FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_lock.c
1 /*-
2 * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org>
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 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26 /*
27 * This module holds the global variables and functions used to maintain
28 * lock_object structures.
29 */
30
31 #include <sys/cdefs.h>
32 __FBSDID("$FreeBSD$");
33
34 #include "opt_ddb.h"
35 #include "opt_mprof.h"
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/kernel.h>
40 #include <sys/ktr.h>
41 #include <sys/lock.h>
42 #include <sys/lock_profile.h>
43 #include <sys/malloc.h>
44 #include <sys/mutex.h>
45 #include <sys/pcpu.h>
46 #include <sys/proc.h>
47 #include <sys/sbuf.h>
48 #include <sys/sched.h>
49 #include <sys/smp.h>
50 #include <sys/sysctl.h>
51
52 #ifdef DDB
53 #include <ddb/ddb.h>
54 #endif
55
56 #include <machine/cpufunc.h>
57
58 SDT_PROVIDER_DEFINE(lock);
59 SDT_PROBE_DEFINE1(lock, , , starvation, "u_int");
60
61 CTASSERT(LOCK_CLASS_MAX == 15);
62
63 struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = {
64 &lock_class_mtx_spin,
65 &lock_class_mtx_sleep,
66 &lock_class_sx,
67 &lock_class_rm,
68 &lock_class_rm_sleepable,
69 &lock_class_rw,
70 &lock_class_lockmgr,
71 };
72
73 void
74 lock_init(struct lock_object *lock, struct lock_class *class, const char *name,
75 const char *type, int flags)
76 {
77 int i;
78
79 /* Check for double-init and zero object. */
80 KASSERT(flags & LO_NEW || !lock_initialized(lock),
81 ("lock \"%s\" %p already initialized", name, lock));
82
83 /* Look up lock class to find its index. */
84 for (i = 0; i < LOCK_CLASS_MAX; i++)
85 if (lock_classes[i] == class) {
86 lock->lo_flags = i << LO_CLASSSHIFT;
87 break;
88 }
89 KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class));
90
91 /* Initialize the lock object. */
92 lock->lo_name = name;
93 lock->lo_flags |= flags | LO_INITIALIZED;
94 LOCK_LOG_INIT(lock, 0);
95 WITNESS_INIT(lock, (type != NULL) ? type : name);
96 }
97
98 void
99 lock_destroy(struct lock_object *lock)
100 {
101
102 KASSERT(lock_initialized(lock), ("lock %p is not initialized", lock));
103 WITNESS_DESTROY(lock);
104 LOCK_LOG_DESTROY(lock, 0);
105 lock->lo_flags &= ~LO_INITIALIZED;
106 }
107
108 static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging");
109 static SYSCTL_NODE(_debug_lock, OID_AUTO, delay, CTLFLAG_RD, NULL,
110 "lock delay");
111
112 static u_int __read_mostly starvation_limit = 131072;
113 SYSCTL_INT(_debug_lock_delay, OID_AUTO, starvation_limit, CTLFLAG_RW,
114 &starvation_limit, 0, "");
115
116 static u_int __read_mostly restrict_starvation = 0;
117 SYSCTL_INT(_debug_lock_delay, OID_AUTO, restrict_starvation, CTLFLAG_RW,
118 &restrict_starvation, 0, "");
119
120 void
121 lock_delay(struct lock_delay_arg *la)
122 {
123 struct lock_delay_config *lc = la->config;
124 u_int i;
125
126 la->delay <<= 1;
127 if (__predict_false(la->delay > lc->max))
128 la->delay = lc->max;
129
130 for (i = la->delay; i > 0; i--)
131 cpu_spinwait();
132
133 la->spin_cnt += la->delay;
134 if (__predict_false(la->spin_cnt > starvation_limit)) {
135 SDT_PROBE1(lock, , , starvation, la->delay);
136 if (restrict_starvation)
137 la->delay = lc->base;
138 }
139 }
140
141 static u_int
142 lock_roundup_2(u_int val)
143 {
144 u_int res;
145
146 for (res = 1; res <= val; res <<= 1)
147 continue;
148
149 return (res);
150 }
151
152 void
153 lock_delay_default_init(struct lock_delay_config *lc)
154 {
155
156 lc->base = lock_roundup_2(mp_ncpus) / 4;
157 lc->max = lc->base * 1024;
158 }
159
160 #ifdef DDB
161 DB_SHOW_COMMAND(lock, db_show_lock)
162 {
163 struct lock_object *lock;
164 struct lock_class *class;
165
166 if (!have_addr)
167 return;
168 lock = (struct lock_object *)addr;
169 if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) {
170 db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock));
171 return;
172 }
173 class = LOCK_CLASS(lock);
174 db_printf(" class: %s\n", class->lc_name);
175 db_printf(" name: %s\n", lock->lo_name);
176 class->lc_ddb_show(lock);
177 }
178 #endif
179
180 #ifdef LOCK_PROFILING
181
182 /*
183 * One object per-thread for each lock the thread owns. Tracks individual
184 * lock instances.
