xref: /dflybsd-src/sys/kern/subr_cpu_topology.c (revision 653318caa8600d01ee0a9c8acfef377de5ea5e99)
1 /*
2  * Copyright (c) 2012 The DragonFly Project.  All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in
12  *    the documentation and/or other materials provided with the
13  *    distribution.
14  * 3. Neither the name of The DragonFly Project nor the names of its
15  *    contributors may be used to endorse or promote products derived
16  *    from this software without specific, prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
21  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
22  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
23  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
24  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
26  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
27  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
28  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  */
32 
33 #include <sys/param.h>
34 #include <sys/systm.h>
35 #include <sys/kernel.h>
36 #include <sys/sysctl.h>
37 #include <sys/sbuf.h>
38 #include <sys/cpu_topology.h>
39 
40 #include <machine/smp.h>
41 
42 #ifndef NAPICID
43 #define NAPICID 256
44 #endif
45 
46 #define INDENT_BUF_SIZE LEVEL_NO*3
47 #define INVALID_ID -1
48 
49 /* Per-cpu sysctl nodes and info */
50 struct per_cpu_sysctl_info {
51 	struct sysctl_ctx_list sysctl_ctx;
52 	struct sysctl_oid *sysctl_tree;
53 	char cpu_name[32];
54 	int physical_id;
55 	int core_id;
56 	char physical_siblings[8*MAXCPU];
57 	char core_siblings[8*MAXCPU];
58 };
59 typedef struct per_cpu_sysctl_info per_cpu_sysctl_info_t;
60 
61 static cpu_node_t cpu_topology_nodes[MAXCPU];	/* Memory for topology */
62 static cpu_node_t *cpu_root_node;		/* Root node pointer */
63 
64 static struct sysctl_ctx_list cpu_topology_sysctl_ctx;
65 static struct sysctl_oid *cpu_topology_sysctl_tree;
66 static char cpu_topology_members[8*MAXCPU];
67 static per_cpu_sysctl_info_t pcpu_sysctl[MAXCPU];
68 
69 int cpu_topology_levels_number = 1;
70 cpu_node_t *root_cpu_node;
71 
72 /* Get the next valid apicid starting
73  * from current apicid (curr_apicid
74  */
75 static int
76 get_next_valid_apicid(int curr_apicid)
77 {
78 	int next_apicid = curr_apicid;
79 	do {
80 		next_apicid++;
81 	}
82 	while(get_cpuid_from_apicid(next_apicid) == -1 &&
83 	   next_apicid < NAPICID);
84 	if (next_apicid == NAPICID) {
85 		kprintf("Warning: No next valid APICID found. Returning -1\n");
86 		return -1;
87 	}
88 	return next_apicid;
89 }
90 
91 /* Generic topology tree. The parameters have the following meaning:
92  * - children_no_per_level : the number of children on each level
93  * - level_types : the type of the level (THREAD, CORE, CHIP, etc)
94  * - cur_level : the current level of the tree
95  * - node : the current node
96  * - last_free_node : the last free node in the global array.
97  * - cpuid : basicly this are the ids of the leafs
98  */
99 static void
100 build_topology_tree(int *children_no_per_level,
101    uint8_t *level_types,
102    int cur_level,
103    cpu_node_t *node,
104    cpu_node_t **last_free_node,
105    int *apicid)
106 {
107 	int i;
108 
109 	node->child_no = children_no_per_level[cur_level];
110 	node->type = level_types[cur_level];
111 	node->members = 0;
112 	node->compute_unit_id = -1;
113 
114 	if (node->child_no == 0) {
115 		*apicid = get_next_valid_apicid(*apicid);
116 		node->members = CPUMASK(get_cpuid_from_apicid(*apicid));
117 		return;
118 	}
119 
120 	if (node->parent_node == NULL)
121 		root_cpu_node = node;
122 
123 	for (i = 0; i < node->child_no; i++) {
124 		node->child_node[i] = *last_free_node;
125 		(*last_free_node)++;
126 
127 		node->child_node[i]->parent_node = node;
128 
129 		build_topology_tree(children_no_per_level,
130 		    level_types,
131 		    cur_level + 1,
132 		    node->child_node[i],
133 		    last_free_node,
134 		    apicid);
135 
136 		node->members |= node->child_node[i]->members;
137 	}
138 }
139 
140 #if defined(__x86_64__) && !defined(_KERNEL_VIRTUAL)
141 static void
142 migrate_elements(cpu_node_t **a, int n, int pos)
143 {
144 	int i;
145 
146 	for (i = pos; i < n - 1 ; i++) {
147 		a[i] = a[i+1];
148 	}
149 	a[i] = NULL;
150 }
151 #endif
152 
153 /* Build CPU topology. The detection is made by comparing the
154  * chip, core and logical IDs of each CPU with the IDs of the
155  * BSP. When we found a match, at that level the CPUs are siblings.
