Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_lock.c
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1 /*- 2 * Copyright (c) 2006 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 functions used to maintain 29 * lock_object structures. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD: releng/10.4/sys/kern/subr_lock.c 323872 2017-09-21 20:13:03Z marius $"); 34 35 #include "opt_ddb.h" 36 #include "opt_mprof.h" 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/kernel.h> 41 #include <sys/ktr.h> 42 #include <sys/lock.h> 43 #include <sys/lock_profile.h> 44 #include <sys/malloc.h> 45 #include <sys/mutex.h> 46 #include <sys/pcpu.h> 47 #include <sys/proc.h> 48 #include <sys/sbuf.h> 49 #include <sys/sched.h> 50 #include <sys/smp.h> 51 #include <sys/sysctl.h> 52 53 #ifdef DDB 54 #include <ddb/ddb.h> 55 #endif 56 57 #include <machine/cpufunc.h> 58 #include <machine/cpu.h> 59 60 CTASSERT(LOCK_CLASS_MAX == 15); 61 62 struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = { 63 &lock_class_mtx_spin, 64 &lock_class_mtx_sleep, 65 &lock_class_sx, 66 &lock_class_rm, 67 &lock_class_rm_sleepable, 68 &lock_class_rw, 69 &lock_class_lockmgr, 70 }; 71 72 void 73 lock_init(struct lock_object *lock, struct lock_class *class, const char *name, 74 const char *type, int flags) 75 { 76 int i; 77 78 /* Check for double-init and zero object. */ 79 KASSERT(flags & LO_NEW || !lock_initalized(lock), 80 ("lock \"%s\" %p already initialized", name, lock)); 81 82 /* Look up lock class to find its index. */ 83 for (i = 0; i < LOCK_CLASS_MAX; i++) 84 if (lock_classes[i] == class) { 85 lock->lo_flags = i << LO_CLASSSHIFT; 86 break; 87 } 88 KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class)); 89 90 /* Initialize the lock object. */ 91 lock->lo_name = name; 92 lock->lo_flags |= flags | LO_INITIALIZED; 93 LOCK_LOG_INIT(lock, 0); 94 WITNESS_INIT(lock, (type != NULL) ? type : name); 95 } 96 97 void 98 lock_destroy(struct lock_object *lock) 99 { 100 101 KASSERT(lock_initalized(lock), ("lock %p is not initialized", lock)); 102 WITNESS_DESTROY(lock); 103 LOCK_LOG_DESTROY(lock, 0); 104 lock->lo_flags &= ~LO_INITIALIZED; 105 } 106 107 void 108 lock_delay(struct lock_delay_arg *la) 109 { 110 u_int i, delay, backoff, min, max; 111 struct lock_delay_config *lc = la->config; 112 113 delay = la->delay; 114 115 if (delay == 0) 116 delay = lc->initial; 117 else { 118 delay += lc->step; 119 max = lc->max; 120 if (delay > max) 121 delay = max; 122 } 123 124 backoff = cpu_ticks() % delay; 125 min = lc->min; 126 if (backoff < min) 127 backoff = min; 128 for (i = 0; i < backoff; i++) 129 cpu_spinwait(); 130 131 la->delay = delay; 132 la->spin_cnt += backoff; 133 } 134 135 #ifdef DDB 136 DB_SHOW_COMMAND(lock, db_show_lock) 137 { 138 struct lock_object *lock; 139 struct lock_class *class; 140 141 if (!have_addr) 142 return; 143 lock = (struct lock_object *)addr; 144 if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) { 145 db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock)); 146 return; 147 } 148 class = LOCK_CLASS(lock); 149 db_printf(" class: %s\n", class->lc_name); 150 db_printf(" name: %s\n", lock->lo_name); 151 class->lc_ddb_show(lock); 152 } 153 #endif 154 155 #ifdef LOCK_PROFILING 156 157 /* 158 * One object per-thread for each lock the thread owns. Tracks individual 159 * lock instances. 160 */ 161 struct lock_profile_object { 162 LIST_ENTRY(lock_profile_object) lpo_link; 163 struct lock_object *lpo_obj; 164 const char *lpo_file; 165 int lpo_line; 166 uint16_t lpo_ref; 167 uint16_t lpo_cnt; 168 uint64_t lpo_acqtime; 169 uint64_t lpo_waittime; 170 u_int lpo_contest_locking; 171 }; 172 173 /* 174 * One lock_prof for each (file, line, lock object) triple. 