185 */
186 struct lock_profile_object {
187 LIST_ENTRY(lock_profile_object) lpo_link;
188 struct lock_object *lpo_obj;
189 const char *lpo_file;
190 int lpo_line;
191 uint16_t lpo_ref;
192 uint16_t lpo_cnt;
193 uint64_t lpo_acqtime;
194 uint64_t lpo_waittime;
195 u_int lpo_contest_locking;
196 };
197
198 /*
199 * One lock_prof for each (file, line, lock object) triple.
200 */
201 struct lock_prof {
202 SLIST_ENTRY(lock_prof) link;
203 struct lock_class *class;
204 const char *file;
205 const char *name;
206 int line;
207 int ticks;
208 uintmax_t cnt_wait_max;
209 uintmax_t cnt_max;
210 uintmax_t cnt_tot;
211 uintmax_t cnt_wait;
212 uintmax_t cnt_cur;
213 uintmax_t cnt_contest_locking;
214 };
215
216 SLIST_HEAD(lphead, lock_prof);
217
218 #define LPROF_HASH_SIZE 4096
219 #define LPROF_HASH_MASK (LPROF_HASH_SIZE - 1)
220 #define LPROF_CACHE_SIZE 4096
221
222 /*
223 * Array of objects and profs for each type of object for each cpu. Spinlocks
224 * are handled separately because a thread may be preempted and acquire a
225 * spinlock while in the lock profiling code of a non-spinlock. In this way
226 * we only need a critical section to protect the per-cpu lists.
227 */
228 struct lock_prof_type {
229 struct lphead lpt_lpalloc;
230 struct lpohead lpt_lpoalloc;
231 struct lphead lpt_hash[LPROF_HASH_SIZE];
232 struct lock_prof lpt_prof[LPROF_CACHE_SIZE];
233 struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE];
234 };
235
236 struct lock_prof_cpu {
237 struct lock_prof_type lpc_types[2]; /* One for spin one for other. */
238 };
239
240 struct lock_prof_cpu *lp_cpu[MAXCPU];
241
242 volatile int __read_mostly lock_prof_enable;
243 static volatile int lock_prof_resetting;
244
245 #define LPROF_SBUF_SIZE 256
246
247 static int lock_prof_rejected;
248 static int lock_prof_skipspin;
249 static int lock_prof_skipcount;
250
251 #ifndef USE_CPU_NANOSECONDS
252 uint64_t
253 nanoseconds(void)
254 {
255 struct bintime bt;
256 uint64_t ns;
257
258 binuptime(&bt);
259 /* From bintime2timespec */
260 ns = bt.sec * (uint64_t)1000000000;
261 ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32;
262 return (ns);
263 }
264 #endif
265
266 static void
267 lock_prof_init_type(struct lock_prof_type *type)
268 {
269 int i;
270
271 SLIST_INIT(&type->lpt_lpalloc);
272 LIST_INIT(&type->lpt_lpoalloc);
273 for (i = 0; i < LPROF_CACHE_SIZE; i++) {
274 SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i],
275 link);
276 LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i],
277 lpo_link);
278 }
279 }
280
281 static void
282 lock_prof_init(void *arg)
283 {
284 int cpu;
285
286 for (cpu = 0; cpu <= mp_maxid; cpu++) {
287 lp_cpu[cpu] = malloc(sizeof(*lp_cpu[cpu]), M_DEVBUF,
288 M_WAITOK | M_ZERO);
289 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[0]);
290 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[1]);
291 }
292 }
293 SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL);
294
295 static void
296 lock_prof_reset_wait(void)
297 {
298
299 /*
300 * Spin relinquishing our cpu so that quiesce_all_cpus may
301 * complete.
