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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: */
10static cpumask_var_t sched_domains_tmpmask;
11static cpumask_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 printk(KERN_CONT "span=%*pbl level=%s\n",
37 cpumask_pr_args(sched_domain_span(sd)), sd->name);
38
39 if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
40 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
41 }
42 if (group && !cpumask_test_cpu(cpu, sched_group_span(group))) {
43 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
44 }
45
46 printk(KERN_DEBUG "%*s groups:", level + 1, "");
47 do {
48 if (!group) {
49 printk("\n");
50 printk(KERN_ERR "ERROR: group is NULL\n");
51 break;
52 }
53
54 if (!cpumask_weight(sched_group_span(group))) {
55 printk(KERN_CONT "\n");
56 printk(KERN_ERR "ERROR: empty group\n");
57 break;
58 }
59
60 if (!(sd->flags & SD_OVERLAP) &&
61 cpumask_intersects(groupmask, sched_group_span(group))) {
62 printk(KERN_CONT "\n");
63 printk(KERN_ERR "ERROR: repeated CPUs\n");
64 break;
65 }
66
67 cpumask_or(groupmask, groupmask, sched_group_span(group));
68
69 printk(KERN_CONT " %d:{ span=%*pbl",
70 group->sgc->id,
71 cpumask_pr_args(sched_group_span(group)));
72
73 if ((sd->flags & SD_OVERLAP) &&
74 !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
75 printk(KERN_CONT " mask=%*pbl",
76 cpumask_pr_args(group_balance_mask(group)));
77 }
78
79 if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
80 printk(KERN_CONT " cap=%lu", group->sgc->capacity);
81
82 if (group == sd->groups && sd->child &&
83 !cpumask_equal(sched_domain_span(sd->child),
84 sched_group_span(group))) {
85 printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
86 }
87
88 printk(KERN_CONT " }");
89
90 group = group->next;
91
92 if (group != sd->groups)
93 printk(KERN_CONT ",");
94
95 } while (group != sd->groups);
96 printk(KERN_CONT "\n");
97
98 if (!cpumask_equal(sched_domain_span(sd), groupmask))
99 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
100
101 if (sd->parent &&
102 !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
103 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
104 return 0;
105}
106
107static void sched_domain_debug(struct sched_domain *sd, int cpu)
108{
109 int level = 0;
110
111 if (!sched_debug_enabled)
112 return;
113
114 if (!sd) {
115 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
116 return;
117 }
118
119 printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
120
121 for (;;) {
122 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
123 break;
124 level++;
125 sd = sd->parent;
126 if (!sd)
127 break;
128 }
129}
130#else /* !CONFIG_SCHED_DEBUG */
131
132# define sched_debug_enabled 0
133# define sched_domain_debug(sd, cpu) do { } while (0)
134static inline bool sched_debug(void)
135{
136 return false;
137}
138#endif /* CONFIG_SCHED_DEBUG */
139
140static int sd_degenerate(struct sched_domain *sd)
141{
142 if (cpumask_weight(sched_domain_span(sd)) == 1)
143 return 1;
144
145 /* Following flags need at least 2 groups */
146 if (sd->flags & (SD_BALANCE_NEWIDLE |
147 SD_BALANCE_FORK |
148 SD_BALANCE_EXEC |
149 SD_SHARE_CPUCAPACITY |
150 SD_ASYM_CPUCAPACITY |
151 SD_SHARE_PKG_RESOURCES |
152 SD_SHARE_POWERDOMAIN)) {
153 if (sd->groups != sd->groups->next)
154 return 0;
155 }
156
157 /* Following flags don't use groups */
158 if (sd->flags & (SD_WAKE_AFFINE))
159 return 0;
160
161 return 1;
162}
163
164static int
165sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
166{
167 unsigned long cflags = sd->flags, pflags = parent->flags;
168
169 if (sd_degenerate(parent))
170 return 1;
171
172 if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
173 return 0;
174
175 /* Flags needing groups don't count if only 1 group in parent */
176 if (parent->groups == parent->groups->next) {
177 pflags &= ~(SD_BALANCE_NEWIDLE |
178 SD_BALANCE_FORK |
179 SD_BALANCE_EXEC |
180 SD_ASYM_CPUCAPACITY |
181 SD_SHARE_CPUCAPACITY |
182 SD_SHARE_PKG_RESOURCES |
183 SD_PREFER_SIBLING |
184 SD_SHARE_POWERDOMAIN);
185 if (nr_node_ids == 1)
186 pflags &= ~SD_SERIALIZE;
187 }
188 if (~cflags & pflags)
189 return 0;
190
191 return 1;
192}
193
194#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
195DEFINE_STATIC_KEY_FALSE(sched_energy_present);
196unsigned int sysctl_sched_energy_aware = 1;
197DEFINE_MUTEX(sched_energy_mutex);
198bool sched_energy_update;
199
200#ifdef CONFIG_PROC_SYSCTL
201int sched_energy_aware_handler(struct ctl_table *table, int write,
202 void *buffer, size_t *lenp, loff_t *ppos)
203{
204 int ret, state;
205
206 if (write && !capable(CAP_SYS_ADMIN))
207 return -EPERM;
208
209 ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
210 if (!ret && write) {
211 state = static_branch_unlikely(&sched_energy_present);
212 if (state != sysctl_sched_energy_aware) {
213 mutex_lock(&sched_energy_mutex);
214 sched_energy_update = 1;
215 rebuild_sched_domains();
216 sched_energy_update = 0;
217 mutex_unlock(&sched_energy_mutex);
218 }
219 }
220
221 return ret;
222}
223#endif
224
225static void free_pd(struct perf_domain *pd)
226{
227 struct perf_domain *tmp;
228
229 while (pd) {
230 tmp = pd->next;
231 kfree(pd);
232 pd = tmp;
233 }
234}
235
236static struct perf_domain *find_pd(struct perf_domain *pd, int cpu)
237{
238 while (pd) {
239 if (cpumask_test_cpu(cpu, perf_domain_span(pd)))
240 return pd;
241 pd = pd->next;
242 }
243
244 return NULL;
245}
246
247static struct perf_domain *pd_init(int cpu)
248{
249 struct em_perf_domain *obj = em_cpu_get(cpu);
250 struct perf_domain *pd;
251
252 if (!obj) {
253 if (sched_debug())
254 pr_info("%s: no EM found for CPU%d\n", __func__, cpu);
255 return NULL;
256 }
257
258 pd = kzalloc(sizeof(*pd), GFP_KERNEL);
259 if (!pd)
260 return NULL;
261 pd->em_pd = obj;
262
263 return pd;
264}
265
266static void perf_domain_debug(const struct cpumask *cpu_map,
267 struct perf_domain *pd)
268{
269 if (!sched_debug() || !pd)
270 return;
271
272 printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map));
273
274 while (pd) {
275 printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }",
276 cpumask_first(perf_domain_span(pd)),
277 cpumask_pr_args(perf_domain_span(pd)),
278 em_pd_nr_perf_states(pd->em_pd));
279 pd = pd->next;
280 }
281
282 printk(KERN_CONT "\n");
283}
284
285static void destroy_perf_domain_rcu(struct rcu_head *rp)
286{
287 struct perf_domain *pd;
288
289 pd = container_of(rp, struct perf_domain, rcu);
290 free_pd(pd);
291}
292
293static void sched_energy_set(bool has_eas)
294{
295 if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
296 if (sched_debug())
297 pr_info("%s: stopping EAS\n", __func__);
298 static_branch_disable_cpuslocked(&sched_energy_present);
299 } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
300 if (sched_debug())
301 pr_info("%s: starting EAS\n", __func__);
302 static_branch_enable_cpuslocked(&sched_energy_present);
303 }
304}
305
306/*
307 * EAS can be used on a root domain if it meets all the following conditions:
308 * 1. an Energy Model (EM) is available;
309 * 2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy.
310 * 3. no SMT is detected.
311 * 4. the EM complexity is low enough to keep scheduling overheads low;
312 * 5. schedutil is driving the frequency of all CPUs of the rd;
313 *
314 * The complexity of the Energy Model is defined as:
315 *
316 * C = nr_pd * (nr_cpus + nr_ps)
317 *
318 * with parameters defined as:
319 * - nr_pd: the number of performance domains
320 * - nr_cpus: the number of CPUs
321 * - nr_ps: the sum of the number of performance states of all performance
322 * domains (for example, on a system with 2 performance domains,
323 * with 10 performance states each, nr_ps = 2 * 10 = 20).
324 *
325 * It is generally not a good idea to use such a model in the wake-up path on
326 * very complex platforms because of the associated scheduling overheads. The
327 * arbitrary constraint below prevents that. It makes EAS usable up to 16 CPUs
328 * with per-CPU DVFS and less than 8 performance states each, for example.
