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 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 /* 30 * This module holds the global variables and functions used to maintain 31 * lock_object structures. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD: releng/12.0/sys/kern/subr_lock.c 332285 2018-04-08 16:34:10Z mjg $"); 36 37 #include "opt_ddb.h" 38 #include "opt_mprof.h" 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/kernel.h> 43 #include <sys/ktr.h> 44 #include <sys/lock.h> 45 #include <sys/lock_profile.h> 46 #include <sys/malloc.h> 47 #include <sys/mutex.h> 48 #include <sys/pcpu.h> 49 #include <sys/proc.h> 50 #include <sys/sbuf.h> 51 #include <sys/sched.h> 52 #include <sys/smp.h> 53 #include <sys/sysctl.h> 54 55 #ifdef DDB 56 #include <ddb/ddb.h> 57 #endif 58 59 #include <machine/cpufunc.h> 60 61 SDT_PROVIDER_DEFINE(lock); 62 SDT_PROBE_DEFINE1(lock, , , starvation, "u_int"); 63 64 CTASSERT(LOCK_CLASS_MAX == 15); 65 66 struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = { 67 &lock_class_mtx_spin, 68 &lock_class_mtx_sleep, 69 &lock_class_sx, 70 &lock_class_rm, 71 &lock_class_rm_sleepable, 72 &lock_class_rw, 73 &lock_class_lockmgr, 74 }; 75 76 void 77 lock_init(struct lock_object *lock, struct lock_class *class, const char *name, 78 const char *type, int flags) 79 { 80 int i; 81 82 /* Check for double-init and zero object. */ 83 KASSERT(flags & LO_NEW || !lock_initialized(lock), 84 ("lock \"%s\" %p already initialized", name, lock)); 85 86 /* Look up lock class to find its index. */ 87 for (i = 0; i < LOCK_CLASS_MAX; i++) 88 if (lock_classes[i] == class) { 89 lock->lo_flags = i << LO_CLASSSHIFT; 90 break; 91 } 92 KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class)); 93 94 /* Initialize the lock object. */ 95 lock->lo_name = name; 96 lock->lo_flags |= flags | LO_INITIALIZED; 97 LOCK_LOG_INIT(lock, 0); 98 WITNESS_INIT(lock, (type != NULL) ? type : name); 99 } 100 101 void 102 lock_destroy(struct lock_object *lock) 103 { 104 105 KASSERT(lock_initialized(lock), ("lock %p is not initialized", lock)); 106 WITNESS_DESTROY(lock); 107 LOCK_LOG_DESTROY(lock, 0); 108 lock->lo_flags &= ~LO_INITIALIZED; 109 } 110 111 static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging"); 112 static SYSCTL_NODE(_debug_lock, OID_AUTO, delay, CTLFLAG_RD, NULL, 113 "lock delay"); 114 115 static u_int __read_mostly starvation_limit = 131072; 116 SYSCTL_INT(_debug_lock_delay, OID_AUTO, starvation_limit, CTLFLAG_RW, 117 &starvation_limit, 0, ""); 118 119 static u_int __read_mostly restrict_starvation = 0; 120 SYSCTL_INT(_debug_lock_delay, OID_AUTO, restrict_starvation, CTLFLAG_RW, 121 &restrict_starvation, 0, ""); 122 123 void 124 lock_delay(struct lock_delay_arg *la) 125 { 126 struct lock_delay_config *lc = la->config; 127 u_int i; 128 129 la->delay <<= 1; 130 if (__predict_false(la->delay > lc->max)) 131 la->delay = lc->max; 132 133 for (i = la->delay; i > 0; i--) 134 cpu_spinwait(); 135 136 la->spin_cnt += la->delay; 137 if (__predict_false(la->spin_cnt > starvation_limit)) { 138 SDT_PROBE1(lock, , , starvation, la->delay); 139 if (restrict_starvation) 140 la->delay = lc->base; 141 } 142 } 143 144 static u_int 145 lock_roundup_2(u_int val) 146 { 147 u_int res; 148 149 for (res = 1; res <= val; res <<= 1) 150 continue; 151 152 return (res); 153 } 154 155 void 156 lock_delay_default_init(struct lock_delay_config *lc) 157 { 158 159 lc->base = 1; 160 lc->max = lock_roundup_2(mp_ncpus) * 256; 161 if (lc->max > 32678) 162 lc->max = 32678; 163 } 164 165 #ifdef DDB 166 DB_SHOW_COMMAND(lock, db_show_lock) 167 { 168 struct lock_object *lock; 169 struct lock_class *class; 170 171 if (!have_addr) 172 return; 173 lock = (struct lock_object *)addr; 174 if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) { 175 db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock)); 176 return; 177 } 178 class = LOCK_CLASS(lock); 179 db_printf(" class: %s\n", class->lc_name); 180 db_printf(" name: %s\n", lock->lo_name); 181 class->lc_ddb_show(lock); 182 } 183 #endif 184 185 #ifdef LOCK_PROFILING 186 187 /* 188 * One object per-thread for each lock the thread owns. Tracks individual 189 * lock instances. 