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 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 /* 29 * This module holds the global variables and functions used to maintain 30 * lock_object structures. 31 */ 32 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include "opt_ddb.h" 37 #include "opt_mprof.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/kernel.h> 42 #include <sys/ktr.h> 43 #include <sys/lock.h> 44 #include <sys/lock_profile.h> 45 #include <sys/malloc.h> 46 #include <sys/mutex.h> 47 #include <sys/pcpu.h> 48 #include <sys/proc.h> 49 #include <sys/sbuf.h> 50 #include <sys/sched.h> 51 #include <sys/smp.h> 52 #include <sys/sysctl.h> 53 54 #ifdef DDB 55 #include <ddb/ddb.h> 56 #endif 57 58 #include <machine/cpufunc.h> 59 60 /* 61 * Uncomment to validate that spin argument to acquire/release routines matches 62 * the flag in the lock 63 */ 64 //#define LOCK_PROFILING_DEBUG_SPIN 65 66 SDT_PROVIDER_DEFINE(lock); 67 SDT_PROBE_DEFINE1(lock, , , starvation, "u_int"); 68 69 CTASSERT(LOCK_CLASS_MAX == 15); 70 71 struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = { 72 &lock_class_mtx_spin, 73 &lock_class_mtx_sleep, 74 &lock_class_sx, 75 &lock_class_rm, 76 &lock_class_rm_sleepable, 77 &lock_class_rw, 78 &lock_class_lockmgr, 79 }; 80 81 void 82 lock_init(struct lock_object *lock, struct lock_class *class, const char *name, 83 const char *type, int flags) 84 { 85 int i; 86 87 /* Check for double-init and zero object. */ 88 KASSERT(flags & LO_NEW || !lock_initialized(lock), 89 ("lock \"%s\" %p already initialized", name, lock)); 90 91 /* Look up lock class to find its index. */ 92 for (i = 0; i < LOCK_CLASS_MAX; i++) 93 if (lock_classes[i] == class) { 94 lock->lo_flags = i << LO_CLASSSHIFT; 95 break; 96 } 97 KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class)); 98 99 /* Initialize the lock object. */ 100 lock->lo_name = name; 101 lock->lo_flags |= flags | LO_INITIALIZED; 102 LOCK_LOG_INIT(lock, 0); 103 WITNESS_INIT(lock, (type != NULL) ? type : name); 104 } 105 106 void 107 lock_destroy(struct lock_object *lock) 108 { 109 110 KASSERT(lock_initialized(lock), ("lock %p is not initialized", lock)); 111 WITNESS_DESTROY(lock); 112 LOCK_LOG_DESTROY(lock, 0); 113 lock->lo_flags &= ~LO_INITIALIZED; 114 } 115 116 static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 117 "lock debugging"); 118 static SYSCTL_NODE(_debug_lock, OID_AUTO, delay, 119 CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 120 "lock delay"); 121 122 static u_int __read_mostly starvation_limit = 131072; 123 SYSCTL_INT(_debug_lock_delay, OID_AUTO, starvation_limit, CTLFLAG_RW, 124 &starvation_limit, 0, ""); 125 126 static u_int __read_mostly restrict_starvation = 0; 127 SYSCTL_INT(_debug_lock_delay, OID_AUTO, restrict_starvation, CTLFLAG_RW, 128 &restrict_starvation, 0, ""); 129 130 void 131 lock_delay(struct lock_delay_arg *la) 132 { 133 struct lock_delay_config *lc = la->config; 134 u_short i; 135 136 la->delay <<= 1; 137 if (__predict_false(la->delay > lc->max)) 138 la->delay = lc->max; 139 140 for (i = la->delay; i > 0; i--) 141 cpu_spinwait(); 142 143 la->spin_cnt += la->delay; 144 if (__predict_false(la->spin_cnt > starvation_limit)) { 145 SDT_PROBE1(lock, , , starvation, la->delay); 146 if (restrict_starvation) 147 la->delay = lc->base; 148 } 149 } 150 151 static u_int 152 lock_roundup_2(u_int val) 153 { 154 u_int res; 155 156 for (res = 1; res <= val; res <<= 1) 157 continue; 158 159 return (res); 160 } 161 162 void 163 lock_delay_default_init(struct lock_delay_config *lc) 164 { 165 166 lc->base = 1; 167 lc->max = lock_roundup_2(mp_ncpus) * 256; 168 if (lc->max > 32678) 169 lc->max = 32678; 170 } 171 172 struct lock_delay_config __read_frequently locks_delay; 173 u_short __read_frequently locks_delay_retries; 174 u_short __read_frequently locks_delay_loops; 175 176 SYSCTL_U16(_debug_lock, OID_AUTO, delay_base, CTLFLAG_RW, &locks_delay.base, 177 0, ""); 178 SYSCTL_U16(_debug_lock, OID_AUTO, delay_max, CTLFLAG_RW, &locks_delay.max, 179 0, ""); 180 SYSCTL_U16(_debug_lock, OID_AUTO, delay_retries, CTLFLAG_RW, &locks_delay_retries, 181 0, ""); 182 SYSCTL_U16(_debug_lock, OID_AUTO, delay_loops, CTLFLAG_RW, &locks_delay_loops, 183 0, ""); 184 185 static void 186 locks_delay_init(void *arg __unused) 187 { 188 189 lock_delay_default_init(&locks_delay); 190 locks_delay_retries = 10; 191 locks_delay_loops = max(10000, locks_delay.max); 192 } 193 LOCK_DELAY_SYSINIT(locks_delay_init); 194 195 #ifdef DDB 196 DB_SHOW_COMMAND(lock, db_show_lock) 197 { 198 struct lock_object *lock; 199 struct lock_class *class; 200 201 if (!have_addr) 202 return; 203 lock = (struct lock_object *)addr; 204 if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) { 205 db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock)); 206 return; 207 } 208 class = LOCK_CLASS(lock); 209 db_printf(" class: %s\n", class->lc_name); 210 db_printf(" name: %s\n", lock->lo_name); 211 class->lc_ddb_show(lock); 212 } 213 #endif 214 215 #ifdef LOCK_PROFILING 216 217 /* 218 * One object per-thread for each lock the thread owns. Tracks individual 219 * lock instances. 220 */ 221 struct lock_profile_object { 222 LIST_ENTRY(lock_profile_object) lpo_link; 223 struct lock_object *lpo_obj; 224 const char *lpo_file; 225 int lpo_line; 226 uint16_t lpo_ref; 227 uint16_t lpo_cnt; 228 uint64_t lpo_acqtime; 229 uint64_t lpo_waittime; 230 u_int lpo_contest_locking; 231 }; 232 233 /* 234 * One lock_prof for each (file, line, lock object) triple. 235 */ 236 struct lock_prof { 237 SLIST_ENTRY(lock_prof) link; 238 struct lock_class *class; 239 const char *file; 240 const char *name; 241 int line; 242 int ticks; 243 uintmax_t cnt_wait_max; 244 uintmax_t cnt_max; 245 uintmax_t cnt_tot; 246 uintmax_t cnt_wait; 247 uintmax_t cnt_cur; 248 uintmax_t cnt_contest_locking; 249 }; 250 251 SLIST_HEAD(lphead, lock_prof); 252 253 #define LPROF_HASH_SIZE 4096 254 #define LPROF_HASH_MASK (LPROF_HASH_SIZE - 1) 255 #define LPROF_CACHE_SIZE 4096 256 257 /* 258 * Array of objects and profs for each type of object for each cpu. Spinlocks 259 * are handled separately because a thread may be preempted and acquire a 260 * spinlock while in the lock profiling code of a non-spinlock. In this way 261 * we only need a critical section to protect the per-cpu lists. 262 */ 263 struct lock_prof_type { 264 struct lphead lpt_lpalloc; 265 struct lpohead lpt_lpoalloc; 266 struct lphead lpt_hash[LPROF_HASH_SIZE]; 267 struct lock_prof lpt_prof[LPROF_CACHE_SIZE]; 268 struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE]; 269 }; 270 271 struct lock_prof_cpu { 272 struct lock_prof_type lpc_types[2]; /* One for spin one for other. */ 273 }; 274 275 DPCPU_DEFINE_STATIC(struct lock_prof_cpu, lp); 276 #define LP_CPU_SELF (DPCPU_PTR(lp)) 277 #define LP_CPU(cpu) (DPCPU_ID_PTR((cpu), lp)) 278 279 volatile int __read_mostly lock_prof_enable; 280 int __read_mostly lock_contested_only; 281 static volatile int lock_prof_resetting; 282 283 #define LPROF_SBUF_SIZE 256 284 285 static int lock_prof_rejected; 286 static int lock_prof_skipspin; 287 288 #ifndef USE_CPU_NANOSECONDS 289 uint64_t 290 nanoseconds(void) 291 { 292 struct bintime bt; 293 uint64_t ns; 294 295 binuptime(&bt); 296 /* From bintime2timespec */ 297 ns = bt.sec * (uint64_t)1000000000; 298 ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32; 299 return (ns); 300 } 301 #endif 302 303 static void 304 lock_prof_init_type(struct lock_prof_type *type) 305 { 306 int i; 307 308 SLIST_INIT(&type->lpt_lpalloc); 309 LIST_INIT(&type->lpt_lpoalloc); 310 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 311 SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i], 312 link); 313 LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i], 314 lpo_link); 315 } 316 } 317 318 static void 319 lock_prof_init(void *arg) 320 { 321 int cpu; 322 323 CPU_FOREACH(cpu) { 324 lock_prof_init_type(&LP_CPU(cpu)->lpc_types[0]); 325 lock_prof_init_type(&LP_CPU(cpu)->lpc_types[1]); 326 } 327 } 328 SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL); 329 330 static void 331 lock_prof_reset_wait(void) 332 { 333 334 /* 335 * Spin relinquishing our cpu so that quiesce_all_cpus may 336 * complete. 337 */ 338 while (lock_prof_resetting) 339 sched_relinquish(curthread); 340 } 341 342 static void 343 lock_prof_reset(void) 344 { 345 struct lock_prof_cpu *lpc; 346 int enabled, i, cpu; 347 348 /* 349 * We not only race with acquiring and releasing locks but also 350 * thread exit. To be certain that threads exit without valid head 351 * pointers they must see resetting set before enabled is cleared. 352 * Otherwise a lock may not be removed from a per-thread list due 353 * to disabled being set but not wait for reset() to remove it below. 354 */ 355 atomic_store_rel_int(&lock_prof_resetting, 1); 356 enabled = lock_prof_enable; 357 lock_prof_enable = 0; 358 /* 359 * This both publishes lock_prof_enable as disabled and makes sure 360 * everyone else reads it if they are not far enough. We wait for the 361 * rest down below. 362 */ 363 cpus_fence_seq_cst(); 364 quiesce_all_critical(); 365 /* 366 * Some objects may have migrated between CPUs. Clear all links 367 * before we zero the structures. Some items may still be linked 368 * into per-thread lists as well. 369 */ 370 CPU_FOREACH(cpu) { 371 lpc = LP_CPU(cpu); 372 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 373 LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link); 374 LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link); 375 } 376 } 377 CPU_FOREACH(cpu) { 378 lpc = LP_CPU(cpu); 379 bzero(lpc, sizeof(*lpc)); 380 lock_prof_init_type(&lpc->lpc_types[0]); 381 lock_prof_init_type(&lpc->lpc_types[1]); 382 } 383 /* 384 * Paired with the fence from cpus_fence_seq_cst() 385 */ 386 atomic_store_rel_int(&lock_prof_resetting, 0); 387 lock_prof_enable = enabled; 388 } 389 390 static void 391 lock_prof_output(struct lock_prof *lp, struct sbuf *sb) 392 { 393 const char *p; 394 395 for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3); 396 sbuf_printf(sb, 397 "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n", 398 lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000, 399 lp->cnt_wait / 1000, lp->cnt_cur, 400 lp->cnt_cur == 0 ? (uintmax_t)0 : 401 lp->cnt_tot / (lp->cnt_cur * 1000), 402 lp->cnt_cur == 0 ? (uintmax_t)0 : 403 lp->cnt_wait / (lp->cnt_cur * 1000), 404 (uintmax_t)0, lp->cnt_contest_locking, 405 p, lp->line, lp->class->lc_name, lp->name); 406 } 407 408 static void 409 lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash, 410 int spin, int t) 411 { 412 struct lock_prof_type *type; 413 struct lock_prof *l; 414 int cpu; 415 416 dst->file = match->file; 417 dst->line = match->line; 418 dst->class = match->class; 419 dst->name = match->name; 420 421 CPU_FOREACH(cpu) { 422 type = &LP_CPU(cpu)->lpc_types[spin]; 423 SLIST_FOREACH(l, &type->lpt_hash[hash], link) { 424 if (l->ticks == t) 425 continue; 426 if (l->file != match->file || l->line != match->line || 427 l->name != match->name) 428 continue; 429 l->ticks = t; 430 if (l->cnt_max > dst->cnt_max) 431 dst->cnt_max = l->cnt_max; 432 if (l->cnt_wait_max > dst->cnt_wait_max) 433 dst->cnt_wait_max = l->cnt_wait_max; 434 dst->cnt_tot += l->cnt_tot; 435 dst->cnt_wait += l->cnt_wait; 436 dst->cnt_cur += l->cnt_cur; 437 dst->cnt_contest_locking += l->cnt_contest_locking; 438 } 439 } 440 } 441 442 static void 443 lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin, 444 int t) 445 { 446 struct lock_prof *l; 447 int i; 448 449 for (i = 0; i < LPROF_HASH_SIZE; ++i) { 450 SLIST_FOREACH(l, &type->lpt_hash[i], link) { 451 struct lock_prof lp = {}; 452 453 if (l->ticks == t) 454 continue; 455 lock_prof_sum(l, &lp, i, spin, t); 456 lock_prof_output(&lp, sb); 457 } 458 } 459 } 460 461 static int 462 dump_lock_prof_stats(SYSCTL_HANDLER_ARGS) 463 { 464 struct sbuf *sb; 465 int error, cpu, t; 466 int enabled; 467 468 error = sysctl_wire_old_buffer(req, 0); 469 if (error != 0) 470 return (error); 471 sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req); 472 sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n", 473 "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name"); 474 enabled = lock_prof_enable; 475 lock_prof_enable = 0; 476 /* 477 * See the comment in lock_prof_reset 478 */ 479 cpus_fence_seq_cst(); 480 quiesce_all_critical(); 481 t = ticks; 482 CPU_FOREACH(cpu) { 483 lock_prof_type_stats(&LP_CPU(cpu)->lpc_types[0], sb, 0, t); 484 lock_prof_type_stats(&LP_CPU(cpu)->lpc_types[1], sb, 1, t); 485 } 486 atomic_thread_fence_rel(); 487 lock_prof_enable = enabled; 488 489 error = sbuf_finish(sb); 490 /* Output a trailing NUL. */ 491 if (error == 0) 492 error = SYSCTL_OUT(req, "", 1); 493 sbuf_delete(sb); 494 return (error); 495 } 496 497 static int 498 enable_lock_prof(SYSCTL_HANDLER_ARGS) 499 { 500 int error, v; 501 502 v = lock_prof_enable; 503 error = sysctl_handle_int(oidp, &v, v, req); 504 if (error) 505 return (error); 506 if (req->newptr == NULL) 507 return (error); 508 if (v == lock_prof_enable) 509 return (0); 510 if (v == 1) 511 lock_prof_reset(); 512 lock_prof_enable = !!v; 513 514 return (0); 515 } 516 517 static int 518 reset_lock_prof_stats(SYSCTL_HANDLER_ARGS) 519 { 520 int error, v; 521 522 v = 0; 523 error = sysctl_handle_int(oidp, &v, 0, req); 524 if (error) 525 return (error); 526 if (req->newptr == NULL) 527 return (error); 528 if (v == 0) 529 return (0); 530 lock_prof_reset(); 531 532 return (0); 533 } 534 535 static struct lock_prof * 536 lock_profile_lookup(struct lock_object *lo, int spin, const char *file, 537 int line) 538 { 539 const char *unknown = "(unknown)"; 540 struct lock_prof_type *type; 541 struct lock_prof *lp; 542 struct