329 */
330#define EM_MAX_COMPLEXITY 2048
331
332extern struct cpufreq_governor schedutil_gov;
333static bool build_perf_domains(const struct cpumask *cpu_map)
334{
335 int i, nr_pd = 0, nr_ps = 0, nr_cpus = cpumask_weight(cpu_map);
336 struct perf_domain *pd = NULL, *tmp;
337 int cpu = cpumask_first(cpu_map);
338 struct root_domain *rd = cpu_rq(cpu)->rd;
339 struct cpufreq_policy *policy;
340 struct cpufreq_governor *gov;
341
342 if (!sysctl_sched_energy_aware)
343 goto free;
344
345 /* EAS is enabled for asymmetric CPU capacity topologies. */
346 if (!per_cpu(sd_asym_cpucapacity, cpu)) {
347 if (sched_debug()) {
348 pr_info("rd %*pbl: CPUs do not have asymmetric capacities\n",
349 cpumask_pr_args(cpu_map));
350 }
351 goto free;
352 }
353
354 /* EAS definitely does *not* handle SMT */
355 if (sched_smt_active()) {
356 pr_warn("rd %*pbl: Disabling EAS, SMT is not supported\n",
357 cpumask_pr_args(cpu_map));
358 goto free;
359 }
360
361 for_each_cpu(i, cpu_map) {
362 /* Skip already covered CPUs. */
363 if (find_pd(pd, i))
364 continue;
365
366 /* Do not attempt EAS if schedutil is not being used. */
367 policy = cpufreq_cpu_get(i);
368 if (!policy)
369 goto free;
370 gov = policy->governor;
371 cpufreq_cpu_put(policy);
372 if (gov != &schedutil_gov) {
373 if (rd->pd)
374 pr_warn("rd %*pbl: Disabling EAS, schedutil is mandatory\n",
375 cpumask_pr_args(cpu_map));
376 goto free;
377 }
378
379 /* Create the new pd and add it to the local list. */
380 tmp = pd_init(i);
381 if (!tmp)
382 goto free;
383 tmp->next = pd;
384 pd = tmp;
385
386 /*
387 * Count performance domains and performance states for the
388 * complexity check.
389 */
390 nr_pd++;
391 nr_ps += em_pd_nr_perf_states(pd->em_pd);
392 }
393
394 /* Bail out if the Energy Model complexity is too high. */
395 if (nr_pd * (nr_ps + nr_cpus) > EM_MAX_COMPLEXITY) {
396 WARN(1, "rd %*pbl: Failed to start EAS, EM complexity is too high\n",
397 cpumask_pr_args(cpu_map));
398 goto free;
399 }
400
401 perf_domain_debug(cpu_map, pd);
402
403 /* Attach the new list of performance domains to the root domain. */
404 tmp = rd->pd;
405 rcu_assign_pointer(rd->pd, pd);
406 if (tmp)
407 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
408
409 return !!pd;
410
411free:
412 free_pd(pd);
413 tmp = rd->pd;
414 rcu_assign_pointer(rd->pd, NULL);
415 if (tmp)
416 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
417
418 return false;
419}
420#else
421static void free_pd(struct perf_domain *pd) { }
422#endif /* CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL*/
423
424static void free_rootdomain(struct rcu_head *rcu)
425{
426 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
427
428 cpupri_cleanup(&rd->cpupri);
429 cpudl_cleanup(&rd->cpudl);
430 free_cpumask_var(rd->dlo_mask);
431 free_cpumask_var(rd->rto_mask);
432 free_cpumask_var(rd->online);
433 free_cpumask_var(rd->span);
434 free_pd(rd->pd);
435 kfree(rd);
436}
437
438void rq_attach_root(struct rq *rq, struct root_domain *rd)
439{
440 struct root_domain *old_rd = NULL;
441 unsigned long flags;
442
443 raw_spin_lock_irqsave(&rq->lock, flags);
444
445 if (rq->rd) {
446 old_rd = rq->rd;
447
448 if (cpumask_test_cpu(rq->cpu, old_rd->online))
449 set_rq_offline(rq);
450
451 cpumask_clear_cpu(rq->cpu, old_rd->span);
452
453 /*
454 * If we dont want to free the old_rd yet then
455 * set old_rd to NULL to skip the freeing later
456 * in this function:
457 */
458 if (!atomic_dec_and_test(&old_rd->refcount))
459 old_rd = NULL;
460 }
461
462 atomic_inc(&rd->refcount);
463 rq->rd = rd;
464
465 cpumask_set_cpu(rq->cpu, rd->span);
466 if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
467 set_rq_online(rq);
468
469 raw_spin_unlock_irqrestore(&rq->lock, flags);
470
471 if (old_rd)
472 call_rcu(&old_rd->rcu, free_rootdomain);
473}
474
475void sched_get_rd(struct root_domain *rd)
476{
477 atomic_inc(&rd->refcount);
478}
479
480void sched_put_rd(struct root_domain *rd)
481{
482 if (!atomic_dec_and_test(&rd->refcount))
483 return;
484
485 call_rcu(&rd->rcu, free_rootdomain);
486}
487
488static int init_rootdomain(struct root_domain *rd)
489{
490 if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
491 goto out;
492 if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
493 goto free_span;
494 if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
495 goto free_online;
496 if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
497 goto free_dlo_mask;
498
499#ifdef HAVE_RT_PUSH_IPI
500 rd->rto_cpu = -1;
501 raw_spin_lock_init(&rd->rto_lock);
502 init_irq_work(&rd->rto_push_work, rto_push_irq_work_func);
503#endif
504
505 init_dl_bw(&rd->dl_bw);
506 if (cpudl_init(&rd->cpudl) != 0)
507 goto free_rto_mask;
508
509 if (cpupri_init(&rd->cpupri) != 0)
510 goto free_cpudl;
511 return 0;
512
513free_cpudl:
514 cpudl_cleanup(&rd->cpudl);
515free_rto_mask:
516 free_cpumask_var(rd->rto_mask);
517free_dlo_mask:
518 free_cpumask_var(rd->dlo_mask);
519free_online:
520 free_cpumask_var(rd->online);
521free_span:
522 free_cpumask_var(rd->span);
523out:
524 return -ENOMEM;
525}
526
527/*
528 * By default the system creates a single root-domain with all CPUs as
529 * members (mimicking the global state we have today).
530 */
531struct root_domain def_root_domain;
532
533void init_defrootdomain(void)
534{
535 init_rootdomain(&def_root_domain);
536
537 atomic_set(&def_root_domain.refcount, 1);
538}
539
540static struct root_domain *alloc_rootdomain(void)
541{
542 struct root_domain *rd;
543
544 rd = kzalloc(sizeof(*rd), GFP_KERNEL);
545 if (!rd)
546 return NULL;
547
548 if (init_rootdomain(rd) != 0) {
549 kfree(rd);
550 return NULL;
551 }
552
553 return rd;
554}
555
556static void free_sched_groups(struct sched_group *sg, int free_sgc)
557{
558 struct sched_group *tmp, *first;
559
560 if (!sg)
561 return;
562
563 first = sg;
564 do {
565 tmp = sg->next;
566
567 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
568 kfree(sg->sgc);
569
570 if (atomic_dec_and_test(&sg->ref))
571 kfree(sg);
572 sg = tmp;
573 } while (sg != first);
574}
575
576static void destroy_sched_domain(struct sched_domain *sd)
577{
578 /*
579 * A normal sched domain may have multiple group references, an
580 * overlapping domain, having private groups, only one. Iterate,
581 * dropping group/capacity references, freeing where none remain.
582 */
583 free_sched_groups(sd->groups, 1);
584
585 if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
586 kfree(sd->shared);
587 kfree(sd);
588}
589
590static void destroy_sched_domains_rcu(struct rcu_head *rcu)
591{
592 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
593
594 while (sd) {
595 struct sched_domain *parent = sd->parent;
596 destroy_sched_domain(sd);
597 sd = parent;
598 }
599}
600
601static void destroy_sched_domains(struct sched_domain *sd)
602{
603 if (sd)
604 call_rcu(&sd->rcu, destroy_sched_domains_rcu);
605}
606
607/*
608 * Keep a special pointer to the highest sched_domain that has
609 * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
610 * allows us to avoid some pointer chasing select_idle_sibling().
611 *
612 * Also keep a unique ID per domain (we use the first CPU number in
613 * the cpumask of the domain), this allows us to quickly tell if
614 * two CPUs are in the same cache domain, see cpus_share_cache().
