FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_smp.c
1 /*-
2 * Copyright (c) 2001, John Baldwin <jhb@FreeBSD.org>.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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 the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 /*
28 * This module holds the global variables and machine independent functions
29 * used for the kernel SMP support.
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD: releng/11.1/sys/kern/subr_smp.c 308438 2016-11-08 09:51:55Z kib $");
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/kernel.h>
38 #include <sys/ktr.h>
39 #include <sys/proc.h>
40 #include <sys/bus.h>
41 #include <sys/lock.h>
42 #include <sys/malloc.h>
43 #include <sys/mutex.h>
44 #include <sys/pcpu.h>
45 #include <sys/sched.h>
46 #include <sys/smp.h>
47 #include <sys/sysctl.h>
48
49 #include <machine/cpu.h>
50 #include <machine/smp.h>
51
52 #include "opt_sched.h"
53
54 #ifdef SMP
55 MALLOC_DEFINE(M_TOPO, "toponodes", "SMP topology data");
56
57 volatile cpuset_t stopped_cpus;
58 volatile cpuset_t started_cpus;
59 volatile cpuset_t suspended_cpus;
60 cpuset_t hlt_cpus_mask;
61 cpuset_t logical_cpus_mask;
62
63 void (*cpustop_restartfunc)(void);
64 #endif
65
66 static int sysctl_kern_smp_active(SYSCTL_HANDLER_ARGS);
67
68 /* This is used in modules that need to work in both SMP and UP. */
69 cpuset_t all_cpus;
70
71 int mp_ncpus;
72 /* export this for libkvm consumers. */
73 int mp_maxcpus = MAXCPU;
74
75 volatile int smp_started;
76 u_int mp_maxid;
77
78 static SYSCTL_NODE(_kern, OID_AUTO, smp, CTLFLAG_RD|CTLFLAG_CAPRD, NULL,
79 "Kernel SMP");
80
81 SYSCTL_INT(_kern_smp, OID_AUTO, maxid, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_maxid, 0,
82 "Max CPU ID.");
83
84 SYSCTL_INT(_kern_smp, OID_AUTO, maxcpus, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_maxcpus,
85 0, "Max number of CPUs that the system was compiled for.");
86
87 SYSCTL_PROC(_kern_smp, OID_AUTO, active, CTLFLAG_RD | CTLTYPE_INT, NULL, 0,
88 sysctl_kern_smp_active, "I", "Indicates system is running in SMP mode");
89
90 int smp_disabled = 0; /* has smp been disabled? */
91 SYSCTL_INT(_kern_smp, OID_AUTO, disabled, CTLFLAG_RDTUN|CTLFLAG_CAPRD,
92 &smp_disabled, 0, "SMP has been disabled from the loader");
93
94 int smp_cpus = 1; /* how many cpu's running */
95 SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD|CTLFLAG_CAPRD, &smp_cpus, 0,
96 "Number of CPUs online");
97
98 int smp_topology = 0; /* Which topology we're using. */
99 SYSCTL_INT(_kern_smp, OID_AUTO, topology, CTLFLAG_RDTUN, &smp_topology, 0,
100 "Topology override setting; 0 is default provided by hardware.");
101
102 #ifdef SMP
103 /* Enable forwarding of a signal to a process running on a different CPU */
104 static int forward_signal_enabled = 1;
105 SYSCTL_INT(_kern_smp, OID_AUTO, forward_signal_enabled, CTLFLAG_RW,
106 &forward_signal_enabled, 0,
107 "Forwarding of a signal to a process on a different CPU");
108
109 /* Variables needed for SMP rendezvous. */
110 static volatile int smp_rv_ncpus;
111 static void (*volatile smp_rv_setup_func)(void *arg);
112 static void (*volatile smp_rv_action_func)(void *arg);
113 static void (*volatile smp_rv_teardown_func)(void *arg);
114 static void *volatile smp_rv_func_arg;
115 static volatile int smp_rv_waiters[4];
116
117 /*
118 * Shared mutex to restrict busywaits between smp_rendezvous() and
119 * smp(_targeted)_tlb_shootdown(). A deadlock occurs if both of these
120 * functions trigger at once and cause multiple CPUs to busywait with
121 * interrupts disabled.
122 */
123 struct mtx smp_ipi_mtx;
124
125 /*
126 * Let the MD SMP code initialize mp_maxid very early if it can.
127 */
128 static void
129 mp_setmaxid(void *dummy)
130 {
131
132 cpu_mp_setmaxid();
133
134 KASSERT(mp_ncpus >= 1, ("%s: CPU count < 1", __func__));
135 KASSERT(mp_ncpus > 1 || mp_maxid == 0,
136 ("%s: one CPU but mp_maxid is not zero", __func__));
137 KASSERT(mp_maxid >= mp_ncpus - 1,
138 ("%s: counters out of sync: max %d, count %d", __func__,
139 mp_maxid, mp_ncpus));
140 }
141 SYSINIT(cpu_mp_setmaxid, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setmaxid, NULL);
142
143 /*
144 * Call the MD SMP initialization code.
