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