1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Scheduler topology setup/handling methods
4 */
5
6#include <linux/sched/isolation.h>
7#include <linux/bsearch.h>
8#include "sched.h"
9
10DEFINE_MUTEX(sched_domains_mutex);
11void sched_domains_mutex_lock(void)
12{
13 mutex_lock(lock: &sched_domains_mutex);
14}
15void sched_domains_mutex_unlock(void)
16{
17 mutex_unlock(lock: &sched_domains_mutex);
18}
19
20/* Protected by sched_domains_mutex: */
21static cpumask_var_t sched_domains_tmpmask;
22static cpumask_var_t sched_domains_tmpmask2;
23
24static int __init sched_debug_setup(char *str)
25{
26 sched_debug_verbose = true;
27
28 return 0;
29}
30early_param("sched_verbose", sched_debug_setup);
31
32static inline bool sched_debug(void)
33{
34 return sched_debug_verbose;
35}
36
37#define SD_FLAG(_name, mflags) [__##_name] = { .meta_flags = mflags, .name = #_name },
38const struct sd_flag_debug sd_flag_debug[] = {
39#include <linux/sched/sd_flags.h>
40};
41#undef SD_FLAG
42
43static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
44 struct cpumask *groupmask)
45{
46 struct sched_group *group = sd->groups;
47 unsigned long flags = sd->flags;
48 unsigned int idx;
49
50 cpumask_clear(dstp: groupmask);
51
52 printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
53 printk(KERN_CONT "span=%*pbl level=%s\n",
54 cpumask_pr_args(sched_domain_span(sd)), sd->name);
55
56 if (!cpumask_test_cpu(cpu, cpumask: sched_domain_span(sd))) {
57 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
58 }
59 if (group && !cpumask_test_cpu(cpu, cpumask: sched_group_span(sg: group))) {
60 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
61 }
62
63 for_each_set_bit(idx, &flags, __SD_FLAG_CNT) {
64 unsigned int flag = BIT(idx);
65 unsigned int meta_flags = sd_flag_debug[idx].meta_flags;
66
67 if ((meta_flags & SDF_SHARED_CHILD) && sd->child &&
68 !(sd->child->flags & flag))
69 printk(KERN_ERR "ERROR: flag %s set here but not in child\n",
70 sd_flag_debug[idx].name);
71
72 if ((meta_flags & SDF_SHARED_PARENT) && sd->parent &&
73 !(sd->parent->flags & flag))
74 printk(KERN_ERR "ERROR: flag %s set here but not in parent\n",
75 sd_flag_debug[idx].name);
76 }
77
78 printk(KERN_DEBUG "%*s groups:", level + 1, "");
79 do {
80 if (!group) {
81 printk("\n");
82 printk(KERN_ERR "ERROR: group is NULL\n");
83 break;
84 }
85
86 if (cpumask_empty(srcp: sched_group_span(sg: group))) {
87 printk(KERN_CONT "\n");
88 printk(KERN_ERR "ERROR: empty group\n");
89 break;
90 }
91
92 if (!(sd->flags & SD_NUMA) &&
93 cpumask_intersects(src1p: groupmask, src2p: sched_group_span(sg: group))) {
94 printk(KERN_CONT "\n");
95 printk(KERN_ERR "ERROR: repeated CPUs\n");
96 break;
97 }
98
99 cpumask_or(dstp: groupmask, src1p: groupmask, src2p: sched_group_span(sg: group));
100
101 printk(KERN_CONT " %d:{ span=%*pbl",
102 group->sgc->id,
103 cpumask_pr_args(sched_group_span(group)));
104
105 if ((sd->flags & SD_NUMA) &&
106 !cpumask_equal(src1p: group_balance_mask(sg: group), src2p: sched_group_span(sg: group))) {
107 printk(KERN_CONT " mask=%*pbl",
108 cpumask_pr_args(group_balance_mask(group)));
109 }
110
111 if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
112 printk(KERN_CONT " cap=%lu", group->sgc->capacity);
113
114 if (group == sd->groups && sd->child &&
115 !cpumask_equal(src1p: sched_domain_span(sd: sd->child),
116 src2p: sched_group_span(sg: group))) {
117 printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
118 }
119
120 printk(KERN_CONT " }");
121
122 group = group->next;
123
124 if (group != sd->groups)
125 printk(KERN_CONT ",");
126
127 } while (group != sd->groups);
128 printk(KERN_CONT "\n");
129
130 if (!cpumask_equal(src1p: sched_domain_span(sd), src2p: groupmask))
131 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
132
133 if (sd->parent &&
134 !cpumask_subset(src1p: groupmask, src2p: sched_domain_span(sd: sd->parent)))
135 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
136 return 0;
137}
138
139static void sched_domain_debug(struct sched_domain *sd, int cpu)
140{
141 int level = 0;
142
143 if (!sched_debug_verbose)
144 return;
145
146 if (!sd) {
147 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
148 return;
149 }
150
151 printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
152
153 for (;;) {
154 if (sched_domain_debug_one(sd, cpu, level, groupmask: sched_domains_tmpmask))
155 break;
156 level++;
157 sd = sd->parent;
158 if (!sd)
159 break;
160 }
161}
162
163/* Generate a mask of SD flags with the SDF_NEEDS_GROUPS metaflag */
164#define SD_FLAG(name, mflags) (name * !!((mflags) & SDF_NEEDS_GROUPS)) |
165static const unsigned int SD_DEGENERATE_GROUPS_MASK =
166#include <linux/sched/sd_flags.h>
1670;
168#undef SD_FLAG
169
170static int sd_degenerate(struct sched_domain *sd)
171{
172 if (cpumask_weight(srcp: sched_domain_span(sd)) == 1)
173 return 1;
174
175 /* Following flags need at least 2 groups */
176 if ((sd->flags & SD_DEGENERATE_GROUPS_MASK) &&
177 (sd->groups != sd->groups->next))
178 return 0;
179
180 /* Following flags don't use groups */
181 if (sd->flags & (SD_WAKE_AFFINE))
182 return 0;
183
184 return 1;
185}
186
187static int
188sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
189{
190 unsigned long cflags = sd->flags, pflags = parent->flags;
191
192 if (sd_degenerate(sd: parent))
193 return 1;
194
195 if (!cpumask_equal(src1p: sched_domain_span(sd), src2p: sched_domain_span(sd: parent)))
196 return 0;
197
198 /* Flags needing groups don't count if only 1 group in parent */
199 if (parent->groups == parent->groups->next)
200 pflags &= ~SD_DEGENERATE_GROUPS_MASK;
201
202 if (~cflags & pflags)
203 return 0;
204
205 return 1;
206}
207
208#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
209DEFINE_STATIC_KEY_FALSE(sched_energy_present);
210static unsigned int sysctl_sched_energy_aware = 1;
211static DEFINE_MUTEX(sched_energy_mutex);
212static bool sched_energy_update;
213
214static bool sched_is_eas_possible(const struct cpumask *cpu_mask)
215{
216 bool any_asym_capacity = false;
217 int i;
218
219 /* EAS is enabled for asymmetric CPU capacity topologies. */
220 for_each_cpu(i, cpu_mask) {
221 if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, i))) {
222 any_asym_capacity = true;
223 break;
224 }
225 }
226 if (!any_asym_capacity) {
227 if (sched_debug()) {
228 pr_info("rd %*pbl: Checking EAS, CPUs do not have asymmetric capacities\n",
229 cpumask_pr_args(cpu_mask));
230 }
231 return false;
232 }
233
234 /* EAS definitely does *not* handle SMT */
235 if (sched_smt_active()) {
236 if (sched_debug()) {
237 pr_info("rd %*pbl: Checking EAS, SMT is not supported\n",
238 cpumask_pr_args(cpu_mask));
239 }
240 return false;
241 }
242
243 if (!arch_scale_freq_invariant()) {
244 if (sched_debug()) {
245 pr_info("rd %*pbl: Checking EAS: frequency-invariant load tracking not yet supported",
246 cpumask_pr_args(cpu_mask));
247 }
248 return false;
249 }
250
251 if (!cpufreq_ready_for_eas(cpu_mask)) {
252 if (sched_debug()) {
253 pr_info("rd %*pbl: Checking EAS: cpufreq is not ready\n",
254 cpumask_pr_args(cpu_mask));
255 }
256 return false;
257 }
258
259 return true;
260}
261
262void rebuild_sched_domains_energy(void)
263{
264 mutex_lock(&sched_energy_mutex);
265 sched_energy_update = true;
266 rebuild_sched_domains();
267 sched_energy_update = false;
268 mutex_unlock(&sched_energy_mutex);
269}
270
271#ifdef CONFIG_PROC_SYSCTL
272static int sched_energy_aware_handler(const struct ctl_table *table, int write,
273 void *buffer, size_t *lenp, loff_t *ppos)
274{
275 int ret, state;
276
277 if (write && !capable(CAP_SYS_ADMIN))
278 return -EPERM;
279
280 if (!sched_is_eas_possible(cpu_active_mask)) {
281 if (write) {
282 return -EOPNOTSUPP;
283 } else {
284 *lenp = 0;
285 return 0;
286 }
287 }
288
289 ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
290 if (!ret && write) {
291 state = static_branch_unlikely(&sched_energy_present);
292 if (state != sysctl_sched_energy_aware)
293 rebuild_sched_domains_energy();
294 }
295
296 return ret;
297}
298
299static const struct ctl_table sched_energy_aware_sysctls[] = {
300 {
301 .procname = "sched_energy_aware",
302 .data = &sysctl_sched_energy_aware,
303 .maxlen = sizeof(unsigned int),
304 .mode = 0644,
305 .proc_handler = sched_energy_aware_handler,
306 .extra1 = SYSCTL_ZERO,
307 .extra2 = SYSCTL_ONE,
308 },
309};
310
311static int __init sched_energy_aware_sysctl_init(void)
312{
313 register_sysctl_init("kernel", sched_energy_aware_sysctls);
314 return 0;
315}
316
317late_initcall(sched_energy_aware_sysctl_init);
318#endif /* CONFIG_PROC_SYSCTL */
319
320static void free_pd(struct perf_domain *pd)
321{
322 struct perf_domain *tmp;
323
324 while (pd) {
325 tmp = pd->next;
326 kfree(pd);
327 pd = tmp;
328 }
329}
330
331static struct perf_domain *find_pd(struct perf_domain *pd, int cpu)
332{
333 while (pd) {
334 if (cpumask_test_cpu(cpu, perf_domain_span(pd)))
335 return pd;
336 pd = pd->next;
337 }
338
339 return NULL;
340}
341
342static struct perf_domain *pd_init(int cpu)
343{
344 struct em_perf_domain *obj = em_cpu_get(cpu);
345 struct perf_domain *pd;
346
347 if (!obj) {
348 if (sched_debug())
349 pr_info("%s: no EM found for CPU%d\n", __func__, cpu);
350 return NULL;
351 }
352
353 pd = kzalloc(sizeof(*pd), GFP_KERNEL);
354 if (!pd)
355 return NULL;
356 pd->em_pd = obj;
357
358 return pd;
359}
360
361static void perf_domain_debug(const struct cpumask *cpu_map,
362 struct perf_domain *pd)
363{
364 if (!sched_debug() || !pd)
365 return;
366
367 printk(KERN_DEBUG "root_domain %*pbl:", cpumask_pr_args(cpu_map));
368
369 while (pd) {
370 printk(KERN_CONT " pd%d:{ cpus=%*pbl nr_pstate=%d }",
371 cpumask_first(perf_domain_span(pd)),
372 cpumask_pr_args(perf_domain_span(pd)),
373 em_pd_nr_perf_states(pd->em_pd));
374 pd = pd->next;
375 }
376
377 printk(KERN_CONT "\n");
378}
379
380static void destroy_perf_domain_rcu(struct rcu_head *rp)
381{
382 struct perf_domain *pd;
383
384 pd = container_of(rp, struct perf_domain, rcu);
385 free_pd(pd);
386}
387
388static void sched_energy_set(bool has_eas)
389{
390 if (!has_eas && static_branch_unlikely(&sched_energy_present)) {
391 if (sched_debug())
392 pr_info("%s: stopping EAS\n", __func__);
393 static_branch_disable_cpuslocked(&sched_energy_present);
394 } else if (has_eas && !static_branch_unlikely(&sched_energy_present)) {
395 if (sched_debug())
396 pr_info("%s: starting EAS\n", __func__);
397 static_branch_enable_cpuslocked(&sched_energy_present);
398 }
399}
400
401/*
402 * EAS can be used on a root domain if it meets all the following conditions:
403 * 1. an Energy Model (EM) is available;
404 * 2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy.