175 */ 176 struct lock_prof { 177 SLIST_ENTRY(lock_prof) link; 178 struct lock_class *class; 179 const char *file; 180 const char *name; 181 int line; 182 int ticks; 183 uintmax_t cnt_wait_max; 184 uintmax_t cnt_max; 185 uintmax_t cnt_tot; 186 uintmax_t cnt_wait; 187 uintmax_t cnt_cur; 188 uintmax_t cnt_contest_locking; 189 }; 190 191 SLIST_HEAD(lphead, lock_prof); 192 193 #define LPROF_HASH_SIZE 4096 194 #define LPROF_HASH_MASK (LPROF_HASH_SIZE - 1) 195 #define LPROF_CACHE_SIZE 4096 196 197 /* 198 * Array of objects and profs for each type of object for each cpu. Spinlocks 199 * are handled separately because a thread may be preempted and acquire a 200 * spinlock while in the lock profiling code of a non-spinlock. In this way 201 * we only need a critical section to protect the per-cpu lists. 202 */ 203 struct lock_prof_type { 204 struct lphead lpt_lpalloc; 205 struct lpohead lpt_lpoalloc; 206 struct lphead lpt_hash[LPROF_HASH_SIZE]; 207 struct lock_prof lpt_prof[LPROF_CACHE_SIZE]; 208 struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE]; 209 }; 210 211 struct lock_prof_cpu { 212 struct lock_prof_type lpc_types[2]; /* One for spin one for other. */ 213 }; 214 215 struct lock_prof_cpu *lp_cpu[MAXCPU]; 216 217 volatile int lock_prof_enable = 0; 218 static volatile int lock_prof_resetting; 219 220 #define LPROF_SBUF_SIZE 256 221 222 static int lock_prof_rejected; 223 static int lock_prof_skipspin; 224 static int lock_prof_skipcount; 225 226 #ifndef USE_CPU_NANOSECONDS 227 uint64_t 228 nanoseconds(void) 229 { 230 struct bintime bt; 231 uint64_t ns; 232 233 binuptime(&bt); 234 /* From bintime2timespec */ 235 ns = bt.sec * (uint64_t)1000000000; 236 ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32; 237 return (ns); 238 } 239 #endif 240 241 static void 242 lock_prof_init_type(struct lock_prof_type *type) 243 { 244 int i; 245 246 SLIST_INIT(&type->lpt_lpalloc); 247 LIST_INIT(&type->lpt_lpoalloc); 248 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 249 SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i], 250 link); 251 LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i], 252 lpo_link); 253 } 254 } 255 256 static void 257 lock_prof_init(void *arg) 258 { 259 int cpu; 260 261 for (cpu = 0; cpu <= mp_maxid; cpu++) { 262 lp_cpu[cpu] = malloc(sizeof(*lp_cpu[cpu]), M_DEVBUF, 263 M_WAITOK | M_ZERO); 264 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[0]); 265 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[1]); 266 } 267 } 268 SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL); 269 270 static void 271 lock_prof_reset_wait(void) 272 { 273 274 /* 275 * Spin relinquishing our cpu so that quiesce_all_cpus may 276 * complete. 277 */ 278 while (lock_prof_resetting) 279 sched_relinquish(curthread); 280 } 281 282 static void 283 lock_prof_reset(void) 284 { 285 struct lock_prof_cpu *lpc; 286 int enabled, i, cpu; 287 288 /* 289 * We not only race with acquiring and releasing locks but also 290 * thread exit. To be certain that threads exit without valid head 291 * pointers they must see resetting set before enabled is cleared. 292 * Otherwise a lock may not be removed from a per-thread list due 293 * to disabled being set but not wait for reset() to remove it below. 