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/limits.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 /* 62 * Uncomment to validate that spin argument to acquire/release routines matches 63 * the flag in the lock 64 */ 65 //#define LOCK_PROFILING_DEBUG_SPIN 66 67 CTASSERT(LOCK_CLASS_MAX == 15); 68 69 struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = { 70 &lock_class_mtx_spin, 71 &lock_class_mtx_sleep, 72 &lock_class_sx, 73 &lock_class_rm, 74 &lock_class_rm_sleepable, 75 &lock_class_rw, 76 &lock_class_lockmgr, 77 }; 78 79 void 80 lock_init(struct lock_object *lock, struct lock_class *class, const char *name, 81 const char *type, int flags) 82 { 83 int i; 84 85 /* Check for double-init and zero object. */ 86 KASSERT(flags & LO_NEW || !lock_initialized(lock), 87 ("lock \"%s\" %p already initialized", name, lock)); 88 89 /* Look up lock class to find its index. */ 90 for (i = 0; i < LOCK_CLASS_MAX; i++) 91 if (lock_classes[i] == class) { 92 lock->lo_flags = i << LO_CLASSSHIFT; 93 break; 94 } 95 KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class)); 96 97 /* Initialize the lock object. */ 98 lock->lo_name = name; 99 lock->lo_flags |= flags | LO_INITIALIZED; 100 LOCK_LOG_INIT(lock, 0); 101 WITNESS_INIT(lock, (type != NULL) ? type : name); 102 } 103 104 void 105 lock_destroy(struct lock_object *lock) 106 { 107 108 KASSERT(lock_initialized(lock), ("lock %p is not initialized", lock)); 109 WITNESS_DESTROY(lock); 110 LOCK_LOG_DESTROY(lock, 0); 111 lock->lo_flags &= ~LO_INITIALIZED; 112 } 113 114 static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 115 "lock debugging"); 116 static SYSCTL_NODE(_debug_lock, OID_AUTO, delay, 117 CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 118 "lock delay"); 119 120 void 121 lock_delay(struct lock_delay_arg *la) 122 { 123 struct lock_delay_config *lc = la->config; 124 u_short i; 125 126 for (i = la->delay; i > 0; i--) 127 cpu_spinwait(); 128 la->spin_cnt += la->delay; 129 130 la->delay <<= 1; 131 if (__predict_false(la->delay > lc->max)) 132 la->delay = lc->max; 133 } 134 135 static u_int 136 lock_roundup_2(u_int val) 137 { 138 u_int res; 139 140 for (res = 1; res <= val; res <<= 1) 141 continue; 142 143 return (res); 144 } 145 146 void 147 lock_delay_default_init(struct lock_delay_config *lc) 148 { 149 150 lc->base = 1; 151 lc->max = lock_roundup_2(mp_ncpus) * 256; 152 if (lc->max > 32678) 153 lc->max = 32678; 154 } 155 156 struct lock_delay_config __read_frequently locks_delay; 157 u_short __read_frequently locks_delay_retries; 158 u_short __read_frequently locks_delay_loops; 159 160 SYSCTL_U16(_debug_lock, OID_AUTO, delay_base, CTLFLAG_RW, &locks_delay.base, 161 0, ""); 162 SYSCTL_U16(_debug_lock, OID_AUTO, delay_max, CTLFLAG_RW, &locks_delay.max, 163 0, ""); 164 SYSCTL_U16(_debug_lock, OID_AUTO, delay_retries, CTLFLAG_RW, &locks_delay_retries, 165 0, ""); 166 SYSCTL_U16(_debug_lock, OID_AUTO, delay_loops, CTLFLAG_RW, &locks_delay_loops, 167 0, ""); 168 169 static void 170 locks_delay_init(void *arg __unused) 171 { 172 173 lock_delay_default_init(&locks_delay); 174 locks_delay_retries = 10; 175 locks_delay_loops = max(10000, locks_delay.max); 176 } 177 LOCK_DELAY_SYSINIT(locks_delay_init); 178 179 #ifdef DDB 180 DB_SHOW_COMMAND(lock, db_show_lock) 181 { 182 struct lock_object *lock; 183 struct lock_class *class; 184 185 if (!have_addr) 186 return; 187 lock = (struct lock_object *)addr; 188 if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) { 189 db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock)); 190 return; 191 } 192 class = LOCK_CLASS(lock); 193 db_printf(" class: %s\n", class->lc_name); 194 db_printf(" name: %s\n", lock->lo_name); 195 class->lc_ddb_show(lock); 196 } 197 #endif 198 199 #ifdef LOCK_PROFILING 200 201 /* 202 * One object per-thread for each lock the thread owns. Tracks individual 203 * lock instances. 