156  */
157 static void
158 build_cpu_topology(void)
159 {
160 	detect_cpu_topology();
161 	int i;
162 	int BSPID = 0;
163 	int threads_per_core = 0;
164 	int cores_per_chip = 0;
165 	int chips_per_package = 0;
166 	int children_no_per_level[LEVEL_NO];
167 	uint8_t level_types[LEVEL_NO];
168 	int apicid = -1;
169 
170 	cpu_node_t *root = &cpu_topology_nodes[0];
171 	cpu_node_t *last_free_node = root + 1;
172 
173 	/* Assume that the topology is uniform.
174 	 * Find the number of siblings within chip
175 	 * and witin core to build up the topology
176 	 */
177 	for (i = 0; i < ncpus; i++) {
178 
179 		cpumask_t mask = CPUMASK(i);
180 
181 		if ((mask & smp_active_mask) == 0)
182 			continue;
183 
184 		if (get_chip_ID(BSPID) == get_chip_ID(i))
185 			cores_per_chip++;
186 		else
187 			continue;
188 
189 		if (get_core_number_within_chip(BSPID) ==
190 		    get_core_number_within_chip(i))
191 			threads_per_core++;
192 	}
193 
194 	cores_per_chip /= threads_per_core;
195 	chips_per_package = ncpus / (cores_per_chip * threads_per_core);
196 
197 	if (bootverbose)
198 		kprintf("CPU Topology: cores_per_chip: %d; threads_per_core: %d; chips_per_package: %d;\n",
199 		    cores_per_chip, threads_per_core, chips_per_package);
200 
201 	if (threads_per_core > 1) { /* HT available - 4 levels */
202 
203 		children_no_per_level[0] = chips_per_package;
204 		children_no_per_level[1] = cores_per_chip;
205 		children_no_per_level[2] = threads_per_core;
206 		children_no_per_level[3] = 0;
207 
208 		level_types[0] = PACKAGE_LEVEL;
209 		level_types[1] = CHIP_LEVEL;
210 		level_types[2] = CORE_LEVEL;
211 		level_types[3] = THREAD_LEVEL;
212 
213 		build_topology_tree(children_no_per_level,
214 		    level_types,
215 		    0,
216 		    root,
217 		    &last_free_node,
218 		    &apicid);
219 
220 		cpu_topology_levels_number = 4;
221 
222 	} else if (cores_per_chip > 1) { /* No HT available - 3 levels */
223 
224 		children_no_per_level[0] = chips_per_package;
225 		children_no_per_level[1] = cores_per_chip;
226 		children_no_per_level[2] = 0;
227 
228 		level_types[0] = PACKAGE_LEVEL;
229 		level_types[1] = CHIP_LEVEL;
230 		level_types[2] = CORE_LEVEL;
231 
232 		build_topology_tree(children_no_per_level,
233 		    level_types,
234 		    0,
235 		    root,
236 		    &last_free_node,
237 		    &apicid);
238 
239 		cpu_topology_levels_number = 3;
240 
241 	} else { /* No HT and no Multi-Core - 2 levels */
242 
243 		children_no_per_level[0] = chips_per_package;
244 		children_no_per_level[1] = 0;
245 
246 		level_types[0] = PACKAGE_LEVEL;
247 		level_types[1] = CHIP_LEVEL;
248 
249 		build_topology_tree(children_no_per_level,
250 		    level_types,
251 		    0,
252 		    root,
253 		    &last_free_node,
254 		    &apicid);
255 
256 		cpu_topology_levels_number = 2;
257 
258 	}
259 
260 	cpu_root_node = root;
261 
262 