145 */
146 static void
147 mp_start(void *dummy)
148 {
149
150 mtx_init(&smp_ipi_mtx, "smp rendezvous", NULL, MTX_SPIN);
151
152 /* Probe for MP hardware. */
153 if (smp_disabled != 0 || cpu_mp_probe() == 0) {
154 mp_ncpus = 1;
155 CPU_SETOF(PCPU_GET(cpuid), &all_cpus);
156 return;
157 }
158
159 cpu_mp_start();
160 printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n",
161 mp_ncpus);
162 cpu_mp_announce();
163 }
164 SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_THIRD, mp_start, NULL);
165
166 void
167 forward_signal(struct thread *td)
168 {
169 int id;
170
171 /*
172 * signotify() has already set TDF_ASTPENDING and TDF_NEEDSIGCHECK on
173 * this thread, so all we need to do is poke it if it is currently
174 * executing so that it executes ast().
175 */
176 THREAD_LOCK_ASSERT(td, MA_OWNED);
177 KASSERT(TD_IS_RUNNING(td),
178 ("forward_signal: thread is not TDS_RUNNING"));
179
180 CTR1(KTR_SMP, "forward_signal(%p)", td->td_proc);
181
182 if (!smp_started || cold || panicstr)
183 return;
184 if (!forward_signal_enabled)
185 return;
186
187 /* No need to IPI ourself. */
188 if (td == curthread)
189 return;
190
191 id = td->td_oncpu;
192 if (id == NOCPU)
193 return;
194 ipi_cpu(id, IPI_AST);
195 }
196
197 /*
198 * When called the executing CPU will send an IPI to all other CPUs
199 * requesting that they halt execution.
200 *
201 * Usually (but not necessarily) called with 'other_cpus' as its arg.
202 *
203 * - Signals all CPUs in map to stop.
204 * - Waits for each to stop.
205 *
206 * Returns:
207 * -1: error
208 * 0: NA
209 * 1: ok
210 *
211 */
212 #if defined(__amd64__) || defined(__i386__)
213 #define X86 1
214 #else
215 #define X86 0
216 #endif
217 static int
218 generic_stop_cpus(cpuset_t map, u_int type)
219 {
220 #ifdef KTR
221 char cpusetbuf[CPUSETBUFSIZ];
222 #endif
223 static volatile u_int stopping_cpu = NOCPU;
224 int i;
225 volatile cpuset_t *cpus;
226
227 KASSERT(
228 type == IPI_STOP || type == IPI_STOP_HARD
229 #if X86
230 || type == IPI_SUSPEND
231 #endif
232 , ("%s: invalid stop type", __func__));
233
234 if (!smp_started)
235 return (0);
236
237 CTR2(KTR_SMP, "stop_cpus(%s) with %u type",
238 cpusetobj_strprint(cpusetbuf, &map), type);
239
240 #if X86
241 /*
242 * When suspending, ensure there are are no IPIs in progress.
243 * IPIs that have been issued, but not yet delivered (e.g.
244 * not pending on a vCPU when running under virtualization)
245 * will be lost, violating FreeBSD's assumption of reliable
246 * IPI delivery.
247 */
248 if (type == IPI_SUSPEND)
249 mtx_lock_spin(&smp_ipi_mtx);
250 #endif
251
252 #if X86
253 if (!nmi_is_broadcast || nmi_kdb_lock == 0) {
254 #endif
255 if (stopping_cpu != PCPU_GET(cpuid))
256 while (atomic_cmpset_int(&stopping_cpu, NOCPU,
257 PCPU_GET(cpuid)) == 0)
258 while (stopping_cpu != NOCPU)
259 cpu_spinwait(); /* spin */
260
261 /* send the stop IPI to all CPUs in map */
262 ipi_selected(map, type);
263 #if X86
264 }
265 #endif
266
267 #if X86
268 if (type == IPI_SUSPEND)
269 cpus = &suspended_cpus;
270 else
271 #endif
272 cpus = &stopped_cpus;
273
274 i = 0;
275 while (!CPU_SUBSET(cpus, &map)) {
276 /* spin */
277 cpu_spinwait();
278 i++;
279 if (i == 100000000) {
280 printf("timeout stopping cpus\n");
281 break;
282 }
283 }
284
285 #if X86
286 if (type == IPI_SUSPEND)
287 mtx_unlock_spin(&smp_ipi_mtx);
288 #endif
289
290 stopping_cpu = NOCPU;
291 return (1);
292 }
293
294 int
295 stop_cpus(cpuset_t map)
296 {
297
298 return (generic_stop_cpus(map, IPI_STOP));
299 }
300
301 int
302 stop_cpus_hard(cpuset_t map)
303 {
304
305 return (generic_stop_cpus(map, IPI_STOP_HARD));
306 }
307
308 #if X86
309 int
310 suspend_cpus(cpuset_t map)
311 {
312
313 return (generic_stop_cpus(map, IPI_SUSPEND));
314 }
315 #endif
316
317 /*
318 * Called by a CPU to restart stopped CPUs.