405 * 3. no SMT is detected.
406 * 4. schedutil is driving the frequency of all CPUs of the rd;
407 * 5. frequency invariance support is present;
408 */
409static bool build_perf_domains(const struct cpumask *cpu_map)
410{
411 int i;
412 struct perf_domain *pd = NULL, *tmp;
413 int cpu = cpumask_first(cpu_map);
414 struct root_domain *rd = cpu_rq(cpu)->rd;
415
416 if (!sysctl_sched_energy_aware)
417 goto free;
418
419 if (!sched_is_eas_possible(cpu_map))
420 goto free;
421
422 for_each_cpu(i, cpu_map) {
423 /* Skip already covered CPUs. */
424 if (find_pd(pd, i))
425 continue;
426
427 /* Create the new pd and add it to the local list. */
428 tmp = pd_init(i);
429 if (!tmp)
430 goto free;
431 tmp->next = pd;
432 pd = tmp;
433 }
434
435 perf_domain_debug(cpu_map, pd);
436
437 /* Attach the new list of performance domains to the root domain. */
438 tmp = rd->pd;
439 rcu_assign_pointer(rd->pd, pd);
440 if (tmp)
441 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
442
443 return !!pd;
444
445free:
446 free_pd(pd);
447 tmp = rd->pd;
448 rcu_assign_pointer(rd->pd, NULL);
449 if (tmp)
450 call_rcu(&tmp->rcu, destroy_perf_domain_rcu);
451
452 return false;
453}
454#else /* !(CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL): */
455static void free_pd(struct perf_domain *pd) { }
456#endif /* !(CONFIG_ENERGY_MODEL && CONFIG_CPU_FREQ_GOV_SCHEDUTIL) */
457
458static void free_rootdomain(struct rcu_head *rcu)
459{
460 struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
461
462 cpupri_cleanup(cp: &rd->cpupri);
463 cpudl_cleanup(cp: &rd->cpudl);
464 free_cpumask_var(mask: rd->dlo_mask);
465 free_cpumask_var(mask: rd->rto_mask);
466 free_cpumask_var(mask: rd->online);
467 free_cpumask_var(mask: rd->span);
468 free_pd(pd: rd->pd);
469 kfree(objp: rd);
470}
471
472void rq_attach_root(struct rq *rq, struct root_domain *rd)
473{
474 struct root_domain *old_rd = NULL;
475 struct rq_flags rf;
476
477 rq_lock_irqsave(rq, rf: &rf);
478
479 if (rq->rd) {
480 old_rd = rq->rd;
481
482 if (cpumask_test_cpu(cpu: rq->cpu, cpumask: old_rd->online))
483 set_rq_offline(rq);
484
485 cpumask_clear_cpu(cpu: rq->cpu, dstp: old_rd->span);
486
487 /*
488 * If we don't want to free the old_rd yet then
489 * set old_rd to NULL to skip the freeing later
490 * in this function:
491 */
492 if (!atomic_dec_and_test(v: &old_rd->refcount))
493 old_rd = NULL;
494 }
495
496 atomic_inc(v: &rd->refcount);
497 rq->rd = rd;
498
499 cpumask_set_cpu(cpu: rq->cpu, dstp: rd->span);
500 if (cpumask_test_cpu(cpu: rq->cpu, cpu_active_mask))
501 set_rq_online(rq);
502
503 /*
504 * Because the rq is not a task, dl_add_task_root_domain() did not
505 * move the fair server bw to the rd if it already started.
506 * Add it now.
507 */
508 if (rq->fair_server.dl_server)
509 __dl_server_attach_root(dl_se: &rq->fair_server, rq);
510
511 rq_unlock_irqrestore(rq, rf: &rf);
512
513 if (old_rd)
514 call_rcu(head: &old_rd->rcu, func: free_rootdomain);
515}
516
517void sched_get_rd(struct root_domain *rd)
518{
519 atomic_inc(v: &rd->refcount);
520}
521
522void sched_put_rd(struct root_domain *rd)
523{
524 if (!atomic_dec_and_test(v: &rd->refcount))
525 return;
526
527 call_rcu(head: &rd->rcu, func: free_rootdomain);
528}
529
530static int init_rootdomain(struct root_domain *rd)
531{
532 if (!zalloc_cpumask_var(mask: &rd->span, GFP_KERNEL))
533 goto out;
534 if (!zalloc_cpumask_var(mask: &rd->online, GFP_KERNEL))
535 goto free_span;
536 if (!zalloc_cpumask_var(mask: &rd->dlo_mask, GFP_KERNEL))
537 goto free_online;
538 if (!zalloc_cpumask_var(mask: &rd->rto_mask, GFP_KERNEL))
539 goto free_dlo_mask;
540
541#ifdef HAVE_RT_PUSH_IPI
542 rd->rto_cpu = -1;
543 raw_spin_lock_init(&rd->rto_lock);
544 rd->rto_push_work = IRQ_WORK_INIT_HARD(rto_push_irq_work_func);
545#endif
546
547 rd->visit_cookie = 0;
548 init_dl_bw(dl_b: &rd->dl_bw);
549 if (cpudl_init(cp: &rd->cpudl) != 0)
550 goto free_rto_mask;
551
552 if (cpupri_init(cp: &rd->cpupri) != 0)
553 goto free_cpudl;
554 return 0;
555
556free_cpudl:
557 cpudl_cleanup(cp: &rd->cpudl);
558free_rto_mask:
559 free_cpumask_var(mask: rd->rto_mask);
560free_dlo_mask:
561 free_cpumask_var(mask: rd->dlo_mask);
562free_online:
563 free_cpumask_var(mask: rd->online);
564free_span:
565 free_cpumask_var(mask: rd->span);
566out:
567 return -ENOMEM;
568}
569
570/*
571 * By default the system creates a single root-domain with all CPUs as
572 * members (mimicking the global state we have today).
573 */
574struct root_domain def_root_domain;
575
576void __init init_defrootdomain(void)
577{
578 init_rootdomain(rd: &def_root_domain);
579
580 atomic_set(v: &def_root_domain.refcount, i: 1);
581}
582
583static struct root_domain *alloc_rootdomain(void)
584{
585 struct root_domain *rd;
586
587 rd = kzalloc(sizeof(*rd), GFP_KERNEL);
588 if (!rd)
589 return NULL;
590
591 if (init_rootdomain(rd) != 0) {
592 kfree(objp: rd);
593 return NULL;
594 }
595
596 return rd;
597}
598
599static void free_sched_groups(struct sched_group *sg, int free_sgc)
600{
601 struct sched_group *tmp, *first;
602
603 if (!sg)
604 return;
605
606 first = sg;
607 do {
608 tmp = sg->next;
609
610 if (free_sgc && atomic_dec_and_test(v: &sg->sgc->ref))
611 kfree(objp: sg->sgc);
612
613 if (atomic_dec_and_test(v: &sg->ref))
614 kfree(objp: sg);
615 sg = tmp;
616 } while (sg != first);
617}
618
619static void destroy_sched_domain(struct sched_domain *sd)
620{
621 /*
622 * A normal sched domain may have multiple group references, an
623 * overlapping domain, having private groups, only one. Iterate,
624 * dropping group/capacity references, freeing where none remain.
625 */
626 free_sched_groups(sg: sd->groups, free_sgc: 1);
627
628 if (sd->shared && atomic_dec_and_test(v: &sd->shared->ref))
629 kfree(objp: sd->shared);
630 kfree(objp: sd);
631}
632
633static void destroy_sched_domains_rcu(struct rcu_head *rcu)
634{
635 struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
636
637 while (sd) {
638 struct sched_domain *parent = sd->parent;
639 destroy_sched_domain(sd);
640 sd = parent;
641 }
642}
643
644static void destroy_sched_domains(struct sched_domain *sd)
645{
646 if (sd)
647 call_rcu(head: &sd->rcu, func: destroy_sched_domains_rcu);
648}
649
650/*
651 * Keep a special pointer to the highest sched_domain that has SD_SHARE_LLC set
652 * (Last Level Cache Domain) for this allows us to avoid some pointer chasing
653 * select_idle_sibling().
654 *
655 * Also keep a unique ID per domain (we use the first CPU number in the cpumask
656 * of the domain), this allows us to quickly tell if two CPUs are in the same
657 * cache domain, see cpus_share_cache().
658 */
659DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
660DEFINE_PER_CPU(int, sd_llc_size);
661DEFINE_PER_CPU(int, sd_llc_id);
662DEFINE_PER_CPU(int, sd_share_id);
663DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
664DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
665DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
666DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
667
668DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);
669DEFINE_STATIC_KEY_FALSE(sched_cluster_active);
670
671static void update_top_cache_domain(int cpu)
672{
673 struct sched_domain_shared *sds = NULL;
674 struct sched_domain *sd;
675 int id = cpu;
676 int size = 1;
677
678 sd = highest_flag_domain(cpu, flag: SD_SHARE_LLC);
679 if (sd) {
680 id = cpumask_first(srcp: sched_domain_span(sd));
681 size = cpumask_weight(srcp: sched_domain_span(sd));
682 sds = sd->shared;
683 }
684
685 rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
686 per_cpu(sd_llc_size, cpu) = size;
687 per_cpu(sd_llc_id, cpu) = id;
688 rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
689
690 sd = lowest_flag_domain(cpu, flag: SD_CLUSTER);
691 if (sd)
692 id = cpumask_first(srcp: sched_domain_span(sd));
693
694 /*
695 * This assignment should be placed after the sd_llc_id as
696 * we want this id equals to cluster id on cluster machines
697 * but equals to LLC id on non-Cluster machines.
698 */
699 per_cpu(sd_share_id, cpu) = id;
700
701 sd = lowest_flag_domain(cpu, flag: SD_NUMA);
702 rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
703
704 sd = highest_flag_domain(cpu, flag: SD_ASYM_PACKING);
705 rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd);
706
707 sd = lowest_flag_domain(cpu, flag: SD_ASYM_CPUCAPACITY_FULL);
708 rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd);
709}
710
711/*
712 * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
713 * hold the hotplug lock.
714 */
715static void
716cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
717{
718 struct rq *rq = cpu_rq(cpu);
719 struct sched_domain *tmp;
720
721 /* Remove the sched domains which do not contribute to scheduling. */
722 for (tmp = sd; tmp; ) {
723 struct sched_domain *parent = tmp->parent;
724 if (!parent)
725 break;
726
727 if (sd_parent_degenerate(sd: tmp, parent)) {
728 tmp->parent = parent->parent;
729
730 if (parent->parent) {
731 parent->parent->child = tmp;
732 parent->parent->groups->flags = tmp->flags;
733 }
734
735 /*
736 * Transfer SD_PREFER_SIBLING down in case of a
737 * degenerate parent; the spans match for this
738 * so the property transfers.
739 */
740 if (parent->flags & SD_PREFER_SIBLING)
741 tmp->flags |= SD_PREFER_SIBLING;
742 destroy_sched_domain(sd: parent);
743 } else
744 tmp = tmp->parent;
745 }
746
747 if (sd && sd_degenerate(sd)) {
748 tmp = sd;
749 sd = sd->parent;
750 destroy_sched_domain(sd: tmp);
751 if (sd) {
752 struct sched_group *sg = sd->groups;
753
754 /*
755 * sched groups hold the flags of the child sched
756 * domain for convenience. Clear such flags since
757 * the child is being destroyed.
758 */
759 do {
760 sg->flags = 0;
761 } while (sg != sd->groups);
762
763 sd->child = NULL;
764 }
765 }
766
767 sched_domain_debug(sd, cpu);
768
769 rq_attach_root(rq, rd);
770 tmp = rq->sd;
771 rcu_assign_pointer(rq->sd, sd);
772 dirty_sched_domain_sysctl(cpu);
773 destroy_sched_domains(sd: tmp);
774
775 update_top_cache_domain(cpu);
776}
777
778struct s_data {
779 struct sched_domain * __percpu *sd;
780 struct root_domain *rd;
781};
782
783enum s_alloc {
784 sa_rootdomain,
785 sa_sd,
786 sa_sd_storage,
787 sa_none,
788};
789
790/*
791 * Return the canonical balance CPU for this group, this is the first CPU
792 * of this group that's also in the balance mask.