615 */
616DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
617DEFINE_PER_CPU(int, sd_llc_size);
618DEFINE_PER_CPU(int, sd_llc_id);
619DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
620DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
621DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
622DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
623DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
624
625static void update_top_cache_domain(int cpu)
626{
627 struct sched_domain_shared *sds = NULL;
628 struct sched_domain *sd;
629 int id = cpu;
630 int size = 1;
631
632 sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
633 if (sd) {
634 id = cpumask_first(sched_domain_span(sd));
635 size = cpumask_weight(sched_domain_span(sd));
636 sds = sd->shared;
637 }
638
639 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
640 per_cpu(sd_llc_size, cpu) = size;
641 per_cpu(sd_llc_id, cpu) = id;
642 rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
643
644 sd = lowest_flag_domain(cpu, SD_NUMA);
645 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
646
647 sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
648 rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd);
649
650 sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY);
651 rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd);
652}
653
654/*
655 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
656 * hold the hotplug lock.
657 */
658static void
659cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
660{
661 struct rq *rq = cpu_rq(cpu);
662 struct sched_domain *tmp;
663
664 /* Remove the sched domains which do not contribute to scheduling. */
665 for (tmp = sd; tmp; ) {
666 struct sched_domain *parent = tmp->parent;
667 if (!parent)
668 break;
669
670 if (sd_parent_degenerate(tmp, parent)) {
671 tmp->parent = parent->parent;
672 if (parent->parent)
673 parent->parent->child = tmp;
674 /*
675 * Transfer SD_PREFER_SIBLING down in case of a
676 * degenerate parent; the spans match for this
677 * so the property transfers.
678 */
679 if (parent->flags & SD_PREFER_SIBLING)
680 tmp->flags |= SD_PREFER_SIBLING;
681 destroy_sched_domain(parent);
682 } else
683 tmp = tmp->parent;
684 }
685
686 if (sd && sd_degenerate(sd)) {
687 tmp = sd;
688 sd = sd->parent;
689 destroy_sched_domain(tmp);
690 if (sd)
691 sd->child = NULL;
692 }
693
694 sched_domain_debug(sd, cpu);
695
696 rq_attach_root(rq, rd);
697 tmp = rq->sd;
698 rcu_assign_pointer(rq->sd, sd);
699 dirty_sched_domain_sysctl(cpu);
700 destroy_sched_domains(tmp);
701
702 update_top_cache_domain(cpu);
703}
704
705struct s_data {
706 struct sched_domain * __percpu *sd;
707 struct root_domain *rd;
708};
709
710enum s_alloc {
711 sa_rootdomain,
712 sa_sd,
713 sa_sd_storage,
714 sa_none,
715};
716
717/*
718 * Return the canonical balance CPU for this group, this is the first CPU
719 * of this group that's also in the balance mask.
720 *
721 * The balance mask are all those CPUs that could actually end up at this
722 * group. See build_balance_mask().
723 *
724 * Also see should_we_balance().
725 */
726int group_balance_cpu(struct sched_group *sg)
727{
728 return cpumask_first(group_balance_mask(sg));
729}
730
731
732/*
733 * NUMA topology (first read the regular topology blurb below)
734 *
735 * Given a node-distance table, for example:
736 *
737 * node 0 1 2 3
738 * 0: 10 20 30 20
739 * 1: 20 10 20 30
740 * 2: 30 20 10 20
741 * 3: 20 30 20 10
742 *
743 * which represents a 4 node ring topology like:
744 *
745 * 0 ----- 1
746 * | |
747 * | |
748 * | |
749 * 3 ----- 2
750 *
751 * We want to construct domains and groups to represent this. The way we go
752 * about doing this is to build the domains on 'hops'. For each NUMA level we
753 * construct the mask of all nodes reachable in @level hops.
754 *
755 * For the above NUMA topology that gives 3 levels:
756 *
757 * NUMA-2 0-3 0-3 0-3 0-3
758 * groups: {0-1,3},{1-3} {0-2},{0,2-3} {1-3},{0-1,3} {0,2-3},{0-2}
759 *
760 * NUMA-1 0-1,3 0-2 1-3 0,2-3
761 * groups: {0},{1},{3} {0},{1},{2} {1},{2},{3} {0},{2},{3}
762 *
763 * NUMA-0 0 1 2 3
764 *
765 *
766 * As can be seen; things don't nicely line up as with the regular topology.
767 * When we iterate a domain in child domain chunks some nodes can be
768 * represented multiple times -- hence the "overlap" naming for this part of
769 * the topology.
770 *
771 * In order to minimize this overlap, we only build enough groups to cover the
772 * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
773 *
774 * Because:
775 *
776 * - the first group of each domain is its child domain; this
777 * gets us the first 0-1,3
778 * - the only uncovered node is 2, who's child domain is 1-3.
779 *
780 * However, because of the overlap, computing a unique CPU for each group is
781 * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
782 * groups include the CPUs of Node-0, while those CPUs would not in fact ever
783 * end up at those groups (they would end up in group: 0-1,3).
784 *
785 * To correct this we have to introduce the group balance mask. This mask
786 * will contain those CPUs in the group that can reach this group given the
787 * (child) domain tree.
788 *
789 * With this we can once again compute balance_cpu and sched_group_capacity
790 * relations.
791 *
792 * XXX include words on how balance_cpu is unique and therefore can be
793 * used for sched_group_capacity links.
794 *
795 *
796 * Another 'interesting' topology is:
797 *
798 * node 0 1 2 3
799 * 0: 10 20 20 30
800 * 1: 20 10 20 20
801 * 2: 20 20 10 20
802 * 3: 30 20 20 10
803 *
804 * Which looks a little like:
805 *
806 * 0 ----- 1
807 * | / |
808 * | / |
809 * | / |
810 * 2 ----- 3
811 *
812 * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
813 * are not.
814 *
815 * This leads to a few particularly weird cases where the sched_domain's are
816 * not of the same number for each CPU. Consider:
817 *
818 * NUMA-2 0-3 0-3
819 * groups: {0-2},{1-3} {1-3},{0-2}
820 *
821 * NUMA-1 0-2 0-3 0-3 1-3
822 *
823 * NUMA-0 0 1 2 3
824 *
825 */
826
827
828/*
829 * Build the balance mask; it contains only those CPUs that can arrive at this
830 * group and should be considered to continue balancing.
831 *
832 * We do this during the group creation pass, therefore the group information
833 * isn't complete yet, however since each group represents a (child) domain we
834 * can fully construct this using the sched_domain bits (which are already
835 * complete).
836 */
837static void
838build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
839{
840 const struct cpumask *sg_span = sched_group_span(sg);
841 struct sd_data *sdd = sd->private;
842 struct sched_domain *sibling;
843 int i;
844
845 cpumask_clear(mask);
846
847 for_each_cpu(i, sg_span) {
848 sibling = *per_cpu_ptr(sdd->sd, i);
849
850 /*
851 * Can happen in the asymmetric case, where these siblings are
852 * unused. The mask will not be empty because those CPUs that
853 * do have the top domain _should_ span the domain.
854 */
855 if (!sibling->child)
856 continue;
857
858 /* If we would not end up here, we can't continue from here */
859 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
860 continue;
861
862 cpumask_set_cpu(i, mask);
863 }
864
865 /* We must not have empty masks here */
866 WARN_ON_ONCE(cpumask_empty(mask));
867}
868
869/*
870 * XXX: This creates per-node group entries; since the load-balancer will
871 * immediately access remote memory to construct this group's load-balance
872 * statistics having the groups node local is of dubious benefit.
873 */
874static struct sched_group *
875build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
876{
877 struct sched_group *sg;
878 struct cpumask *sg_span;
879
880 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
881 GFP_KERNEL, cpu_to_node(cpu));
882
883 if (!sg)
884 return NULL;
885
886 sg_span = sched_group_span(sg);
887 if (sd->child)
888 cpumask_copy(sg_span, sched_domain_span(sd->child));
889 else
890 cpumask_copy(sg_span, sched_domain_span(sd));
891
892 atomic_inc(&sg->ref);
893 return sg;
894}
895
896static void init_overlap_sched_group(struct sched_domain *sd,
897 struct sched_group *sg)
898{
899 struct cpumask *mask = sched_domains_tmpmask2;
900 struct sd_data *sdd = sd->private;
901 struct cpumask *sg_span;
902 int cpu;
903
904 build_balance_mask(sd, sg, mask);
905 cpu = cpumask_first_and(sched_group_span(sg), mask);
906
907 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
908 if (atomic_inc_return(&sg->sgc->ref) == 1)
909 cpumask_copy(group_balance_mask(sg), mask);
910 else
911 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
912
913 /*
914 * Initialize sgc->capacity such that even if we mess up the
915 * domains and no possible iteration will get us here, we won't
916 * die on a /0 trap.