263 #if defined(__x86_64__) && !defined(_KERNEL_VIRTUAL)
264 	if (fix_amd_topology() == 0) {
265 		int visited[MAXCPU], i, j, pos, cpuid;
266 		cpu_node_t *leaf, *parent;
267 
268 		bzero(visited, MAXCPU * sizeof(int));
269 
270 		for (i = 0; i < ncpus; i++) {
271 			if (visited[i] == 0) {
272 				pos = 0;
273 				visited[i] = 1;
274 				leaf = get_cpu_node_by_cpuid(i);
275 
276 				if (leaf->type == CORE_LEVEL) {
277 					parent = leaf->parent_node;
278 
279 					last_free_node->child_node[0] = leaf;
280 					last_free_node->child_no = 1;
281 					last_free_node->members = leaf->members;
282 					last_free_node->compute_unit_id = leaf->compute_unit_id;
283 					last_free_node->parent_node = parent;
284 					last_free_node->type = CORE_LEVEL;
285 
286 
287 					for (j = 0; j < parent->child_no; j++) {
288 						if (parent->child_node[j] != leaf) {
289 
290 							cpuid = BSFCPUMASK(parent->child_node[j]->members);
291 							if (visited[cpuid] == 0 &&
292 							    parent->child_node[j]->compute_unit_id == leaf->compute_unit_id) {
293 
294 								last_free_node->child_node[last_free_node->child_no] = parent->child_node[j];
295 								last_free_node->child_no++;
296 								last_free_node->members |= parent->child_node[j]->members;
297 
298 								parent->child_node[j]->type = THREAD_LEVEL;
299 								parent->child_node[j]->parent_node = last_free_node;
300 								visited[cpuid] = 1;
301 
302 								migrate_elements(parent->child_node, parent->child_no, j);
303 								parent->child_no--;
304 								j--;
305 							}
306 						} else {
307 							pos = j;
308 						}
309 					}
310 					if (last_free_node->child_no > 1) {
311 						parent->child_node[pos] = last_free_node;
312 						leaf->type = THREAD_LEVEL;
313 						leaf->parent_node = last_free_node;
314 						last_free_node++;
315 					}
316 				}
317 			}
318 		}
319 	}
320 #endif
321 }
322 
323 /* Recursive function helper to print the CPU topology tree */
324 static void
325 print_cpu_topology_tree_sysctl_helper(cpu_node_t *node,
326     struct sbuf *sb,
327     char * buf,
328     int buf_len,
329     int last)
330 {
331 	int i;
332 	int bsr_member;
333 
334 	sbuf_bcat(sb, buf, buf_len);
335 	if (last) {
336 		sbuf_printf(sb, "\\-");
337 		buf[buf_len] = ' ';buf_len++;
338 		buf[buf_len] = ' ';buf_len++;
339 	} else {
340 		sbuf_printf(sb, "|-");
341 		buf[buf_len] = '|';buf_len++;
342 		buf[buf_len] = ' ';buf_len++;
343 	}
344 
345 	bsr_member = BSRCPUMASK(node->members);
346 
347 	if (node->type == PACKAGE_LEVEL) {
348 		sbuf_printf(sb,"PACKAGE MEMBERS: ");
349 	} else if (node->type == CHIP_LEVEL) {
350 		sbuf_printf(sb,"CHIP ID %d: ",
351 			get_chip_ID(bsr_member));
352 	} else if (node->type == CORE_LEVEL) {
353 		if (node->compute_unit_id != -1) {
354 			sbuf_printf(sb,"Compute Unit ID %d: ",
355 				node->compute_unit_id);
356 		} else {
357 			sbuf_printf(sb,"CORE ID %d: ",