793 *
794 * The balance mask are all those CPUs that could actually end up at this
795 * group. See build_balance_mask().
796 *
797 * Also see should_we_balance().
798 */
799int group_balance_cpu(struct sched_group *sg)
800{
801 return cpumask_first(srcp: group_balance_mask(sg));
802}
803
804
805/*
806 * NUMA topology (first read the regular topology blurb below)
807 *
808 * Given a node-distance table, for example:
809 *
810 * node 0 1 2 3
811 * 0: 10 20 30 20
812 * 1: 20 10 20 30
813 * 2: 30 20 10 20
814 * 3: 20 30 20 10
815 *
816 * which represents a 4 node ring topology like:
817 *
818 * 0 ----- 1
819 * | |
820 * | |
821 * | |
822 * 3 ----- 2
823 *
824 * We want to construct domains and groups to represent this. The way we go
825 * about doing this is to build the domains on 'hops'. For each NUMA level we
826 * construct the mask of all nodes reachable in @level hops.
827 *
828 * For the above NUMA topology that gives 3 levels:
829 *
830 * NUMA-2 0-3 0-3 0-3 0-3
831 * groups: {0-1,3},{1-3} {0-2},{0,2-3} {1-3},{0-1,3} {0,2-3},{0-2}
832 *
833 * NUMA-1 0-1,3 0-2 1-3 0,2-3
834 * groups: {0},{1},{3} {0},{1},{2} {1},{2},{3} {0},{2},{3}
835 *
836 * NUMA-0 0 1 2 3
837 *
838 *
839 * As can be seen; things don't nicely line up as with the regular topology.
840 * When we iterate a domain in child domain chunks some nodes can be
841 * represented multiple times -- hence the "overlap" naming for this part of
842 * the topology.
843 *
844 * In order to minimize this overlap, we only build enough groups to cover the
845 * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
846 *
847 * Because:
848 *
849 * - the first group of each domain is its child domain; this
850 * gets us the first 0-1,3
851 * - the only uncovered node is 2, who's child domain is 1-3.
852 *
853 * However, because of the overlap, computing a unique CPU for each group is
854 * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
855 * groups include the CPUs of Node-0, while those CPUs would not in fact ever
856 * end up at those groups (they would end up in group: 0-1,3).
857 *
858 * To correct this we have to introduce the group balance mask. This mask
859 * will contain those CPUs in the group that can reach this group given the
860 * (child) domain tree.
861 *
862 * With this we can once again compute balance_cpu and sched_group_capacity
863 * relations.
864 *
865 * XXX include words on how balance_cpu is unique and therefore can be
866 * used for sched_group_capacity links.
867 *
868 *
869 * Another 'interesting' topology is:
870 *
871 * node 0 1 2 3
872 * 0: 10 20 20 30
873 * 1: 20 10 20 20
874 * 2: 20 20 10 20
875 * 3: 30 20 20 10
876 *
877 * Which looks a little like:
878 *
879 * 0 ----- 1
880 * | / |
881 * | / |
882 * | / |
883 * 2 ----- 3
884 *
885 * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
886 * are not.
887 *
888 * This leads to a few particularly weird cases where the sched_domain's are
889 * not of the same number for each CPU. Consider:
890 *
891 * NUMA-2 0-3 0-3
892 * groups: {0-2},{1-3} {1-3},{0-2}
893 *
894 * NUMA-1 0-2 0-3 0-3 1-3
895 *
896 * NUMA-0 0 1 2 3
897 *
898 */
899
900
901/*
902 * Build the balance mask; it contains only those CPUs that can arrive at this
903 * group and should be considered to continue balancing.
904 *
905 * We do this during the group creation pass, therefore the group information
906 * isn't complete yet, however since each group represents a (child) domain we
907 * can fully construct this using the sched_domain bits (which are already
908 * complete).
909 */
910static void
911build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
912{
913 const struct cpumask *sg_span = sched_group_span(sg);
914 struct sd_data *sdd = sd->private;
915 struct sched_domain *sibling;
916 int i;
917
918 cpumask_clear(dstp: mask);
919
920 for_each_cpu(i, sg_span) {
921 sibling = *per_cpu_ptr(sdd->sd, i);
922
923 /*
924 * Can happen in the asymmetric case, where these siblings are
925 * unused. The mask will not be empty because those CPUs that
926 * do have the top domain _should_ span the domain.
927 */
928 if (!sibling->child)
929 continue;
930
931 /* If we would not end up here, we can't continue from here */
932 if (!cpumask_equal(src1p: sg_span, src2p: sched_domain_span(sd: sibling->child)))
933 continue;
934
935 cpumask_set_cpu(cpu: i, dstp: mask);
936 }
937
938 /* We must not have empty masks here */
939 WARN_ON_ONCE(cpumask_empty(mask));
940}
941
942/*
943 * XXX: This creates per-node group entries; since the load-balancer will
944 * immediately access remote memory to construct this group's load-balance
945 * statistics having the groups node local is of dubious benefit.
946 */
947static struct sched_group *
948build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
949{
950 struct sched_group *sg;
951 struct cpumask *sg_span;
952
953 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
954 GFP_KERNEL, cpu_to_node(cpu));
955
956 if (!sg)
957 return NULL;
958
959 sg_span = sched_group_span(sg);
960 if (sd->child) {
961 cpumask_copy(dstp: sg_span, srcp: sched_domain_span(sd: sd->child));
962 sg->flags = sd->child->flags;
963 } else {
964 cpumask_copy(dstp: sg_span, srcp: sched_domain_span(sd));
965 }
966
967 atomic_inc(v: &sg->ref);
968 return sg;
969}
970
971static void init_overlap_sched_group(struct sched_domain *sd,
972 struct sched_group *sg)
973{
974 struct cpumask *mask = sched_domains_tmpmask2;
975 struct sd_data *sdd = sd->private;
976 struct cpumask *sg_span;
977 int cpu;
978
979 build_balance_mask(sd, sg, mask);
980 cpu = cpumask_first(srcp: mask);
981
982 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
983 if (atomic_inc_return(v: &sg->sgc->ref) == 1)
984 cpumask_copy(dstp: group_balance_mask(sg), srcp: mask);
985 else
986 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
987
988 /*
989 * Initialize sgc->capacity such that even if we mess up the
990 * domains and no possible iteration will get us here, we won't
991 * die on a /0 trap.
992 */
993 sg_span = sched_group_span(sg);
994 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(srcp: sg_span);
995 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
996 sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
997}
998
999static struct sched_domain *
1000find_descended_sibling(struct sched_domain *sd, struct sched_domain *sibling)
1001{
1002 /*
1003 * The proper descendant would be the one whose child won't span out
1004 * of sd
1005 */
1006 while (sibling->child &&
1007 !cpumask_subset(src1p: sched_domain_span(sd: sibling->child),
1008 src2p: sched_domain_span(sd)))
1009 sibling = sibling->child;
1010
1011 /*
1012 * As we are referencing sgc across different topology level, we need
1013 * to go down to skip those sched_domains which don't contribute to
1014 * scheduling because they will be degenerated in cpu_attach_domain
1015 */
1016 while (sibling->child &&
1017 cpumask_equal(src1p: sched_domain_span(sd: sibling->child),
1018 src2p: sched_domain_span(sd: sibling)))
1019 sibling = sibling->child;
1020
1021 return sibling;
1022}
1023
1024static int
1025build_overlap_sched_groups(struct sched_domain *sd, int cpu)
1026{
1027 struct sched_group *first = NULL, *last = NULL, *sg;
1028 const struct cpumask *span = sched_domain_span(sd);
1029 struct cpumask *covered = sched_domains_tmpmask;
1030 struct sd_data *sdd = sd->private;
1031 struct sched_domain *sibling;
1032 int i;
1033
1034 cpumask_clear(dstp: covered);
1035
1036 for_each_cpu_wrap(i, span, cpu) {
1037 struct cpumask *sg_span;
1038
1039 if (cpumask_test_cpu(cpu: i, cpumask: covered))
1040 continue;
1041
1042 sibling = *per_cpu_ptr(sdd->sd, i);
1043
1044 /*
1045 * Asymmetric node setups can result in situations where the
1046 * domain tree is of unequal depth, make sure to skip domains
1047 * that already cover the entire range.
1048 *
1049 * In that case build_sched_domains() will have terminated the
1050 * iteration early and our sibling sd spans will be empty.
1051 * Domains should always include the CPU they're built on, so
1052 * check that.
1053 */
1054 if (!cpumask_test_cpu(cpu: i, cpumask: sched_domain_span(sd: sibling)))
1055 continue;
1056
1057 /*
1058 * Usually we build sched_group by sibling's child sched_domain
1059 * But for machines whose NUMA diameter are 3 or above, we move
1060 * to build sched_group by sibling's proper descendant's child
1061 * domain because sibling's child sched_domain will span out of
1062 * the sched_domain being built as below.
1063 *
1064 * Smallest diameter=3 topology is:
1065 *
1066 * node 0 1 2 3
1067 * 0: 10 20 30 40
1068 * 1: 20 10 20 30
1069 * 2: 30 20 10 20
1070 * 3: 40 30 20 10
1071 *
1072 * 0 --- 1 --- 2 --- 3
1073 *
1074 * NUMA-3 0-3 N/A N/A 0-3
1075 * groups: {0-2},{1-3} {1-3},{0-2}
1076 *
1077 * NUMA-2 0-2 0-3 0-3 1-3
1078 * groups: {0-1},{1-3} {0-2},{2-3} {1-3},{0-1} {2-3},{0-2}
1079 *
1080 * NUMA-1 0-1 0-2 1-3 2-3
1081 * groups: {0},{1} {1},{2},{0} {2},{3},{1} {3},{2}
1082 *
1083 * NUMA-0 0 1 2 3
1084 *
1085 * The NUMA-2 groups for nodes 0 and 3 are obviously buggered, as the
1086 * group span isn't a subset of the domain span.
1087 */
1088 if (sibling->child &&
1089 !cpumask_subset(src1p: sched_domain_span(sd: sibling->child), src2p: span))
1090 sibling = find_descended_sibling(sd, sibling);
1091
1092 sg = build_group_from_child_sched_domain(sd: sibling, cpu);
1093 if (!sg)
1094 goto fail;
1095
1096 sg_span = sched_group_span(sg);
1097 cpumask_or(dstp: covered, src1p: covered, src2p: sg_span);
1098
1099 init_overlap_sched_group(sd: sibling, sg);
1100
1101 if (!first)
1102 first = sg;
1103 if (last)
1104 last->next = sg;
1105 last = sg;
1106 last->next = first;
1107 }
1108 sd->groups = first;
1109
1110 return 0;
1111
1112fail:
1113 free_sched_groups(sg: first, free_sgc: 0);
1114
1115 return -ENOMEM;
1116}
1117
1118
1119/*
1120 * Package topology (also see the load-balance blurb in fair.c)
1121 *
1122 * The scheduler builds a tree structure to represent a number of important
1123 * topology features. By default (default_topology[]) these include:
1124 *
1125 * - Simultaneous multithreading (SMT)
1126 * - Multi-Core Cache (MC)
1127 * - Package (PKG)
1128 *
1129 * Where the last one more or less denotes everything up to a NUMA node.
1130 *
1131 * The tree consists of 3 primary data structures:
1132 *
1133 * sched_domain -> sched_group -> sched_group_capacity
1134 * ^ ^ ^ ^
1135 * `-' `-'
1136 *
1137 * The sched_domains are per-CPU and have a two way link (parent & child) and
1138 * denote the ever growing mask of CPUs belonging to that level of topology.
1139 *
1140 * Each sched_domain has a circular (double) linked list of sched_group's, each
1141 * denoting the domains of the level below (or individual CPUs in case of the
1142 * first domain level). The sched_group linked by a sched_domain includes the
1143 * CPU of that sched_domain [*].
1144 *
1145 * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
1146 *
1147 * CPU 0 1 2 3 4 5 6 7
1148 *
1149 * PKG [ ]
1150 * MC [ ] [ ]
1151 * SMT [ ] [ ] [ ] [ ]
1152 *
1153 * - or -
1154 *
1155 * PKG 0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
1156 * MC 0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
1157 * SMT 0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
1158 *
1159 * CPU 0 1 2 3 4 5 6 7
1160 *
1161 * One way to think about it is: sched_domain moves you up and down among these
1162 * topology levels, while sched_group moves you sideways through it, at child
1163 * domain granularity.
