the old_rd yet then
234 * set old_rd to NULL to skip the freeing later
235 * in this function:
236 */
237 if (!atomic_dec_and_test(&old_rd->refcount))
238 old_rd = NULL;
239 }
240
241 atomic_inc(&rd->refcount);
242 rq->rd = rd;
243
244 cpumask_set_cpu(rq->cpu, rd->span);
245 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
246 set_rq_online(rq);
247
248 raw_spin_unlock_irqrestore(&rq->lock, flags);
249
250 if (old_rd)
251 call_rcu_sched(&old_rd->rcu, free_rootdomain);
252}
253
254void sched_get_rd(struct root_domain *rd)
255{
256 atomic_inc(&rd->refcount);
257}
258
259void sched_put_rd(struct root_domain *rd)
260{
261 if (!atomic_dec_and_test(&rd->refcount))
262 return;
263
264 call_rcu_sched(&rd->rcu, free_rootdomain);
265}
266
267static int init_rootdomain(struct root_domain *rd)
268{
269 if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
270 goto out;
271 if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
272 goto free_span;
273 if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
274 goto free_online;
275 if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
276 goto free_dlo_mask;
277
278#ifdef HAVE_RT_PUSH_IPI
279 rd->rto_cpu = -1;
280 raw_spin_lock_init(&rd->rto_lock);
281 init_irq_work(&rd->rto_push_work, rto_push_irq_work_func);
282#endif
283
284 init_dl_bw(&rd->dl_bw);
285 if (cpudl_init(&rd->cpudl) != 0)
286 goto free_rto_mask;
287
288 if (cpupri_init(&rd->cpupri) != 0)
289 goto free_cpudl;
290 return 0;
291
292free_cpudl:
293 cpudl_cleanup(&rd->cpudl);
294free_rto_mask:
295 free_cpumask_var(rd->rto_mask);
296free_dlo_mask:
297 free_cpumask_var(rd->dlo_mask);
298free_online:
299 free_cpumask_var(rd->online);
300free_span:
301 free_cpumask_var(rd->span);
302out:
303 return -ENOMEM;
304}
305
306/*
307 * By default the system creates a single root-domain with all CPUs as
308 * members (mimicking the global state we have today).
309 */
310struct root_domain def_root_domain;
311
312void init_defrootdomain(void)
313{
314 init_rootdomain(&def_root_domain);
315
316 atomic_set(&def_root_domain.refcount, 1);
317}
318
319static struct root_domain *alloc_rootdomain(void)
320{
321 struct root_domain *rd;
322
323 rd = kzalloc(sizeof(*rd), GFP_KERNEL);
324 if (!rd)
325 return NULL;
326
327 if (init_rootdomain(rd) != 0) {
328 kfree(rd);
329 return NULL;
330 }
331
332 return rd;
333}
334
335static void free_sched_groups(struct sched_group *sg, int free_sgc)
336{
337 struct sched_group *tmp, *first;
338
339 if (!sg)
340 return;
341
342 first = sg;
343 do {
344 tmp = sg->next;
345
346 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
347 kfree(sg->sgc);
348
349 if (atomic_dec_and_test(&sg->ref))
350 kfree(sg);
351 sg = tmp;
352 } while (sg != first);
353}
354
355static void destroy_sched_domain(struct sched_domain *sd)
356{
357 /*
358 * A normal sched domain may have multiple group references, an
359 * overlapping domain, having private groups, only one. Iterate,
360 * dropping group/capacity references, freeing where none remain.
361 */
362 free_sched_groups(sd->groups, 1);
363
364 if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
365 kfree(sd->shared);
366 kfree(sd);
367}
368
369static void destroy_sched_domains_rcu(struct rcu_head *rcu)
370{
371 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
372
373 while (sd) {
374 struct sched_domain *parent = sd->parent;
375 destroy_sched_domain(sd);
376 sd = parent;
377 }
378}
379
380static void destroy_sched_domains(struct sched_domain *sd)
381{
382 if (sd)
383 call_rcu(&sd->rcu, destroy_sched_domains_rcu);
384}
385
386/*
387 * Keep a special pointer to the highest sched_domain that has
388 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
389 * allows us to avoid some pointer chasing select_idle_sibling().
390 *
391 * Also keep a unique ID per domain (we use the first CPU number in
392 * the cpumask of the domain), this allows us to quickly tell if
393 * two CPUs are in the same cache domain, see cpus_share_cache().
394 */
395DEFINE_PER_CPU(struct sched_domain *, sd_llc);
396DEFINE_PER_CPU(int, sd_llc_size);
397DEFINE_PER_CPU(int, sd_llc_id);
398DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
399DEFINE_PER_CPU(struct sched_domain *, sd_numa);
400DEFINE_PER_CPU(struct sched_domain *, sd_asym);
401
402static void update_top_cache_domain(int cpu)
403{
404 struct sched_domain_shared *sds = NULL;
405 struct sched_domain *sd;
406 int id = cpu;
407 int size = 1;
408
409 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
410 if (sd) {
411 id = cpumask_first(sched_domain_span(sd));
412 size = cpumask_weight(sched_domain_span(sd));
413 sds = sd->shared;
414 }
415
416 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
417 per_cpu(sd_llc_size, cpu) = size;
418 per_cpu(sd_llc_id, cpu) = id;
419 rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
420
421 sd = lowest_flag_domain(cpu, SD_NUMA);
422 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
423
424 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
425 rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
426}
427
428/*
429 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
430 * hold the hotplug lock.
431 */
432static void
433cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
434{
435 struct rq *rq = cpu_rq(cpu);
436 struct sched_domain *tmp;
437
438 /* Remove the sched domains which do not contribute to scheduling. */
439 for (tmp = sd; tmp; ) {
440 struct sched_domain *parent = tmp->parent;
441 if (!parent)
442 break;
443
444 if (sd_parent_degenerate(tmp, parent)) {
445 tmp->parent = parent->parent;
446 if (parent->parent)
447 parent->parent->child = tmp;
448 /*
449 * Transfer SD_PREFER_SIBLING down in case of a
450 * degenerate parent; the spans match for this
451 * so the property transfers.