294 */ 295 atomic_store_rel_int(&lock_prof_resetting, 1); 296 enabled = lock_prof_enable; 297 lock_prof_enable = 0; 298 quiesce_all_cpus("profreset", 0); 299 /* 300 * Some objects may have migrated between CPUs. Clear all links 301 * before we zero the structures. Some items may still be linked 302 * into per-thread lists as well. 303 */ 304 for (cpu = 0; cpu <= mp_maxid; cpu++) { 305 lpc = lp_cpu[cpu]; 306 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 307 LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link); 308 LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link); 309 } 310 } 311 for (cpu = 0; cpu <= mp_maxid; cpu++) { 312 lpc = lp_cpu[cpu]; 313 bzero(lpc, sizeof(*lpc)); 314 lock_prof_init_type(&lpc->lpc_types[0]); 315 lock_prof_init_type(&lpc->lpc_types[1]); 316 } 317 atomic_store_rel_int(&lock_prof_resetting, 0); 318 lock_prof_enable = enabled; 319 } 320 321 static void 322 lock_prof_output(struct lock_prof *lp, struct sbuf *sb) 323 { 324 const char *p; 325 326 for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3); 327 sbuf_printf(sb, 328 "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n", 329 lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000, 330 lp->cnt_wait / 1000, lp->cnt_cur, 331 lp->cnt_cur == 0 ? (uintmax_t)0 : 332 lp->cnt_tot / (lp->cnt_cur * 1000), 333 lp->cnt_cur == 0 ? (uintmax_t)0 : 334 lp->cnt_wait / (lp->cnt_cur * 1000), 335 (uintmax_t)0, lp->cnt_contest_locking, 336 p, lp->line, lp->class->lc_name, lp->name); 337 } 338 339 static void 340 lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash, 341 int spin, int t) 342 { 343 struct lock_prof_type *type; 344 struct lock_prof *l; 345 int cpu; 346 347 dst->file = match->file; 348 dst->line = match->line; 349 dst->class = match->class; 350 dst->name = match->name; 351 352 for (cpu = 0; cpu <= mp_maxid; cpu++) { 353 if (lp_cpu[cpu] == NULL) 354 continue; 355 type = &lp_cpu[cpu]->lpc_types[spin]; 356 SLIST_FOREACH(l, &type->lpt_hash[hash], link) { 357 if (l->ticks == t) 358 continue; 359 if (l->file != match->file || l->line != match->line || 360 l->name != match->name) 361 continue; 362 l->ticks = t; 363 if (l->cnt_max > dst->cnt_max) 364 dst->cnt_max = l->cnt_max; 365 if (l->cnt_wait_max > dst->cnt_wait_max) 366 dst->cnt_wait_max = l->cnt_wait_max; 367 dst->cnt_tot += l->cnt_tot; 368 dst->cnt_wait += l->cnt_wait; 369 dst->cnt_cur += l->cnt_cur; 370 dst->cnt_contest_locking += l->cnt_contest_locking; 371 } 372 } 373 374 } 375 376 static void 377 lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin, 378 int t) 379 { 380 struct lock_prof *l; 381 int i; 382 383 for (i = 0; i < LPROF_HASH_SIZE; ++i) { 384 SLIST_FOREACH(l, &type->lpt_hash[i], link) { 385 struct lock_prof lp = {}; 386 387 if (l->ticks == t) 388 continue; 389 lock_prof_sum(l, &lp, i, spin, t); 390 lock_prof_output(&lp, sb); 391 } 392 } 393 } 394 395 static int 396 dump_lock_prof_stats(SYSCTL_HANDLER_ARGS) 397 { 398 struct sbuf *sb; 399 int error, cpu, t; 400 int enabled; 401 402 error = sysctl_wire_old_buffer(req, 0); 403 if (error != 0) 404 return (error); 405 sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req); 406 sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n", 407 "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name"); 408 enabled = lock_prof_enable; 409 lock_prof_enable = 0; 410 quiesce_all_cpus("profstat", 0); 411 t = ticks; 412 for (cpu = 0; cpu <= mp_maxid; cpu++) { 413 if (lp_cpu[cpu] == NULL) 414 continue; 415 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t); 416 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t); 417 } 418 lock_prof_enable = enabled; 419 420 error = sbuf_finish(sb); 421 /* Output a trailing NUL. */ 422 if (error == 0) 423 error = SYSCTL_OUT(req, "", 1); 