1164 *
1165 * sched_group_capacity ensures each unique sched_group has shared storage.
1166 *
1167 * There are two related construction problems, both require a CPU that
1168 * uniquely identify each group (for a given domain):
1169 *
1170 * - The first is the balance_cpu (see should_we_balance() and the
1171 * load-balance blurb in fair.c); for each group we only want 1 CPU to
1172 * continue balancing at a higher domain.
1173 *
1174 * - The second is the sched_group_capacity; we want all identical groups
1175 * to share a single sched_group_capacity.
1176 *
1177 * Since these topologies are exclusive by construction. That is, its
1178 * impossible for an SMT thread to belong to multiple cores, and cores to
1179 * be part of multiple caches. There is a very clear and unique location
1180 * for each CPU in the hierarchy.
1181 *
1182 * Therefore computing a unique CPU for each group is trivial (the iteration
1183 * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
1184 * group), we can simply pick the first CPU in each group.
1185 *
1186 *
1187 * [*] in other words, the first group of each domain is its child domain.
1188 */
1189
1190static struct sched_group *get_group(int cpu, struct sd_data *sdd)
1191{
1192 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1193 struct sched_domain *child = sd->child;
1194 struct sched_group *sg;
1195 bool already_visited;
1196
1197 if (child)
1198 cpu = cpumask_first(srcp: sched_domain_span(sd: child));
1199
1200 sg = *per_cpu_ptr(sdd->sg, cpu);
1201 sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
1202
1203 /* Increase refcounts for claim_allocations: */
1204 already_visited = atomic_inc_return(v: &sg->ref) > 1;
1205 /* sgc visits should follow a similar trend as sg */
1206 WARN_ON(already_visited != (atomic_inc_return(&sg->sgc->ref) > 1));
1207
1208 /* If we have already visited that group, it's already initialized. */
1209 if (already_visited)
1210 return sg;
1211
1212 if (child) {
1213 cpumask_copy(dstp: sched_group_span(sg), srcp: sched_domain_span(sd: child));
1214 cpumask_copy(dstp: group_balance_mask(sg), srcp: sched_group_span(sg));
1215 sg->flags = child->flags;
1216 } else {
1217 cpumask_set_cpu(cpu, dstp: sched_group_span(sg));
1218 cpumask_set_cpu(cpu, dstp: group_balance_mask(sg));
1219 }
1220
1221 sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(srcp: sched_group_span(sg));
1222 sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
1223 sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
1224
1225 return sg;
1226}
1227
1228/*
1229 * build_sched_groups will build a circular linked list of the groups
1230 * covered by the given span, will set each group's ->cpumask correctly,
1231 * and will initialize their ->sgc.
1232 *
1233 * Assumes the sched_domain tree is fully constructed
1234 */
1235static int
1236build_sched_groups(struct sched_domain *sd, int cpu)
1237{
1238 struct sched_group *first = NULL, *last = NULL;
1239 struct sd_data *sdd = sd->private;
1240 const struct cpumask *span = sched_domain_span(sd);
1241 struct cpumask *covered;
1242 int i;
1243
1244 lockdep_assert_held(&sched_domains_mutex);
1245 covered = sched_domains_tmpmask;
1246
1247 cpumask_clear(dstp: covered);
1248
1249 for_each_cpu_wrap(i, span, cpu) {
1250 struct sched_group *sg;
1251
1252 if (cpumask_test_cpu(cpu: i, cpumask: covered))
1253 continue;
1254
1255 sg = get_group(cpu: i, sdd);
1256
1257 cpumask_or(dstp: covered, src1p: covered, src2p: sched_group_span(sg));
1258
1259 if (!first)
1260 first = sg;
1261 if (last)
1262 last->next = sg;
1263 last = sg;
1264 }
1265 last->next = first;
1266 sd->groups = first;
1267
1268 return 0;
1269}
1270
1271/*
1272 * Initialize sched groups cpu_capacity.
1273 *
1274 * cpu_capacity indicates the capacity of sched group, which is used while
1275 * distributing the load between different sched groups in a sched domain.
1276 * Typically cpu_capacity for all the groups in a sched domain will be same
1277 * unless there are asymmetries in the topology. If there are asymmetries,
1278 * group having more cpu_capacity will pickup more load compared to the
1279 * group having less cpu_capacity.
1280 */
1281static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
1282{
1283 struct sched_group *sg = sd->groups;
1284 struct cpumask *mask = sched_domains_tmpmask2;
1285
1286 WARN_ON(!sg);
1287
1288 do {
1289 int cpu, cores = 0, max_cpu = -1;
1290
1291 sg->group_weight = cpumask_weight(srcp: sched_group_span(sg));
1292
1293 cpumask_copy(dstp: mask, srcp: sched_group_span(sg));
1294 for_each_cpu(cpu, mask) {
1295 cores++;
1296#ifdef CONFIG_SCHED_SMT
1297 cpumask_andnot(dstp: mask, src1p: mask, src2p: cpu_smt_mask(cpu));
1298#endif
1299 }
1300 sg->cores = cores;
1301
1302 if (!(sd->flags & SD_ASYM_PACKING))
1303 goto next;
1304
1305 for_each_cpu(cpu, sched_group_span(sg)) {
1306 if (max_cpu < 0)
1307 max_cpu = cpu;
1308 else if (sched_asym_prefer(a: cpu, b: max_cpu))
1309 max_cpu = cpu;
1310 }
1311 sg->asym_prefer_cpu = max_cpu;
1312
1313next:
1314 sg = sg->next;
1315 } while (sg != sd->groups);
1316
1317 if (cpu != group_balance_cpu(sg))
1318 return;
1319
1320 update_group_capacity(sd, cpu);
1321}
1322
1323/* Update the "asym_prefer_cpu" when arch_asym_cpu_priority() changes. */
1324void sched_update_asym_prefer_cpu(int cpu, int old_prio, int new_prio)
1325{
1326 int asym_prefer_cpu = cpu;
1327 struct sched_domain *sd;
1328
1329 guard(rcu)();
1330
1331 for_each_domain(cpu, sd) {
1332 struct sched_group *sg;
1333 int group_cpu;
1334
1335 if (!(sd->flags & SD_ASYM_PACKING))
1336 continue;
1337
1338 /*
1339 * Groups of overlapping domain are replicated per NUMA
1340 * node and will require updating "asym_prefer_cpu" on
1341 * each local copy.
1342 *
1343 * If you are hitting this warning, consider moving
1344 * "sg->asym_prefer_cpu" to "sg->sgc->asym_prefer_cpu"
1345 * which is shared by all the overlapping groups.
1346 */
1347 WARN_ON_ONCE(sd->flags & SD_NUMA);
1348
1349 sg = sd->groups;
1350 if (cpu != sg->asym_prefer_cpu) {
1351 /*
1352 * Since the parent is a superset of the current group,
1353 * if the cpu is not the "asym_prefer_cpu" at the
1354 * current level, it cannot be the preferred CPU at a
1355 * higher levels either.
1356 */
1357 if (!sched_asym_prefer(a: cpu, b: sg->asym_prefer_cpu))
1358 return;
1359
1360 WRITE_ONCE(sg->asym_prefer_cpu, cpu);
1361 continue;
1362 }
1363
1364 /* Ranking has improved; CPU is still the preferred one. */
1365 if (new_prio >= old_prio)
1366 continue;
1367
1368 for_each_cpu(group_cpu, sched_group_span(sg)) {
1369 if (sched_asym_prefer(a: group_cpu, b: asym_prefer_cpu))
1370 asym_prefer_cpu = group_cpu;
1371 }
1372
1373 WRITE_ONCE(sg->asym_prefer_cpu, asym_prefer_cpu);
1374 }
1375}
1376
1377/*
1378 * Set of available CPUs grouped by their corresponding capacities
1379 * Each list entry contains a CPU mask reflecting CPUs that share the same
1380 * capacity.
1381 * The lifespan of data is unlimited.
1382 */
1383LIST_HEAD(asym_cap_list);
1384
1385/*
1386 * Verify whether there is any CPU capacity asymmetry in a given sched domain.
1387 * Provides sd_flags reflecting the asymmetry scope.
1388 */
1389static inline int
1390asym_cpu_capacity_classify(const struct cpumask *sd_span,
1391 const struct cpumask *cpu_map)
1392{
1393 struct asym_cap_data *entry;
1394 int count = 0, miss = 0;
1395
1396 /*
1397 * Count how many unique CPU capacities this domain spans across
1398 * (compare sched_domain CPUs mask with ones representing available
1399 * CPUs capacities). Take into account CPUs that might be offline:
1400 * skip those.
1401 */
1402 list_for_each_entry(entry, &asym_cap_list, link) {
1403 if (cpumask_intersects(src1p: sd_span, cpu_capacity_span(entry)))
1404 ++count;
1405 else if (cpumask_intersects(src1p: cpu_map, cpu_capacity_span(entry)))
1406 ++miss;
1407 }
1408
1409 WARN_ON_ONCE(!count && !list_empty(&asym_cap_list));
1410
1411 /* No asymmetry detected */
1412 if (count < 2)
1413 return 0;
1414 /* Some of the available CPU capacity values have not been detected */
1415 if (miss)
1416 return SD_ASYM_CPUCAPACITY;
1417
1418 /* Full asymmetry */
1419 return SD_ASYM_CPUCAPACITY | SD_ASYM_CPUCAPACITY_FULL;
1420
1421}
1422
1423static void free_asym_cap_entry(struct rcu_head *head)
1424{
1425 struct asym_cap_data *entry = container_of(head, struct asym_cap_data, rcu);
1426 kfree(objp: entry);
1427}
1428
1429static inline void asym_cpu_capacity_update_data(int cpu)
1430{
1431 unsigned long capacity = arch_scale_cpu_capacity(cpu);
1432 struct asym_cap_data *insert_entry = NULL;
1433 struct asym_cap_data *entry;
1434
1435 /*
1436 * Search if capacity already exits. If not, track which the entry
1437 * where we should insert to keep the list ordered descending.
1438 */
1439 list_for_each_entry(entry, &asym_cap_list, link) {
1440 if (capacity == entry->capacity)
1441 goto done;
1442 else if (!insert_entry && capacity > entry->capacity)
1443 insert_entry = list_prev_entry(entry, link);
1444 }
1445
1446 entry = kzalloc(sizeof(*entry) + cpumask_size(), GFP_KERNEL);
1447 if (WARN_ONCE(!entry, "Failed to allocate memory for asymmetry data\n"))
1448 return;
1449 entry->capacity = capacity;
1450
1451 /* If NULL then the new capacity is the smallest, add last. */
1452 if (!insert_entry)
1453 list_add_tail_rcu(new: &entry->link, head: &asym_cap_list);
1454 else
1455 list_add_rcu(new: &entry->link, head: &insert_entry->link);
1456done:
1457 __cpumask_set_cpu(cpu, cpu_capacity_span(entry));
1458}
1459
1460/*
1461 * Build-up/update list of CPUs grouped by their capacities
1462 * An update requires explicit request to rebuild sched domains
1463 * with state indicating CPU topology changes.
1464 */
1465static void asym_cpu_capacity_scan(void)
1466{
1467 struct asym_cap_data *entry, *next;
1468 int cpu;
1469
1470 list_for_each_entry(entry, &asym_cap_list, link)
1471 cpumask_clear(cpu_capacity_span(entry));
1472
1473 for_each_cpu_and(cpu, cpu_possible_mask, housekeeping_cpumask(HK_TYPE_DOMAIN))
1474 asym_cpu_capacity_update_data(cpu);
1475
1476 list_for_each_entry_safe(entry, next, &asym_cap_list, link) {
1477 if (cpumask_empty(cpu_capacity_span(entry))) {
1478 list_del_rcu(entry: &entry->link);
1479 call_rcu(head: &entry->rcu, func: free_asym_cap_entry);
1480 }
1481 }
1482
1483 /*
1484 * Only one capacity value has been detected i.e. this system is symmetric.
1485 * No need to keep this data around.
