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