452 */
453 if (parent->flags & SD_PREFER_SIBLING)
454 tmp->flags |= SD_PREFER_SIBLING;
455 destroy_sched_domain(parent);
456 } else
457 tmp = tmp->parent;
458 }
459
460 if (sd && sd_degenerate(sd)) {
461 tmp = sd;
462 sd = sd->parent;
463 destroy_sched_domain(tmp);
464 if (sd)
465 sd->child = NULL;
466 }
467
468 sched_domain_debug(sd, cpu);
469
470 rq_attach_root(rq, rd);
471 tmp = rq->sd;
472 rcu_assign_pointer(rq->sd, sd);
473 dirty_sched_domain_sysctl(cpu);
474 destroy_sched_domains(tmp);
475
476 update_top_cache_domain(cpu);
477}
478
479struct s_data {
480 struct sched_domain ** __percpu sd;
481 struct root_domain *rd;
482};
483
484enum s_alloc {
485 sa_rootdomain,
486 sa_sd,
487 sa_sd_storage,
488 sa_none,
489};
490
491/*
492 * Return the canonical balance CPU for this group, this is the first CPU
493 * of this group that's also in the balance mask.
494 *
495 * The balance mask are all those CPUs that could actually end up at this
496 * group. See build_balance_mask().
497 *
498 * Also see should_we_balance().
499 */
500int group_balance_cpu(struct sched_group *sg)
501{
502 return cpumask_first(group_balance_mask(sg));
503}
504
505
506/*
507 * NUMA topology (first read the regular topology blurb below)
508 *
509 * Given a node-distance table, for example:
510 *
511 * node 0 1 2 3
512 * 0: 10 20 30 20
513 * 1: 20 10 20 30
514 * 2: 30 20 10 20
515 * 3: 20 30 20 10
516 *
517 * which represents a 4 node ring topology like:
518 *
519 * 0 ----- 1
520 * | |
521 * | |
522 * | |
523 * 3 ----- 2
524 *
525 * We want to construct domains and groups to represent this. The way we go
526 * about doing this is to build the domains on 'hops'. For each NUMA level we
527 * construct the mask of all nodes reachable in @level hops.
528 *
529 * For the above NUMA topology that gives 3 levels:
530 *
531 * NUMA-2 0-3 0-3 0-3 0-3
532 * groups: {0-1,3},{1-3} {0-2},{0,2-3} {1-3},{0-1,3} {0,2-3},{0-2}
533 *
534 * NUMA-1 0-1,3 0-2 1-3 0,2-3
535 * groups: {0},{1},{3} {0},{1},{2} {1},{2},{3} {0},{2},{3}
536 *
537 * NUMA-0 0 1 2 3
538 *
539 *
540 * As can be seen; things don't nicely line up as with the regular topology.
541 * When we iterate a domain in child domain chunks some nodes can be
542 * represented multiple times -- hence the "overlap" naming for this part of
543 * the topology.
544 *
545 * In order to minimize this overlap, we only build enough groups to cover the
546 * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
547 *
548 * Because:
549 *
550 * - the first group of each domain is its child domain; this
551 * gets us the first 0-1,3
552 * - the only uncovered node is 2, who's child domain is 1-3.
553 *
554 * However, because of the overlap, computing a unique CPU for each group is
555 * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
556 * groups include the CPUs of Node-0, while those CPUs would not in fact ever
557 * end up at those groups (they would end up in group: 0-1,3).
558 *
559 * To correct this we have to introduce the group balance mask. This mask
560 * will contain those CPUs in the group that can reach this group given the
561 * (child) domain tree.
562 *
563 * With this we can once again compute balance_cpu and sched_group_capacity
564 * relations.
565 *
566 * XXX include words on how balance_cpu is unique and therefore can be
567 * used for sched_group_capacity links.
568 *
569 *
570 * Another 'interesting' topology is:
571 *
572 * node 0 1 2 3
573 * 0: 10 20 20 30
574 * 1: 20 10 20 20
575 * 2: 20 20 10 20
576 * 3: 30 20 20 10
577 *
578 * Which looks a little like:
579 *
580 * 0 ----- 1
581 * | / |
582 * | / |
583 * | / |
584 * 2 ----- 3
585 *
586 * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
587 * are not.
588 *
589 * This leads to a few particularly weird cases where the sched_domain's are
590 * not of the same number for each CPU. Consider:
591 *
592 * NUMA-2 0-3 0-3
593 * groups: {0-2},{1-3} {1-3},{0-2}
594 *
595 * NUMA-1 0-2 0-3 0-3 1-3
596 *
597 * NUMA-0 0 1 2 3
598 *
599 */
600
601
602/*
603 * Build the balance mask; it contains only those CPUs that can arrive at this
604 * group and should be considered to continue balancing.
605 *
606 * We do this during the group creation pass, therefore the group information
607 * isn't complete yet, however since each group represents a (child) domain we
608 * can fully construct this using the sched_domain bits (which are already
609 * complete).
610 */
611static void
612build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
613{
614 const struct cpumask *sg_span = sched_group_span(sg);
615 struct sd_data *sdd = sd->private;
616 struct sched_domain *sibling;
617 int i;
618
619 cpumask_clear(mask);
620
621 for_each_cpu(i, sg_span) {
622 sibling = *per_cpu_ptr(sdd->sd, i);
623
624 /*
625 * Can happen in the asymmetric case, where these siblings are
626 * unused. The mask will not be empty because those CPUs that
627 * do have the top domain _should_ span the domain.
628 */
629 if (!sibling->child)
630 continue;
631
632 /* If we would not end up here, we can't continue from here */
633 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
634 continue;
635
636 cpumask_set_cpu(i, mask);
637 }
638
639 /* We must not have empty masks here */
640 WARN_ON_ONCE(cpumask_empty(mask));
641}
642
643/*
644 * XXX: This creates per-node group entries; since the load-balancer will
645 * immediately access remote memory to construct this group's load-balance
646 * statistics having the groups node local is of dubious benefit.
647 */
648static struct sched_group *
649build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
650{
651 struct sched_group *sg;
652 struct cpumask *sg_span;
653
654 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
655 GFP_KERNEL, cpu_to_node(cpu));
656
657 if (!sg)
658 return NULL;
659
660 sg_span = sched_group_span(sg);
661 if (sd->child)
662 cpumask_copy(sg_span, sched_domain_span(sd->child));
663 else
664 cpumask_copy(sg_span, sched_domain_span(sd));
665
666 atomic_inc(&sg->ref);
667 return sg;
668}
669
670static void init_overlap_sched_group(struct sched_domain *sd,
671 struct sched_group *sg)
672{
673 struct cpumask *mask = sched_domains_tmpmask2;
674 struct sd_data *sdd = sd->private;
675 struct cpumask *sg_span;
676 int cpu;
677
678 build_balance_mask(sd, sg, mask);
679 cpu = cpumask_first_and(sched_group_span(sg), mask);
680
681 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
682 if (atomic_inc_return(&sg->sgc->ref) == 1)
683 cpumask_copy(group_balance_mask(sg), mask);
684 else
685 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
686
687 /*
688 * Initialize sgc->capacity such that even if we mess up the
689 * domains and no possible iteration will get us here, we won't
690 * die on a /0 trap.