190 */ 191 struct lock_profile_object { 192 LIST_ENTRY(lock_profile_object) lpo_link; 193 struct lock_object *lpo_obj; 194 const char *lpo_file; 195 int lpo_line; 196 uint16_t lpo_ref; 197 uint16_t lpo_cnt; 198 uint64_t lpo_acqtime; 199 uint64_t lpo_waittime; 200 u_int lpo_contest_locking; 201 }; 202 203 /* 204 * One lock_prof for each (file, line, lock object) triple. 205 */ 206 struct lock_prof { 207 SLIST_ENTRY(lock_prof) link; 208 struct lock_class *class; 209 const char *file; 210 const char *name; 211 int line; 212 int ticks; 213 uintmax_t cnt_wait_max; 214 uintmax_t cnt_max; 215 uintmax_t cnt_tot; 216 uintmax_t cnt_wait; 217 uintmax_t cnt_cur; 218 uintmax_t cnt_contest_locking; 219 }; 220 221 SLIST_HEAD(lphead, lock_prof); 222 223 #define LPROF_HASH_SIZE 4096 224 #define LPROF_HASH_MASK (LPROF_HASH_SIZE - 1) 225 #define LPROF_CACHE_SIZE 4096 226 227 /* 228 * Array of objects and profs for each type of object for each cpu. Spinlocks 229 * are handled separately because a thread may be preempted and acquire a 230 * spinlock while in the lock profiling code of a non-spinlock. In this way 231 * we only need a critical section to protect the per-cpu lists. 232 */ 233 struct lock_prof_type { 234 struct lphead lpt_lpalloc; 235 struct lpohead lpt_lpoalloc; 236 struct lphead lpt_hash[LPROF_HASH_SIZE]; 237 struct lock_prof lpt_prof[LPROF_CACHE_SIZE]; 238 struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE]; 239 }; 240 241 struct lock_prof_cpu { 242 struct lock_prof_type lpc_types[2]; /* One for spin one for other. */ 243 }; 244 245 struct lock_prof_cpu *lp_cpu[MAXCPU]; 246 247 volatile int __read_mostly lock_prof_enable; 248 static volatile int lock_prof_resetting; 249 250 #define LPROF_SBUF_SIZE 256 251 252 static int lock_prof_rejected; 253 static int lock_prof_skipspin; 254 static int lock_prof_skipcount; 255 256 #ifndef USE_CPU_NANOSECONDS 257 uint64_t 258 nanoseconds(void) 259 { 260 struct bintime bt; 261 uint64_t ns; 262 263 binuptime(&bt); 264 /* From bintime2timespec */ 265 ns = bt.sec * (uint64_t)1000000000; 266 ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32; 267 return (ns); 268 } 269 #endif 270 271 static void 272 lock_prof_init_type(struct lock_prof_type *type) 273 { 274 int i; 275 276 SLIST_INIT(&type->lpt_lpalloc); 277 LIST_INIT(&type->lpt_lpoalloc); 278 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 279 SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i], 280 link); 281 LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i], 282 lpo_link); 283 } 284 } 285 286 static void 287 lock_prof_init(void *arg) 288 { 289 int cpu; 290 291 for (cpu = 0; cpu <= mp_maxid; cpu++) { 292 lp_cpu[cpu] = malloc(sizeof(*lp_cpu[cpu]), M_DEVBUF, 293 M_WAITOK | M_ZERO); 294 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[0]); 295 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[1]); 296 } 297 } 298 SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL); 299 300 static void 301 lock_prof_reset_wait(void) 302 { 303 304 /* 305 * Spin relinquishing our cpu so that quiesce_all_cpus may 306 * complete. 307 */ 308 while (lock_prof_resetting) 309 sched_relinquish(curthread); 310 } 311 312 static void 313 lock_prof_reset(void) 314 { 315 struct lock_prof_cpu *lpc; 316 int enabled, i, cpu; 317 318 /* 319 * We not only race with acquiring and releasing locks but also 320 * thread exit. To be certain that threads exit without valid head 321 * pointers they must see resetting set before enabled is cleared. 