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