691 */
692 sg_span = sched_group_span(sg);
693 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
694 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
695}
696
697static int
698build_overlap_sched_groups(struct sched_domain *sd, int cpu)
699{
700 struct sched_group *first = NULL, *last = NULL, *sg;
701 const struct cpumask *span = sched_domain_span(sd);
702 struct cpumask *covered = sched_domains_tmpmask;
703 struct sd_data *sdd = sd->private;
704 struct sched_domain *sibling;
705 int i;
706
707 cpumask_clear(covered);
708
709 for_each_cpu_wrap(i, span, cpu) {
710 struct cpumask *sg_span;
711
712 if (cpumask_test_cpu(i, covered))
713 continue;
714
715 sibling = *per_cpu_ptr(sdd->sd, i);
716
717 /*
718 * Asymmetric node setups can result in situations where the
719 * domain tree is of unequal depth, make sure to skip domains
720 * that already cover the entire range.
721 *
722 * In that case build_sched_domains() will have terminated the
723 * iteration early and our sibling sd spans will be empty.
724 * Domains should always include the CPU they're built on, so
725 * check that.
726 */
727 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
728 continue;
729
730 sg = build_group_from_child_sched_domain(sibling, cpu);
731 if (!sg)
732 goto fail;
733
734 sg_span = sched_group_span(sg);
735 cpumask_or(covered, covered, sg_span);
736
737 init_overlap_sched_group(sd, sg);
738
739 if (!first)
740 first = sg;
741 if (last)
742 last->next = sg;
743 last = sg;
744 last->next = first;
745 }
746 sd->groups = first;
747
748 return 0;
749
750fail:
751 free_sched_groups(first, 0);
752
753 return -ENOMEM;
754}
755
756
757/*
758 * Package topology (also see the load-balance blurb in fair.c)
759 *
760 * The scheduler builds a tree structure to represent a number of important
761 * topology features. By default (default_topology[]) these include:
762 *
763 * - Simultaneous multithreading (SMT)
764 * - Multi-Core Cache (MC)
765 * - Package (DIE)
766 *
767 * Where the last one more or less denotes everything up to a NUMA node.
768 *
769 * The tree consists of 3 primary data structures:
770 *
771 * sched_domain -> sched_group -> sched_group_capacity
772 * ^ ^ ^ ^
773 * `-' `-'
774 *
775 * The sched_domains are per-CPU and have a two way link (parent & child) and
776 * denote the ever growing mask of CPUs belonging to that level of topology.
777 *
778 * Each sched_domain has a circular (double) linked list of sched_group's, each
779 * denoting the domains of the level below (or individual CPUs in case of the
780 * first domain level). The sched_group linked by a sched_domain includes the
781 * CPU of that sched_domain [*].
782 *
783 * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
784 *
785 * CPU 0 1 2 3 4 5 6 7
786 *
787 * DIE [ ]
788 * MC [ ] [ ]
789 * SMT [ ] [ ] [ ] [ ]
790 *
791 * - or -
792 *
793 * DIE 0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
794 * MC 0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
795 * SMT 0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
796 *
797 * CPU 0 1 2 3 4 5 6 7
798 *
799 * One way to think about it is: sched_domain moves you up and down among these
800 * topology levels, while sched_group moves you sideways through it, at child
801 * domain granularity.
802 *
803 * sched_group_capacity ensures each unique sched_group has shared storage.
804 *
805 * There are two related construction problems, both require a CPU that
806 * uniquely identify each group (for a given domain):
807 *
808 * - The first is the balance_cpu (see should_we_balance() and the
809 * load-balance blub in fair.c); for each group we only want 1 CPU to
810 * continue balancing at a higher domain.
811 *
812 * - The second is the sched_group_capacity; we want all identical groups
813 * to share a single sched_group_capacity.
814 *
815 * Since these topologies are exclusive by construction. That is, its
816 * impossible for an SMT thread to belong to multiple cores, and cores to
817 * be part of multiple caches. There is a very clear and unique location
818 * for each CPU in the hierarchy.
819 *
820 * Therefore computing a unique CPU for each group is trivial (the iteration
821 * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
822 * group), we can simply pick the first CPU in each group.
823 *
824 *
825 * [*] in other words, the first group of each domain is its child domain.
826 */
827
828static struct sched_group *get_group(int cpu, struct sd_data *sdd)
829{
830 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
831 struct sched_domain *child = sd->child;
832 struct sched_group *sg;
833
834 if (child)
835 cpu = cpumask_first(sched_domain_span(child));
836
837 sg = *per_cpu_ptr(sdd->sg, cpu);
838 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
839
840 /* For claim_allocations: */
841 atomic_inc(&sg->ref);
842 atomic_inc(&sg->sgc->ref);
843
844 if (child) {
845 cpumask_copy(sched_group_span(sg), sched_domain_span(child));
846 cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
847 } else {
848 cpumask_set_cpu(cpu, sched_group_span(sg));
849 cpumask_set_cpu(cpu, group_balance_mask(sg));
850 }
851
852 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
853 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
854
855 return sg;
856}
857
858/*
859 * build_sched_groups will build a circular linked list of the groups
860 * covered by the given span, and will set each group's ->cpumask correctly,
861 * and ->cpu_capacity to 0.
862 *
863 * Assumes the sched_domain tree is fully constructed
864 */
865static int
866build_sched_groups(struct sched_domain *sd, int cpu)
867{
868 struct sched_group *first = NULL, *last = NULL;
869 struct sd_data *sdd = sd->private;
870 const struct cpumask *span = sched_domain_span(sd);
871 struct cpumask *covered;
872 int i;
873
874 lockdep_assert_held(&sched_domains_mutex);
875 covered = sched_domains_tmpmask;
876
877 cpumask_clear(covered);
878
879 for_each_cpu_wrap(i, span, cpu) {
880 struct sched_group *sg;
881
882 if (cpumask_test_cpu(i, covered))
883 continue;
884
885 sg = get_group(i, sdd);
886
887 cpumask_or(covered, covered, sched_group_span(sg));
888
889 if (!first)
890 first = sg;
891 if (last)
892 last->next = sg;
893 last = sg;
894 }
895 last->next = first;
896 sd->groups = first;
897
898 return 0;
899}
900
901/*
902 * Initialize sched groups cpu_capacity.