1486 */
1487 if (list_is_singular(head: &asym_cap_list)) {
1488 entry = list_first_entry(&asym_cap_list, typeof(*entry), link);
1489 list_del_rcu(entry: &entry->link);
1490 call_rcu(head: &entry->rcu, func: free_asym_cap_entry);
1491 }
1492}
1493
1494/*
1495 * Initializers for schedule domains
1496 * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
1497 */
1498
1499static int default_relax_domain_level = -1;
1500int sched_domain_level_max;
1501
1502static int __init setup_relax_domain_level(char *str)
1503{
1504 if (kstrtoint(s: str, base: 0, res: &default_relax_domain_level))
1505 pr_warn("Unable to set relax_domain_level\n");
1506
1507 return 1;
1508}
1509__setup("relax_domain_level=", setup_relax_domain_level);
1510
1511static void set_domain_attribute(struct sched_domain *sd,
1512 struct sched_domain_attr *attr)
1513{
1514 int request;
1515
1516 if (!attr || attr->relax_domain_level < 0) {
1517 if (default_relax_domain_level < 0)
1518 return;
1519 request = default_relax_domain_level;
1520 } else
1521 request = attr->relax_domain_level;
1522
1523 if (sd->level >= request) {
1524 /* Turn off idle balance on this domain: */
1525 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
1526 }
1527}
1528
1529static void __sdt_free(const struct cpumask *cpu_map);
1530static int __sdt_alloc(const struct cpumask *cpu_map);
1531
1532static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
1533 const struct cpumask *cpu_map)
1534{
1535 switch (what) {
1536 case sa_rootdomain:
1537 if (!atomic_read(v: &d->rd->refcount))
1538 free_rootdomain(rcu: &d->rd->rcu);
1539 fallthrough;
1540 case sa_sd:
1541 free_percpu(pdata: d->sd);
1542 fallthrough;
1543 case sa_sd_storage:
1544 __sdt_free(cpu_map);
1545 fallthrough;
1546 case sa_none:
1547 break;
1548 }
1549}
1550
1551static enum s_alloc
1552__visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1553{
1554 memset(s: d, c: 0, n: sizeof(*d));
1555
1556 if (__sdt_alloc(cpu_map))
1557 return sa_sd_storage;
1558 d->sd = alloc_percpu(struct sched_domain *);
1559 if (!d->sd)
1560 return sa_sd_storage;
1561 d->rd = alloc_rootdomain();
1562 if (!d->rd)
1563 return sa_sd;
1564
1565 return sa_rootdomain;
1566}
1567
1568/*
1569 * NULL the sd_data elements we've used to build the sched_domain and
1570 * sched_group structure so that the subsequent __free_domain_allocs()
1571 * will not free the data we're using.
1572 */
1573static void claim_allocations(int cpu, struct sched_domain *sd)
1574{
1575 struct sd_data *sdd = sd->private;
1576
1577 WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1578 *per_cpu_ptr(sdd->sd, cpu) = NULL;
1579
1580 if (atomic_read(v: &(*per_cpu_ptr(sdd->sds, cpu))->ref))
1581 *per_cpu_ptr(sdd->sds, cpu) = NULL;
1582
1583 if (atomic_read(v: &(*per_cpu_ptr(sdd->sg, cpu))->ref))
1584 *per_cpu_ptr(sdd->sg, cpu) = NULL;
1585
1586 if (atomic_read(v: &(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1587 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1588}
1589
1590#ifdef CONFIG_NUMA
1591enum numa_topology_type sched_numa_topology_type;
1592
1593static int sched_domains_numa_levels;
1594
1595int sched_max_numa_distance;
1596static int *sched_domains_numa_distance;
1597static struct cpumask ***sched_domains_numa_masks;
1598#endif /* CONFIG_NUMA */
1599
1600/*
1601 * SD_flags allowed in topology descriptions.
1602 *
1603 * These flags are purely descriptive of the topology and do not prescribe
1604 * behaviour. Behaviour is artificial and mapped in the below sd_init()
1605 * function. For details, see include/linux/sched/sd_flags.h.
1606 *
1607 * SD_SHARE_CPUCAPACITY
1608 * SD_SHARE_LLC
1609 * SD_CLUSTER
1610 * SD_NUMA
1611 *
1612 * Odd one out, which beside describing the topology has a quirk also
1613 * prescribes the desired behaviour that goes along with it:
1614 *
1615 * SD_ASYM_PACKING - describes SMT quirks
1616 */
1617#define TOPOLOGY_SD_FLAGS \
1618 (SD_SHARE_CPUCAPACITY | \
1619 SD_CLUSTER | \
1620 SD_SHARE_LLC | \
1621 SD_NUMA | \
1622 SD_ASYM_PACKING)
1623
1624static struct sched_domain *
1625sd_init(struct sched_domain_topology_level *tl,
1626 const struct cpumask *cpu_map,
1627 struct sched_domain *child, int cpu)
1628{
1629 struct sd_data *sdd = &tl->data;
1630 struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1631 int sd_id, sd_weight, sd_flags = 0;
1632 struct cpumask *sd_span;
1633
1634 sd_weight = cpumask_weight(srcp: tl->mask(tl, cpu));
1635
1636 if (tl->sd_flags)
1637 sd_flags = (*tl->sd_flags)();
1638 if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1639 "wrong sd_flags in topology description\n"))
1640 sd_flags &= TOPOLOGY_SD_FLAGS;
1641
1642 *sd = (struct sched_domain){
1643 .min_interval = sd_weight,
1644 .max_interval = 2*sd_weight,
1645 .busy_factor = 16,
1646 .imbalance_pct = 117,
1647
1648 .cache_nice_tries = 0,
1649
1650 .flags = 1*SD_BALANCE_NEWIDLE
1651 | 1*SD_BALANCE_EXEC
1652 | 1*SD_BALANCE_FORK
1653 | 0*SD_BALANCE_WAKE
1654 | 1*SD_WAKE_AFFINE
1655 | 0*SD_SHARE_CPUCAPACITY
1656 | 0*SD_SHARE_LLC
1657 | 0*SD_SERIALIZE
1658 | 1*SD_PREFER_SIBLING
1659 | 0*SD_NUMA
1660 | sd_flags
1661 ,
1662
1663 .last_balance = jiffies,
1664 .balance_interval = sd_weight,
1665 .max_newidle_lb_cost = 0,
1666 .last_decay_max_lb_cost = jiffies,
1667 .child = child,
1668 .name = tl->name,
1669 };
1670
1671 sd_span = sched_domain_span(sd);
1672 cpumask_and(dstp: sd_span, src1p: cpu_map, src2p: tl->mask(tl, cpu));
1673 sd_id = cpumask_first(srcp: sd_span);
1674
1675 sd->flags |= asym_cpu_capacity_classify(sd_span, cpu_map);
1676
1677 WARN_ONCE((sd->flags & (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY)) ==
1678 (SD_SHARE_CPUCAPACITY | SD_ASYM_CPUCAPACITY),
1679 "CPU capacity asymmetry not supported on SMT\n");
1680
1681 /*
1682 * Convert topological properties into behaviour.
1683 */
1684 /* Don't attempt to spread across CPUs of different capacities. */
1685 if ((sd->flags & SD_ASYM_CPUCAPACITY) && sd->child)
1686 sd->child->flags &= ~SD_PREFER_SIBLING;
1687
1688 if (sd->flags & SD_SHARE_CPUCAPACITY) {
1689 sd->imbalance_pct = 110;
1690
1691 } else if (sd->flags & SD_SHARE_LLC) {
1692 sd->imbalance_pct = 117;
1693 sd->cache_nice_tries = 1;
1694
1695#ifdef CONFIG_NUMA
1696 } else if (sd->flags & SD_NUMA) {
1697 sd->cache_nice_tries = 2;
1698
1699 sd->flags &= ~SD_PREFER_SIBLING;
1700 sd->flags |= SD_SERIALIZE;
1701 if (sched_domains_numa_distance[tl->numa_level] > node_reclaim_distance) {
1702 sd->flags &= ~(SD_BALANCE_EXEC |
1703 SD_BALANCE_FORK |
1704 SD_WAKE_AFFINE);
1705 }
1706
1707#endif /* CONFIG_NUMA */
1708 } else {
1709 sd->cache_nice_tries = 1;
1710 }
1711
1712 /*
1713 * For all levels sharing cache; connect a sched_domain_shared
1714 * instance.
1715 */
1716 if (sd->flags & SD_SHARE_LLC) {
1717 sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1718 atomic_inc(v: &sd->shared->ref);
1719 atomic_set(v: &sd->shared->nr_busy_cpus, i: sd_weight);
1720 }
1721
1722 sd->private = sdd;
1723
1724 return sd;
1725}
1726
1727#ifdef CONFIG_SCHED_SMT
1728int cpu_smt_flags(void)
1729{
1730 return SD_SHARE_CPUCAPACITY | SD_SHARE_LLC;
1731}
1732
1733const struct cpumask *tl_smt_mask(struct sched_domain_topology_level *tl, int cpu)
1734{
1735 return cpu_smt_mask(cpu);
1736}
1737#endif
1738
1739#ifdef CONFIG_SCHED_CLUSTER
1740int cpu_cluster_flags(void)
1741{
1742 return SD_CLUSTER | SD_SHARE_LLC;
1743}
1744
1745const struct cpumask *tl_cls_mask(struct sched_domain_topology_level *tl, int cpu)
1746{
1747 return cpu_clustergroup_mask(cpu);
1748}
1749#endif
1750
1751#ifdef CONFIG_SCHED_MC
1752int cpu_core_flags(void)
1753{
1754 return SD_SHARE_LLC;
1755}
1756
1757const struct cpumask *tl_mc_mask(struct sched_domain_topology_level *tl, int cpu)
1758{
1759 return cpu_coregroup_mask(cpu);
1760}
1761#endif
1762
1763const struct cpumask *tl_pkg_mask(struct sched_domain_topology_level *tl, int cpu)
1764{
1765 return cpu_node_mask(cpu);
1766}
1767
1768/*
1769 * Topology list, bottom-up.
1770 */
1771static struct sched_domain_topology_level default_topology[] = {
1772#ifdef CONFIG_SCHED_SMT
1773 SDTL_INIT(tl_smt_mask, cpu_smt_flags, SMT),
1774#endif
1775
1776#ifdef CONFIG_SCHED_CLUSTER
1777 SDTL_INIT(tl_cls_mask, cpu_cluster_flags, CLS),
1778#endif
1779
1780#ifdef CONFIG_SCHED_MC
1781 SDTL_INIT(tl_mc_mask, cpu_core_flags, MC),
1782#endif
1783 SDTL_INIT(tl_pkg_mask, NULL, PKG),
1784 { NULL, },
1785};
1786
1787static struct sched_domain_topology_level *sched_domain_topology =
1788 default_topology;
1789static struct sched_domain_topology_level *sched_domain_topology_saved;
1790
1791#define for_each_sd_topology(tl) \
1792 for (tl = sched_domain_topology; tl->mask; tl++)
1793
1794void __init set_sched_topology(struct sched_domain_topology_level *tl)
1795{
1796 if (WARN_ON_ONCE(sched_smp_initialized))
1797 return;
1798
1799 sched_domain_topology = tl;
1800 sched_domain_topology_saved = NULL;
1801}
1802
1803#ifdef CONFIG_NUMA
1804static int cpu_numa_flags(void)
1805{
1806 return SD_NUMA;
1807}
1808
1809static const struct cpumask *sd_numa_mask(struct sched_domain_topology_level *tl, int cpu)
1810{
1811 return sched_domains_numa_masks[tl->numa_level][cpu_to_node(cpu)];
1812}
1813
1814static void sched_numa_warn(const char *str)
1815{
1816 static int done = false;
1817 int i,j;
1818
1819 if (done)
1820 return;
1821
1822 done = true;
1823
1824 printk(KERN_WARNING "ERROR: %s\n\n", str);
1825
1826 for (i = 0; i < nr_node_ids; i++) {
1827 printk(KERN_WARNING " ");
1828 for (j = 0; j < nr_node_ids; j++) {
1829 if (!node_state(node: i, state: N_CPU) || !node_state(node: j, state: N_CPU))
1830 printk(KERN_CONT "(%02d) ", node_distance(i,j));
1831 else
1832 printk(KERN_CONT " %02d ", node_distance(i,j));
1833 }
1834 printk(KERN_CONT "\n");
1835 }
1836 printk(KERN_WARNING "\n");
1837}
1838
1839bool find_numa_distance(int distance)
1840{
1841 bool found = false;
1842 int i, *distances;
1843
1844 if (distance == node_distance(0, 0))
1845 return true;
1846
1847 rcu_read_lock();
1848 distances = rcu_dereference(sched_domains_numa_distance);
1849 if (!distances)
1850 goto unlock;
1851 for (i = 0; i < sched_domains_numa_levels; i++) {
1852 if (distances[i] == distance) {
1853 found = true;
1854 break;
1855 }
1856 }
1857unlock:
1858 rcu_read_unlock();
1859
1860 return found;
1861}
1862
1863#define for_each_cpu_node_but(n, nbut) \
1864 for_each_node_state(n, N_CPU) \
1865 if (n == nbut) \
1866 continue; \
1867 else
1868
1869/*
1870 * A system can have three types of NUMA topology:
1871 * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1872 * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1873 * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1874 *
1875 * The difference between a glueless mesh topology and a backplane
1876 * topology lies in whether communication between not directly
1877 * connected nodes goes through intermediary nodes (where programs
1878 * could run), or through backplane controllers. This affects
1879 * placement of programs.