302 */
303 while (lock_prof_resetting)
304 sched_relinquish(curthread);
305 }
306
307 static void
308 lock_prof_reset(void)
309 {
310 struct lock_prof_cpu *lpc;
311 int enabled, i, cpu;
312
313 /*
314 * We not only race with acquiring and releasing locks but also
315 * thread exit. To be certain that threads exit without valid head
316 * pointers they must see resetting set before enabled is cleared.
317 * Otherwise a lock may not be removed from a per-thread list due
318 * to disabled being set but not wait for reset() to remove it below.
319 */
320 atomic_store_rel_int(&lock_prof_resetting, 1);
321 enabled = lock_prof_enable;
322 lock_prof_enable = 0;
323 quiesce_all_cpus("profreset", 0);
324 /*
325 * Some objects may have migrated between CPUs. Clear all links
326 * before we zero the structures. Some items may still be linked
327 * into per-thread lists as well.
328 */
329 for (cpu = 0; cpu <= mp_maxid; cpu++) {
330 lpc = lp_cpu[cpu];
331 for (i = 0; i < LPROF_CACHE_SIZE; i++) {
332 LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link);
333 LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link);
334 }
335 }
336 for (cpu = 0; cpu <= mp_maxid; cpu++) {
337 lpc = lp_cpu[cpu];
338 bzero(lpc, sizeof(*lpc));
339 lock_prof_init_type(&lpc->lpc_types[0]);
340 lock_prof_init_type(&lpc->lpc_types[1]);
341 }
342 atomic_store_rel_int(&lock_prof_resetting, 0);
343 lock_prof_enable = enabled;
344 }
345
346 static void
347 lock_prof_output(struct lock_prof *lp, struct sbuf *sb)
348 {
349 const char *p;
350
351 for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3);
352 sbuf_printf(sb,
353 "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n",
354 lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000,
355 lp->cnt_wait / 1000, lp->cnt_cur,
356 lp->cnt_cur == 0 ? (uintmax_t)0 :
357 lp->cnt_tot / (lp->cnt_cur * 1000),
358 lp->cnt_cur == 0 ? (uintmax_t)0 :
359 lp->cnt_wait / (lp->cnt_cur * 1000),
360 (uintmax_t)0, lp->cnt_contest_locking,
361 p, lp->line, lp->class->lc_name, lp->name);
362 }
363
364 static void
365 lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash,
366 int spin, int t)
367 {
368 struct lock_prof_type *type;
369 struct lock_prof *l;
370 int cpu;
371
372 dst->file = match->file;
373 dst->line = match->line;
374 dst->class = match->class;
375 dst->name = match->name;
376
377 for (cpu = 0; cpu <= mp_maxid; cpu++) {
378 if (lp_cpu[cpu] == NULL)
379 continue;
380 type = &lp_cpu[cpu]->lpc_types[spin];
381 SLIST_FOREACH(l, &type->lpt_hash[hash], link) {
382 if (l->ticks == t)
383 continue;
384 if (l->file != match->file || l->line != match->line ||
385 l->name != match->name)
386 continue;
387 l->ticks = t;
388 if (l->cnt_max > dst->cnt_max)
389 dst->cnt_max = l->cnt_max;
390 if (l->cnt_wait_max > dst->cnt_wait_max)
391 dst->cnt_wait_max = l->cnt_wait_max;
392 dst->cnt_tot += l->cnt_tot;
393 dst->cnt_wait += l->cnt_wait;
394 dst->cnt_cur += l->cnt_cur;
395 dst->cnt_contest_locking += l->cnt_contest_locking;
396 }
397 }
398
399 }
400
401 static void
402 lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin,
403 int t)
404 {
405 struct lock_prof *l;
406 int i;
407
408 for (i = 0; i < LPROF_HASH_SIZE; ++i) {
409 SLIST_FOREACH(l, &type->lpt_hash[i], link) {
410 struct lock_prof lp = {};
411
412 if (l->ticks == t)
413 continue;
414 lock_prof_sum(l, &lp, i, spin, t);
415 lock_prof_output(&lp, sb);
416 }
417 }
418 }
419
420 static int
421 dump_lock_prof_stats(SYSCTL_HANDLER_ARGS)
422 {
423 struct sbuf *sb;
424 int error, cpu, t;
425 int enabled;
426
427 error = sysctl_wire_old_buffer(req, 0);
428 if (error != 0)
429 return (error);
430 sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req);
431 sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n",
432 "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name");