lphead *head; 543 const char *p; 544 u_int hash; 545 546 p = file; 547 if (p == NULL || *p == '\0') 548 p = unknown; 549 hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line; 550 hash &= LPROF_HASH_MASK; 551 type = &LP_CPU_SELF->lpc_types[spin]; 552 head = &type->lpt_hash[hash]; 553 SLIST_FOREACH(lp, head, link) { 554 if (lp->line == line && lp->file == p && 555 lp->name == lo->lo_name) 556 return (lp); 557 } 558 lp = SLIST_FIRST(&type->lpt_lpalloc); 559 if (lp == NULL) { 560 lock_prof_rejected++; 561 return (lp); 562 } 563 SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link); 564 lp->file = p; 565 lp->line = line; 566 lp->class = LOCK_CLASS(lo); 567 lp->name = lo->lo_name; 568 SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link); 569 return (lp); 570 } 571 572 static struct lock_profile_object * 573 lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file, 574 int line) 575 { 576 struct lock_profile_object *l; 577 struct lock_prof_type *type; 578 struct lpohead *head; 579 580 head = &curthread->td_lprof[spin]; 581 LIST_FOREACH(l, head, lpo_link) 582 if (l->lpo_obj == lo && l->lpo_file == file && 583 l->lpo_line == line) 584 return (l); 585 type = &LP_CPU_SELF->lpc_types[spin]; 586 l = LIST_FIRST(&type->lpt_lpoalloc); 587 if (l == NULL) { 588 lock_prof_rejected++; 589 return (NULL); 590 } 591 LIST_REMOVE(l, lpo_link); 592 l->lpo_obj = lo; 593 l->lpo_file = file; 594 l->lpo_line = line; 595 l->lpo_cnt = 0; 596 LIST_INSERT_HEAD(head, l, lpo_link); 597 598 return (l); 599 } 600 601 void 602 lock_profile_obtain_lock_success(struct lock_object *lo, bool spin, 603 int contested, uint64_t waittime, const char *file, int line) 604 { 605 struct lock_profile_object *l; 606 607 #ifdef LOCK_PROFILING_DEBUG_SPIN 608 bool is_spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK); 609 if ((spin && !is_spin) || (!spin && is_spin)) 610 printf("%s: lock %s spin mismatch (arg %d, flag %d)\n", __func__, 611 lo->lo_name, spin, is_spin); 612 #endif 613 614 /* don't reset the timer when/if recursing */ 615 if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) 616 return; 617 if (lock_contested_only && !contested) 618 return; 619 if (spin && lock_prof_skipspin == 1) 620 return; 621 622 if (SCHEDULER_STOPPED()) 623 return; 624 625 critical_enter(); 626 /* Recheck enabled now that we're in a critical section. */ 627 if (lock_prof_enable == 0) 628 goto out; 629 l = lock_profile_object_lookup(lo, spin, file, line); 630 if (l == NULL) 631 goto out; 632 l->lpo_cnt++; 633 if (++l->lpo_ref > 1) 634 goto out; 635 l->lpo_contest_locking = contested; 636 l->lpo_acqtime = nanoseconds(); 637 if (waittime && (l->lpo_acqtime > waittime)) 638 l->lpo_waittime = l->lpo_acqtime - waittime; 639 else 640 l->lpo_waittime = 0; 641 out: 642 /* 643 * Paired with cpus_fence_seq_cst(). 644 */ 645 atomic_thread_fence_rel(); 646 critical_exit(); 647 } 648 649 void 650 lock_profile_thread_exit(struct thread *td) 651 { 652 #ifdef INVARIANTS 653 struct lock_profile_object *l; 654 655 MPASS(curthread->td_critnest == 0); 656 #endif 657 /* 658 * If lock profiling was disabled we have to wait for reset to 659 * clear our pointers before we can exit safely. 