1880 *
1881 * The type of topology can be discerned with the following tests:
1882 * - If the maximum distance between any nodes is 1 hop, the system
1883 * is directly connected.
1884 * - If for two nodes A and B, located N > 1 hops away from each other,
1885 * there is an intermediary node C, which is < N hops away from both
1886 * nodes A and B, the system is a glueless mesh.
1887 */
1888static void init_numa_topology_type(int offline_node)
1889{
1890 int a, b, c, n;
1891
1892 n = sched_max_numa_distance;
1893
1894 if (sched_domains_numa_levels <= 2) {
1895 sched_numa_topology_type = NUMA_DIRECT;
1896 return;
1897 }
1898
1899 for_each_cpu_node_but(a, offline_node) {
1900 for_each_cpu_node_but(b, offline_node) {
1901 /* Find two nodes furthest removed from each other. */
1902 if (node_distance(a, b) < n)
1903 continue;
1904
1905 /* Is there an intermediary node between a and b? */
1906 for_each_cpu_node_but(c, offline_node) {
1907 if (node_distance(a, c) < n &&
1908 node_distance(b, c) < n) {
1909 sched_numa_topology_type =
1910 NUMA_GLUELESS_MESH;
1911 return;
1912 }
1913 }
1914
1915 sched_numa_topology_type = NUMA_BACKPLANE;
1916 return;
1917 }
1918 }
1919
1920 pr_err("Failed to find a NUMA topology type, defaulting to DIRECT\n");
1921 sched_numa_topology_type = NUMA_DIRECT;
1922}
1923
1924
1925#define NR_DISTANCE_VALUES (1 << DISTANCE_BITS)
1926
1927void sched_init_numa(int offline_node)
1928{
1929 struct sched_domain_topology_level *tl;
1930 unsigned long *distance_map;
1931 int nr_levels = 0;
1932 int i, j;
1933 int *distances;
1934 struct cpumask ***masks;
1935
1936 /*
1937 * O(nr_nodes^2) de-duplicating selection sort -- in order to find the
1938 * unique distances in the node_distance() table.
1939 */
1940 distance_map = bitmap_alloc(NR_DISTANCE_VALUES, GFP_KERNEL);
1941 if (!distance_map)
1942 return;
1943
1944 bitmap_zero(dst: distance_map, NR_DISTANCE_VALUES);
1945 for_each_cpu_node_but(i, offline_node) {
1946 for_each_cpu_node_but(j, offline_node) {
1947 int distance = node_distance(i, j);
1948
1949 if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) {
1950 sched_numa_warn(str: "Invalid distance value range");
1951 bitmap_free(bitmap: distance_map);
1952 return;
1953 }
1954
1955 bitmap_set(map: distance_map, start: distance, nbits: 1);
1956 }
1957 }
1958 /*
1959 * We can now figure out how many unique distance values there are and
1960 * allocate memory accordingly.
1961 */
1962 nr_levels = bitmap_weight(src: distance_map, NR_DISTANCE_VALUES);
1963
1964 distances = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
1965 if (!distances) {
1966 bitmap_free(bitmap: distance_map);
1967 return;
1968 }
1969
1970 for (i = 0, j = 0; i < nr_levels; i++, j++) {
1971 j = find_next_bit(addr: distance_map, NR_DISTANCE_VALUES, offset: j);
1972 distances[i] = j;
1973 }
1974 rcu_assign_pointer(sched_domains_numa_distance, distances);
1975
1976 bitmap_free(bitmap: distance_map);
1977
1978 /*
1979 * 'nr_levels' contains the number of unique distances
1980 *
1981 * The sched_domains_numa_distance[] array includes the actual distance
1982 * numbers.
1983 */
1984
1985 /*
1986 * Here, we should temporarily reset sched_domains_numa_levels to 0.
1987 * If it fails to allocate memory for array sched_domains_numa_masks[][],
1988 * the array will contain less then 'nr_levels' members. This could be
1989 * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1990 * in other functions.
1991 *
1992 * We reset it to 'nr_levels' at the end of this function.
1993 */
1994 sched_domains_numa_levels = 0;
1995
1996 masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
1997 if (!masks)
1998 return;
1999
2000 /*
2001 * Now for each level, construct a mask per node which contains all
2002 * CPUs of nodes that are that many hops away from us.
2003 */
2004 for (i = 0; i < nr_levels; i++) {
2005 masks[i] = kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
2006 if (!masks[i])
2007 return;
2008
2009 for_each_cpu_node_but(j, offline_node) {
2010 struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
2011 int k;
2012
2013 if (!mask)
2014 return;
2015
2016 masks[i][j] = mask;
2017
2018 for_each_cpu_node_but(k, offline_node) {
2019 if (sched_debug() && (node_distance(j, k) != node_distance(k, j)))
2020 sched_numa_warn(str: "Node-distance not symmetric");
2021
2022 if (node_distance(j, k) > sched_domains_numa_distance[i])
2023 continue;
2024
2025 cpumask_or(dstp: mask, src1p: mask, src2p: cpumask_of_node(node: k));
2026 }
2027 }
2028 }
2029 rcu_assign_pointer(sched_domains_numa_masks, masks);
2030
2031 /* Compute default topology size */
2032 for (i = 0; sched_domain_topology[i].mask; i++);
2033
2034 tl = kzalloc((i + nr_levels + 1) *
2035 sizeof(struct sched_domain_topology_level), GFP_KERNEL);
2036 if (!tl)
2037 return;
2038
2039 /*
2040 * Copy the default topology bits..
2041 */
2042 for (i = 0; sched_domain_topology[i].mask; i++)
2043 tl[i] = sched_domain_topology[i];
2044
2045 /*
2046 * Add the NUMA identity distance, aka single NODE.
2047 */
2048 tl[i++] = SDTL_INIT(sd_numa_mask, NULL, NODE);
2049
2050 /*
2051 * .. and append 'j' levels of NUMA goodness.
2052 */
2053 for (j = 1; j < nr_levels; i++, j++) {
2054 tl[i] = SDTL_INIT(sd_numa_mask, cpu_numa_flags, NUMA);
2055 tl[i].numa_level = j;
2056 }
2057
2058 sched_domain_topology_saved = sched_domain_topology;
2059 sched_domain_topology = tl;
2060
2061 sched_domains_numa_levels = nr_levels;
2062 WRITE_ONCE(sched_max_numa_distance, sched_domains_numa_distance[nr_levels - 1]);
2063
2064 init_numa_topology_type(offline_node);
2065}
2066
2067
2068static void sched_reset_numa(void)
2069{
2070 int nr_levels, *distances;
2071 struct cpumask ***masks;
2072
2073 nr_levels = sched_domains_numa_levels;
2074 sched_domains_numa_levels = 0;
2075 sched_max_numa_distance = 0;
2076 sched_numa_topology_type = NUMA_DIRECT;
2077 distances = sched_domains_numa_distance;
2078 rcu_assign_pointer(sched_domains_numa_distance, NULL);
2079 masks = sched_domains_numa_masks;
2080 rcu_assign_pointer(sched_domains_numa_masks, NULL);
2081 if (distances || masks) {
2082 int i, j;
2083
2084 synchronize_rcu();
2085 kfree(objp: distances);
2086 for (i = 0; i < nr_levels && masks; i++) {
2087 if (!masks[i])
2088 continue;
2089 for_each_node(j)
2090 kfree(objp: masks[i][j]);
2091 kfree(objp: masks[i]);
2092 }
2093 kfree(objp: masks);
2094 }
2095 if (sched_domain_topology_saved) {
2096 kfree(objp: sched_domain_topology);
2097 sched_domain_topology = sched_domain_topology_saved;
2098 sched_domain_topology_saved = NULL;
2099 }
2100}
2101
2102/*
2103 * Call with hotplug lock held
2104 */
2105void sched_update_numa(int cpu, bool online)
2106{
2107 int node;
2108
2109 node = cpu_to_node(cpu);
2110 /*
2111 * Scheduler NUMA topology is updated when the first CPU of a
2112 * node is onlined or the last CPU of a node is offlined.
2113 */
2114 if (cpumask_weight(srcp: cpumask_of_node(node)) != 1)
2115 return;
2116
2117 sched_reset_numa();
2118 sched_init_numa(offline_node: online ? NUMA_NO_NODE : node);
2119}
2120
2121void sched_domains_numa_masks_set(unsigned int cpu)
2122{
2123 int node = cpu_to_node(cpu);
2124 int i, j;
2125
2126 for (i = 0; i < sched_domains_numa_levels; i++) {
2127 for (j = 0; j < nr_node_ids; j++) {
2128 if (!node_state(node: j, state: N_CPU))
2129 continue;
2130
2131 /* Set ourselves in the remote node's masks */
2132 if (node_distance(j, node) <= sched_domains_numa_distance[i])
2133 cpumask_set_cpu(cpu, dstp: sched_domains_numa_masks[i][j]);
2134 }
2135 }
2136}
2137
2138void sched_domains_numa_masks_clear(unsigned int cpu)
2139{
2140 int i, j;
2141
2142 for (i = 0; i < sched_domains_numa_levels; i++) {
2143 for (j = 0; j < nr_node_ids; j++) {
2144 if (sched_domains_numa_masks[i][j])
2145 cpumask_clear_cpu(cpu, dstp: sched_domains_numa_masks[i][j]);
2146 }
2147 }
2148}
2149
2150/*
2151 * sched_numa_find_closest() - given the NUMA topology, find the cpu
2152 * closest to @cpu from @cpumask.
2153 * cpumask: cpumask to find a cpu from
2154 * cpu: cpu to be close to
2155 *
2156 * returns: cpu, or nr_cpu_ids when nothing found.
2157 */
2158int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
2159{
2160 int i, j = cpu_to_node(cpu), found = nr_cpu_ids;
2161 struct cpumask ***masks;
2162
2163 rcu_read_lock();
2164 masks = rcu_dereference(sched_domains_numa_masks);
2165 if (!masks)
2166 goto unlock;
2167 for (i = 0; i < sched_domains_numa_levels; i++) {
2168 if (!masks[i][j])
2169 break;
2170 cpu = cpumask_any_and_distribute(src1p: cpus, src2p: masks[i][j]);
2171 if (cpu < nr_cpu_ids) {
2172 found = cpu;
2173 break;
2174 }
2175 }
2176unlock:
2177 rcu_read_unlock();
2178
2179 return found;
2180}
2181
2182struct __cmp_key {
2183 const struct cpumask *cpus;
2184 struct cpumask ***masks;
2185 int node;
2186 int cpu;
2187 int w;
2188};
2189
2190static int hop_cmp(const void *a, const void *b)
2191{
2192 struct cpumask **prev_hop, **cur_hop = *(struct cpumask ***)b;
2193 struct __cmp_key *k = (struct __cmp_key *)a;
2194
2195 if (cpumask_weight_and(srcp1: k->cpus, srcp2: cur_hop[k->node]) <= k->cpu)
2196 return 1;
2197
2198 if (b == k->masks) {
2199 k->w = 0;
2200 return 0;
2201 }
2202
2203 prev_hop = *((struct cpumask ***)b - 1);
2204 k->w = cpumask_weight_and(srcp1: k->cpus, srcp2: prev_hop[k->node]);
2205 if (k->w <= k->cpu)
2206 return 0;
2207
2208 return -1;
2209}
2210
2211/**
2212 * sched_numa_find_nth_cpu() - given the NUMA topology, find the Nth closest CPU
2213 * from @cpus to @cpu, taking into account distance
2214 * from a given @node.