319 *
320 * Usually (but not necessarily) called with 'stopped_cpus' as its arg.
321 *
322 * - Signals all CPUs in map to restart.
323 * - Waits for each to restart.
324 *
325 * Returns:
326 * -1: error
327 * 0: NA
328 * 1: ok
329 */
330 static int
331 generic_restart_cpus(cpuset_t map, u_int type)
332 {
333 #ifdef KTR
334 char cpusetbuf[CPUSETBUFSIZ];
335 #endif
336 volatile cpuset_t *cpus;
337
338 KASSERT(type == IPI_STOP || type == IPI_STOP_HARD
339 #if X86
340 || type == IPI_SUSPEND
341 #endif
342 , ("%s: invalid stop type", __func__));
343
344 if (!smp_started)
345 return (0);
346
347 CTR1(KTR_SMP, "restart_cpus(%s)", cpusetobj_strprint(cpusetbuf, &map));
348
349 #if X86
350 if (type == IPI_SUSPEND)
351 cpus = &suspended_cpus;
352 else
353 #endif
354 cpus = &stopped_cpus;
355
356 /* signal other cpus to restart */
357 CPU_COPY_STORE_REL(&map, &started_cpus);
358
359 #if X86
360 if (!nmi_is_broadcast || nmi_kdb_lock == 0) {
361 #endif
362 /* wait for each to clear its bit */
363 while (CPU_OVERLAP(cpus, &map))
364 cpu_spinwait();
365 #if X86
366 }
367 #endif
368
369 return (1);
370 }
371
372 int
373 restart_cpus(cpuset_t map)
374 {
375
376 return (generic_restart_cpus(map, IPI_STOP));
377 }
378
379 #if X86
380 int
381 resume_cpus(cpuset_t map)
382 {
383
384 return (generic_restart_cpus(map, IPI_SUSPEND));
385 }
386 #endif
387 #undef X86
388
389 /*
390 * All-CPU rendezvous. CPUs are signalled, all execute the setup function
391 * (if specified), rendezvous, execute the action function (if specified),
392 * rendezvous again, execute the teardown function (if specified), and then
393 * resume.
394 *
395 * Note that the supplied external functions _must_ be reentrant and aware
396 * that they are running in parallel and in an unknown lock context.
397 */
398 void
399 smp_rendezvous_action(void)
400 {
401 struct thread *td;
402 void *local_func_arg;
403 void (*local_setup_func)(void*);
404 void (*local_action_func)(void*);
405 void (*local_teardown_func)(void*);
406 #ifdef INVARIANTS
407 int owepreempt;
408 #endif
409
410 /* Ensure we have up-to-date values. */
411 atomic_add_acq_int(&smp_rv_waiters[0], 1);
412 while (smp_rv_waiters[0] < smp_rv_ncpus)
413 cpu_spinwait();
414
415 /* Fetch rendezvous parameters after acquire barrier. */
416 local_func_arg = smp_rv_func_arg;
417 local_setup_func = smp_rv_setup_func;
418 local_action_func = smp_rv_action_func;
419 local_teardown_func = smp_rv_teardown_func;
420
421 /*
422 * Use a nested critical section to prevent any preemptions
423 * from occurring during a rendezvous action routine.
424 * Specifically, if a rendezvous handler is invoked via an IPI
425 * and the interrupted thread was in the critical_exit()
426 * function after setting td_critnest to 0 but before
427 * performing a deferred preemption, this routine can be
428 * invoked with td_critnest set to 0 and td_owepreempt true.
429 * In that case, a critical_exit() during the rendezvous
430 * action would trigger a preemption which is not permitted in
431 * a rendezvous action. To fix this, wrap all of the
432 * rendezvous action handlers in a critical section. We
433 * cannot use a regular critical section however as having
434 * critical_exit() preempt from this routine would also be
435 * problematic (the preemption must not occur before the IPI
436 * has been acknowledged via an EOI). Instead, we
437 * intentionally ignore td_owepreempt when leaving the
438 * critical section. This should be harmless because we do
439 * not permit rendezvous action routines to schedule threads,
440 * and thus td_owepreempt should never transition from 0 to 1
441 * during this routine.