358 				get_core_number_within_chip(bsr_member));
359 		}
360 	} else if (node->type == THREAD_LEVEL) {
361 		if (node->compute_unit_id != -1) {
362 			sbuf_printf(sb,"CORE ID %d: ",
363 				get_core_number_within_chip(bsr_member));
364 		} else {
365 			sbuf_printf(sb,"THREAD ID %d: ",
366 				get_logical_CPU_number_within_core(bsr_member));
367 		}
368 	} else {
369 		sbuf_printf(sb,"UNKNOWN: ");
370 	}
371 	CPUSET_FOREACH(i, node->members) {
372 		sbuf_printf(sb,"cpu%d ", i);
373 	}
374 
375 	sbuf_printf(sb,"\n");
376 
377 	for (i = 0; i < node->child_no; i++) {
378 		print_cpu_topology_tree_sysctl_helper(node->child_node[i],
379 		    sb, buf, buf_len, i == (node->child_no -1));
380 	}
381 }
382 
383 /* SYSCTL PROCEDURE for printing the CPU Topology tree */
384 static int
385 print_cpu_topology_tree_sysctl(SYSCTL_HANDLER_ARGS)
386 {
387 	struct sbuf *sb;
388 	int ret;
389 	char buf[INDENT_BUF_SIZE];
390 
391 	KASSERT(cpu_root_node != NULL, ("cpu_root_node isn't initialized"));
392 
393 	sb = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND);
394 	if (sb == NULL) {
395 		return (ENOMEM);
396 	}
397 	sbuf_printf(sb,"\n");
398 	print_cpu_topology_tree_sysctl_helper(cpu_root_node, sb, buf, 0, 1);
399 
400 	sbuf_finish(sb);
401 
402 	ret = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb));
403 
404 	sbuf_delete(sb);
405 
406 	return ret;
407 }
408 
409 /* SYSCTL PROCEDURE for printing the CPU Topology level description */
410 static int
411 print_cpu_topology_level_description_sysctl(SYSCTL_HANDLER_ARGS)
412 {
413 	struct sbuf *sb;
414 	int ret;
415 
416 	sb = sbuf_new(NULL, NULL, 500, SBUF_AUTOEXTEND);
417 	if (sb == NULL)
418 		return (ENOMEM);
419 
420 	if (cpu_topology_levels_number == 4) /* HT available */
421 		sbuf_printf(sb, "0 - thread; 1 - core; 2 - socket; 3 - anything");
422 	else if (cpu_topology_levels_number == 3) /* No HT available */
423 		sbuf_printf(sb, "0 - core; 1 - socket; 2 - anything");
424 	else if (cpu_topology_levels_number == 2) /* No HT and no Multi-Core */
425 		sbuf_printf(sb, "0 - socket; 1 - anything");
426 	else
427 		sbuf_printf(sb, "Unknown");
428 
429 	sbuf_finish(sb);
430 
431 	ret = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb));
432 
433 	sbuf_delete(sb);
434 
435 	return ret;
436 }
437 
438 /* Find a cpu_node_t by a mask */
439 static cpu_node_t *
440 get_cpu_node_by_cpumask(cpu_node_t * node,
441 			cpumask_t mask) {
442 
443 	cpu_node_t * found = NULL;
444 	int i;
445 
446 	if (node->members == mask) {
447 		return node;
448 	}
449 
450 	for (i = 0; i < node->child_no; i++) {
451 		found = get_cpu_node_by_cpumask(node->child_node[i], mask);
452 		if (found != NULL) {
453 			return found;
454 		}
455 	}
456 	return NULL;
457 }
458 
459 cpu_node_t *
460 get_cpu_node_by_cpuid(int cpuid) {
461 	cpumask_t mask = CPUMASK(cpuid);
462 