204 */ 205 struct lock_profile_object { 206 LIST_ENTRY(lock_profile_object) lpo_link; 207 struct lock_object *lpo_obj; 208 const char *lpo_file; 209 int lpo_line; 210 uint16_t lpo_ref; 211 uint16_t lpo_cnt; 212 uint64_t lpo_acqtime; 213 uint64_t lpo_waittime; 214 u_int lpo_contest_locking; 215 }; 216 217 /* 218 * One lock_prof for each (file, line, lock object) triple. 219 */ 220 struct lock_prof { 221 SLIST_ENTRY(lock_prof) link; 222 struct lock_class *class; 223 const char *file; 224 const char *name; 225 int line; 226 int ticks; 227 uintmax_t cnt_wait_max; 228 uintmax_t cnt_max; 229 uintmax_t cnt_tot; 230 uintmax_t cnt_wait; 231 uintmax_t cnt_cur; 232 uintmax_t cnt_contest_locking; 233 }; 234 235 SLIST_HEAD(lphead, lock_prof); 236 237 #define LPROF_HASH_SIZE 4096 238 #define LPROF_HASH_MASK (LPROF_HASH_SIZE - 1) 239 #define LPROF_CACHE_SIZE 4096 240 241 /* 242 * Array of objects and profs for each type of object for each cpu. Spinlocks 243 * are handled separately because a thread may be preempted and acquire a 244 * spinlock while in the lock profiling code of a non-spinlock. In this way 245 * we only need a critical section to protect the per-cpu lists. 246 */ 247 struct lock_prof_type { 248 struct lphead lpt_lpalloc; 249 struct lpohead lpt_lpoalloc; 250 struct lphead lpt_hash[LPROF_HASH_SIZE]; 251 struct lock_prof lpt_prof[LPROF_CACHE_SIZE]; 252 struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE]; 253 }; 254 255 struct lock_prof_cpu { 256 struct lock_prof_type lpc_types[2]; /* One for spin one for other. */ 257 }; 258 259 DPCPU_DEFINE_STATIC(struct lock_prof_cpu, lp); 260 #define LP_CPU_SELF (DPCPU_PTR(lp)) 261 #define LP_CPU(cpu) (DPCPU_ID_PTR((cpu), lp)) 262 263 volatile int __read_mostly lock_prof_enable; 264 int __read_mostly lock_contested_only; 265 static volatile int lock_prof_resetting; 266 267 #define LPROF_SBUF_SIZE 256 268 269 static int lock_prof_rejected; 270 static int lock_prof_skipspin; 271 272 #ifndef USE_CPU_NANOSECONDS 273 uint64_t 274 nanoseconds(void) 275 { 276 struct bintime bt; 277 uint64_t ns; 278 279 binuptime(&bt); 280 /* From bintime2timespec */ 281 ns = bt.sec * (uint64_t)1000000000; 282 ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32; 283 return (ns); 284 } 285 #endif 286 287 static void 288 lock_prof_init_type(struct lock_prof_type *type) 289 { 290 int i; 291 292 SLIST_INIT(&type->lpt_lpalloc); 293 LIST_INIT(&type->lpt_lpoalloc); 294 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 295 SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i], 296 link); 297 LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i], 298 lpo_link); 299 } 300 } 301 302 static void 303 lock_prof_init(void *arg) 304 { 305 int cpu; 306 307 CPU_FOREACH(cpu) { 308 lock_prof_init_type(&LP_CPU(cpu)->lpc_types[0]); 309 lock_prof_init_type(&LP_CPU(cpu)->lpc_types[1]); 310 } 311 } 312 SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL); 313 314 static void 315 lock_prof_reset_wait(void) 316 { 317 318 /* 319 * Spin relinquishing our cpu so that quiesce_all_cpus may 320 * complete. 321 */ 322 while (lock_prof_resetting) 323 sched_relinquish(curthread); 324 } 325 326 static void 327 lock_prof_reset(void) 328 { 329 struct lock_prof_cpu *lpc; 330 int enabled, i, cpu; 331 332 /* 333 * We not only race with acquiring and releasing locks but also 334 * thread exit. To be certain that threads exit without valid head 335 * pointers they must see resetting set before enabled is cleared. 336 * Otherwise a lock may not be removed from a per-thread list due 337 * to disabled being set but not wait for reset() to remove it below. 338 */ 339 atomic_store_rel_int(&lock_prof_resetting, 1); 340 enabled = lock_prof_enable; 341 lock_prof_enable = 0; 342 /* 343 * This both publishes lock_prof_enable as disabled and makes sure 344 * everyone else reads it if they are not far enough. We wait for the 345 * rest down below. 