442 */
443 td = curthread;
444 td->td_critnest++;
445 #ifdef INVARIANTS
446 owepreempt = td->td_owepreempt;
447 #endif
448
449 /*
450 * If requested, run a setup function before the main action
451 * function. Ensure all CPUs have completed the setup
452 * function before moving on to the action function.
453 */
454 if (local_setup_func != smp_no_rendevous_barrier) {
455 if (smp_rv_setup_func != NULL)
456 smp_rv_setup_func(smp_rv_func_arg);
457 atomic_add_int(&smp_rv_waiters[1], 1);
458 while (smp_rv_waiters[1] < smp_rv_ncpus)
459 cpu_spinwait();
460 }
461
462 if (local_action_func != NULL)
463 local_action_func(local_func_arg);
464
465 if (local_teardown_func != smp_no_rendevous_barrier) {
466 /*
467 * Signal that the main action has been completed. If a
468 * full exit rendezvous is requested, then all CPUs will
469 * wait here until all CPUs have finished the main action.
470 */
471 atomic_add_int(&smp_rv_waiters[2], 1);
472 while (smp_rv_waiters[2] < smp_rv_ncpus)
473 cpu_spinwait();
474
475 if (local_teardown_func != NULL)
476 local_teardown_func(local_func_arg);
477 }
478
479 /*
480 * Signal that the rendezvous is fully completed by this CPU.
481 * This means that no member of smp_rv_* pseudo-structure will be
482 * accessed by this target CPU after this point; in particular,
483 * memory pointed by smp_rv_func_arg.
484 *
485 * The release semantic ensures that all accesses performed by
486 * the current CPU are visible when smp_rendezvous_cpus()
487 * returns, by synchronizing with the
488 * atomic_load_acq_int(&smp_rv_waiters[3]).
489 */
490 atomic_add_rel_int(&smp_rv_waiters[3], 1);
491
492 td->td_critnest--;
493 KASSERT(owepreempt == td->td_owepreempt,
494 ("rendezvous action changed td_owepreempt"));
495 }
496
497 void
498 smp_rendezvous_cpus(cpuset_t map,
499 void (* setup_func)(void *),
500 void (* action_func)(void *),
501 void (* teardown_func)(void *),
502 void *arg)
503 {
504 int curcpumap, i, ncpus = 0;
505
506 /* Look comments in the !SMP case. */
507 if (!smp_started) {
508 spinlock_enter();
509 if (setup_func != NULL)
510 setup_func(arg);
511 if (action_func != NULL)
512 action_func(arg);
513 if (teardown_func != NULL)
514 teardown_func(arg);
515 spinlock_exit();
516 return;
517 }
518
519 CPU_FOREACH(i) {
520 if (CPU_ISSET(i, &map))
521 ncpus++;
522 }
523 if (ncpus == 0)
524 panic("ncpus is 0 with non-zero map");
525
526 mtx_lock_spin(&smp_ipi_mtx);
527
528 /* Pass rendezvous parameters via global variables. */
529 smp_rv_ncpus = ncpus;
530 smp_rv_setup_func = setup_func;
531 smp_rv_action_func = action_func;
532 smp_rv_teardown_func = teardown_func;
533 smp_rv_func_arg = arg;
534 smp_rv_waiters[1] = 0;
535 smp_rv_waiters[2] = 0;
536 smp_rv_waiters[3] = 0;
537 atomic_store_rel_int(&smp_rv_waiters[0], 0);
538
539 /*
540 * Signal other processors, which will enter the IPI with
541 * interrupts off.
542 */
543 curcpumap = CPU_ISSET(curcpu, &map);
544 CPU_CLR(curcpu, &map);
545 ipi_selected(map, IPI_RENDEZVOUS);
546
547 /* Check if the current CPU is in the map */
548 if (curcpumap != 0)
549 smp_rendezvous_action();
550
551 /*
552 * Ensure that the master CPU waits for all the other
553 * CPUs to finish the rendezvous, so that smp_rv_*
554 * pseudo-structure and the arg are guaranteed to not
555 * be in use.
556 *
557 * Load acquire synchronizes with the release add in
558 * smp_rendezvous_action(), which ensures that our caller sees
559 * all memory actions done by the called functions on other
560 * CPUs.
561 */
562 while (atomic_load_acq_int(&smp_rv_waiters[3]) < ncpus)
563 cpu_spinwait();
564
565 mtx_unlock_spin(&smp_ipi_mtx);
566 }
567
568 void
569 smp_rendezvous(void (* setup_func)(void *),
570 void (* action_func)(void *),
571 void (* teardown_func)(void *),
572 void *arg)
573 {
574 smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, arg);
575 }
576
577 static struct cpu_group group[MAXCPU * MAX_CACHE_LEVELS + 1];
578
579 struct cpu_group *
580 smp_topo(void)
581 {
582 char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ];
583 struct cpu_group *top;
584
585 /*
586 * Check for a fake topology request for debugging purposes.