2215 * @cpus: cpumask to find a cpu from
2216 * @cpu: CPU to start searching
2217 * @node: NUMA node to order CPUs by distance
2218 *
2219 * Return: cpu, or nr_cpu_ids when nothing found.
2220 */
2221int sched_numa_find_nth_cpu(const struct cpumask *cpus, int cpu, int node)
2222{
2223 struct __cmp_key k = { .cpus = cpus, .cpu = cpu };
2224 struct cpumask ***hop_masks;
2225 int hop, ret = nr_cpu_ids;
2226
2227 if (node == NUMA_NO_NODE)
2228 return cpumask_nth_and(cpu, srcp1: cpus, cpu_online_mask);
2229
2230 rcu_read_lock();
2231
2232 /* CPU-less node entries are uninitialized in sched_domains_numa_masks */
2233 node = numa_nearest_node(node, state: N_CPU);
2234 k.node = node;
2235
2236 k.masks = rcu_dereference(sched_domains_numa_masks);
2237 if (!k.masks)
2238 goto unlock;
2239
2240 hop_masks = bsearch(key: &k, base: k.masks, num: sched_domains_numa_levels, size: sizeof(k.masks[0]), cmp: hop_cmp);
2241 if (!hop_masks)
2242 goto unlock;
2243 hop = hop_masks - k.masks;
2244
2245 ret = hop ?
2246 cpumask_nth_and_andnot(cpu: cpu - k.w, srcp1: cpus, srcp2: k.masks[hop][node], srcp3: k.masks[hop-1][node]) :
2247 cpumask_nth_and(cpu, srcp1: cpus, srcp2: k.masks[0][node]);
2248unlock:
2249 rcu_read_unlock();
2250 return ret;
2251}
2252EXPORT_SYMBOL_GPL(sched_numa_find_nth_cpu);
2253
2254/**
2255 * sched_numa_hop_mask() - Get the cpumask of CPUs at most @hops hops away from
2256 * @node
2257 * @node: The node to count hops from.
2258 * @hops: Include CPUs up to that many hops away. 0 means local node.
2259 *
2260 * Return: On success, a pointer to a cpumask of CPUs at most @hops away from
2261 * @node, an error value otherwise.
2262 *
2263 * Requires rcu_lock to be held. Returned cpumask is only valid within that
2264 * read-side section, copy it if required beyond that.
2265 *
2266 * Note that not all hops are equal in distance; see sched_init_numa() for how
2267 * distances and masks are handled.
2268 * Also note that this is a reflection of sched_domains_numa_masks, which may change
2269 * during the lifetime of the system (offline nodes are taken out of the masks).
2270 */
2271const struct cpumask *sched_numa_hop_mask(unsigned int node, unsigned int hops)
2272{
2273 struct cpumask ***masks;
2274
2275 if (node >= nr_node_ids || hops >= sched_domains_numa_levels)
2276 return ERR_PTR(error: -EINVAL);
2277
2278 masks = rcu_dereference(sched_domains_numa_masks);
2279 if (!masks)
2280 return ERR_PTR(error: -EBUSY);
2281
2282 return masks[hops][node];
2283}
2284EXPORT_SYMBOL_GPL(sched_numa_hop_mask);
2285
2286#endif /* CONFIG_NUMA */
2287
2288static int __sdt_alloc(const struct cpumask *cpu_map)
2289{
2290 struct sched_domain_topology_level *tl;
2291 int j;
2292
2293 for_each_sd_topology(tl) {
2294 struct sd_data *sdd = &tl->data;
2295
2296 sdd->sd = alloc_percpu(struct sched_domain *);
2297 if (!sdd->sd)
2298 return -ENOMEM;
2299
2300 sdd->sds = alloc_percpu(struct sched_domain_shared *);
2301 if (!sdd->sds)
2302 return -ENOMEM;
2303
2304 sdd->sg = alloc_percpu(struct sched_group *);
2305 if (!sdd->sg)
2306 return -ENOMEM;
2307
2308 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
2309 if (!sdd->sgc)
2310 return -ENOMEM;
2311
2312 for_each_cpu(j, cpu_map) {
2313 struct sched_domain *sd;
2314 struct sched_domain_shared *sds;
2315 struct sched_group *sg;
2316 struct sched_group_capacity *sgc;
2317
2318 sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
2319 GFP_KERNEL, cpu_to_node(j));
2320 if (!sd)
2321 return -ENOMEM;
2322
2323 *per_cpu_ptr(sdd->sd, j) = sd;
2324
2325 sds = kzalloc_node(sizeof(struct sched_domain_shared),
2326 GFP_KERNEL, cpu_to_node(j));
2327 if (!sds)
2328 return -ENOMEM;
2329
2330 *per_cpu_ptr(sdd->sds, j) = sds;
2331
2332 sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
2333 GFP_KERNEL, cpu_to_node(j));
2334 if (!sg)
2335 return -ENOMEM;
2336
2337 sg->next = sg;
2338
2339 *per_cpu_ptr(sdd->sg, j) = sg;
2340
2341 sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
2342 GFP_KERNEL, cpu_to_node(j));
2343 if (!sgc)
2344 return -ENOMEM;
2345
2346 sgc->id = j;
2347
2348 *per_cpu_ptr(sdd->sgc, j) = sgc;
2349 }
2350 }
2351
2352 return 0;
2353}
2354
2355static void __sdt_free(const struct cpumask *cpu_map)
2356{
2357 struct sched_domain_topology_level *tl;
2358 int j;
2359
2360 for_each_sd_topology(tl) {
2361 struct sd_data *sdd = &tl->data;
2362
2363 for_each_cpu(j, cpu_map) {
2364 struct sched_domain *sd;
2365
2366 if (sdd->sd) {
2367 sd = *per_cpu_ptr(sdd->sd, j);
2368 if (sd && (sd->flags & SD_NUMA))
2369 free_sched_groups(sg: sd->groups, free_sgc: 0);
2370 kfree(objp: *per_cpu_ptr(sdd->sd, j));
2371 }
2372
2373 if (sdd->sds)
2374 kfree(objp: *per_cpu_ptr(sdd->sds, j));
2375 if (sdd->sg)
2376 kfree(objp: *per_cpu_ptr(sdd->sg, j));
2377 if (sdd->sgc)
2378 kfree(objp: *per_cpu_ptr(sdd->sgc, j));
2379 }
2380 free_percpu(pdata: sdd->sd);
2381 sdd->sd = NULL;
2382 free_percpu(pdata: sdd->sds);
2383 sdd->sds = NULL;
2384 free_percpu(pdata: sdd->sg);
2385 sdd->sg = NULL;
2386 free_percpu(pdata: sdd->sgc);
2387 sdd->sgc = NULL;
2388 }
2389}
2390
2391static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
2392 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
2393 struct sched_domain *child, int cpu)
2394{
2395 struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
2396
2397 if (child) {
2398 sd->level = child->level + 1;
2399 sched_domain_level_max = max(sched_domain_level_max, sd->level);
2400 child->parent = sd;
2401
2402 if (!cpumask_subset(src1p: sched_domain_span(sd: child),
2403 src2p: sched_domain_span(sd))) {
2404 pr_err("BUG: arch topology borken\n");
2405 pr_err(" the %s domain not a subset of the %s domain\n",
2406 child->name, sd->name);
2407 /* Fixup, ensure @sd has at least @child CPUs. */
2408 cpumask_or(dstp: sched_domain_span(sd),
2409 src1p: sched_domain_span(sd),
2410 src2p: sched_domain_span(sd: child));
2411 }
2412
2413 }
2414 set_domain_attribute(sd, attr);
2415
2416 return sd;
2417}
2418
2419/*
2420 * Ensure topology masks are sane, i.e. there are no conflicts (overlaps) for
2421 * any two given CPUs on non-NUMA topology levels.
2422 */
2423static bool topology_span_sane(const struct cpumask *cpu_map)
2424{
2425 struct sched_domain_topology_level *tl;
2426 struct cpumask *covered, *id_seen;
2427 int cpu;
2428
2429 lockdep_assert_held(&sched_domains_mutex);
2430 covered = sched_domains_tmpmask;
2431 id_seen = sched_domains_tmpmask2;
2432
2433 for_each_sd_topology(tl) {
2434 int tl_common_flags = 0;
2435
2436 if (tl->sd_flags)
2437 tl_common_flags = (*tl->sd_flags)();
2438
2439 /* NUMA levels are allowed to overlap */
2440 if (tl_common_flags & SD_NUMA)
2441 continue;
2442
2443 cpumask_clear(dstp: covered);
2444 cpumask_clear(dstp: id_seen);
2445
2446 /*
2447 * Non-NUMA levels cannot partially overlap - they must be either
2448 * completely equal or completely disjoint. Otherwise we can end up
2449 * breaking the sched_group lists - i.e. a later get_group() pass
2450 * breaks the linking done for an earlier span.
2451 */
2452 for_each_cpu(cpu, cpu_map) {
2453 const struct cpumask *tl_cpu_mask = tl->mask(tl, cpu);
2454 int id;
2455
2456 /* lowest bit set in this mask is used as a unique id */
2457 id = cpumask_first(srcp: tl_cpu_mask);
2458
2459 if (cpumask_test_cpu(cpu: id, cpumask: id_seen)) {
2460 /* First CPU has already been seen, ensure identical spans */
2461 if (!cpumask_equal(src1p: tl->mask(tl, id), src2p: tl_cpu_mask))
2462 return false;
2463 } else {
2464 /* First CPU hasn't been seen before, ensure it's a completely new span */
2465 if (cpumask_intersects(src1p: tl_cpu_mask, src2p: covered))
2466 return false;
2467
2468 cpumask_or(dstp: covered, src1p: covered, src2p: tl_cpu_mask);
2469 cpumask_set_cpu(cpu: id, dstp: id_seen);
2470 }
2471 }
2472 }
2473 return true;
2474}
2475
2476/*
2477 * Build sched domains for a given set of CPUs and attach the sched domains
2478 * to the individual CPUs
2479 */
2480static int
2481build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
2482{
2483 enum s_alloc alloc_state = sa_none;
2484 struct sched_domain *sd;
2485 struct s_data d;
2486 struct rq *rq = NULL;
2487 int i, ret = -ENOMEM;
2488 bool has_asym = false;
2489 bool has_cluster = false;
2490
2491 if (WARN_ON(cpumask_empty(cpu_map)))
2492 goto error;
2493
2494 alloc_state = __visit_domain_allocation_hell(d: &d, cpu_map);
2495 if (alloc_state != sa_rootdomain)
2496 goto error;
2497
2498 /* Set up domains for CPUs specified by the cpu_map: */
2499 for_each_cpu(i, cpu_map) {
2500 struct sched_domain_topology_level *tl;
2501
2502 sd = NULL;
2503 for_each_sd_topology(tl) {
2504
2505 sd = build_sched_domain(tl, cpu_map, attr, child: sd, cpu: i);
2506
2507 has_asym |= sd->flags & SD_ASYM_CPUCAPACITY;
2508
2509 if (tl == sched_domain_topology)
2510 *per_cpu_ptr(d.sd, i) = sd;
2511 if (cpumask_equal(src1p: cpu_map, src2p: sched_domain_span(sd)))
2512 break;
2513 }
2514 }
2515
2516 if (WARN_ON(!topology_span_sane(cpu_map)))
2517 goto error;
2518
2519 /* Build the groups for the domains */
2520 for_each_cpu(i, cpu_map) {
2521 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2522 sd->span_weight = cpumask_weight(srcp: sched_domain_span(sd));
2523 if (sd->flags & SD_NUMA) {
2524 if (build_overlap_sched_groups(sd, cpu: i))
2525 goto error;
2526 } else {
2527 if (build_sched_groups(sd, cpu: i))
2528 goto error;
2529 }
2530 }
2531 }
2532
2533 /*
2534 * Calculate an allowed NUMA imbalance such that LLCs do not get
2535 * imbalanced.