346 */ 347 cpus_fence_seq_cst(); 348 quiesce_all_critical(); 349 /* 350 * Some objects may have migrated between CPUs. Clear all links 351 * before we zero the structures. Some items may still be linked 352 * into per-thread lists as well. 353 */ 354 CPU_FOREACH(cpu) { 355 lpc = LP_CPU(cpu); 356 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 357 LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link); 358 LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link); 359 } 360 } 361 CPU_FOREACH(cpu) { 362 lpc = LP_CPU(cpu); 363 bzero(lpc, sizeof(*lpc)); 364 lock_prof_init_type(&lpc->lpc_types[0]); 365 lock_prof_init_type(&lpc->lpc_types[1]); 366 } 367 /* 368 * Paired with the fence from cpus_fence_seq_cst() 369 */ 370 atomic_store_rel_int(&lock_prof_resetting, 0); 371 lock_prof_enable = enabled; 372 } 373 374 static void 375 lock_prof_output(struct lock_prof *lp, struct sbuf *sb) 376 { 377 const char *p; 378 379 for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3); 380 sbuf_printf(sb, 381 "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n", 382 lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000, 383 lp->cnt_wait / 1000, lp->cnt_cur, 384 lp->cnt_cur == 0 ? (uintmax_t)0 : 385 lp->cnt_tot / (lp->cnt_cur * 1000), 386 lp->cnt_cur == 0 ? (uintmax_t)0 : 387 lp->cnt_wait / (lp->cnt_cur * 1000), 388 (uintmax_t)0, lp->cnt_contest_locking, 389 p, lp->line, lp->class->lc_name, lp->name); 390 } 391 392 static void 393 lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash, 394 int spin, int t) 395 { 396 struct lock_prof_type *type; 397 struct lock_prof *l; 398 int cpu; 399 400 dst->file = match->file; 401 dst->line = match->line; 402 dst->class = match->class; 403 dst->name = match->name; 404 405 CPU_FOREACH(cpu) { 406 type = &LP_CPU(cpu)->lpc_types[spin]; 407 SLIST_FOREACH(l, &type->lpt_hash[hash], link) { 408 if (l->ticks == t) 409 continue; 410 if (l->file != match->file || l->line != match->line || 411 l->name != match->name) 412 continue; 413 l->ticks = t; 414 if (l->cnt_max > dst->cnt_max) 415 dst->cnt_max = l->cnt_max; 416 if (l->cnt_wait_max > dst->cnt_wait_max) 417 dst->cnt_wait_max = l->cnt_wait_max; 418 dst->cnt_tot += l->cnt_tot; 419 dst->cnt_wait += l->cnt_wait; 420 dst->cnt_cur += l->cnt_cur; 421 dst->cnt_contest_locking += l->cnt_contest_locking; 422 } 423 } 424 } 425 426 static void 427 lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin, 428 int t) 429 { 430 struct lock_prof *l; 431 int i; 432 433 for (i = 0; i < LPROF_HASH_SIZE; ++i) { 434 SLIST_FOREACH(l, &type->lpt_hash[i], link) { 435 struct lock_prof lp = {}; 436 437 if (l->ticks == t) 438 continue; 439 lock_prof_sum(l, &lp, i, spin, t); 440 lock_prof_output(&lp, sb); 441 } 442 } 443 } 444 445 static int 446 dump_lock_prof_stats(SYSCTL_HANDLER_ARGS) 447 { 448 struct sbuf *sb; 449 int error, cpu, t; 450 int enabled; 451 452 error = sysctl_wire_old_buffer(req, 0); 453 if (error != 0) 454 return (error); 455 sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req); 456 sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n", 457 "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name"); 458 enabled = lock_prof_enable; 459 lock_prof_enable = 0; 460 /* 461 * See the comment in lock_prof_reset 462 */ 463 cpus_fence_seq_cst(); 464 quiesce_all_critical(); 465 t = ticks; 466 CPU_FOREACH(cpu) { 467 lock_prof_type_stats(&LP_CPU(cpu)->lpc_types[0], sb, 0, t); 468 lock_prof_type_stats(&LP_CPU(cpu)->lpc_types[1], sb, 1, t); 469 } 470 atomic_thread_fence_rel(); 471 lock_prof_enable = enabled; 472 473 error = sbuf_finish(sb); 474 /* Output a trailing NUL. */ 475 if (error == 0) 476 error = SYSCTL_OUT(req, "", 1); 477 sbuf_delete(sb); 478 return (error); 479 } 480 481 static int 482 enable_lock_prof(SYSCTL_HANDLER_ARGS) 483 { 484 int error, v; 