917 */
918 sg_span = sched_group_span(sg);
919 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
920 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
921 sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
922}
923
924static int
925build_overlap_sched_groups(struct sched_domain *sd, int cpu)
926{
927 struct sched_group *first = NULL, *last = NULL, *sg;
928 const struct cpumask *span = sched_domain_span(sd);
929 struct cpumask *covered = sched_domains_tmpmask;
930 struct sd_data *sdd = sd->private;
931 struct sched_domain *sibling;
932 int i;
933
934 cpumask_clear(covered);
935
936 for_each_cpu_wrap(i, span, cpu) {
937 struct cpumask *sg_span;
938
939 if (cpumask_test_cpu(i, covered))
940 continue;
941
942 sibling = *per_cpu_ptr(sdd->sd, i);
943
944 /*
945 * Asymmetric node setups can result in situations where the
946 * domain tree is of unequal depth, make sure to skip domains
947 * that already cover the entire range.
948 *
949 * In that case build_sched_domains() will have terminated the
950 * iteration early and our sibling sd spans will be empty.
951 * Domains should always include the CPU they're built on, so
952 * check that.
953 */
954 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
955 continue;
956
957 sg = build_group_from_child_sched_domain(sibling, cpu);
958 if (!sg)
959 goto fail;
960
961 sg_span = sched_group_span(sg);
962 cpumask_or(covered, covered, sg_span);
963
964 init_overlap_sched_group(sd, sg);
965
966 if (!first)
967 first = sg;
968 if (last)
969 last->next = sg;
970 last = sg;
971 last->next = first;
972 }
973 sd->groups = first;
974
975 return 0;
976
977fail:
978 free_sched_groups(first, 0);
979
980 return -ENOMEM;
981}
982
983
984/*
985 * Package topology (also see the load-balance blurb in fair.c)
986 *
987 * The scheduler builds a tree structure to represent a number of important
988 * topology features. By default (default_topology[]) these include:
989 *
990 * - Simultaneous multithreading (SMT)
991 * - Multi-Core Cache (MC)
992 * - Package (DIE)
993 *
994 * Where the last one more or less denotes everything up to a NUMA node.
995 *
996 * The tree consists of 3 primary data structures:
997 *
998 * sched_domain -> sched_group -> sched_group_capacity
999 * ^ ^ ^ ^
1000 * `-' `-'
1001 *
1002 * The sched_domains are per-CPU and have a two way link (parent & child) and
1003 * denote the ever growing mask of CPUs belonging to that level of topology.
1004 *
1005 * Each sched_domain has a circular (double) linked list of sched_group's, each
1006 * denoting the domains of the level below (or individual CPUs in case of the
1007 * first domain level). The sched_group linked by a sched_domain includes the
1008 * CPU of that sched_domain [*].
1009 *
1010 * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
1011 *
1012 * CPU 0 1 2 3 4 5 6 7
1013 *
1014 * DIE [ ]
1015 * MC [ ] [ ]
1016 * SMT [ ] [ ] [ ] [ ]
1017 *
1018 * - or -
1019 *
1020 * DIE 0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
1021 * MC 0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
1022 * SMT 0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
1023 *
1024 * CPU 0 1 2 3 4 5 6 7
1025 *
1026 * One way to think about it is: sched_domain moves you up and down among these
1027 * topology levels, while sched_group moves you sideways through it, at child
1028 * domain granularity.
1029 *
1030 * sched_group_capacity ensures each unique sched_group has shared storage.
1031 *
1032 * There are two related construction problems, both require a CPU that
1033 * uniquely identify each group (for a given domain):
1034 *
1035 * - The first is the balance_cpu (see should_we_balance() and the
1036 * load-balance blub in fair.c); for each group we only want 1 CPU to
1037 * continue balancing at a higher domain.
1038 *
1039 * - The second is the sched_group_capacity; we want all identical groups
1040 * to share a single sched_group_capacity.
1041 *
1042 * Since these topologies are exclusive by construction. That is, its
1043 * impossible for an SMT thread to belong to multiple cores, and cores to
1044 * be part of multiple caches. There is a very clear and unique location
1045 * for each CPU in the hierarchy.
1046 *
1047 * Therefore computing a unique CPU for each group is trivial (the iteration
1048 * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
1049 * group), we can simply pick the first CPU in each group.
1050 *
1051 *
1052 * [*] in other words, the first group of each domain is its child domain.
1053 */
1054
1055static struct sched_group *get_group(int cpu, struct sd_data *sdd)
1056{
1057 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1058 struct sched_domain *child = sd->child;
1059 struct sched_group *sg;
1060 bool already_visited;
1061
1062 if (child)
1063 cpu = cpumask_first(sched_domain_span(child));
1064
1065 sg = *per_cpu_ptr(sdd->sg, cpu);
1066 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
1067
1068 /* Increase refcounts for claim_allocations: */
1069 already_visited = atomic_inc_return(&sg->ref) > 1;
1070 /* sgc visits should follow a similar trend as sg */
1071 WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1));
1072
1073 /* If we have already visited that group, it's already initialized. */
1074 if (already_visited)
1075 return sg;
1076
1077 if (child) {
1078 cpumask_copy(sched_group_span(sg), sched_domain_span(child));
1079 cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
1080 } else {
1081 cpumask_set_cpu(cpu, sched_group_span(sg));
1082 cpumask_set_cpu(cpu, group_balance_mask(sg));
1083 }
1084
1085 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
1086 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
1087 sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
1088
1089 return sg;
1090}
1091
1092/*
1093 * build_sched_groups will build a circular linked list of the groups
1094 * covered by the given span, will set each group's ->cpumask correctly,
1095 * and will initialize their ->sgc.
1096 *
1097 * Assumes the sched_domain tree is fully constructed
1098 */
1099static int
1100build_sched_groups(struct sched_domain *sd, int cpu)
1101{
1102 struct sched_group *first = NULL, *last = NULL;
1103 struct sd_data *sdd = sd->private;
1104 const struct cpumask *span = sched_domain_span(sd);
1105 struct cpumask *covered;
1106 int i;
1107
1108 lockdep_assert_held(&sched_domains_mutex);
1109 covered = sched_domains_tmpmask;
1110
1111 cpumask_clear(covered);
1112
1113 for_each_cpu_wrap(i, span, cpu) {
1114 struct sched_group *sg;
1115
1116 if (cpumask_test_cpu(i, covered))
1117 continue;
1118
1119 sg = get_group(i, sdd);
1120
1121 cpumask_or(covered, covered, sched_group_span(sg));
1122
1123 if (!first)
1124 first = sg;
1125 if (last)
1126 last->next = sg;
1127 last = sg;
1128 }
1129 last->next = first;
1130 sd->groups = first;
1131
1132 return 0;
1133}
1134
1135/*
1136 * Initialize sched groups cpu_capacity.
1137 *
1138 * cpu_capacity indicates the capacity of sched group, which is used while
1139 * distributing the load between different sched groups in a sched domain.
1140 * Typically cpu_capacity for all the groups in a sched domain will be same
1141 * unless there are asymmetries in the topology. If there are asymmetries,
1142 * group having more cpu_capacity will pickup more load compared to the
1143 * group having less cpu_capacity.
1144 */
1145static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
1146{
1147 struct sched_group *sg = sd->groups;
1148
1149 WARN_ON(!sg);
1150
1151 do {
1152 int cpu, max_cpu = -1;
1153
1154 sg->group_weight = cpumask_weight(sched_group_span(sg));
1155
1156 if (!(sd->flags & SD_ASYM_PACKING))
1157 goto next;
1158
1159 for_each_cpu(cpu, sched_group_span(sg)) {
1160 if (max_cpu < 0)
1161 max_cpu = cpu;
1162 else if (sched_asym_prefer(cpu, max_cpu))
1163 max_cpu = cpu;
1164 }
1165 sg->asym_prefer_cpu = max_cpu;
1166
1167next:
1168 sg = sg->next;
1169 } while (sg != sd->groups);
1170
1171 if (cpu != group_balance_cpu(sg))
1172 return;
1173
1174 update_group_capacity(sd, cpu);
1175}
1176
1177/*
1178 * Initializers for schedule domains
1179 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
1180 */
1181
1182static int default_relax_domain_level = -1;
1183int sched_domain_level_max;
1184
1185static int __init setup_relax_domain_level(char *str)
1186{
1187 if (kstrtoint(str, 0, &default_relax_domain_level))
1188 pr_warn("Unable to set relax_domain_level\n");
1189
1190 return 1;
1191}
1192__setup("relax_domain_level=", setup_relax_domain_level);
1193
1194static void set_domain_attribute(struct sched_domain *sd,
1195 struct sched_domain_attr *attr)
1196{
1197 int request;
1198
1199 if (!attr || attr->relax_domain_level < 0) {
1200 if (default_relax_domain_level < 0)
1201 return;
1202 request = default_relax_domain_level;
1203 } else
1204 request = attr->relax_domain_level;
1205
1206 if (sd->level > request) {
1207 /* Turn off idle balance on this domain: */
1208 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
1209 }
1210}
1211
1212static void __sdt_free(const struct cpumask *cpu_map);
1213static int __sdt_alloc(const struct cpumask *cpu_map);
1214
1215static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
1216 const struct cpumask *cpu_map)
1217{
1218 switch (what) {
1219 case sa_rootdomain:
1220 if (!atomic_read(&d->rd->refcount))
1221 free_rootdomain(&d->rd->rcu);
1222 fallthrough;
1223 case sa_sd:
1224 free_percpu(d->sd);
1225 fallthrough;
1226 case sa_sd_storage:
1227 __sdt_free(cpu_map);
1228 fallthrough;
1229 case sa_none:
1230 break;
1231 }
1232}
1233
1234static enum s_alloc
1235__visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1236{
1237 memset(d, 0, sizeof(*d));
1238
1239 if (__sdt_alloc(cpu_map))
1240 return sa_sd_storage;
1241 d->sd = alloc_percpu(struct sched_domain *);
1242 if (!d->sd)
1243 return sa_sd_storage;
1244 d->rd = alloc_rootdomain();
1245 if (!d->rd)
1246 return sa_sd;
1247
1248 return sa_rootdomain;
1249}
1250
1251/*
1252 * NULL the sd_data elements we've used to build the sched_domain and
1253 * sched_group structure so that the subsequent __free_domain_allocs()
1254 * will not free the data we're using.