903 *
904 * cpu_capacity indicates the capacity of sched group, which is used while
905 * distributing the load between different sched groups in a sched domain.
906 * Typically cpu_capacity for all the groups in a sched domain will be same
907 * unless there are asymmetries in the topology. If there are asymmetries,
908 * group having more cpu_capacity will pickup more load compared to the
909 * group having less cpu_capacity.
910 */
911static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
912{
913 struct sched_group *sg = sd->groups;
914
915 WARN_ON(!sg);
916
917 do {
918 int cpu, max_cpu = -1;
919
920 sg->group_weight = cpumask_weight(sched_group_span(sg));
921
922 if (!(sd->flags & SD_ASYM_PACKING))
923 goto next;
924
925 for_each_cpu(cpu, sched_group_span(sg)) {
926 if (max_cpu < 0)
927 max_cpu = cpu;
928 else if (sched_asym_prefer(cpu, max_cpu))
929 max_cpu = cpu;
930 }
931 sg->asym_prefer_cpu = max_cpu;
932
933next:
934 sg = sg->next;
935 } while (sg != sd->groups);
936
937 if (cpu != group_balance_cpu(sg))
938 return;
939
940 update_group_capacity(sd, cpu);
941}
942
943/*
944 * Initializers for schedule domains
945 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
946 */
947
948static int default_relax_domain_level = -1;
949int sched_domain_level_max;
950
951static int __init setup_relax_domain_level(char *str)
952{
953 if (kstrtoint(str, 0, &default_relax_domain_level))
954 pr_warn("Unable to set relax_domain_level\n");
955
956 return 1;
957}
958__setup("relax_domain_level=", setup_relax_domain_level);
959
960static void set_domain_attribute(struct sched_domain *sd,
961 struct sched_domain_attr *attr)
962{
963 int request;
964
965 if (!attr || attr->relax_domain_level < 0) {
966 if (default_relax_domain_level < 0)
967 return;
968 else
969 request = default_relax_domain_level;
970 } else
971 request = attr->relax_domain_level;
972 if (request < sd->level) {
973 /* Turn off idle balance on this domain: */
974 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
975 } else {
976 /* Turn on idle balance on this domain: */
977 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
978 }
979}
980
981static void __sdt_free(const struct cpumask *cpu_map);
982static int __sdt_alloc(const struct cpumask *cpu_map);
983
984static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
985 const struct cpumask *cpu_map)
986{
987 switch (what) {
988 case sa_rootdomain:
989 if (!atomic_read(&d->rd->refcount))
990 free_rootdomain(&d->rd->rcu);
991 /* Fall through */
992 case sa_sd:
993 free_percpu(d->sd);
994 /* Fall through */
995 case sa_sd_storage:
996 __sdt_free(cpu_map);
997 /* Fall through */
998 case sa_none:
999 break;
1000 }
1001}
1002
1003static enum s_alloc
1004__visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1005{
1006 memset(d, 0, sizeof(*d));
1007
1008 if (__sdt_alloc(cpu_map))
1009 return sa_sd_storage;
1010 d->sd = alloc_percpu(struct sched_domain *);
1011 if (!d->sd)
1012 return sa_sd_storage;
1013 d->rd = alloc_rootdomain();
1014 if (!d->rd)
1015 return sa_sd;
1016
1017 return sa_rootdomain;
1018}
1019
1020/*
1021 * NULL the sd_data elements we've used to build the sched_domain and
1022 * sched_group structure so that the subsequent __free_domain_allocs()
1023 * will not free the data we're using.
1024 */
1025static void claim_allocations(int cpu, struct sched_domain *sd)
1026{
1027 struct sd_data *sdd = sd->private;
1028
1029 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1030 *per_cpu_ptr(sdd->sd, cpu) = NULL;
1031
1032 if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
1033 *per_cpu_ptr(sdd->sds, cpu) = NULL;
1034
1035 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
1036 *per_cpu_ptr(sdd->sg, cpu) = NULL;
1037
1038 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1039 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1040}
1041
1042#ifdef CONFIG_NUMA
1043enum numa_topology_type sched_numa_topology_type;
1044
1045static int sched_domains_numa_levels;
1046static int sched_domains_curr_level;
1047
1048int sched_max_numa_distance;
1049static int *sched_domains_numa_distance;
1050static struct cpumask ***sched_domains_numa_masks;
1051#endif
1052
1053/*
1054 * SD_flags allowed in topology descriptions.
1055 *
1056 * These flags are purely descriptive of the topology and do not prescribe
1057 * behaviour. Behaviour is artificial and mapped in the below sd_init()
1058 * function:
1059 *
1060 * SD_SHARE_CPUCAPACITY - describes SMT topologies
1061 * SD_SHARE_PKG_RESOURCES - describes shared caches
1062 * SD_NUMA - describes NUMA topologies
1063 * SD_SHARE_POWERDOMAIN - describes shared power domain
1064 * SD_ASYM_CPUCAPACITY - describes mixed capacity topologies
1065 *
1066 * Odd one out, which beside describing the topology has a quirk also
1067 * prescribes the desired behaviour that goes along with it:
1068 *
1069 * SD_ASYM_PACKING - describes SMT quirks
1070 */
1071#define TOPOLOGY_SD_FLAGS \
1072 (SD_SHARE_CPUCAPACITY | \
1073 SD_SHARE_PKG_RESOURCES | \
1074 SD_NUMA | \
1075 SD_ASYM_PACKING | \
1076 SD_ASYM_CPUCAPACITY | \
1077 SD_SHARE_POWERDOMAIN)
1078
1079static struct sched_domain *
1080sd_init(struct sched_domain_topology_level *tl,
1081 const struct cpumask *cpu_map,
1082 struct sched_domain *child, int cpu)
1083{
1084 struct sd_data *sdd = &tl->data;
1085 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1086 int sd_id, sd_weight, sd_flags = 0;
1087
1088#ifdef CONFIG_NUMA
1089 /*
1090 * Ugly hack to pass state to sd_numa_mask()...