587 */
588 switch (smp_topology) {
589 case 1:
590 /* Dual core with no sharing. */
591 top = smp_topo_1level(CG_SHARE_NONE, 2, 0);
592 break;
593 case 2:
594 /* No topology, all cpus are equal. */
595 top = smp_topo_none();
596 break;
597 case 3:
598 /* Dual core with shared L2. */
599 top = smp_topo_1level(CG_SHARE_L2, 2, 0);
600 break;
601 case 4:
602 /* quad core, shared l3 among each package, private l2. */
603 top = smp_topo_1level(CG_SHARE_L3, 4, 0);
604 break;
605 case 5:
606 /* quad core, 2 dualcore parts on each package share l2. */
607 top = smp_topo_2level(CG_SHARE_NONE, 2, CG_SHARE_L2, 2, 0);
608 break;
609 case 6:
610 /* Single-core 2xHTT */
611 top = smp_topo_1level(CG_SHARE_L1, 2, CG_FLAG_HTT);
612 break;
613 case 7:
614 /* quad core with a shared l3, 8 threads sharing L2. */
615 top = smp_topo_2level(CG_SHARE_L3, 4, CG_SHARE_L2, 8,
616 CG_FLAG_SMT);
617 break;
618 default:
619 /* Default, ask the system what it wants. */
620 top = cpu_topo();
621 break;
622 }
623 /*
624 * Verify the returned topology.
625 */
626 if (top->cg_count != mp_ncpus)
627 panic("Built bad topology at %p. CPU count %d != %d",
628 top, top->cg_count, mp_ncpus);
629 if (CPU_CMP(&top->cg_mask, &all_cpus))
630 panic("Built bad topology at %p. CPU mask (%s) != (%s)",
631 top, cpusetobj_strprint(cpusetbuf, &top->cg_mask),
632 cpusetobj_strprint(cpusetbuf2, &all_cpus));
633 return (top);
634 }
635
636 struct cpu_group *
637 smp_topo_alloc(u_int count)
638 {
639 static u_int index;
640 u_int curr;
641
642 curr = index;
643 index += count;
644 return (&group[curr]);
645 }
646
647 struct cpu_group *
648 smp_topo_none(void)
649 {
650 struct cpu_group *top;
651
652 top = &group[0];
653 top->cg_parent = NULL;
654 top->cg_child = NULL;
655 top->cg_mask = all_cpus;
656 top->cg_count = mp_ncpus;
657 top->cg_children = 0;
658 top->cg_level = CG_SHARE_NONE;
659 top->cg_flags = 0;
660
661 return (top);
662 }
663
664 static int
665 smp_topo_addleaf(struct cpu_group *parent, struct cpu_group *child, int share,
666 int count, int flags, int start)
667 {
668 char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ];
669 cpuset_t mask;
670 int i;
671
672 CPU_ZERO(&mask);
673 for (i = 0; i < count; i++, start++)
674 CPU_SET(start, &mask);
675 child->cg_parent = parent;
676 child->cg_child = NULL;
677 child->cg_children = 0;
678 child->cg_level = share;
679 child->cg_count = count;
680 child->cg_flags = flags;
681 child->cg_mask = mask;
682 parent->cg_children++;
683 for (; parent != NULL; parent = parent->cg_parent) {
684 if (CPU_OVERLAP(&parent->cg_mask, &child->cg_mask))
685 panic("Duplicate children in %p. mask (%s) child (%s)",
686 parent,
687 cpusetobj_strprint(cpusetbuf, &parent->cg_mask),
688 cpusetobj_strprint(cpusetbuf2, &child->cg_mask));
689 CPU_OR(&parent->cg_mask, &child->cg_mask);
690 parent->cg_count += child->cg_count;
691 }
692
693 return (start);
694 }
695
696 struct cpu_group *
697 smp_topo_1level(int share, int count, int flags)
698 {
699 struct cpu_group *child;
700 struct cpu_group *top;
701 int packages;
702 int cpu;
703 int i;
704
705 cpu = 0;
706 top = &group[0];
707 packages = mp_ncpus / count;
708 top->cg_child = child = &group[1];
709 top->cg_level = CG_SHARE_NONE;