485 486 v = lock_prof_enable; 487 error = sysctl_handle_int(oidp, &v, v, req); 488 if (error) 489 return (error); 490 if (req->newptr == NULL) 491 return (error); 492 if (v == lock_prof_enable) 493 return (0); 494 if (v == 1) 495 lock_prof_reset(); 496 lock_prof_enable = !!v; 497 498 return (0); 499 } 500 501 static int 502 reset_lock_prof_stats(SYSCTL_HANDLER_ARGS) 503 { 504 int error, v; 505 506 v = 0; 507 error = sysctl_handle_int(oidp, &v, 0, req); 508 if (error) 509 return (error); 510 if (req->newptr == NULL) 511 return (error); 512 if (v == 0) 513 return (0); 514 lock_prof_reset(); 515 516 return (0); 517 } 518 519 static struct lock_prof * 520 lock_profile_lookup(struct lock_object *lo, int spin, const char *file, 521 int line) 522 { 523 const char *unknown = "(unknown)"; 524 struct lock_prof_type *type; 525 struct lock_prof *lp; 526 struct lphead *head; 527 const char *p; 528 u_int hash; 529 530 p = file; 531 if (p == NULL || *p == '\0') 532 p = unknown; 533 hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line; 534 hash &= LPROF_HASH_MASK; 535 type = &LP_CPU_SELF->lpc_types[spin]; 536 head = &type->lpt_hash[hash]; 537 SLIST_FOREACH(lp, head, link) { 538 if (lp->line == line && lp->file == p && 539 lp->name == lo->lo_name) 540 return (lp); 541 } 542 lp = SLIST_FIRST(&type->lpt_lpalloc); 543 if (lp == NULL) { 544 lock_prof_rejected++; 545 return (lp); 546 } 547 SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link); 548 lp->file = p; 549 lp->line = line; 550 lp->class = LOCK_CLASS(lo); 551 lp->name = lo->lo_name; 552 SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link); 553 return (lp); 554 } 555 556 static struct lock_profile_object * 557 lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file, 558 int line) 559 { 560 struct lock_profile_object *l; 561 struct lock_prof_type *type; 562 struct lpohead *head; 563 564 head = &curthread->td_lprof[spin]; 565 LIST_FOREACH(l, head, lpo_link) 566 if (l->lpo_obj == lo && l->lpo_file == file && 567 l->lpo_line == line) 568 return (l); 569 type = &LP_CPU_SELF->lpc_types[spin]; 570 l = LIST_FIRST(&type->lpt_lpoalloc); 571 if (l == NULL) { 572 lock_prof_rejected++; 573 return (NULL); 574 } 575 LIST_REMOVE(l, lpo_link); 576 l->lpo_obj = lo; 577 l->lpo_file = file; 578 l->lpo_line = line; 579 l->lpo_cnt = 0; 580 LIST_INSERT_HEAD(head, l, lpo_link); 581 582 return (l); 583 } 584 585 void 586 lock_profile_obtain_lock_success(struct lock_object *lo, bool spin, 587 int contested, uint64_t waittime, const char *file, int line) 588 { 589 struct lock_profile_object *l; 590 591 #ifdef LOCK_PROFILING_DEBUG_SPIN 592 bool is_spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK); 593 if ((spin && !is_spin) || (!spin && is_spin)) 594 printf("%s: lock %s spin mismatch (arg %d, flag %d)\n", __func__, 595 lo->lo_name, spin, is_spin); 596 #endif 597 598 /* don't reset the timer when/if recursing */ 599 if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) 600 return; 601 if (lock_contested_only && !contested) 602 return; 603 if (spin && lock_prof_skipspin == 1) 604 return; 605 606 if (SCHEDULER_STOPPED()) 607 return; 608 609 critical_enter(); 610 /* Recheck enabled now that we're in a critical section. */ 611 if (lock_prof_enable == 0) 612 goto out; 613 l = lock_profile_object_lookup(lo, spin, file, line); 614 if (l == NULL) 615 goto out; 616 l->lpo_cnt++; 617 if (++l->lpo_ref > 1) 618 goto out; 619 l->lpo_contest_locking = contested; 620 l->lpo_acqtime = nanoseconds(); 621 if (waittime && (l->lpo_acqtime > waittime)) 622 l->lpo_waittime = l->lpo_acqtime - waittime; 623 else 624 l->lpo_waittime = 0; 625 out: 626 /* 627 * Paired with cpus_fence_seq_cst(). 