1255 */
1256static void claim_allocations(int cpu, struct sched_domain *sd)
1257{
1258 struct sd_data *sdd = sd->private;
1259
1260 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1261 *per_cpu_ptr(sdd->sd, cpu) = NULL;
1262
1263 if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
1264 *per_cpu_ptr(sdd->sds, cpu) = NULL;
1265
1266 if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
1267 *per_cpu_ptr(sdd->sg, cpu) = NULL;
1268
1269 if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1270 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1271}
1272
1273#ifdef CONFIG_NUMA
1274enum numa_topology_type sched_numa_topology_type;
1275
1276static int sched_domains_numa_levels;
1277static int sched_domains_curr_level;
1278
1279int sched_max_numa_distance;
1280static int *sched_domains_numa_distance;
1281static struct cpumask ***sched_domains_numa_masks;
1282int __read_mostly node_reclaim_distance = RECLAIM_DISTANCE;
1283#endif
1284
1285/*
1286 * SD_flags allowed in topology descriptions.
1287 *
1288 * These flags are purely descriptive of the topology and do not prescribe
1289 * behaviour. Behaviour is artificial and mapped in the below sd_init()
1290 * function:
1291 *
1292 * SD_SHARE_CPUCAPACITY - describes SMT topologies
1293 * SD_SHARE_PKG_RESOURCES - describes shared caches
1294 * SD_NUMA - describes NUMA topologies
1295 * SD_SHARE_POWERDOMAIN - describes shared power domain
1296 *
1297 * Odd one out, which beside describing the topology has a quirk also
1298 * prescribes the desired behaviour that goes along with it:
1299 *
1300 * SD_ASYM_PACKING - describes SMT quirks
1301 */
1302#define TOPOLOGY_SD_FLAGS \
1303 (SD_SHARE_CPUCAPACITY | \
1304 SD_SHARE_PKG_RESOURCES | \
1305 SD_NUMA | \
1306 SD_ASYM_PACKING | \
1307 SD_SHARE_POWERDOMAIN)
1308
1309static struct sched_domain *
1310sd_init(struct sched_domain_topology_level *tl,
1311 const struct cpumask *cpu_map,
1312 struct sched_domain *child, int dflags, int cpu)
1313{
1314 struct sd_data *sdd = &tl->data;
1315 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1316 int sd_id, sd_weight, sd_flags = 0;
1317
1318#ifdef CONFIG_NUMA
1319 /*
1320 * Ugly hack to pass state to sd_numa_mask()...
1321 */
1322 sched_domains_curr_level = tl->numa_level;
1323#endif
1324
1325 sd_weight = cpumask_weight(tl->mask(cpu));
1326
1327 if (tl->sd_flags)
1328 sd_flags = (*tl->sd_flags)();
1329 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1330 "wrong sd_flags in topology description\n"))
1331 sd_flags &= TOPOLOGY_SD_FLAGS;
1332
1333 /* Apply detected topology flags */
1334 sd_flags |= dflags;
1335
1336 *sd = (struct sched_domain){
1337 .min_interval = sd_weight,
1338 .max_interval = 2*sd_weight,
1339 .busy_factor = 32,
1340 .imbalance_pct = 125,
1341
1342 .cache_nice_tries = 0,
1343
1344 .flags = 1*SD_BALANCE_NEWIDLE
1345 | 1*SD_BALANCE_EXEC
1346 | 1*SD_BALANCE_FORK
1347 | 0*SD_BALANCE_WAKE
1348 | 1*SD_WAKE_AFFINE
1349 | 0*SD_SHARE_CPUCAPACITY
1350 | 0*SD_SHARE_PKG_RESOURCES
1351 | 0*SD_SERIALIZE
1352 | 1*SD_PREFER_SIBLING
1353 | 0*SD_NUMA
1354 | sd_flags
1355 ,
1356
1357 .last_balance = jiffies,
1358 .balance_interval = sd_weight,
1359 .max_newidle_lb_cost = 0,
1360 .next_decay_max_lb_cost = jiffies,
1361 .child = child,
1362#ifdef CONFIG_SCHED_DEBUG
1363 .name = tl->name,
1364#endif
1365 };
1366
1367 cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
1368 sd_id = cpumask_first(sched_domain_span(sd));
1369
1370 /*
1371 * Convert topological properties into behaviour.
1372 */
1373
1374 /* Don't attempt to spread across CPUs of different capacities. */
1375 if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child)
1376 sd->child->flags &= ~SD_PREFER_SIBLING;
1377
1378 if (sd->flags & SD_SHARE_CPUCAPACITY) {
1379 sd->imbalance_pct = 110;
1380
1381 } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1382 sd->imbalance_pct = 117;
1383 sd->cache_nice_tries = 1;
1384
1385#ifdef CONFIG_NUMA
1386 } else if (sd->flags & SD_NUMA) {
1387 sd->cache_nice_tries = 2;
1388
1389 sd->flags &= ~SD_PREFER_SIBLING;
1390 sd->flags |= SD_SERIALIZE;
1391 if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) {
1392 sd->flags &= ~(SD_BALANCE_EXEC |
1393 SD_BALANCE_FORK |
1394 SD_WAKE_AFFINE);
1395 }
1396
1397#endif
1398 } else {
1399 sd->cache_nice_tries = 1;
1400 }
1401
1402 /*
1403 * For all levels sharing cache; connect a sched_domain_shared
1404 * instance.
1405 */
1406 if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1407 sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1408 atomic_inc(&sd->shared->ref);
1409 atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
1410 }
1411
1412 sd->private = sdd;
1413
1414 return sd;
1415}
1416
1417/*
1418 * Topology list, bottom-up.
1419 */
1420static struct sched_domain_topology_level default_topology[] = {
1421#ifdef CONFIG_SCHED_SMT
1422 { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
1423#endif
1424#ifdef CONFIG_SCHED_MC
1425 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
1426#endif
1427 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
1428 { NULL, },
1429};
1430
1431static struct sched_domain_topology_level *sched_domain_topology =
1432 default_topology;
1433
1434#define for_each_sd_topology(tl) \
1435 for (tl = sched_domain_topology; tl->mask; tl++)
1436
1437void set_sched_topology(struct sched_domain_topology_level *tl)
1438{
1439 if (WARN_ON_ONCE(sched_smp_initialized))
1440 return;
1441
1442 sched_domain_topology = tl;
1443}
1444
1445#ifdef CONFIG_NUMA
1446
1447static const struct cpumask *sd_numa_mask(int cpu)
1448{
1449 return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
1450}
1451
1452static void sched_numa_warn(const char *str)
1453{
1454 static int done = false;
1455 int i,j;
1456
1457 if (done)
1458 return;
1459
1460 done = true;
1461
1462 printk(KERN_WARNING "ERROR: %s\n\n", str);
1463
1464 for (i = 0; i < nr_node_ids; i++) {
1465 printk(KERN_WARNING " ");
1466 for (j = 0; j < nr_node_ids; j++)
1467 printk(KERN_CONT "%02d ", node_distance(i,j));
1468 printk(KERN_CONT "\n");
1469 }
1470 printk(KERN_WARNING "\n");
1471}
1472
1473bool find_numa_distance(int distance)
1474{
1475 int i;
1476
1477 if (distance == node_distance(0, 0))
1478 return true;
1479
1480 for (i = 0; i < sched_domains_numa_levels; i++) {
1481 if (sched_domains_numa_distance[i] == distance)
1482 return true;
1483 }
1484
1485 return false;
1486}
1487
1488/*
1489 * A system can have three types of NUMA topology:
1490 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1491 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1492 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1493 *
1494 * The difference between a glueless mesh topology and a backplane
1495 * topology lies in whether communication between not directly
1496 * connected nodes goes through intermediary nodes (where programs
1497 * could run), or through backplane controllers. This affects
1498 * placement of programs.