710 for (i = 0; i < packages; i++, child++)
711 cpu = smp_topo_addleaf(top, child, share, count, flags, cpu);
712 return (top);
713 }
714
715 struct cpu_group *
716 smp_topo_2level(int l2share, int l2count, int l1share, int l1count,
717 int l1flags)
718 {
719 struct cpu_group *top;
720 struct cpu_group *l1g;
721 struct cpu_group *l2g;
722 int cpu;
723 int i;
724 int j;
725
726 cpu = 0;
727 top = &group[0];
728 l2g = &group[1];
729 top->cg_child = l2g;
730 top->cg_level = CG_SHARE_NONE;
731 top->cg_children = mp_ncpus / (l2count * l1count);
732 l1g = l2g + top->cg_children;
733 for (i = 0; i < top->cg_children; i++, l2g++) {
734 l2g->cg_parent = top;
735 l2g->cg_child = l1g;
736 l2g->cg_level = l2share;
737 for (j = 0; j < l2count; j++, l1g++)
738 cpu = smp_topo_addleaf(l2g, l1g, l1share, l1count,
739 l1flags, cpu);
740 }
741 return (top);
742 }
743
744
745 struct cpu_group *
746 smp_topo_find(struct cpu_group *top, int cpu)
747 {
748 struct cpu_group *cg;
749 cpuset_t mask;
750 int children;
751 int i;
752
753 CPU_SETOF(cpu, &mask);
754 cg = top;
755 for (;;) {
756 if (!CPU_OVERLAP(&cg->cg_mask, &mask))
757 return (NULL);
758 if (cg->cg_children == 0)
759 return (cg);
760 children = cg->cg_children;
761 for (i = 0, cg = cg->cg_child; i < children; cg++, i++)
762 if (CPU_OVERLAP(&cg->cg_mask, &mask))
763 break;
764 }
765 return (NULL);
766 }
767 #else /* !SMP */
768
769 void
770 smp_rendezvous_cpus(cpuset_t map,
771 void (*setup_func)(void *),
772 void (*action_func)(void *),
773 void (*teardown_func)(void *),
774 void *arg)
775 {
776 /*
777 * In the !SMP case we just need to ensure the same initial conditions
778 * as the SMP case.
779 */
780 spinlock_enter();
781 if (setup_func != NULL)
782 setup_func(arg);
783 if (action_func != NULL)
784 action_func(arg);
785 if (teardown_func != NULL)
786 teardown_func(arg);
787 spinlock_exit();
788 }
789
790 void
791 smp_rendezvous(void (*setup_func)(void *),
792 void (*action_func)(void *),
793 void (*teardown_func)(void *),
794 void *arg)
795 {
796
797 /* Look comments in the smp_rendezvous_cpus() case. */
798 spinlock_enter();
799 if (setup_func != NULL)
800 setup_func(arg);
801 if (action_func != NULL)
802 action_func(arg);
803 if (teardown_func != NULL)
804 teardown_func(arg);
805 spinlock_exit();
806 }
807
808 /*
809 * Provide dummy SMP support for UP kernels. Modules that need to use SMP
810 * APIs will still work using this dummy support.
811 */
812 static void
813 mp_setvariables_for_up(void *dummy)
814 {
815 mp_ncpus = 1;
816 mp_maxid = PCPU_GET(cpuid);
817 CPU_SETOF(mp_maxid, &all_cpus);
818 KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero"));
819 }
820 SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST,
821 mp_setvariables_for_up, NULL);
822 #endif /* SMP */
823
824 void
825 smp_no_rendevous_barrier(void *dummy)
826 {
827 #ifdef SMP
828 KASSERT((!smp_started),("smp_no_rendevous called and smp is started"));
829 #endif
830 }
831
832 /*
833 * Wait specified idle threads to switch once. This ensures that even
834 * preempted threads have cycled through the switch function once,
835 * exiting their codepaths. This allows us to change global pointers
836 * with no other synchronization.