322 * Otherwise a lock may not be removed from a per-thread list due 323 * to disabled being set but not wait for reset() to remove it below. 324 */ 325 atomic_store_rel_int(&lock_prof_resetting, 1); 326 enabled = lock_prof_enable; 327 lock_prof_enable = 0; 328 quiesce_all_cpus("profreset", 0); 329 /* 330 * Some objects may have migrated between CPUs. Clear all links 331 * before we zero the structures. Some items may still be linked 332 * into per-thread lists as well. 333 */ 334 for (cpu = 0; cpu <= mp_maxid; cpu++) { 335 lpc = lp_cpu[cpu]; 336 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 337 LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link); 338 LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link); 339 } 340 } 341 for (cpu = 0; cpu <= mp_maxid; cpu++) { 342 lpc = lp_cpu[cpu]; 343 bzero(lpc, sizeof(*lpc)); 344 lock_prof_init_type(&lpc->lpc_types[0]); 345 lock_prof_init_type(&lpc->lpc_types[1]); 346 } 347 atomic_store_rel_int(&lock_prof_resetting, 0); 348 lock_prof_enable = enabled; 349 } 350 351 static void 352 lock_prof_output(struct lock_prof *lp, struct sbuf *sb) 353 { 354 const char *p; 355 356 for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3); 357 sbuf_printf(sb, 358 "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n", 359 lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000, 360 lp->cnt_wait / 1000, lp->cnt_cur, 361 lp->cnt_cur == 0 ? (uintmax_t)0 : 362 lp->cnt_tot / (lp->cnt_cur * 1000), 363 lp->cnt_cur == 0 ? (uintmax_t)0 : 364 lp->cnt_wait / (lp->cnt_cur * 1000), 365 (uintmax_t)0, lp->cnt_contest_locking, 366 p, lp->line, lp->class->lc_name, lp->name); 367 } 368 369 static void 370 lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash, 371 int spin, int t) 372 { 373 struct lock_prof_type *type; 374 struct lock_prof *l; 375 int cpu; 376 377 dst->file = match->file; 378 dst->line = match->line; 379 dst->class = match->class; 380 dst->name = match->name; 381 382 for (cpu = 0; cpu <= mp_maxid; cpu++) { 383 if (lp_cpu[cpu] == NULL) 384 continue; 385 type = &lp_cpu[cpu]->lpc_types[spin]; 386 SLIST_FOREACH(l, &type->lpt_hash[hash], link) { 387 if (l->ticks == t) 388 continue; 389 if (l->file != match->file || l->line != match->line || 390 l->name != match->name) 391 continue; 392 l->ticks = t; 393 if (l->cnt_max > dst->cnt_max) 394 dst->cnt_max = l->cnt_max; 395 if (l->cnt_wait_max > dst->cnt_wait_max) 396 dst->cnt_wait_max = l->cnt_wait_max; 397 dst->cnt_tot += l->cnt_tot; 398 dst->cnt_wait += l->cnt_wait; 399 dst->cnt_cur += l->cnt_cur; 400 dst->cnt_contest_locking += l->cnt_contest_locking; 401 } 402 } 403 404 } 405 406 static void 407 lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin, 408 int t) 409 { 410 struct lock_prof *l; 411 int i; 412 413 for (i = 0; i < LPROF_HASH_SIZE; ++i) { 414 SLIST_FOREACH(l, &type->lpt_hash[i], link) { 415 struct lock_prof lp = {}; 416 417 if (l->ticks == t) 418 continue; 419 lock_prof_sum(l, &lp, i, spin, t); 420 lock_prof_output(&lp, sb); 421 } 422 } 423 } 424 425 static int 426 dump_lock_prof_stats(SYSCTL_HANDLER_ARGS) 427 { 428 struct sbuf *sb; 429 int error, cpu, t; 430 int enabled; 431 432 error = sysctl_wire_old_buffer(req, 0); 433 if (error != 0) 434 return (error); 435 sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req); 436 sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n", 437 "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name"); 438 enabled = lock_prof_enable; 439 lock_prof_enable = 0; 440 quiesce_all_cpus("profstat", 0); 441 t = ticks; 442 for (cpu = 