463 	KASSERT(cpu_root_node != NULL, ("cpu_root_node isn't initialized"));
464 
465 	return get_cpu_node_by_cpumask(cpu_root_node, mask);
466 }
467 
468 /* Get the mask of siblings for level_type of a cpuid */
469 cpumask_t
470 get_cpumask_from_level(int cpuid,
471 			uint8_t level_type)
472 {
473 	cpu_node_t * node;
474 	cpumask_t mask = CPUMASK(cpuid);
475 
476 	KASSERT(cpu_root_node != NULL, ("cpu_root_node isn't initialized"));
477 
478 	node = get_cpu_node_by_cpumask(cpu_root_node, mask);
479 
480 	if (node == NULL) {
481 		return 0;
482 	}
483 
484 	while (node != NULL) {
485 		if (node->type == level_type) {
486 			return node->members;
487 		}
488 		node = node->parent_node;
489 	}
490 
491 	return 0;
492 }
493 
494 /* init pcpu_sysctl structure info */
495 static void
496 init_pcpu_topology_sysctl(void)
497 {
498 	int cpu;
499 	int i;
500 	cpumask_t mask;
501 	struct sbuf sb;
502 
503 	for (i = 0; i < ncpus; i++) {
504 
505 		sbuf_new(&sb, pcpu_sysctl[i].cpu_name,
506 		    sizeof(pcpu_sysctl[i].cpu_name), SBUF_FIXEDLEN);
507 		sbuf_printf(&sb,"cpu%d", i);
508 		sbuf_finish(&sb);
509 
510 
511 		/* Get physical siblings */
512 		mask = get_cpumask_from_level(i, CHIP_LEVEL);
513 		if (mask == 0) {
514 			pcpu_sysctl[i].physical_id = INVALID_ID;
515 			continue;
516 		}
517 
518 		sbuf_new(&sb, pcpu_sysctl[i].physical_siblings,
519 		    sizeof(pcpu_sysctl[i].physical_siblings), SBUF_FIXEDLEN);
520 		CPUSET_FOREACH(cpu, mask) {
521 			sbuf_printf(&sb,"cpu%d ", cpu);
522 		}
523 		sbuf_trim(&sb);
524 		sbuf_finish(&sb);
525 
526 		pcpu_sysctl[i].physical_id = get_chip_ID(i);
527 
528 		/* Get core siblings */
529 		mask = get_cpumask_from_level(i, CORE_LEVEL);
530 		if (mask == 0) {
531 			pcpu_sysctl[i].core_id = INVALID_ID;
532 			continue;
533 		}
534 
535 		sbuf_new(&sb, pcpu_sysctl[i].core_siblings,
536 		    sizeof(pcpu_sysctl[i].core_siblings), SBUF_FIXEDLEN);
537 		CPUSET_FOREACH(cpu, mask) {
538 			sbuf_printf(&sb,"cpu%d ", cpu);
539 		}
540 		sbuf_trim(&sb);
541 		sbuf_finish(&sb);
542 
543 		pcpu_sysctl[i].core_id = get_core_number_within_chip(i);
544 
545 	}
546 }
547 
548 /* Build SYSCTL structure for revealing
549  * the CPU Topology to user-space.
550  */
551 static void
552 build_sysctl_cpu_topology(void)
553 {
554 	int i;
555 	struct sbuf sb;
556 
557 	/* SYSCTL new leaf for "cpu_topology" */
558 	sysctl_ctx_init(&cpu_topology_sysctl_ctx);
559 	cpu_topology_sysctl_tree = SYSCTL_ADD_NODE(&cpu_topology_sysctl_ctx,
560 	    SYSCTL_STATIC_CHILDREN(_hw),
561 	    OID_AUTO,
562 	    "cpu_topology",
563 	    CTLFLAG_RD, 0, "");
564 
565 	/* SYSCTL cpu_topology "tree" entry */
566 	SYSCTL_ADD_PROC(&cpu_topology_sysctl_ctx,
567 	    SYSCTL_CHILDREN(cpu_topology_sysctl_tree),
568 	    OID_AUTO, "tree", CTLTYPE_STRING | CTLFLAG_RD,
569 	    NULL, 0, print_cpu_topology_tree_sysctl, "A",
570 	    "Tree print of CPU topology");