1499 *
1500 * The type of topology can be discerned with the following tests:
1501 * - If the maximum distance between any nodes is 1 hop, the system
1502 * is directly connected.
1503 * - If for two nodes A and B, located N > 1 hops away from each other,
1504 * there is an intermediary node C, which is < N hops away from both
1505 * nodes A and B, the system is a glueless mesh.
1506 */
1507static void init_numa_topology_type(void)
1508{
1509 int a, b, c, n;
1510
1511 n = sched_max_numa_distance;
1512
1513 if (sched_domains_numa_levels <= 2) {
1514 sched_numa_topology_type = NUMA_DIRECT;
1515 return;
1516 }
1517
1518 for_each_online_node(a) {
1519 for_each_online_node(b) {
1520 /* Find two nodes furthest removed from each other. */
1521 if (node_distance(a, b) < n)
1522 continue;
1523
1524 /* Is there an intermediary node between a and b? */
1525 for_each_online_node(c) {
1526 if (node_distance(a, c) < n &&
1527 node_distance(b, c) < n) {
1528 sched_numa_topology_type =
1529 NUMA_GLUELESS_MESH;
1530 return;
1531 }
1532 }
1533
1534 sched_numa_topology_type = NUMA_BACKPLANE;
1535 return;
1536 }
1537 }
1538}
1539
1540void sched_init_numa(void)
1541{
1542 int next_distance, curr_distance = node_distance(0, 0);
1543 struct sched_domain_topology_level *tl;
1544 int level = 0;
1545 int i, j, k;
1546
1547 sched_domains_numa_distance = kzalloc(sizeof(int) * (nr_node_ids + 1), GFP_KERNEL);
1548 if (!sched_domains_numa_distance)
1549 return;
1550
1551 /* Includes NUMA identity node at level 0. */
1552 sched_domains_numa_distance[level++] = curr_distance;
1553 sched_domains_numa_levels = level;
1554
1555 /*
1556 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1557 * unique distances in the node_distance() table.
1558 *
1559 * Assumes node_distance(0,j) includes all distances in
1560 * node_distance(i,j) in order to avoid cubic time.
1561 */
1562 next_distance = curr_distance;
1563 for (i = 0; i < nr_node_ids; i++) {
1564 for (j = 0; j < nr_node_ids; j++) {
1565 for (k = 0; k < nr_node_ids; k++) {
1566 int distance = node_distance(i, k);
1567
1568 if (distance > curr_distance &&
1569 (distance < next_distance ||
1570 next_distance == curr_distance))
1571 next_distance = distance;
1572
1573 /*
1574 * While not a strong assumption it would be nice to know
1575 * about cases where if node A is connected to B, B is not
1576 * equally connected to A.
1577 */
1578 if (sched_debug() && node_distance(k, i) != distance)
1579 sched_numa_warn("Node-distance not symmetric");
1580
1581 if (sched_debug() && i && !find_numa_distance(distance))
1582 sched_numa_warn("Node-0 not representative");
1583 }
1584 if (next_distance != curr_distance) {
1585 sched_domains_numa_distance[level++] = next_distance;
1586 sched_domains_numa_levels = level;
1587 curr_distance = next_distance;
1588 } else break;
1589 }
1590
1591 /*
1592 * In case of sched_debug() we verify the above assumption.
1593 */
1594 if (!sched_debug())
1595 break;
1596 }
1597
1598 /*
1599 * 'level' contains the number of unique distances
1600 *
1601 * The sched_domains_numa_distance[] array includes the actual distance
1602 * numbers.
1603 */
1604
1605 /*
1606 * Here, we should temporarily reset sched_domains_numa_levels to 0.
1607 * If it fails to allocate memory for array sched_domains_numa_masks[][],
1608 * the array will contain less then 'level' members. This could be
1609 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1610 * in other functions.
1611 *
1612 * We reset it to 'level' at the end of this function.
1613 */
1614 sched_domains_numa_levels = 0;
1615
1616 sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
1617 if (!sched_domains_numa_masks)
1618 return;
1619
1620 /*
1621 * Now for each level, construct a mask per node which contains all
1622 * CPUs of nodes that are that many hops away from us.
1623 */
1624 for (i = 0; i < level; i++) {
1625 sched_domains_numa_masks[i] =
1626 kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1627 if (!sched_domains_numa_masks[i])
1628 return;
1629
1630 for (j = 0; j < nr_node_ids; j++) {
1631 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1632 if (!mask)
1633 return;
1634
1635 sched_domains_numa_masks[i][j] = mask;
1636
1637 for_each_node(k) {
1638 if (node_distance(j, k) > sched_domains_numa_distance[i])
1639 continue;
1640
1641 cpumask_or(mask, mask, cpumask_of_node(k));
1642 }
1643 }
1644 }
1645
1646 /* Compute default topology size */
1647 for (i = 0; sched_domain_topology[i].mask; i++);
1648
1649 tl = kzalloc((i + level + 1) *
1650 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1651 if (!tl)
1652 return;
1653
1654 /*
1655 * Copy the default topology bits..
1656 */
1657 for (i = 0; sched_domain_topology[i].mask; i++)
1658 tl[i] = sched_domain_topology[i];
1659
1660 /*
1661 * Add the NUMA identity distance, aka single NODE.
1662 */
1663 tl[i++] = (struct sched_domain_topology_level){
1664 .mask = sd_numa_mask,
1665 .numa_level = 0,
1666 SD_INIT_NAME(NODE)
1667 };
1668
1669 /*
1670 * .. and append 'j' levels of NUMA goodness.
1671 */
1672 for (j = 1; j < level; i++, j++) {
1673 tl[i] = (struct sched_domain_topology_level){
1674 .mask = sd_numa_mask,
1675 .sd_flags = cpu_numa_flags,
1676 .flags = SDTL_OVERLAP,
1677 .numa_level = j,
1678 SD_INIT_NAME(NUMA)
1679 };
1680 }
1681
1682 sched_domain_topology = tl;
1683
1684 sched_domains_numa_levels = level;
1685 sched_max_numa_distance = sched_domains_numa_distance[level - 1];
1686
1687 init_numa_topology_type();
1688}
1689
1690void sched_domains_numa_masks_set(unsigned int cpu)
1691{
1692 int node = cpu_to_node(cpu);
1693 int i, j;
1694
1695 for (i = 0; i < sched_domains_numa_levels; i++) {
1696 for (j = 0; j < nr_node_ids; j++) {
1697 if (node_distance(j, node) <= sched_domains_numa_distance[i])
1698 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
1699 }
1700 }
1701}
1702
1703void sched_domains_numa_masks_clear(unsigned int cpu)
1704{
1705 int i, j;
1706
1707 for (i = 0; i < sched_domains_numa_levels; i++) {
1708 for (j = 0; j < nr_node_ids; j++)
1709 cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
1710 }
1711}
1712
1713/*
1714 * sched_numa_find_closest() - given the NUMA topology, find the cpu
1715 * closest to @cpu from @cpumask.
1716 * cpumask: cpumask to find a cpu from
1717 * cpu: cpu to be close to
1718 *
1719 * returns: cpu, or nr_cpu_ids when nothing found.