0; cpu <= mp_maxid; cpu++) { 443 if (lp_cpu[cpu] == NULL) 444 continue; 445 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t); 446 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t); 447 } 448 lock_prof_enable = enabled; 449 450 error = sbuf_finish(sb); 451 /* Output a trailing NUL. */ 452 if (error == 0) 453 error = SYSCTL_OUT(req, "", 1); 454 sbuf_delete(sb); 455 return (error); 456 } 457 458 static int 459 enable_lock_prof(SYSCTL_HANDLER_ARGS) 460 { 461 int error, v; 462 463 v = lock_prof_enable; 464 error = sysctl_handle_int(oidp, &v, v, req); 465 if (error) 466 return (error); 467 if (req->newptr == NULL) 468 return (error); 469 if (v == lock_prof_enable) 470 return (0); 471 if (v == 1) 472 lock_prof_reset(); 473 lock_prof_enable = !!v; 474 475 return (0); 476 } 477 478 static int 479 reset_lock_prof_stats(SYSCTL_HANDLER_ARGS) 480 { 481 int error, v; 482 483 v = 0; 484 error = sysctl_handle_int(oidp, &v, 0, req); 485 if (error) 486 return (error); 487 if (req->newptr == NULL) 488 return (error); 489 if (v == 0) 490 return (0); 491 lock_prof_reset(); 492 493 return (0); 494 } 495 496 static struct lock_prof * 497 lock_profile_lookup(struct lock_object *lo, int spin, const char *file, 498 int line) 499 { 500 const char *unknown = "(unknown)"; 501 struct lock_prof_type *type; 502 struct lock_prof *lp; 503 struct lphead *head; 504 const char *p; 505 u_int hash; 506 507 p = file; 508 if (p == NULL || *p == '\0') 509 p = unknown; 510 hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line; 511 hash &= LPROF_HASH_MASK; 512 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 513 head = &type->lpt_hash[hash]; 514 SLIST_FOREACH(lp, head, link) { 515 if (lp->line == line && lp->file == p && 516 lp->name == lo->lo_name) 517 return (lp); 518 519 } 520 lp = SLIST_FIRST(&type->lpt_lpalloc); 521 if (lp == NULL) { 522 lock_prof_rejected++; 523 return (lp); 524 } 525 SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link); 526 lp->file = p; 527 lp->line = line; 528 lp->class = LOCK_CLASS(lo); 529 lp->name = lo->lo_name; 530 SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link); 531 return (lp); 532 } 533 534 static struct lock_profile_object * 535 lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file, 536 int line) 537 { 538 struct lock_profile_object *l; 539 struct lock_prof_type *type; 540 struct lpohead *head; 541 542 head = &curthread->td_lprof[spin]; 543 LIST_FOREACH(l, head, lpo_link) 544 if (l->lpo_obj == lo && l->lpo_file == file && 545 l->lpo_line == line) 546 return (l); 547 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 548 l = LIST_FIRST(&type->lpt_lpoalloc); 549 if (l == NULL) { 550 lock_prof_rejected++; 551 return (NULL); 552 } 553 LIST_REMOVE(l, lpo_link); 554 l->lpo_obj = lo; 555 l->lpo_file = file; 556 l->lpo_line = line; 557 l->lpo_cnt = 0; 558 LIST_INSERT_HEAD(head, l, lpo_link); 559 560 return (l); 561 } 562 563 void 564 lock_profile_obtain_lock_success(struct lock_object *lo, int contested, 565 uint64_t waittime, const char *file, int line) 566 { 567 static int lock_prof_count; 568 struct lock_profile_object *l; 569 int spin; 570 571 if (SCHEDULER_STOPPED()) 572 return; 573 574 /* don't reset the timer when/if recursing */ 575 if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) 576 return; 577 if (lock_prof_skipcount && 578 (++lock_prof_count % lock_prof_skipcount) != 0) 579 return; 580 spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0; 581 if (spin && lock_prof_skipspin == 1) 582 return; 583 critical_enter(); 584 /* Recheck enabled now that we're in a critical section. */ 585 if (lock_prof_enable == 0) 586 goto out; 587 l = lock_profile_object_lookup(lo, spin, file, line); 588 if (l == NULL) 589 goto out; 590 