433 enabled = lock_prof_enable;
434 lock_prof_enable = 0;
435 quiesce_all_cpus("profstat", 0);
436 t = ticks;
437 for (cpu = 0; cpu <= mp_maxid; cpu++) {
438 if (lp_cpu[cpu] == NULL)
439 continue;
440 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t);
441 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t);
442 }
443 lock_prof_enable = enabled;
444
445 error = sbuf_finish(sb);
446 /* Output a trailing NUL. */
447 if (error == 0)
448 error = SYSCTL_OUT(req, "", 1);
449 sbuf_delete(sb);
450 return (error);
451 }
452
453 static int
454 enable_lock_prof(SYSCTL_HANDLER_ARGS)
455 {
456 int error, v;
457
458 v = lock_prof_enable;
459 error = sysctl_handle_int(oidp, &v, v, req);
460 if (error)
461 return (error);
462 if (req->newptr == NULL)
463 return (error);
464 if (v == lock_prof_enable)
465 return (0);
466 if (v == 1)
467 lock_prof_reset();
468 lock_prof_enable = !!v;
469
470 return (0);
471 }
472
473 static int
474 reset_lock_prof_stats(SYSCTL_HANDLER_ARGS)
475 {
476 int error, v;
477
478 v = 0;
479 error = sysctl_handle_int(oidp, &v, 0, req);
480 if (error)
481 return (error);
482 if (req->newptr == NULL)
483 return (error);
484 if (v == 0)
485 return (0);
486 lock_prof_reset();
487
488 return (0);
489 }
490
491 static struct lock_prof *
492 lock_profile_lookup(struct lock_object *lo, int spin, const char *file,
493 int line)
494 {
495 const char *unknown = "(unknown)";
496 struct lock_prof_type *type;
497 struct lock_prof *lp;
498 struct lphead *head;
499 const char *p;
500 u_int hash;
501
502 p = file;
503 if (p == NULL || *p == '\0')
504 p = unknown;
505 hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line;
506 hash &= LPROF_HASH_MASK;
507 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
508 head = &type->lpt_hash[hash];
509 SLIST_FOREACH(lp, head, link) {
510 if (lp->line == line && lp->file == p &&
511 lp->name == lo->lo_name)
512 return (lp);
513
514 }
515 lp = SLIST_FIRST(&type->lpt_lpalloc);
516 if (lp == NULL) {
517 lock_prof_rejected++;
518 return (lp);
519 }
520 SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link);
521 lp->file = p;
522 lp->line = line;
523 lp->class = LOCK_CLASS(lo);
524 lp->name = lo->lo_name;
525 SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link);
526 return (lp);
527 }
528
529 static struct lock_profile_object *
530 lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file,
531 int line)
532 {
533 struct lock_profile_object *l;
534 struct lock_prof_type *type;
535 struct lpohead *head;
536
537 head = &curthread->td_lprof[spin];
538 LIST_FOREACH(l, head, lpo_link)
539 if (l->lpo_obj == lo && l->lpo_file == file &&
540 l->lpo_line == line)
541 return (l);
542 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
543 l = LIST_FIRST(&type->lpt_lpoalloc);
544 if (l == NULL) {
545 lock_prof_rejected++;
546 return (NULL);
547 }
548 LIST_REMOVE(l, lpo_link);
549 l->lpo_obj = lo;
550 l->lpo_file = file;
551 l->lpo_line = line;
552 l->lpo_cnt = 0;
553 LIST_INSERT_HEAD(head, l, lpo_link);
554
555 return (l);
556 }
557
558 void
559 lock_profile_obtain_lock_success(struct lock_object *lo, int contested,
560 uint64_t waittime, const char *file, int line)
561 {
562 static int lock_prof_count;
563 struct lock_profile_object *l;
564 int spin;
565
566 if (SCHEDULER_STOPPED())
567 return;
568
569 /* don't reset the timer when/if recursing */
570 if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE))
571 return;
572 if (lock_prof_skipcount &&
573 (++lock_prof_count % lock_prof_skipcount) != 0)
574 return;
575 spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
576 if (spin && lock_prof_skipspin == 1)
577 return;
578 critical_enter();
579 /* Recheck enabled now that we're in a critical section. */
580 if (lock_prof_enable == 0)
581 goto out;