2536 */
2537 for_each_cpu(i, cpu_map) {
2538 unsigned int imb = 0;
2539 unsigned int imb_span = 1;
2540
2541 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2542 struct sched_domain *child = sd->child;
2543
2544 if (!(sd->flags & SD_SHARE_LLC) && child &&
2545 (child->flags & SD_SHARE_LLC)) {
2546 struct sched_domain __rcu *top_p;
2547 unsigned int nr_llcs;
2548
2549 /*
2550 * For a single LLC per node, allow an
2551 * imbalance up to 12.5% of the node. This is
2552 * arbitrary cutoff based two factors -- SMT and
2553 * memory channels. For SMT-2, the intent is to
2554 * avoid premature sharing of HT resources but
2555 * SMT-4 or SMT-8 *may* benefit from a different
2556 * cutoff. For memory channels, this is a very
2557 * rough estimate of how many channels may be
2558 * active and is based on recent CPUs with
2559 * many cores.
2560 *
2561 * For multiple LLCs, allow an imbalance
2562 * until multiple tasks would share an LLC
2563 * on one node while LLCs on another node
2564 * remain idle. This assumes that there are
2565 * enough logical CPUs per LLC to avoid SMT
2566 * factors and that there is a correlation
2567 * between LLCs and memory channels.
2568 */
2569 nr_llcs = sd->span_weight / child->span_weight;
2570 if (nr_llcs == 1)
2571 imb = sd->span_weight >> 3;
2572 else
2573 imb = nr_llcs;
2574 imb = max(1U, imb);
2575 sd->imb_numa_nr = imb;
2576
2577 /* Set span based on the first NUMA domain. */
2578 top_p = sd->parent;
2579 while (top_p && !(top_p->flags & SD_NUMA)) {
2580 top_p = top_p->parent;
2581 }
2582 imb_span = top_p ? top_p->span_weight : sd->span_weight;
2583 } else {
2584 int factor = max(1U, (sd->span_weight / imb_span));
2585
2586 sd->imb_numa_nr = imb * factor;
2587 }
2588 }
2589 }
2590
2591 /* Calculate CPU capacity for physical packages and nodes */
2592 for (i = nr_cpumask_bits-1; i >= 0; i--) {
2593 if (!cpumask_test_cpu(cpu: i, cpumask: cpu_map))
2594 continue;
2595
2596 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
2597 claim_allocations(cpu: i, sd);
2598 init_sched_groups_capacity(cpu: i, sd);
2599 }
2600 }
2601
2602 /* Attach the domains */
2603 rcu_read_lock();
2604 for_each_cpu(i, cpu_map) {
2605 rq = cpu_rq(i);
2606 sd = *per_cpu_ptr(d.sd, i);
2607
2608 cpu_attach_domain(sd, rd: d.rd, cpu: i);
2609
2610 if (lowest_flag_domain(cpu: i, flag: SD_CLUSTER))
2611 has_cluster = true;
2612 }
2613 rcu_read_unlock();
2614
2615 if (has_asym)
2616 static_branch_inc_cpuslocked(&sched_asym_cpucapacity);
2617
2618 if (has_cluster)
2619 static_branch_inc_cpuslocked(&sched_cluster_active);
2620
2621 if (rq && sched_debug_verbose)
2622 pr_info("root domain span: %*pbl\n", cpumask_pr_args(cpu_map));
2623
2624 ret = 0;
2625error:
2626 __free_domain_allocs(d: &d, what: alloc_state, cpu_map);
2627
2628 return ret;
2629}
2630
2631/* Current sched domains: */
2632static cpumask_var_t *doms_cur;
2633
2634/* Number of sched domains in 'doms_cur': */
2635static int ndoms_cur;
2636
2637/* Attributes of custom domains in 'doms_cur' */
2638static struct sched_domain_attr *dattr_cur;
2639
2640/*
2641 * Special case: If a kmalloc() of a doms_cur partition (array of
2642 * cpumask) fails, then fallback to a single sched domain,
2643 * as determined by the single cpumask fallback_doms.
2644 */
2645static cpumask_var_t fallback_doms;
2646
2647/*
2648 * arch_update_cpu_topology lets virtualized architectures update the
2649 * CPU core maps. It is supposed to return 1 if the topology changed
2650 * or 0 if it stayed the same.
2651 */
2652int __weak arch_update_cpu_topology(void)
2653{
2654 return 0;
2655}
2656
2657cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
2658{
2659 int i;
2660 cpumask_var_t *doms;
2661
2662 doms = kmalloc_array(ndoms, sizeof(*doms), GFP_KERNEL);
2663 if (!doms)
2664 return NULL;
2665 for (i = 0; i < ndoms; i++) {
2666 if (!alloc_cpumask_var(mask: &doms[i], GFP_KERNEL)) {
2667 free_sched_domains(doms, ndoms: i);
2668 return NULL;
2669 }
2670 }
2671 return doms;
2672}
2673
2674void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
2675{
2676 unsigned int i;
2677 for (i = 0; i < ndoms; i++)
2678 free_cpumask_var(mask: doms[i]);
2679 kfree(objp: doms);
2680}
2681
2682/*
2683 * Set up scheduler domains and groups. For now this just excludes isolated
2684 * CPUs, but could be used to exclude other special cases in the future.
2685 */
2686int __init sched_init_domains(const struct cpumask *cpu_map)
2687{
2688 int err;
2689
2690 zalloc_cpumask_var(mask: &sched_domains_tmpmask, GFP_KERNEL);
2691 zalloc_cpumask_var(mask: &sched_domains_tmpmask2, GFP_KERNEL);
2692 zalloc_cpumask_var(mask: &fallback_doms, GFP_KERNEL);
2693
2694 arch_update_cpu_topology();
2695 asym_cpu_capacity_scan();
2696 ndoms_cur = 1;
2697 doms_cur = alloc_sched_domains(ndoms: ndoms_cur);
2698 if (!doms_cur)
2699 doms_cur = &fallback_doms;
2700 cpumask_and(dstp: doms_cur[0], src1p: cpu_map, src2p: housekeeping_cpumask(type: HK_TYPE_DOMAIN));
2701 err = build_sched_domains(cpu_map: doms_cur[0], NULL);
2702
2703 return err;
2704}
2705
2706/*
2707 * Detach sched domains from a group of CPUs specified in cpu_map
2708 * These CPUs will now be attached to the NULL domain
2709 */
2710static void detach_destroy_domains(const struct cpumask *cpu_map)
2711{
2712 unsigned int cpu = cpumask_any(cpu_map);
2713 int i;
2714
2715 if (rcu_access_pointer(per_cpu(sd_asym_cpucapacity, cpu)))
2716 static_branch_dec_cpuslocked(&sched_asym_cpucapacity);
2717
2718 if (static_branch_unlikely(&sched_cluster_active))
2719 static_branch_dec_cpuslocked(&sched_cluster_active);
2720
2721 rcu_read_lock();
2722 for_each_cpu(i, cpu_map)
2723 cpu_attach_domain(NULL, rd: &def_root_domain, cpu: i);
2724 rcu_read_unlock();
2725}
2726
2727/* handle null as "default" */
2728static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
2729 struct sched_domain_attr *new, int idx_new)
2730{
2731 struct sched_domain_attr tmp;
2732
2733 /* Fast path: */
2734 if (!new && !cur)
2735 return 1;
2736
2737 tmp = SD_ATTR_INIT;
2738
2739 return !memcmp(cur ? (cur + idx_cur) : &tmp,
2740 new ? (new + idx_new) : &tmp,
2741 sizeof(struct sched_domain_attr));
2742}
2743
2744/*
2745 * Partition sched domains as specified by the 'ndoms_new'
2746 * cpumasks in the array doms_new[] of cpumasks. This compares
2747 * doms_new[] to the current sched domain partitioning, doms_cur[].
2748 * It destroys each deleted domain and builds each new domain.
2749 *
2750 * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
2751 * The masks don't intersect (don't overlap.) We should setup one
2752 * sched domain for each mask. CPUs not in any of the cpumasks will
2753 * not be load balanced. If the same cpumask appears both in the
2754 * current 'doms_cur' domains and in the new 'doms_new', we can leave
2755 * it as it is.
2756 *
2757 * The passed in 'doms_new' should be allocated using
2758 * alloc_sched_domains. This routine takes ownership of it and will
2759 * free_sched_domains it when done with it. If the caller failed the
2760 * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
2761 * and partition_sched_domains() will fallback to the single partition
2762 * 'fallback_doms', it also forces the domains to be rebuilt.
2763 *
2764 * If doms_new == NULL it will be replaced with cpu_online_mask.
2765 * ndoms_new == 0 is a special case for destroying existing domains,
2766 * and it will not create the default domain.
2767 *
2768 * Call with hotplug lock and sched_domains_mutex held
2769 */
2770static void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
2771 struct sched_domain_attr *dattr_new)
2772{
2773 bool __maybe_unused has_eas = false;
2774 int i, j, n;
2775 int new_topology;
2776
2777 lockdep_assert_held(&sched_domains_mutex);
2778
2779 /* Let the architecture update CPU core mappings: */
2780 new_topology = arch_update_cpu_topology();
2781 /* Trigger rebuilding CPU capacity asymmetry data */
2782 if (new_topology)
2783 asym_cpu_capacity_scan();
2784
2785 if (!doms_new) {
2786 WARN_ON_ONCE(dattr_new);
2787 n = 0;
2788 doms_new = alloc_sched_domains(ndoms: 1);
2789 if (doms_new) {
2790 n = 1;
2791 cpumask_and(dstp: doms_new[0], cpu_active_mask,
2792 src2p: housekeeping_cpumask(type: HK_TYPE_DOMAIN));
2793 }
2794 } else {
2795 n = ndoms_new;
2796 }
2797
2798 /* Destroy deleted domains: */
2799 for (i = 0; i < ndoms_cur; i++) {
2800 for (j = 0; j < n && !new_topology; j++) {
2801 if (cpumask_equal(src1p: doms_cur[i], src2p: doms_new[j]) &&
2802 dattrs_equal(cur: dattr_cur, idx_cur: i, new: dattr_new, idx_new: j))
2803 goto match1;
2804 }
2805 /* No match - a current sched domain not in new doms_new[] */
2806 detach_destroy_domains(cpu_map: doms_cur[i]);
2807match1:
2808 ;
2809 }
2810
2811 n = ndoms_cur;
2812 if (!doms_new) {
2813 n = 0;
2814 doms_new = &fallback_doms;
2815 cpumask_and(dstp: doms_new[0], cpu_active_mask,
2816 src2p: housekeeping_cpumask(type: HK_TYPE_DOMAIN));
2817 }
2818
2819 /* Build new domains: */
2820 for (i = 0; i < ndoms_new; i++) {
2821 for (j = 0; j < n && !new_topology; j++) {
2822 if (cpumask_equal(src1p: doms_new[i], src2p: doms_cur[j]) &&
2823 dattrs_equal(cur: dattr_new, idx_cur: i, new: dattr_cur, idx_new: j))
2824 goto match2;
2825 }
2826 /* No match - add a new doms_new */
2827 build_sched_domains(cpu_map: doms_new[i], attr: dattr_new ? dattr_new + i : NULL);
2828match2:
2829 ;
2830 }
2831
2832#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
2833 /* Build perf domains: */
2834 for (i = 0; i < ndoms_new; i++) {
2835 for (j = 0; j < n && !sched_energy_update; j++) {
2836 if (cpumask_equal(doms_new[i], doms_cur[j]) &&
2837 cpu_rq(cpumask_first(doms_cur[j]))->rd->pd) {
2838 has_eas = true;
2839 goto match3;
2840 }
2841 }
2842 /* No match - add perf domains for a new rd */
2843 has_eas |= build_perf_domains(doms_new[i]);
2844match3:
2845 ;
2846 }
2847 sched_energy_set(has_eas);
2848#endif
2849
2850 /* Remember the new sched domains: */
2851 if (doms_cur != &fallback_doms)
2852 free_sched_domains(doms: doms_cur, ndoms: ndoms_cur);
2853
2854 kfree(objp: dattr_cur);
2855 doms_cur = doms_new;
2856 dattr_cur = dattr_new;
2857 ndoms_cur = ndoms_new;
2858
2859 update_sched_domain_debugfs();
2860 dl_rebuild_rd_accounting();
2861}
2862
2863/*
2864 * Call with hotplug lock held
2865 */
2866void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
2867 struct sched_domain_attr *dattr_new)
2868{
2869 sched_domains_mutex_lock();
2870 partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
2871 sched_domains_mutex_unlock();
2872}
2873