1091 */
1092 sched_domains_curr_level = tl->numa_level;
1093#endif
1094
1095 sd_weight = cpumask_weight(tl->mask(cpu));
1096
1097 if (tl->sd_flags)
1098 sd_flags = (*tl->sd_flags)();
1099 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1100 "wrong sd_flags in topology description\n"))
1101 sd_flags &= ~TOPOLOGY_SD_FLAGS;
1102
1103 *sd = (struct sched_domain){
1104 .min_interval = sd_weight,
1105 .max_interval = 2*sd_weight,
1106 .busy_factor = 32,
1107 .imbalance_pct = 125,
1108
1109 .cache_nice_tries = 0,
1110 .busy_idx = 0,
1111 .idle_idx = 0,
1112 .newidle_idx = 0,
1113 .wake_idx = 0,
1114 .forkexec_idx = 0,
1115
1116 .flags = 1*SD_LOAD_BALANCE
1117 | 1*SD_BALANCE_NEWIDLE
1118 | 1*SD_BALANCE_EXEC
1119 | 1*SD_BALANCE_FORK
1120 | 0*SD_BALANCE_WAKE
1121 | 1*SD_WAKE_AFFINE
1122 | 0*SD_SHARE_CPUCAPACITY
1123 | 0*SD_SHARE_PKG_RESOURCES
1124 | 0*SD_SERIALIZE
1125 | 0*SD_PREFER_SIBLING
1126 | 0*SD_NUMA
1127 | sd_flags
1128 ,
1129
1130 .last_balance = jiffies,
1131 .balance_interval = sd_weight,
1132 .smt_gain = 0,
1133 .max_newidle_lb_cost = 0,
1134 .next_decay_max_lb_cost = jiffies,
1135 .child = child,
1136#ifdef CONFIG_SCHED_DEBUG
1137 .name = tl->name,
1138#endif
1139 };
1140
1141 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
1142 sd_id = cpumask_first(sched_domain_span(sd));
1143
1144 /*
1145 * Convert topological properties into behaviour.
1146 */
1147
1148 if (sd->flags & SD_ASYM_CPUCAPACITY) {
1149 struct sched_domain *t = sd;
1150
1151 for_each_lower_domain(t)
1152 t->flags |= SD_BALANCE_WAKE;
1153 }
1154
1155 if (sd->flags & SD_SHARE_CPUCAPACITY) {
1156 sd->flags |= SD_PREFER_SIBLING;
1157 sd->imbalance_pct = 110;
1158 sd->smt_gain = 1178; /* ~15% */
1159
1160 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1161 sd->flags |= SD_PREFER_SIBLING;
1162 sd->imbalance_pct = 117;
1163 sd->cache_nice_tries = 1;
1164 sd->busy_idx = 2;
1165
1166#ifdef CONFIG_NUMA
1167 } else if (sd->flags & SD_NUMA) {
1168 sd->cache_nice_tries = 2;
1169 sd->busy_idx = 3;
1170 sd->idle_idx = 2;
1171
1172 sd->flags |= SD_SERIALIZE;
1173 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
1174 sd->flags &= ~(SD_BALANCE_EXEC |
1175 SD_BALANCE_FORK |
1176 SD_WAKE_AFFINE);
1177 }
1178
1179#endif
1180 } else {
1181 sd->flags |= SD_PREFER_SIBLING;
1182 sd->cache_nice_tries = 1;
1183 sd->busy_idx = 2;
1184 sd->idle_idx = 1;
1185 }
1186
1187 /*
1188 * For all levels sharing cache; connect a sched_domain_shared
1189 * instance.
1190 */
1191 if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1192 sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1193 atomic_inc(&sd->shared->ref);
1194 atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
1195 }
1196
1197 sd->private = sdd;
1198
1199 return sd;
1200}
1201
1202/*
1203 * Topology list, bottom-up.
1204 */
1205static struct sched_domain_topology_level default_topology[] = {
1206#ifdef CONFIG_SCHED_SMT
1207 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
1208#endif
1209#ifdef CONFIG_SCHED_MC
1210 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
1211#endif
1212 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
1213 { NULL, },
1214};
1215
1216static struct sched_domain_topology_level *sched_domain_topology =
1217 default_topology;
1218
1219#define for_each_sd_topology(tl) \
1220 for (tl = sched_domain_topology; tl->mask; tl++)
1221
1222void set_sched_topology(struct sched_domain_topology_level *tl)
1223{
1224 if (WARN_ON_ONCE(sched_smp_initialized))
1225 return;
1226
1227 sched_domain_topology = tl;
1228}
1229
1230#ifdef CONFIG_NUMA
1231
1232static const struct cpumask *sd_numa_mask(int cpu)
1233{
1234 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
1235}
1236
1237static void sched_numa_warn(const char *str)
1238{
1239 static int done = false;
1240 int i,j;
1241
1242 if (done)
1243 return;
1244
1245 done = true;
1246
1247 printk(KERN_WARNING "ERROR: %s\n\n", str);
1248
1249 for (i = 0; i < nr_node_ids; i++) {
1250 printk(KERN_WARNING " ");
1251 for (j = 0; j < nr_node_ids; j++)
1252 printk(KERN_CONT "%02d ", node_distance(i,j));
1253 printk(KERN_CONT "\n");
1254 }
1255 printk(KERN_WARNING "\n");
1256}
1257
1258bool find_numa_distance(int distance)
1259{
1260 int i;
1261
1262 if (distance == node_distance(0, 0))
1263 return true;
1264
1265 for (i = 0; i < sched_domains_numa_levels; i++) {
1266 if (sched_domains_numa_distance[i] == distance)
1267 return true;
1268 }
1269
1270 return false;
1271}
1272
1273/*
1274 * A system can have three types of NUMA topology:
1275 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1276 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1277 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1278 *
1279 * The difference between a glueless mesh topology and a backplane
1280 * topology lies in whether communication between not directly
1281 * connected nodes goes through intermediary nodes (where programs
1282 * could run), or through backplane controllers. This affects
1283 * placement of programs.
1284 *
1285 * The type of topology can be discerned with the following tests:
1286 * - If the maximum distance between any nodes is 1 hop, the system
1287 * is directly connected.
1288 * - If for two nodes A and B, located N > 1 hops away from each other,
1289 * there is an intermediary node C, which is < N hops away from both
1290 * nodes A and B, the system is a glueless mesh.