l->lpo_cnt++; 591 if (++l->lpo_ref > 1) 592 goto out; 593 l->lpo_contest_locking = contested; 594 l->lpo_acqtime = nanoseconds(); 595 if (waittime && (l->lpo_acqtime > waittime)) 596 l->lpo_waittime = l->lpo_acqtime - waittime; 597 else 598 l->lpo_waittime = 0; 599 out: 600 critical_exit(); 601 } 602 603 void 604 lock_profile_thread_exit(struct thread *td) 605 { 606 #ifdef INVARIANTS 607 struct lock_profile_object *l; 608 609 MPASS(curthread->td_critnest == 0); 610 #endif 611 /* 612 * If lock profiling was disabled we have to wait for reset to 613 * clear our pointers before we can exit safely. 614 */ 615 lock_prof_reset_wait(); 616 #ifdef INVARIANTS 617 LIST_FOREACH(l, &td->td_lprof[0], lpo_link) 618 printf("thread still holds lock acquired at %s:%d\n", 619 l->lpo_file, l->lpo_line); 620 LIST_FOREACH(l, &td->td_lprof[1], lpo_link) 621 printf("thread still holds lock acquired at %s:%d\n", 622 l->lpo_file, l->lpo_line); 623 #endif 624 MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL); 625 MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL); 626 } 627 628 void 629 lock_profile_release_lock(struct lock_object *lo) 630 { 631 struct lock_profile_object *l; 632 struct lock_prof_type *type; 633 struct lock_prof *lp; 634 uint64_t curtime, holdtime; 635 struct lpohead *head; 636 int spin; 637 638 if (SCHEDULER_STOPPED()) 639 return; 640 if (lo->lo_flags & LO_NOPROFILE) 641 return; 642 spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0; 643 head = &curthread->td_lprof[spin]; 644 if (LIST_FIRST(head) == NULL) 645 return; 646 critical_enter(); 647 /* Recheck enabled now that we're in a critical section. */ 648 if (lock_prof_enable == 0 && lock_prof_resetting == 1) 649 goto out; 650 /* 651 * If lock profiling is not enabled we still want to remove the 652 * lpo from our queue. 653 */ 654 LIST_FOREACH(l, head, lpo_link) 655 if (l->lpo_obj == lo) 656 break; 657 if (l == NULL) 658 goto out; 659 if (--l->lpo_ref > 0) 660 goto out; 661 lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line); 662 if (lp == NULL) 663 goto release; 664 curtime = nanoseconds(); 665 if (curtime < l->lpo_acqtime) 666 goto release; 667 holdtime = curtime - l->lpo_acqtime; 668 669 /* 670 * Record if the lock has been held longer now than ever 671 * before. 672 */ 673 if (holdtime > lp->cnt_max) 674 lp->cnt_max = holdtime; 675 if (l->lpo_waittime > lp->cnt_wait_max) 676 lp->cnt_wait_max = l->lpo_waittime; 677 lp->cnt_tot += holdtime; 678 lp->cnt_wait += l->lpo_waittime; 679 lp->cnt_contest_locking += l->lpo_contest_locking; 680 lp->cnt_cur += l->lpo_cnt; 681 release: 682 LIST_REMOVE(l, lpo_link); 683 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 684 LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link); 685 out: 686 critical_exit(); 687 } 688 689 static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL, 690 "lock profiling"); 691 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW, 692 &lock_prof_skipspin, 0, "Skip profiling on spinlocks."); 693 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW, 694 &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions."); 695 SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD, 696 &lock_prof_rejected, 0, "Number of rejected profiling records"); 697 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD, 698 NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics"); 699 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW, 700 NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics"); 701 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW, 702 NULL, 0, enable_lock_prof, "I", "Enable lock profiling"); 703 704 #endif
Cache object: ca3371ab9e2c95e14211ef5c1ae3bd46
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