837 */
838 int
839 quiesce_cpus(cpuset_t map, const char *wmesg, int prio)
840 {
841 struct pcpu *pcpu;
842 u_int gen[MAXCPU];
843 int error;
844 int cpu;
845
846 error = 0;
847 for (cpu = 0; cpu <= mp_maxid; cpu++) {
848 if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu))
849 continue;
850 pcpu = pcpu_find(cpu);
851 gen[cpu] = pcpu->pc_idlethread->td_generation;
852 }
853 for (cpu = 0; cpu <= mp_maxid; cpu++) {
854 if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu))
855 continue;
856 pcpu = pcpu_find(cpu);
857 thread_lock(curthread);
858 sched_bind(curthread, cpu);
859 thread_unlock(curthread);
860 while (gen[cpu] == pcpu->pc_idlethread->td_generation) {
861 error = tsleep(quiesce_cpus, prio, wmesg, 1);
862 if (error != EWOULDBLOCK)
863 goto out;
864 error = 0;
865 }
866 }
867 out:
868 thread_lock(curthread);
869 sched_unbind(curthread);
870 thread_unlock(curthread);
871
872 return (error);
873 }
874
875 int
876 quiesce_all_cpus(const char *wmesg, int prio)
877 {
878
879 return quiesce_cpus(all_cpus, wmesg, prio);
880 }
881
882 /* Extra care is taken with this sysctl because the data type is volatile */
883 static int
884 sysctl_kern_smp_active(SYSCTL_HANDLER_ARGS)
885 {
886 int error, active;
887
888 active = smp_started;
889 error = SYSCTL_OUT(req, &active, sizeof(active));
890 return (error);
891 }
892
893
894 #ifdef SMP
895 void
896 topo_init_node(struct topo_node *node)
897 {
898
899 bzero(node, sizeof(*node));
900 TAILQ_INIT(&node->children);
901 }
902
903 void
904 topo_init_root(struct topo_node *root)
905 {
906
907 topo_init_node(root);
908 root->type = TOPO_TYPE_SYSTEM;
909 }
910
911 /*
912 * Add a child node with the given ID under the given parent.
913 * Do nothing if there is already a child with that ID.
914 */
915 struct topo_node *
916 topo_add_node_by_hwid(struct topo_node *parent, int hwid,
917 topo_node_type type, uintptr_t subtype)
918 {
919 struct topo_node *node;
920
921 TAILQ_FOREACH_REVERSE(node, &parent->children,
922 topo_children, siblings) {
923 if (node->hwid == hwid
924 && node->type == type && node->subtype == subtype) {
925 return (node);
926 }
927 }
928
929 node = malloc(sizeof(*node), M_TOPO, M_WAITOK);
930 topo_init_node(node);
931 node->parent = parent;
932 node->hwid = hwid;
933 node->type = type;
934 node->subtype = subtype;
935 TAILQ_INSERT_TAIL(&parent->children, node, siblings);
936 parent->nchildren++;
937
938 return (node);
939 }
940
941 /*
942 * Find a child node with the given ID under the given parent.
943 */
944 struct topo_node *
945 topo_find_node_by_hwid(struct topo_node *parent, int hwid,
946 topo_node_type type, uintptr_t subtype)
947 {
948
949 struct topo_node *node;
950
951 TAILQ_FOREACH(node, &parent->children, siblings) {
952 if (node->hwid == hwid
953 && node->type == type && node->subtype == subtype) {
954 return (node);
955 }
956 }
957
958 return (NULL);
959 }
960
961 /*
962 * Given a node change the order of its parent's child nodes such
963 * that the node becomes the firt child while preserving the cyclic
964 * order of the children. In other words, the given node is promoted
965 * by rotation.
966 */
967 void
968 topo_promote_child(struct topo_node *child)
969 {
970 struct topo_node *next;
971 struct topo_node *node;
972 struct topo_node *parent;
973
974 parent = child->parent;
975 next = TAILQ_NEXT(child, siblings);
976 TAILQ_REMOVE(&parent->children, child, siblings);
977 TAILQ_INSERT_HEAD(&parent->children, child, siblings);
978
979 while (next != NULL) {
980 node = next;
981 next = TAILQ_NEXT(node, siblings);
982 TAILQ_REMOVE(&parent->children, node, siblings);
983 TAILQ_INSERT_AFTER(&parent->children, child, node, siblings);
984 child = node;
985 }
986 }
987
988 /*
989 * Iterate to the next node in the depth-first search (traversal) of
990 * the topology tree.
991 */
992 struct topo_node *
993 topo_next_node(struct topo_node *top, struct topo_node *node)
994 {
995 struct topo_node *next;
996
997 if ((next = TAILQ_FIRST(&node->children)) != NULL)
998 return (next);
999
1000 if ((next = TAILQ_NEXT(node, siblings)) != NULL)
1001 return (next);
1002
1003 while ((node = node->parent) != top)
1004 if ((next = TAILQ_NEXT(node, siblings)) != NULL)
1005 return (next);
1006
1007 return (NULL);
1008 }
1009
1010 /*
1011 * Iterate to the next node in the depth-first search of the topology tree,
1012 * but without descending below the current node.
1013 */
1014 struct topo_node *
1015 topo_next_nonchild_node(struct topo_node *top, struct topo_node *node)
1016 {
1017 struct topo_node *next;
1018
1019 if ((next = TAILQ_NEXT(node, siblings)) != NULL)
1020 return (next);
1021
1022 while ((node = node->parent) != top)
1023 if ((next = TAILQ_NEXT(node, siblings)) != NULL)
1024 return (next);
1025
1026 return (NULL);
1027 }
1028
1029 /*
1030 * Assign the given ID to the given topology node that represents a logical
1031 * processor.