424 sbuf_delete(sb); 425 return (error); 426 } 427 428 static int 429 enable_lock_prof(SYSCTL_HANDLER_ARGS) 430 { 431 int error, v; 432 433 v = lock_prof_enable; 434 error = sysctl_handle_int(oidp, &v, v, req); 435 if (error) 436 return (error); 437 if (req->newptr == NULL) 438 return (error); 439 if (v == lock_prof_enable) 440 return (0); 441 if (v == 1) 442 lock_prof_reset(); 443 lock_prof_enable = !!v; 444 445 return (0); 446 } 447 448 static int 449 reset_lock_prof_stats(SYSCTL_HANDLER_ARGS) 450 { 451 int error, v; 452 453 v = 0; 454 error = sysctl_handle_int(oidp, &v, 0, req); 455 if (error) 456 return (error); 457 if (req->newptr == NULL) 458 return (error); 459 if (v == 0) 460 return (0); 461 lock_prof_reset(); 462 463 return (0); 464 } 465 466 static struct lock_prof * 467 lock_profile_lookup(struct lock_object *lo, int spin, const char *file, 468 int line) 469 { 470 const char *unknown = "(unknown)"; 471 struct lock_prof_type *type; 472 struct lock_prof *lp; 473 struct lphead *head; 474 const char *p; 475 u_int hash; 476 477 p = file; 478 if (p == NULL || *p == '\0') 479 p = unknown; 480 hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line; 481 hash &= LPROF_HASH_MASK; 482 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 483 head = &type->lpt_hash[hash]; 484 SLIST_FOREACH(lp, head, link) { 485 if (lp->line == line && lp->file == p && 486 lp->name == lo->lo_name) 487 return (lp); 488 489 } 490 lp = SLIST_FIRST(&type->lpt_lpalloc); 491 if (lp == NULL) { 492 lock_prof_rejected++; 493 return (lp); 494 } 495 SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link); 496 lp->file = p; 497 lp->line = line; 498 lp->class = LOCK_CLASS(lo); 499 lp->name = lo->lo_name; 500 SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link); 501 return (lp); 502 } 503 504 static struct lock_profile_object * 505 lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file, 506 int line) 507 { 508 struct lock_profile_object *l; 509 struct lock_prof_type *type; 510 struct lpohead *head; 511 512 head = &curthread->td_lprof[spin]; 513 LIST_FOREACH(l, head, lpo_link) 514 if (l->lpo_obj == lo && l->lpo_file == file && 515 l->lpo_line == line) 516 return (l); 517 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 518 l = LIST_FIRST(&type->lpt_lpoalloc); 519 if (l == NULL) { 520 lock_prof_rejected++; 521 return (NULL); 522 } 523 LIST_REMOVE(l, lpo_link); 524 l->lpo_obj = lo; 525 l->lpo_file = file; 526 l->lpo_line = line; 527 l->lpo_cnt = 0; 528 LIST_INSERT_HEAD(head, l, lpo_link); 529 530 return (l); 531 } 532 533 void 534 lock_profile_obtain_lock_success(struct lock_object *lo, int contested, 535 uint64_t waittime, const char *file, int line) 536 { 537 static int lock_prof_count; 538 struct lock_profile_object *l; 539 int spin; 540 541 if (SCHEDULER_STOPPED()) 542 return; 543 544 /* don't reset the timer when/if recursing */ 545 if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) 546 return; 547 if (lock_prof_skipcount && 548 (++lock_prof_count % lock_prof_skipcount) != 0) 549 return; 550 spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0; 551 if (spin && lock_prof_skipspin == 1) 552 return; 553 critical_enter(); 554 /* Recheck enabled now that we're in a critical section. */ 555 if (lock_prof_enable == 0) 556 goto out; 557 l = lock_profile_object_lookup(lo, spin, file, line); 558 if (l == NULL) 559 goto out; 560 l->lpo_cnt++; 561 if (++l->lpo_ref > 1) 562 goto out; 563 l->lpo_contest_locking = contested; 564 l->lpo_acqtime = nanoseconds(); 565 if (waittime && (l->lpo_acqtime > waittime)) 566 l->lpo_waittime = l->lpo_acqtime - waittime; 567 else 568 l->lpo_waittime = 0; 569 out: 570 critical_exit(); 571 } 572 573 void 574 lock_profile_thread_exit(struct thread *td) 575 { 576 #ifdef INVARIANTS 577 struct lock_profile_object *l; 578 579 MPASS(curthread->td_critnest == 0); 580 #endif 581 /* 582 * If lock profiling was disabled we have to wait for reset to 583 * clear our pointers before we can exit safely. 