571 
572 	/* SYSCTL cpu_topology "level_description" entry */
573 	SYSCTL_ADD_PROC(&cpu_topology_sysctl_ctx,
574 	    SYSCTL_CHILDREN(cpu_topology_sysctl_tree),
575 	    OID_AUTO, "level_description", CTLTYPE_STRING | CTLFLAG_RD,
576 	    NULL, 0, print_cpu_topology_level_description_sysctl, "A",
577 	    "Level description of CPU topology");
578 
579 	/* SYSCTL cpu_topology "members" entry */
580 	sbuf_new(&sb, cpu_topology_members,
581 	    sizeof(cpu_topology_members), SBUF_FIXEDLEN);
582 	CPUSET_FOREACH(i, cpu_root_node->members) {
583 		sbuf_printf(&sb,"cpu%d ", i);
584 	}
585 	sbuf_trim(&sb);
586 	sbuf_finish(&sb);
587 	SYSCTL_ADD_STRING(&cpu_topology_sysctl_ctx,
588 	    SYSCTL_CHILDREN(cpu_topology_sysctl_tree),
589 	    OID_AUTO, "members", CTLFLAG_RD,
590 	    cpu_topology_members, 0,
591 	    "Members of the CPU Topology");
592 
593 	/* SYSCTL per_cpu info */
594 	for (i = 0; i < ncpus; i++) {
595 		/* New leaf : hw.cpu_topology.cpux */
596 		sysctl_ctx_init(&pcpu_sysctl[i].sysctl_ctx);
597 		pcpu_sysctl[i].sysctl_tree = SYSCTL_ADD_NODE(&pcpu_sysctl[i].sysctl_ctx,
598 		    SYSCTL_CHILDREN(cpu_topology_sysctl_tree),
599 		    OID_AUTO,
600 		    pcpu_sysctl[i].cpu_name,
601 		    CTLFLAG_RD, 0, "");
602 
603 		/* Check if the physical_id found is valid */
604 		if (pcpu_sysctl[i].physical_id == INVALID_ID) {
605 			continue;
606 		}
607 
608 		/* Add physical id info */
609 		SYSCTL_ADD_INT(&pcpu_sysctl[i].sysctl_ctx,
610 		    SYSCTL_CHILDREN(pcpu_sysctl[i].sysctl_tree),
611 		    OID_AUTO, "physical_id", CTLFLAG_RD,
612 		    &pcpu_sysctl[i].physical_id, 0,
613 		    "Physical ID");
614 
615 		/* Add physical siblings */
616 		SYSCTL_ADD_STRING(&pcpu_sysctl[i].sysctl_ctx,
617 		    SYSCTL_CHILDREN(pcpu_sysctl[i].sysctl_tree),
618 		    OID_AUTO, "physical_siblings", CTLFLAG_RD,
619 		    pcpu_sysctl[i].physical_siblings, 0,
620 		    "Physical siblings");
621 
622 		/* Check if the core_id found is valid */
623 		if (pcpu_sysctl[i].core_id == INVALID_ID) {
624 			continue;
625 		}
626 
627 		/* Add core id info */
628 		SYSCTL_ADD_INT(&pcpu_sysctl[i].sysctl_ctx,
629 		    SYSCTL_CHILDREN(pcpu_sysctl[i].sysctl_tree),
630 		    OID_AUTO, "core_id", CTLFLAG_RD,
631 		    &pcpu_sysctl[i].core_id, 0,
632 		    "Core ID");
633 
634 		/*Add core siblings */
635 		SYSCTL_ADD_STRING(&pcpu_sysctl[i].sysctl_ctx,
636 		    SYSCTL_CHILDREN(pcpu_sysctl[i].sysctl_tree),
637 		    OID_AUTO, "core_siblings", CTLFLAG_RD,
638 		    pcpu_sysctl[i].core_siblings, 0,
639 		    "Core siblings");
640 	}
641 }
642 
643 /* Build the CPU Topology and SYSCTL Topology tree */
644 static void
645 init_cpu_topology(void)
646 {
647 	build_cpu_topology();
648 
649 	init_pcpu_topology_sysctl();
650 	build_sysctl_cpu_topology();
651 }
652 SYSINIT(cpu_topology, SI_BOOT2_CPU_TOPOLOGY, SI_ORDER_FIRST,
653     init_cpu_topology, NULL)
654