1291 */
1292static void init_numa_topology_type(void)
1293{
1294 int a, b, c, n;
1295
1296 n = sched_max_numa_distance;
1297
1298 if (sched_domains_numa_levels <= 1) {
1299 sched_numa_topology_type = NUMA_DIRECT;
1300 return;
1301 }
1302
1303 for_each_online_node(a) {
1304 for_each_online_node(b) {
1305 /* Find two nodes furthest removed from each other. */
1306 if (node_distance(a, b) < n)
1307 continue;
1308
1309 /* Is there an intermediary node between a and b? */
1310 for_each_online_node(c) {
1311 if (node_distance(a, c) < n &&
1312 node_distance(b, c) < n) {
1313 sched_numa_topology_type =
1314 NUMA_GLUELESS_MESH;
1315 return;
1316 }
1317 }
1318
1319 sched_numa_topology_type = NUMA_BACKPLANE;
1320 return;
1321 }
1322 }
1323}
1324
1325void sched_init_numa(void)
1326{
1327 int next_distance, curr_distance = node_distance(0, 0);
1328 struct sched_domain_topology_level *tl;
1329 int level = 0;
1330 int i, j, k;
1331
1332 sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
1333 if (!sched_domains_numa_distance)
1334 return;
1335
1336 /* Includes NUMA identity node at level 0. */
1337 sched_domains_numa_distance[level++] = curr_distance;
1338 sched_domains_numa_levels = level;
1339
1340 /*
1341 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1342 * unique distances in the node_distance() table.
1343 *
1344 * Assumes node_distance(0,j) includes all distances in
1345 * node_distance(i,j) in order to avoid cubic time.
1346 */
1347 next_distance = curr_distance;
1348 for (i = 0; i < nr_node_ids; i++) {
1349 for (j = 0; j < nr_node_ids; j++) {
1350 for (k = 0; k < nr_node_ids; k++) {
1351 int distance = node_distance(i, k);
1352
1353 if (distance > curr_distance &&
1354 (distance < next_distance ||
1355 next_distance == curr_distance))
1356 next_distance = distance;
1357
1358 /*
1359 * While not a strong assumption it would be nice to know
1360 * about cases where if node A is connected to B, B is not
1361 * equally connected to A.
1362 */
1363 if (sched_debug() && node_distance(k, i) != distance)
1364 sched_numa_warn("Node-distance not symmetric");
1365
1366 if (sched_debug() && i && !find_numa_distance(distance))
1367 sched_numa_warn("Node-0 not representative");
1368 }
1369 if (next_distance != curr_distance) {
1370 sched_domains_numa_distance[level++] = next_distance;
1371 sched_domains_numa_levels = level;
1372 curr_distance = next_distance;
1373 } else break;
1374 }
1375
1376 /*
1377 * In case of sched_debug() we verify the above assumption.
1378 */
1379 if (!sched_debug())
1380 break;
1381 }
1382
1383 if (!level)
1384 return;
1385
1386 /*
1387 * 'level' contains the number of unique distances
1388 *
1389 * The sched_domains_numa_distance[] array includes the actual distance
1390 * numbers.
1391 */
1392
1393 /*
1394 * Here, we should temporarily reset sched_domains_numa_levels to 0.
1395 * If it fails to allocate memory for array sched_domains_numa_masks[][],
1396 * the array will contain less then 'level' members. This could be
1397 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1398 * in other functions.
1399 *
1400 * We reset it to 'level' at the end of this function.
1401 */
1402 sched_domains_numa_levels = 0;
1403
1404 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
1405 if (!sched_domains_numa_masks)
1406 return;
1407
1408 /*
1409 * Now for each level, construct a mask per node which contains all
1410 * CPUs of nodes that are that many hops away from us.
1411 */
1412 for (i = 0; i < level; i++) {
1413 sched_domains_numa_masks[i] =
1414 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1415 if (!sched_domains_numa_masks[i])
1416 return;
1417
1418 for (j = 0; j < nr_node_ids; j++) {
1419 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1420 if (!mask)
1421 return;
1422
1423 sched_domains_numa_masks[i][j] = mask;
1424
1425 for_each_node(k) {
1426 if (node_distance(j, k) > sched_domains_numa_distance[i])
1427 continue;
1428
1429 cpumask_or(mask, mask, cpumask_of_node(k));
1430 }
1431 }
1432 }
1433
1434 /* Compute default topology size */
1435 for (i = 0; sched_domain_topology[i].mask; i++);
1436
1437 tl = kzalloc((i + level + 1) *
1438 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1439 if (!tl)
1440 return;
1441
1442 /*
1443 * Copy the default topology bits..
1444 */
1445 for (i = 0; sched_domain_topology[i].mask; i++)
1446 tl[i] = sched_domain_topology[i];
1447
1448 /*
1449 * Add the NUMA identity distance, aka single NODE.
1450 */
1451 tl[i++] = (struct sched_domain_topology_level){
1452 .mask = sd_numa_mask,
1453 .numa_level = 0,
1454 SD_INIT_NAME(NODE)
1455 };
1456
1457 /*
1458 * .. and append 'j' levels of NUMA goodness.
1459 */
1460 for (j = 1; j < level; i++, j++) {
1461 tl[i] = (struct sched_domain_topology_level){
1462 .mask = sd_numa_mask,
1463 .sd_flags = cpu_numa_flags,
1464 .flags = SDTL_OVERLAP,
1465 .numa_level = j,
1466 SD_INIT_NAME(NUMA)
1467 };
1468 }
1469
1470 sched_domain_topology = tl;
1471
1472 sched_domains_numa_levels = level;
1473 sched_max_numa_distance = sched_domains_numa_distance[level - 1];
1474
1475 init_numa_topology_type();
1476}
1477
1478void sched_domains_numa_masks_set(unsigned int cpu)
1479{
1480 int node = cpu_to_node(cpu);
1481 int i, j;
1482
1483 for (i = 0; i < sched_domains_numa_levels; i++) {
1484 for (j = 0; j < nr_node_ids; j++) {
1485 if (node_distance(j, node) <= sched_domains_numa_distance[i])
1486 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
1487 }
1488 }
1489}
1490
1491void sched_domains_numa_masks_clear(unsigned int cpu)
1492{
1493 int i, j;
1494
1495 for (i = 0; i < sched_domains_numa_levels; i++) {
1496 for (j = 0; j < nr_node_ids; j++)
1497 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
1498 }
1499}
1500
1501#endif /* CONFIG_NUMA */
1502
1503static int __sdt_alloc(const struct cpumask *cpu_map)
1504{
1505 struct sched_domain_topology_level *tl;
1506 int j;
1507
1508 for_each_sd_topology(tl) {
1509 struct sd_data *sdd = &tl->data;