584 */ 585 lock_prof_reset_wait(); 586 #ifdef INVARIANTS 587 LIST_FOREACH(l, &td->td_lprof[0], lpo_link) 588 printf("thread still holds lock acquired at %s:%d\n", 589 l->lpo_file, l->lpo_line); 590 LIST_FOREACH(l, &td->td_lprof[1], lpo_link) 591 printf("thread still holds lock acquired at %s:%d\n", 592 l->lpo_file, l->lpo_line); 593 #endif 594 MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL); 595 MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL); 596 } 597 598 void 599 lock_profile_release_lock(struct lock_object *lo) 600 { 601 struct lock_profile_object *l; 602 struct lock_prof_type *type; 603 struct lock_prof *lp; 604 uint64_t curtime, holdtime; 605 struct lpohead *head; 606 int spin; 607 608 if (SCHEDULER_STOPPED()) 609 return; 610 if (lo->lo_flags & LO_NOPROFILE) 611 return; 612 spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0; 613 head = &curthread->td_lprof[spin]; 614 if (LIST_FIRST(head) == NULL) 615 return; 616 critical_enter(); 617 /* Recheck enabled now that we're in a critical section. */ 618 if (lock_prof_enable == 0 && lock_prof_resetting == 1) 619 goto out; 620 /* 621 * If lock profiling is not enabled we still want to remove the 622 * lpo from our queue. 623 */ 624 LIST_FOREACH(l, head, lpo_link) 625 if (l->lpo_obj == lo) 626 break; 627 if (l == NULL) 628 goto out; 629 if (--l->lpo_ref > 0) 630 goto out; 631 lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line); 632 if (lp == NULL) 633 goto release; 634 curtime = nanoseconds(); 635 if (curtime < l->lpo_acqtime) 636 goto release; 637 holdtime = curtime - l->lpo_acqtime; 638 639 /* 640 * Record if the lock has been held longer now than ever 641 * before. 642 */ 643 if (holdtime > lp->cnt_max) 644 lp->cnt_max = holdtime; 645 if (l->lpo_waittime > lp->cnt_wait_max) 646 lp->cnt_wait_max = l->lpo_waittime; 647 lp->cnt_tot += holdtime; 648 lp->cnt_wait += l->lpo_waittime; 649 lp->cnt_contest_locking += l->lpo_contest_locking; 650 lp->cnt_cur += l->lpo_cnt; 651 release: 652 LIST_REMOVE(l, lpo_link); 653 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 654 LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link); 655 out: 656 critical_exit(); 657 } 658 659 static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging"); 660 static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL, 661 "lock profiling"); 662 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW, 663 &lock_prof_skipspin, 0, "Skip profiling on spinlocks."); 664 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW, 665 &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions."); 666 SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD, 667 &lock_prof_rejected, 0, "Number of rejected profiling records"); 668 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD, 669 NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics"); 670 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW, 671 NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics"); 672 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW, 673 NULL, 0, enable_lock_prof, "I", "Enable lock profiling"); 674 675 #endif
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