1720 */
1721int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
1722{
1723 int i, j = cpu_to_node(cpu);
1724
1725 for (i = 0; i < sched_domains_numa_levels; i++) {
1726 cpu = cpumask_any_and(cpus, sched_domains_numa_masks[i][j]);
1727 if (cpu < nr_cpu_ids)
1728 return cpu;
1729 }
1730 return nr_cpu_ids;
1731}
1732
1733#endif /* CONFIG_NUMA */
1734
1735static int __sdt_alloc(const struct cpumask *cpu_map)
1736{
1737 struct sched_domain_topology_level *tl;
1738 int j;
1739
1740 for_each_sd_topology(tl) {
1741 struct sd_data *sdd = &tl->data;
1742
1743 sdd->sd = alloc_percpu(struct sched_domain *);
1744 if (!sdd->sd)
1745 return -ENOMEM;
1746
1747 sdd->sds = alloc_percpu(struct sched_domain_shared *);
1748 if (!sdd->sds)
1749 return -ENOMEM;
1750
1751 sdd->sg = alloc_percpu(struct sched_group *);
1752 if (!sdd->sg)
1753 return -ENOMEM;
1754
1755 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
1756 if (!sdd->sgc)
1757 return -ENOMEM;
1758
1759 for_each_cpu(j, cpu_map) {
1760 struct sched_domain *sd;
1761 struct sched_domain_shared *sds;
1762 struct sched_group *sg;
1763 struct sched_group_capacity *sgc;
1764
1765 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
1766 GFP_KERNEL, cpu_to_node(j));
1767 if (!sd)
1768 return -ENOMEM;
1769
1770 *per_cpu_ptr(sdd->sd, j) = sd;
1771
1772 sds = kzalloc_node(sizeof(struct sched_domain_shared),
1773 GFP_KERNEL, cpu_to_node(j));
1774 if (!sds)
1775 return -ENOMEM;
1776
1777 *per_cpu_ptr(sdd->sds, j) = sds;
1778
1779 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
1780 GFP_KERNEL, cpu_to_node(j));
1781 if (!sg)
1782 return -ENOMEM;
1783
1784 sg->next = sg;
1785
1786 *per_cpu_ptr(sdd->sg, j) = sg;
1787
1788 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
1789 GFP_KERNEL, cpu_to_node(j));
1790 if (!sgc)
1791 return -ENOMEM;
1792
1793#ifdef CONFIG_SCHED_DEBUG
1794 sgc->id = j;
1795#endif
1796
1797 *per_cpu_ptr(sdd->sgc, j) = sgc;
1798 }
1799 }
1800
1801 return 0;
1802}
1803
1804static void __sdt_free(const struct cpumask *cpu_map)
1805{
1806 struct sched_domain_topology_level *tl;
1807 int j;
1808
1809 for_each_sd_topology(tl) {
1810 struct sd_data *sdd = &tl->data;
1811
1812 for_each_cpu(j, cpu_map) {
1813 struct sched_domain *sd;
1814
1815 if (sdd->sd) {
1816 sd = *per_cpu_ptr(sdd->sd, j);
1817 if (sd && (sd->flags & SD_OVERLAP))
1818 free_sched_groups(sd->groups, 0);
1819 kfree(*per_cpu_ptr(sdd->sd, j));
1820 }
1821
1822 if (sdd->sds)
1823 kfree(*per_cpu_ptr(sdd->sds, j));
1824 if (sdd->sg)
1825 kfree(*per_cpu_ptr(sdd->sg, j));
1826 if (sdd->sgc)
1827 kfree(*per_cpu_ptr(sdd->sgc, j));
1828 }
1829 free_percpu(sdd->sd);
1830 sdd->sd = NULL;
1831 free_percpu(sdd->sds);
1832 sdd->sds = NULL;
1833 free_percpu(sdd->sg);
1834 sdd->sg = NULL;
1835 free_percpu(sdd->sgc);
1836 sdd->sgc = NULL;
1837 }
1838}
1839
1840static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
1841 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
1842 struct sched_domain *child, int dflags, int cpu)
1843{
1844 struct sched_domain *sd = sd_init(tl, cpu_map, child, dflags, cpu);
1845
1846 if (child) {
1847 sd->level = child->level + 1;
1848 sched_domain_level_max = max(sched_domain_level_max, sd->level);
1849 child->parent = sd;
1850
1851 if (!cpumask_subset(sched_domain_span(child),
1852 sched_domain_span(sd))) {
1853 pr_err("BUG: arch topology borken\n");
1854#ifdef CONFIG_SCHED_DEBUG
1855 pr_err(" the %s domain not a subset of the %s domain\n",
1856 child->name, sd->name);
1857#endif
1858 /* Fixup, ensure @sd has at least @child CPUs. */
1859 cpumask_or(sched_domain_span(sd),
1860 sched_domain_span(sd),
1861 sched_domain_span(child));
1862 }
1863
1864 }
1865 set_domain_attribute(sd, attr);
1866
1867 return sd;
1868}
1869
1870/*
1871 * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for
1872 * any two given CPUs at this (non-NUMA) topology level.
1873 */
1874static bool topology_span_sane(struct sched_domain_topology_level *tl,
1875 const struct cpumask *cpu_map, int cpu)
1876{
1877 int i;
1878
1879 /* NUMA levels are allowed to overlap */
1880 if (tl->flags & SDTL_OVERLAP)
1881 return true;
1882
1883 /*
1884 * Non-NUMA levels cannot partially overlap - they must be either
1885 * completely equal or completely disjoint. Otherwise we can end up
1886 * breaking the sched_group lists - i.e. a later get_group() pass
1887 * breaks the linking done for an earlier span.
1888 */
1889 for_each_cpu(i, cpu_map) {
1890 if (i == cpu)
1891 continue;
1892 /*
1893 * We should 'and' all those masks with 'cpu_map' to exactly
1894 * match the topology we're about to build, but that can only
1895 * remove CPUs, which only lessens our ability to detect
1896 * overlaps
1897 */
1898 if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) &&
1899 cpumask_intersects(tl->mask(cpu), tl->mask(i)))
1900 return false;
1901 }
1902
1903 return true;
1904}
1905
1906/*
1907 * Find the sched_domain_topology_level where all CPU capacities are visible
1908 * for all CPUs.
1909 */
1910static struct sched_domain_topology_level
1911*asym_cpu_capacity_level(const struct cpumask *cpu_map)
1912{
1913 int i, j, asym_level = 0;
1914 bool asym = false;
1915 struct sched_domain_topology_level *tl, *asym_tl = NULL;
1916 unsigned long cap;
1917
1918 /* Is there any asymmetry? */
1919 cap = arch_scale_cpu_capacity(cpumask_first(cpu_map));
1920
1921 for_each_cpu(i, cpu_map) {
1922 if (arch_scale_cpu_capacity(i) != cap) {
1923 asym = true;
1924 break;
1925 }
1926 }
1927
1928 if (!asym)
1929 return NULL;
1930
1931 /*
1932 * Examine topology from all CPU's point of views to detect the lowest
1933 * sched_domain_topology_level where a highest capacity CPU is visible
1934 * to everyone.
1935 */
1936 for_each_cpu(i, cpu_map) {
1937 unsigned long max_capacity = arch_scale_cpu_capacity(i);
1938 int tl_id = 0;
1939
1940 for_each_sd_topology(tl) {
1941 if (tl_id < asym_level)
1942 goto next_level;
1943
1944 for_each_cpu_and(j, tl->mask(i), cpu_map) {
1945 unsigned long capacity;
1946
1947 capacity = arch_scale_cpu_capacity(j);
1948
1949 if (capacity <= max_capacity)
1950 continue;
1951
1952 max_capacity = capacity;
1953 asym_level = tl_id;
1954 asym_tl = tl;
1955 }
1956next_level:
1957 tl_id++;
1958 }
1959 }
1960
1961 return asym_tl;
1962}
1963
1964
1965/*
1966 * Build sched domains for a given set of CPUs and attach the sched domains
1967 * to the individual CPUs
1968 */
1969static int
1970build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
1971{
1972 enum s_alloc alloc_state = sa_none;
1973 struct sched_domain *sd;
1974 struct s_data d;
1975 struct rq *rq = NULL;
1976 int i, ret = -ENOMEM;
1977 struct sched_domain_topology_level *tl_asym;
1978 bool has_asym = false;
1979
1980 if (WARN_ON(cpumask_empty(cpu_map)))
1981 goto error;
1982
1983 alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
1984 if (alloc_state != sa_rootdomain)
1985 goto error;
1986
1987 tl_asym = asym_cpu_capacity_level(cpu_map);
1988
1989 /* Set up domains for CPUs specified by the cpu_map: */
1990 for_each_cpu(i, cpu_map) {
1991 struct sched_domain_topology_level *tl;
1992
1993 sd = NULL;
1994 for_each_sd_topology(tl) {
1995 int dflags = 0;
1996
1997 if (tl == tl_asym) {
1998 dflags |= SD_ASYM_CPUCAPACITY;
1999 has_asym = true;
2000 }
2001
2002 if (WARN_ON(!topology_span_sane(tl, cpu_map, i)))
2003 goto error;
2004
2005 sd = build_sched_domain(tl, cpu_map, attr, sd, dflags, i);
2006
2007 if (tl == sched_domain_topology)
2008 *per_cpu_ptr(d.sd, i) = sd;
2009 if (tl->flags & SDTL_OVERLAP)
2010 sd->flags |= SD_OVERLAP;
2011 if (cpumask_equal(cpu_map, sched_domain_span(sd)))
2012 break;
2013 }
2014 }
2015
2016 /* Build the groups for the domains */
2017 for_each_cpu(i, cpu_map) {
2018 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2019 sd->span_weight = cpumask_weight(sched_domain_span(sd));
2020 if (sd->flags & SD_OVERLAP) {
2021 if (build_overlap_sched_groups(sd, i))
2022 goto error;
2023 } else {
2024 if (build_sched_groups(sd, i))
2025 goto error;
2026 }
2027 }
2028 }
2029
2030 /* Calculate CPU capacity for physical packages and nodes */
2031 for (i = nr_cpumask_bits-1; i >= 0; i--) {
2032 if (!cpumask_test_cpu(i, cpu_map))
2033 continue;
2034
2035 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2036 claim_allocations(i, sd);
2037 init_sched_groups_capacity(i, sd);
2038 }
2039 }
2040
2041 /* Attach the domains */
2042 rcu_read_lock();
2043 for_each_cpu(i, cpu_map) {
2044 rq = cpu_rq(i);
2045 sd = *per_cpu_ptr(d.sd, i);
2046
2047 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
2048 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
2049 WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
2050
2051 cpu_attach_domain(sd, d.rd, i);
2052 }
2053 rcu_read_unlock();
2054
2055 if (has_asym)
2056 static_branch_inc_cpuslocked(&sched_asym_cpucapacity);
2057
2058 if (rq && sched_debug_enabled) {
2059 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
2060 cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
2061 }
2062
2063 ret = 0;
2064error:
2065 __free_domain_allocs(&d, alloc_state, cpu_map);
2066
2067 return ret;
2068}
2069
2070/* Current sched domains: */
2071static cpumask_var_t *doms_cur;
2072
2073/* Number of sched domains in 'doms_cur': */
2074static int ndoms_cur;
2075
2076/* Attribues of custom domains in 'doms_cur' */
2077static struct sched_domain_attr *dattr_cur;
2078
2079/*
2080 * Special case: If a kmalloc() of a doms_cur partition (array of
2081 * cpumask) fails, then fallback to a single sched domain,
2082 * as determined by the single cpumask fallback_doms.