1510
1511 sdd->sd = alloc_percpu(struct sched_domain *);
1512 if (!sdd->sd)
1513 return -ENOMEM;
1514
1515 sdd->sds = alloc_percpu(struct sched_domain_shared *);
1516 if (!sdd->sds)
1517 return -ENOMEM;
1518
1519 sdd->sg = alloc_percpu(struct sched_group *);
1520 if (!sdd->sg)
1521 return -ENOMEM;
1522
1523 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
1524 if (!sdd->sgc)
1525 return -ENOMEM;
1526
1527 for_each_cpu(j, cpu_map) {
1528 struct sched_domain *sd;
1529 struct sched_domain_shared *sds;
1530 struct sched_group *sg;
1531 struct sched_group_capacity *sgc;
1532
1533 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
1534 GFP_KERNEL, cpu_to_node(j));
1535 if (!sd)
1536 return -ENOMEM;
1537
1538 *per_cpu_ptr(sdd->sd, j) = sd;
1539
1540 sds = kzalloc_node(sizeof(struct sched_domain_shared),
1541 GFP_KERNEL, cpu_to_node(j));
1542 if (!sds)
1543 return -ENOMEM;
1544
1545 *per_cpu_ptr(sdd->sds, j) = sds;
1546
1547 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
1548 GFP_KERNEL, cpu_to_node(j));
1549 if (!sg)
1550 return -ENOMEM;
1551
1552 sg->next = sg;
1553
1554 *per_cpu_ptr(sdd->sg, j) = sg;
1555
1556 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
1557 GFP_KERNEL, cpu_to_node(j));
1558 if (!sgc)
1559 return -ENOMEM;
1560
1561#ifdef CONFIG_SCHED_DEBUG
1562 sgc->id = j;
1563#endif
1564
1565 *per_cpu_ptr(sdd->sgc, j) = sgc;
1566 }
1567 }
1568
1569 return 0;
1570}
1571
1572static void __sdt_free(const struct cpumask *cpu_map)
1573{
1574 struct sched_domain_topology_level *tl;
1575 int j;
1576
1577 for_each_sd_topology(tl) {
1578 struct sd_data *sdd = &tl->data;
1579
1580 for_each_cpu(j, cpu_map) {
1581 struct sched_domain *sd;
1582
1583 if (sdd->sd) {
1584 sd = *per_cpu_ptr(sdd->sd, j);
1585 if (sd && (sd->flags & SD_OVERLAP))
1586 free_sched_groups(sd->groups, 0);
1587 kfree(*per_cpu_ptr(sdd->sd, j));
1588 }
1589
1590 if (sdd->sds)
1591 kfree(*per_cpu_ptr(sdd->sds, j));
1592 if (sdd->sg)
1593 kfree(*per_cpu_ptr(sdd->sg, j));
1594 if (sdd->sgc)
1595 kfree(*per_cpu_ptr(sdd->sgc, j));
1596 }
1597 free_percpu(sdd->sd);
1598 sdd->sd = NULL;
1599 free_percpu(sdd->sds);
1600 sdd->sds = NULL;
1601 free_percpu(sdd->sg);
1602 sdd->sg = NULL;
1603 free_percpu(sdd->sgc);
1604 sdd->sgc = NULL;
1605 }
1606}
1607
1608static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
1609 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
1610 struct sched_domain *child, int cpu)
1611{
1612 struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
1613
1614 if (child) {
1615 sd->level = child->level + 1;
1616 sched_domain_level_max = max(sched_domain_level_max, sd->level);
1617 child->parent = sd;
1618
1619 if (!cpumask_subset(sched_domain_span(child),
1620 sched_domain_span(sd))) {
1621 pr_err("BUG: arch topology borken\n");
1622#ifdef CONFIG_SCHED_DEBUG
1623 pr_err(" the %s domain not a subset of the %s domain\n",
1624 child->name, sd->name);
1625#endif
1626 /* Fixup, ensure @sd has at least @child CPUs. */
1627 cpumask_or(sched_domain_span(sd),
1628 sched_domain_span(sd),
1629 sched_domain_span(child));
1630 }
1631
1632 }
1633 set_domain_attribute(sd, attr);
1634
1635 return sd;
1636}
1637
1638/*
1639 * Build sched domains for a given set of CPUs and attach the sched domains
1640 * to the individual CPUs
1641 */
1642static int
1643build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
1644{
1645 enum s_alloc alloc_state;
1646 struct sched_domain *sd;
1647 struct s_data d;
1648 struct rq *rq = NULL;
1649 int i, ret = -ENOMEM;
1650
1651 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
1652 if (alloc_state != sa_rootdomain)
1653 goto error;
1654
1655 /* Set up domains for CPUs specified by the cpu_map: */
1656 for_each_cpu(i, cpu_map) {
1657 struct sched_domain_topology_level *tl;
1658
1659 sd = NULL;
1660 for_each_sd_topology(tl) {
1661 sd = build_sched_domain(tl, cpu_map, attr, sd, i);
1662 if (tl == sched_domain_topology)
1663 *per_cpu_ptr(d.sd, i) = sd;
1664 if (tl->flags & SDTL_OVERLAP)
1665 sd->flags |= SD_OVERLAP;
1666 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
1667 break;
1668 }
1669 }
1670
1671 /* Build the groups for the domains */
1672 for_each_cpu(i, cpu_map) {
1673 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
1674 sd->span_weight = cpumask_weight(sched_domain_span(sd));
1675 if (sd->flags & SD_OVERLAP) {
1676 if (build_overlap_sched_groups(sd, i))
1677 goto error;
1678 } else {
1679 if (build_sched_groups(sd, i))
1680 goto error;
1681 }
1682 }
1683 }
1684
1685 /* Calculate CPU capacity for physical packages and nodes */
1686 for (i = nr_cpumask_bits-1; i >= 0; i--) {
1687 if (!cpumask_test_cpu(i, cpu_map))
1688 continue;
1689
1690 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
1691 claim_allocations(i, sd);
1692 init_sched_groups_capacity(i, sd);
1693 }
1694 }
1695
1696 /* Attach the domains */
1697 rcu_read_lock();
1698 for_each_cpu(i, cpu_map) {
1699 rq = cpu_rq(i);
1700 sd = *per_cpu_ptr(d.sd, i);
1701
1702 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
1703 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
1704 WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
1705
1706 cpu_attach_domain(sd, d.rd, i);
1707 }
1708 rcu_read_unlock();
1709
1710 if (rq && sched_debug_enabled) {
1711 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
1712 cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
1713 }
1714
1715 ret = 0;
1716error:
1717 __free_domain_allocs(&d, alloc_state, cpu_map);
1718
1719 return ret;
1720}
1721
1722/* Current sched domains: */
1723static cpumask_var_t *doms_cur;
1724
1725/* Number of sched domains in 'doms_cur': */
1726static int ndoms_cur;
1727
1728/* Attribues of custom domains in 'doms_cur' */
1729static struct sched_domain_attr *dattr_cur;
1730
1731/*
1732 * Special case: If a kmalloc() of a doms_cur partition (array of
1733 * cpumask) fails, then fallback to a single sched domain,
1734 * as determined by the single cpumask fallback_doms.