660 */ 661 lock_prof_reset_wait(); 662 #ifdef INVARIANTS 663 LIST_FOREACH(l, &td->td_lprof[0], lpo_link) 664 printf("thread still holds lock acquired at %s:%d\n", 665 l->lpo_file, l->lpo_line); 666 LIST_FOREACH(l, &td->td_lprof[1], lpo_link) 667 printf("thread still holds lock acquired at %s:%d\n", 668 l->lpo_file, l->lpo_line); 669 #endif 670 MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL); 671 MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL); 672 } 673 674 void 675 lock_profile_release_lock(struct lock_object *lo, bool spin) 676 { 677 struct lock_profile_object *l; 678 struct lock_prof_type *type; 679 struct lock_prof *lp; 680 uint64_t curtime, holdtime; 681 struct lpohead *head; 682 683 #ifdef LOCK_PROFILING_DEBUG_SPIN 684 bool is_spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK); 685 if ((spin && !is_spin) || (!spin && is_spin)) 686 printf("%s: lock %s spin mismatch (arg %d, flag %d)\n", __func__, 687 lo->lo_name, spin, is_spin); 688 #endif 689 690 if (lo->lo_flags & LO_NOPROFILE) 691 return; 692 head = &curthread->td_lprof[spin]; 693 if (LIST_FIRST(head) == NULL) 694 return; 695 if (SCHEDULER_STOPPED()) 696 return; 697 critical_enter(); 698 /* Recheck enabled now that we're in a critical section. */ 699 if (lock_prof_enable == 0 && lock_prof_resetting == 1) 700 goto out; 701 /* 702 * If lock profiling is not enabled we still want to remove the 703 * lpo from our queue. 704 */ 705 LIST_FOREACH(l, head, lpo_link) 706 if (l->lpo_obj == lo) 707 break; 708 if (l == NULL) 709 goto out; 710 if (--l->lpo_ref > 0) 711 goto out; 712 lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line); 713 if (lp == NULL) 714 goto release; 715 curtime = nanoseconds(); 716 if (curtime < l->lpo_acqtime) 717 goto release; 718 holdtime = curtime - l->lpo_acqtime; 719 720 /* 721 * Record if the lock has been held longer now than ever 722 * before. 723 */ 724 if (holdtime > lp->cnt_max) 725 lp->cnt_max = holdtime; 726 if (l->lpo_waittime > lp->cnt_wait_max) 727 lp->cnt_wait_max = l->lpo_waittime; 728 lp->cnt_tot += holdtime; 729 lp->cnt_wait += l->lpo_waittime; 730 lp->cnt_contest_locking += l->lpo_contest_locking; 731 lp->cnt_cur += l->lpo_cnt; 732 release: 733 LIST_REMOVE(l, lpo_link); 734 type = &LP_CPU_SELF->lpc_types[spin]; 735 LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link); 736 out: 737 /* 738 * Paired with cpus_fence_seq_cst(). 739 */ 740 atomic_thread_fence_rel(); 741 critical_exit(); 742 } 743 744 static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, 745 CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 746 "lock profiling"); 747 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW, 748 &lock_prof_skipspin, 0, "Skip profiling on spinlocks."); 749 SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD, 750 &lock_prof_rejected, 0, "Number of rejected profiling records"); 751 SYSCTL_INT(_debug_lock_prof, OID_AUTO, contested_only, CTLFLAG_RW, 752 &lock_contested_only, 0, "Only profile contested acquires"); 753 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, 754 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 755 dump_lock_prof_stats, "A", 756 "Lock profiling statistics"); 757 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, 758 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0, 759 reset_lock_prof_stats, "I", 760 "Reset lock profiling statistics"); 761 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, 762 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, 763 enable_lock_prof, "I", 764 "Enable lock profiling"); 765 766 #endif
Cache object: 18fe74f1f89955fe604ff4c5c2436c00
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