2083 */
2084static cpumask_var_t fallback_doms;
2085
2086/*
2087 * arch_update_cpu_topology lets virtualized architectures update the
2088 * CPU core maps. It is supposed to return 1 if the topology changed
2089 * or 0 if it stayed the same.
2090 */
2091int __weak arch_update_cpu_topology(void)
2092{
2093 return 0;
2094}
2095
2096cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
2097{
2098 int i;
2099 cpumask_var_t *doms;
2100
2101 doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL);
2102 if (!doms)
2103 return NULL;
2104 for (i = 0; i < ndoms; i++) {
2105 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
2106 free_sched_domains(doms, i);
2107 return NULL;
2108 }
2109 }
2110 return doms;
2111}
2112
2113void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
2114{
2115 unsigned int i;
2116 for (i = 0; i < ndoms; i++)
2117 free_cpumask_var(doms[i]);
2118 kfree(doms);
2119}
2120
2121/*
2122 * Set up scheduler domains and groups. For now this just excludes isolated
2123 * CPUs, but could be used to exclude other special cases in the future.
2124 */
2125int sched_init_domains(const struct cpumask *cpu_map)
2126{
2127 int err;
2128
2129 zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
2130 zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
2131 zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
2132
2133 arch_update_cpu_topology();
2134 ndoms_cur = 1;
2135 doms_cur = alloc_sched_domains(ndoms_cur);
2136 if (!doms_cur)
2137 doms_cur = &fallback_doms;
2138 cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN));
2139 err = build_sched_domains(doms_cur[0], NULL);
2140 register_sched_domain_sysctl();
2141
2142 return err;
2143}
2144
2145/*
2146 * Detach sched domains from a group of CPUs specified in cpu_map
2147 * These CPUs will now be attached to the NULL domain
2148 */
2149static void detach_destroy_domains(const struct cpumask *cpu_map)
2150{
2151 unsigned int cpu = cpumask_any(cpu_map);
2152 int i;
2153
2154 if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu)))
2155 static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
2156
2157 rcu_read_lock();
2158 for_each_cpu(i, cpu_map)
2159 cpu_attach_domain(NULL, &def_root_domain, i);
2160 rcu_read_unlock();
2161}
2162
2163/* handle null as "default" */
2164static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
2165 struct sched_domain_attr *new, int idx_new)
2166{
2167 struct sched_domain_attr tmp;
2168
2169 /* Fast path: */
2170 if (!new && !cur)
2171 return 1;
2172
2173 tmp = SD_ATTR_INIT;
2174
2175 return !memcmp(cur ? (cur + idx_cur) : &tmp,
2176 new ? (new + idx_new) : &tmp,
2177 sizeof(struct sched_domain_attr));
2178}
2179
2180/*
2181 * Partition sched domains as specified by the 'ndoms_new'
2182 * cpumasks in the array doms_new[] of cpumasks. This compares
2183 * doms_new[] to the current sched domain partitioning, doms_cur[].
2184 * It destroys each deleted domain and builds each new domain.
2185 *
2186 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
2187 * The masks don't intersect (don't overlap.) We should setup one
2188 * sched domain for each mask. CPUs not in any of the cpumasks will
2189 * not be load balanced. If the same cpumask appears both in the
2190 * current 'doms_cur' domains and in the new 'doms_new', we can leave
2191 * it as it is.
2192 *
2193 * The passed in 'doms_new' should be allocated using
2194 * alloc_sched_domains. This routine takes ownership of it and will
2195 * free_sched_domains it when done with it. If the caller failed the
2196 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
2197 * and partition_sched_domains() will fallback to the single partition
2198 * 'fallback_doms', it also forces the domains to be rebuilt.
2199 *
2200 * If doms_new == NULL it will be replaced with cpu_online_mask.
2201 * ndoms_new == 0 is a special case for destroying existing domains,
2202 * and it will not create the default domain.
2203 *
2204 * Call with hotplug lock and sched_domains_mutex held
2205 */
2206void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
2207 struct sched_domain_attr *dattr_new)
2208{
2209 bool __maybe_unused has_eas = false;
2210 int i, j, n;
2211 int new_topology;
2212
2213 lockdep_assert_held(&sched_domains_mutex);
2214
2215 /* Always unregister in case we don't destroy any domains: */
2216 unregister_sched_domain_sysctl();
2217
2218 /* Let the architecture update CPU core mappings: */
2219 new_topology = arch_update_cpu_topology();
2220
2221 if (!doms_new) {
2222 WARN_ON_ONCE(dattr_new);
2223 n = 0;
2224 doms_new = alloc_sched_domains(1);
2225 if (doms_new) {
2226 n = 1;
2227 cpumask_and(doms_new[0], cpu_active_mask,
2228 housekeeping_cpumask(HK_FLAG_DOMAIN));
2229 }
2230 } else {
2231 n = ndoms_new;
2232 }
2233
2234 /* Destroy deleted domains: */
2235 for (i = 0; i < ndoms_cur; i++) {
2236 for (j = 0; j < n && !new_topology; j++) {
2237 if (cpumask_equal(doms_cur[i], doms_new[j]) &&
2238 dattrs_equal(dattr_cur, i, dattr_new, j)) {
2239 struct root_domain *rd;
2240
2241 /*
2242 * This domain won't be destroyed and as such
2243 * its dl_bw->total_bw needs to be cleared. It
2244 * will be recomputed in function
2245 * update_tasks_root_domain().
2246 */
2247 rd = cpu_rq(cpumask_any(doms_cur[i]))->rd;
2248 dl_clear_root_domain(rd);
2249 goto match1;
2250 }
2251 }
2252 /* No match - a current sched domain not in new doms_new[] */
2253 detach_destroy_domains(doms_cur[i]);
2254match1:
2255 ;
2256 }
2257
2258 n = ndoms_cur;
2259 if (!doms_new) {
2260 n = 0;
2261 doms_new = &fallback_doms;
2262 cpumask_and(doms_new[0], cpu_active_mask,
2263 housekeeping_cpumask(HK_FLAG_DOMAIN));
2264 }
2265
2266 /* Build new domains: */
2267 for (i = 0; i < ndoms_new; i++) {
2268 for (j = 0; j < n && !new_topology; j++) {
2269 if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2270 dattrs_equal(dattr_new, i, dattr_cur, j))
2271 goto match2;
2272 }
2273 /* No match - add a new doms_new */
2274 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
2275match2:
2276 ;
2277 }
2278
2279#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
2280 /* Build perf. domains: */
2281 for (i = 0; i < ndoms_new; i++) {
2282 for (j = 0; j < n && !sched_energy_update; j++) {
2283 if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2284 cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) {
2285 has_eas = true;
2286 goto match3;
2287 }
2288 }
2289 /* No match - add perf. domains for a new rd */
2290 has_eas |= build_perf_domains(doms_new[i]);
2291match3:
2292 ;
2293 }
2294 sched_energy_set(has_eas);
2295#endif
2296
2297 /* Remember the new sched domains: */
2298 if (doms_cur != &fallback_doms)
2299 free_sched_domains(doms_cur, ndoms_cur);
2300
2301 kfree(dattr_cur);
2302 doms_cur = doms_new;
2303 dattr_cur = dattr_new;
2304 ndoms_cur = ndoms_new;
2305
2306 register_sched_domain_sysctl();
2307}
2308
2309/*
2310 * Call with hotplug lock held
2311 */
2312void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
2313 struct sched_domain_attr *dattr_new)
2314{
2315 mutex_lock(&sched_domains_mutex);
2316 partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
2317 mutex_unlock(&sched_domains_mutex);
2318}