1032 */
1033 void
1034 topo_set_pu_id(struct topo_node *node, cpuid_t id)
1035 {
1036
1037 KASSERT(node->type == TOPO_TYPE_PU,
1038 ("topo_set_pu_id: wrong node type: %u", node->type));
1039 KASSERT(CPU_EMPTY(&node->cpuset) && node->cpu_count == 0,
1040 ("topo_set_pu_id: cpuset already not empty"));
1041 node->id = id;
1042 CPU_SET(id, &node->cpuset);
1043 node->cpu_count = 1;
1044 node->subtype = 1;
1045
1046 while ((node = node->parent) != NULL) {
1047 KASSERT(!CPU_ISSET(id, &node->cpuset),
1048 ("logical ID %u is already set in node %p", id, node));
1049 CPU_SET(id, &node->cpuset);
1050 node->cpu_count++;
1051 }
1052 }
1053
1054 /*
1055 * Check if the topology is uniform, that is, each package has the same number
1056 * of cores in it and each core has the same number of threads (logical
1057 * processors) in it. If so, calculate the number of package, the number of
1058 * cores per package and the number of logical processors per core.
1059 * 'all' parameter tells whether to include administratively disabled logical
1060 * processors into the analysis.
1061 */
1062 int
1063 topo_analyze(struct topo_node *topo_root, int all,
1064 int *pkg_count, int *cores_per_pkg, int *thrs_per_core)
1065 {
1066 struct topo_node *pkg_node;
1067 struct topo_node *core_node;
1068 struct topo_node *pu_node;
1069 int thrs_per_pkg;
1070 int cpp_counter;
1071 int tpc_counter;
1072 int tpp_counter;
1073
1074 *pkg_count = 0;
1075 *cores_per_pkg = -1;
1076 *thrs_per_core = -1;
1077 thrs_per_pkg = -1;
1078 pkg_node = topo_root;
1079 while (pkg_node != NULL) {
1080 if (pkg_node->type != TOPO_TYPE_PKG) {
1081 pkg_node = topo_next_node(topo_root, pkg_node);
1082 continue;
1083 }
1084 if (!all && CPU_EMPTY(&pkg_node->cpuset)) {
1085 pkg_node = topo_next_nonchild_node(topo_root, pkg_node);
1086 continue;
1087 }
1088
1089 (*pkg_count)++;
1090
1091 cpp_counter = 0;
1092 tpp_counter = 0;
1093 core_node = pkg_node;
1094 while (core_node != NULL) {
1095 if (core_node->type == TOPO_TYPE_CORE) {
1096 if (!all && CPU_EMPTY(&core_node->cpuset)) {
1097 core_node =
1098 topo_next_nonchild_node(pkg_node,
1099 core_node);
1100 continue;
1101 }
1102
1103 cpp_counter++;
1104
1105 tpc_counter = 0;
1106 pu_node = core_node;
1107 while (pu_node != NULL) {
1108 if (pu_node->type == TOPO_TYPE_PU &&
1109 (all || !CPU_EMPTY(&pu_node->cpuset)))
1110 tpc_counter++;
1111 pu_node = topo_next_node(core_node,
1112 pu_node);
1113 }
1114
1115 if (*thrs_per_core == -1)
1116 *thrs_per_core = tpc_counter;
1117 else if (*thrs_per_core != tpc_counter)
1118 return (0);
1119
1120 core_node = topo_next_nonchild_node(pkg_node,
1121 core_node);
1122 } else {
1123 /* PU node directly under PKG. */
1124 if (core_node->type == TOPO_TYPE_PU &&
1125 (all || !CPU_EMPTY(&core_node->cpuset)))
1126 tpp_counter++;
1127 core_node = topo_next_node(pkg_node,
1128 core_node);
1129 }
1130 }
1131
1132 if (*cores_per_pkg == -1)
1133 *cores_per_pkg = cpp_counter;
1134 else if (*cores_per_pkg != cpp_counter)
1135 return (0);
1136 if (thrs_per_pkg == -1)
1137 thrs_per_pkg = tpp_counter;
1138 else if (thrs_per_pkg != tpp_counter)
1139 return (0);
1140
1141 pkg_node = topo_next_nonchild_node(topo_root, pkg_node);
1142 }
1143
1144 KASSERT(*pkg_count > 0,
1145 ("bug in topology or analysis"));
1146 if (*cores_per_pkg == 0) {
1147 KASSERT(*thrs_per_core == -1 && thrs_per_pkg > 0,
1148 ("bug in topology or analysis"));
1149 *thrs_per_core = thrs_per_pkg;
1150 }
1151
1152 return (1);
1153 }
1154 #endif /* SMP */
1155
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