1735 */
1736static cpumask_var_t fallback_doms;
1737
1738/*
1739 * arch_update_cpu_topology lets virtualized architectures update the
1740 * CPU core maps. It is supposed to return 1 if the topology changed
1741 * or 0 if it stayed the same.
1742 */
1743int __weak arch_update_cpu_topology(void)
1744{
1745 return 0;
1746}
1747
1748cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
1749{
1750 int i;
1751 cpumask_var_t *doms;
1752
1753 doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
1754 if (!doms)
1755 return NULL;
1756 for (i = 0; i < ndoms; i++) {
1757 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
1758 free_sched_domains(doms, i);
1759 return NULL;
1760 }
1761 }
1762 return doms;
1763}
1764
1765void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
1766{
1767 unsigned int i;
1768 for (i = 0; i < ndoms; i++)
1769 free_cpumask_var(doms[i]);
1770 kfree(doms);
1771}
1772
1773/*
1774 * Set up scheduler domains and groups. Callers must hold the hotplug lock.
1775 * For now this just excludes isolated CPUs, but could be used to
1776 * exclude other special cases in the future.
1777 */
1778int sched_init_domains(const struct cpumask *cpu_map)
1779{
1780 int err;
1781
1782 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
1783 zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
1784 zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
1785
1786 arch_update_cpu_topology();
1787 ndoms_cur = 1;
1788 doms_cur = alloc_sched_domains(ndoms_cur);
1789 if (!doms_cur)
1790 doms_cur = &fallback_doms;
1791 cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN));
1792 err = build_sched_domains(doms_cur[0], NULL);
1793 register_sched_domain_sysctl();
1794
1795 return err;
1796}
1797
1798/*
1799 * Detach sched domains from a group of CPUs specified in cpu_map
1800 * These CPUs will now be attached to the NULL domain
1801 */
1802static void detach_destroy_domains(const struct cpumask *cpu_map)
1803{
1804 int i;
1805
1806 rcu_read_lock();
1807 for_each_cpu(i, cpu_map)
1808 cpu_attach_domain(NULL, &def_root_domain, i);
1809 rcu_read_unlock();
1810}
1811
1812/* handle null as "default" */
1813static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
1814 struct sched_domain_attr *new, int idx_new)
1815{
1816 struct sched_domain_attr tmp;
1817
1818 /* Fast path: */
1819 if (!new && !cur)
1820 return 1;
1821
1822 tmp = SD_ATTR_INIT;
1823
1824 return !memcmp(cur ? (cur + idx_cur) : &tmp,
1825 new ? (new + idx_new) : &tmp,
1826 sizeof(struct sched_domain_attr));
1827}
1828
1829/*
1830 * Partition sched domains as specified by the 'ndoms_new'
1831 * cpumasks in the array doms_new[] of cpumasks. This compares
1832 * doms_new[] to the current sched domain partitioning, doms_cur[].
1833 * It destroys each deleted domain and builds each new domain.
1834 *
1835 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
1836 * The masks don't intersect (don't overlap.) We should setup one
1837 * sched domain for each mask. CPUs not in any of the cpumasks will
1838 * not be load balanced. If the same cpumask appears both in the
1839 * current 'doms_cur' domains and in the new 'doms_new', we can leave
1840 * it as it is.
1841 *
1842 * The passed in 'doms_new' should be allocated using
1843 * alloc_sched_domains. This routine takes ownership of it and will
1844 * free_sched_domains it when done with it. If the caller failed the
1845 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
1846 * and partition_sched_domains() will fallback to the single partition
1847 * 'fallback_doms', it also forces the domains to be rebuilt.
1848 *
1849 * If doms_new == NULL it will be replaced with cpu_online_mask.
1850 * ndoms_new == 0 is a special case for destroying existing domains,
1851 * and it will not create the default domain.
1852 *
1853 * Call with hotplug lock held
1854 */
1855void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
1856 struct sched_domain_attr *dattr_new)
1857{
1858 int i, j, n;
1859 int new_topology;
1860
1861 mutex_lock(&sched_domains_mutex);
1862
1863 /* Always unregister in case we don't destroy any domains: */
1864 unregister_sched_domain_sysctl();
1865
1866 /* Let the architecture update CPU core mappings: */
1867 new_topology = arch_update_cpu_topology();
1868
1869 if (!doms_new) {
1870 WARN_ON_ONCE(dattr_new);
1871 n = 0;
1872 doms_new = alloc_sched_domains(1);
1873 if (doms_new) {
1874 n = 1;
1875 cpumask_and(doms_new[0], cpu_active_mask,
1876 housekeeping_cpumask(HK_FLAG_DOMAIN));
1877 }
1878 } else {
1879 n = ndoms_new;
1880 }
1881
1882 /* Destroy deleted domains: */
1883 for (i = 0; i < ndoms_cur; i++) {
1884 for (j = 0; j < n && !new_topology; j++) {
1885 if (cpumask_equal(doms_cur[i], doms_new[j])
1886 && dattrs_equal(dattr_cur, i, dattr_new, j))
1887 goto match1;
1888 }
1889 /* No match - a current sched domain not in new doms_new[] */
1890 detach_destroy_domains(doms_cur[i]);
1891match1:
1892 ;
1893 }
1894
1895 n = ndoms_cur;
1896 if (!doms_new) {
1897 n = 0;
1898 doms_new = &fallback_doms;
1899 cpumask_and(doms_new[0], cpu_active_mask,
1900 housekeeping_cpumask(HK_FLAG_DOMAIN));
1901 }
1902
1903 /* Build new domains: */
1904 for (i = 0; i < ndoms_new; i++) {
1905 for (j = 0; j < n && !new_topology; j++) {
1906 if (cpumask_equal(doms_new[i], doms_cur[j])
1907 && dattrs_equal(dattr_new, i, dattr_cur, j))
1908 goto match2;
1909 }
1910 /* No match - add a new doms_new */
1911 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
1912match2:
1913 ;
1914 }
1915
1916 /* Remember the new sched domains: */
1917 if (doms_cur != &fallback_doms)
1918 free_sched_domains(doms_cur, ndoms_cur);
1919
1920 kfree(dattr_cur);
1921 doms_cur = doms_new;
1922 dattr_cur = dattr_new;
1923 ndoms_cur = ndoms_new;
1924
1925 register_sched_domain_sysctl();
1926
1927 mutex_unlock(&sched_domains_mutex);
1928}