582 l = lock_profile_object_lookup(lo, spin, file, line);
583 if (l == NULL)
584 goto out;
585 l->lpo_cnt++;
586 if (++l->lpo_ref > 1)
587 goto out;
588 l->lpo_contest_locking = contested;
589 l->lpo_acqtime = nanoseconds();
590 if (waittime && (l->lpo_acqtime > waittime))
591 l->lpo_waittime = l->lpo_acqtime - waittime;
592 else
593 l->lpo_waittime = 0;
594 out:
595 critical_exit();
596 }
597
598 void
599 lock_profile_thread_exit(struct thread *td)
600 {
601 #ifdef INVARIANTS
602 struct lock_profile_object *l;
603
604 MPASS(curthread->td_critnest == 0);
605 #endif
606 /*
607 * If lock profiling was disabled we have to wait for reset to
608 * clear our pointers before we can exit safely.
609 */
610 lock_prof_reset_wait();
611 #ifdef INVARIANTS
612 LIST_FOREACH(l, &td->td_lprof[0], lpo_link)
613 printf("thread still holds lock acquired at %s:%d\n",
614 l->lpo_file, l->lpo_line);
615 LIST_FOREACH(l, &td->td_lprof[1], lpo_link)
616 printf("thread still holds lock acquired at %s:%d\n",
617 l->lpo_file, l->lpo_line);
618 #endif
619 MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL);
620 MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL);
621 }
622
623 void
624 lock_profile_release_lock(struct lock_object *lo)
625 {
626 struct lock_profile_object *l;
627 struct lock_prof_type *type;
628 struct lock_prof *lp;
629 uint64_t curtime, holdtime;
630 struct lpohead *head;
631 int spin;
632
633 if (SCHEDULER_STOPPED())
634 return;
635 if (lo->lo_flags & LO_NOPROFILE)
636 return;
637 spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
638 head = &curthread->td_lprof[spin];
639 if (LIST_FIRST(head) == NULL)
640 return;
641 critical_enter();
642 /* Recheck enabled now that we're in a critical section. */
643 if (lock_prof_enable == 0 && lock_prof_resetting == 1)
644 goto out;
645 /*
646 * If lock profiling is not enabled we still want to remove the
647 * lpo from our queue.
648 */
649 LIST_FOREACH(l, head, lpo_link)
650 if (l->lpo_obj == lo)
651 break;
652 if (l == NULL)
653 goto out;
654 if (--l->lpo_ref > 0)
655 goto out;
656 lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line);
657 if (lp == NULL)
658 goto release;
659 curtime = nanoseconds();
660 if (curtime < l->lpo_acqtime)
661 goto release;
662 holdtime = curtime - l->lpo_acqtime;
663
664 /*
665 * Record if the lock has been held longer now than ever
666 * before.
667 */
668 if (holdtime > lp->cnt_max)
669 lp->cnt_max = holdtime;
670 if (l->lpo_waittime > lp->cnt_wait_max)
671 lp->cnt_wait_max = l->lpo_waittime;
672 lp->cnt_tot += holdtime;
673 lp->cnt_wait += l->lpo_waittime;
674 lp->cnt_contest_locking += l->lpo_contest_locking;
675 lp->cnt_cur += l->lpo_cnt;
676 release:
677 LIST_REMOVE(l, lpo_link);
678 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
679 LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link);
680 out:
681 critical_exit();
682 }
683
684 static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL,
685 "lock profiling");
686 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW,
687 &lock_prof_skipspin, 0, "Skip profiling on spinlocks.");
688 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW,
689 &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions.");
690 SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD,
691 &lock_prof_rejected, 0, "Number of rejected profiling records");
692 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
693 NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics");
694 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
695 NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics");
696 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
697 NULL, 0, enable_lock_prof, "I", "Enable lock profiling");
698
699 #endif
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