628 */ 629 atomic_thread_fence_rel(); 630 critical_exit(); 631 } 632 633 void 634 lock_profile_thread_exit(struct thread *td) 635 { 636 #ifdef INVARIANTS 637 struct lock_profile_object *l; 638 639 MPASS(curthread->td_critnest == 0); 640 #endif 641 /* 642 * If lock profiling was disabled we have to wait for reset to 643 * clear our pointers before we can exit safely. 644 */ 645 lock_prof_reset_wait(); 646 #ifdef INVARIANTS 647 LIST_FOREACH(l, &td->td_lprof[0], lpo_link) 648 printf("thread still holds lock acquired at %s:%d\n", 649 l->lpo_file, l->lpo_line); 650 LIST_FOREACH(l, &td->td_lprof[1], lpo_link) 651 printf("thread still holds lock acquired at %s:%d\n", 652 l->lpo_file, l->lpo_line); 653 #endif 654 MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL); 655 MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL); 656 } 657 658 void 659 lock_profile_release_lock(struct lock_object *lo, bool spin) 660 { 661 struct lock_profile_object *l; 662 struct lock_prof_type *type; 663 struct lock_prof *lp; 664 uint64_t curtime, holdtime; 665 struct lpohead *head; 666 667 #ifdef LOCK_PROFILING_DEBUG_SPIN 668 bool is_spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK); 669 if ((spin && !is_spin) || (!spin && is_spin)) 670 printf("%s: lock %s spin mismatch (arg %d, flag %d)\n", __func__, 671 lo->lo_name, spin, is_spin); 672 #endif 673 674 if (lo->lo_flags & LO_NOPROFILE) 675 return; 676 head = &curthread->td_lprof[spin]; 677 if (LIST_FIRST(head) == NULL) 678 return; 679 if (SCHEDULER_STOPPED()) 680 return; 681 critical_enter(); 682 /* Recheck enabled now that we're in a critical section. */ 683 if (lock_prof_enable == 0 && lock_prof_resetting == 1) 684 goto out; 685 /* 686 * If lock profiling is not enabled we still want to remove the 687 * lpo from our queue. 688 */ 689 LIST_FOREACH(l, head, lpo_link) 690 if (l->lpo_obj == lo) 691 break; 692 if (l == NULL) 693 goto out; 694 if (--l->lpo_ref > 0) 695 goto out; 696 lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line); 697 if (lp == NULL) 698 goto release; 699 curtime = nanoseconds(); 700 if (curtime < l->lpo_acqtime) 701 goto release; 702 holdtime = curtime - l->lpo_acqtime; 703 704 /* 705 * Record if the lock has been held longer now than ever 706 * before. 707 */ 708 if (holdtime > lp->cnt_max) 709 lp->cnt_max = holdtime; 710 if (l->lpo_waittime > lp->cnt_wait_max) 711 lp->cnt_wait_max = l->lpo_waittime; 712 lp->cnt_tot += holdtime; 713 lp->cnt_wait += l->lpo_waittime; 714 lp->cnt_contest_locking += l->lpo_contest_locking; 715 lp->cnt_cur += l->lpo_cnt; 716 release: 717 LIST_REMOVE(l, lpo_link); 718 type = &LP_CPU_SELF->lpc_types[spin]; 719 LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link); 720 out: 721 /* 722 * Paired with cpus_fence_seq_cst(). 723 */ 724 atomic_thread_fence_rel(); 725 critical_exit(); 726 } 727 728 static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, 729 CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 730 "lock profiling"); 731 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW, 732 &lock_prof_skipspin, 0, "Skip profiling on spinlocks."); 733 SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD, 734 &lock_prof_rejected, 0, "Number of rejected profiling records"); 735 SYSCTL_INT(_debug_lock_prof, OID_AUTO, contested_only, CTLFLAG_RW, 736 &lock_contested_only, 0, "Only profile contested acquires"); 737 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, 738 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0, 739 dump_lock_prof_stats, "A", 740 "Lock profiling statistics"); 741 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, 742 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, NULL, 0, 743 reset_lock_prof_stats, "I", 744 "Reset lock profiling statistics"); 745 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, 746 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0, 747 enable_lock_prof, "I", 748 "Enable lock profiling"); 749 750 #endif
Cache object: 4f80ce5cdd838721a5f755a463f9553b
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