subr_lock.c revision 175150
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 * 3. Neither the name of the author nor the names of any co-contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30/* 31 * This module holds the global variables and functions used to maintain 32 * lock_object structures. 33 */ 34 35#include <sys/cdefs.h> 36__FBSDID("$FreeBSD: head/sys/kern/subr_lock.c 175150 2008-01-08 01:11:40Z kris $"); 37 38#include "opt_ddb.h" 39#include "opt_mprof.h" 40 41#include <sys/param.h> 42#include <sys/systm.h> 43#include <sys/kernel.h> 44#include <sys/ktr.h> 45#include <sys/linker_set.h> 46#include <sys/lock.h> 47#include <sys/lock_profile.h> 48#include <sys/malloc.h> 49#include <sys/pcpu.h> 50#include <sys/proc.h> 51#include <sys/sbuf.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 61CTASSERT(LOCK_CLASS_MAX == 15); 62 63struct 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_rw, 69 &lock_class_lockmgr, 70}; 71 72void 73lock_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(!lock_initalized(lock), ("lock \"%s\" %p already initialized", 80 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_type = type != NULL ? type : name; 93 lock->lo_flags |= flags | LO_INITIALIZED; 94 LOCK_LOG_INIT(lock, 0); 95 WITNESS_INIT(lock); 96} 97 98void 99lock_destroy(struct lock_object *lock) 100{ 101 102 KASSERT(lock_initalized(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#ifdef DDB 109DB_SHOW_COMMAND(lock, db_show_lock) 110{ 111 struct lock_object *lock; 112 struct lock_class *class; 113 114 if (!have_addr) 115 return; 116 lock = (struct lock_object *)addr; 117 if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) { 118 db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock)); 119 return; 120 } 121 class = LOCK_CLASS(lock); 122 db_printf(" class: %s\n", class->lc_name); 123 db_printf(" name: %s\n", lock->lo_name); 124 if (lock->lo_type && lock->lo_type != lock->lo_name) 125 db_printf(" type: %s\n", lock->lo_type); 126 class->lc_ddb_show(lock); 127} 128#endif 129 130#ifdef LOCK_PROFILING 131 132/* 133 * One object per-thread for each lock the thread owns. Tracks individual 134 * lock instances. 135 */ 136struct lock_profile_object { 137 LIST_ENTRY(lock_profile_object) lpo_link; 138 struct lock_object *lpo_obj; 139 const char *lpo_file; 140 int lpo_line; 141 uint16_t lpo_ref; 142 uint16_t lpo_cnt; 143 u_int64_t lpo_acqtime; 144 u_int64_t lpo_waittime; 145 u_int lpo_contest_locking; 146}; 147 148/* 149 * One lock_prof for each (file, line, lock object) triple. 150 */ 151struct lock_prof { 152 SLIST_ENTRY(lock_prof) link; 153 struct lock_class *class; 154 const char *file; 155 const char *name; 156 int line; 157 int ticks; 158 uintmax_t cnt_max; 159 uintmax_t cnt_tot; 160 uintmax_t cnt_wait; 161 uintmax_t cnt_cur; 162 uintmax_t cnt_contest_locking; 163}; 164 165SLIST_HEAD(lphead, lock_prof); 166 167#define LPROF_HASH_SIZE 4096 168#define LPROF_HASH_MASK (LPROF_HASH_SIZE - 1) 169#define LPROF_CACHE_SIZE 4096 170 171/* 172 * Array of objects and profs for each type of object for each cpu. Spinlocks 173 * are handled seperately because a thread may be preempted and acquire a 174 * spinlock while in the lock profiling code of a non-spinlock. In this way 175 * we only need a critical section to protect the per-cpu lists. 176 */ 177struct lock_prof_type { 178 struct lphead lpt_lpalloc; 179 struct lpohead lpt_lpoalloc; 180 struct lphead lpt_hash[LPROF_HASH_SIZE]; 181 struct lock_prof lpt_prof[LPROF_CACHE_SIZE]; 182 struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE]; 183}; 184 185struct lock_prof_cpu { 186 struct lock_prof_type lpc_types[2]; /* One for spin one for other. */ 187}; 188 189struct lock_prof_cpu *lp_cpu[MAXCPU]; 190 191int lock_prof_enable = 0; 192 193/* SWAG: sbuf size = avg stat. line size * number of locks */ 194#define LPROF_SBUF_SIZE 256 * 400 195 196static int lock_prof_rejected; 197static int lock_prof_skipspin; 198static int lock_prof_skipcount; 199 200#ifndef USE_CPU_NANOSECONDS 201u_int64_t 202nanoseconds(void) 203{ 204 struct bintime bt; 205 u_int64_t ns; 206 207 binuptime(&bt); 208 /* From bintime2timespec */ 209 ns = bt.sec * (u_int64_t)1000000000; 210 ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32; 211 return (ns); 212} 213#endif 214 215static void 216lock_prof_init_type(struct lock_prof_type *type) 217{ 218 int i; 219 220 SLIST_INIT(&type->lpt_lpalloc); 221 LIST_INIT(&type->lpt_lpoalloc); 222 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 223 SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i], 224 link); 225 LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i], 226 lpo_link); 227 } 228} 229 230static void 231lock_prof_init(void *arg) 232{ 233 int cpu; 234 235 for (cpu = 0; cpu <= mp_maxid; cpu++) { 236 lp_cpu[cpu] = malloc(sizeof(*lp_cpu[cpu]), M_DEVBUF, 237 M_WAITOK | M_ZERO); 238 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[0]); 239 lock_prof_init_type(&lp_cpu[cpu]->lpc_types[1]); 240 } 241} 242SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL); 243 244static void 245lock_prof_reset(void) 246{ 247 struct lock_prof_cpu *lpc; 248 int enabled, i, cpu; 249 250 enabled = lock_prof_enable; 251 lock_prof_enable = 0; 252 pause("lpreset", hz / 10); 253 for (cpu = 0; cpu <= mp_maxid; cpu++) { 254 lpc = lp_cpu[cpu]; 255 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 256 LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link); 257 LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link); 258 } 259 bzero(lpc, sizeof(*lpc)); 260 lock_prof_init_type(&lpc->lpc_types[0]); 261 lock_prof_init_type(&lpc->lpc_types[1]); 262 } 263 lock_prof_enable = enabled; 264} 265 266static void 267lock_prof_output(struct lock_prof *lp, struct sbuf *sb) 268{ 269 const char *p; 270 271 for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3); 272 sbuf_printf(sb, 273 "%6ju %12ju %12ju %11ju %5ju %5ju %12ju %12ju %s:%d (%s:%s)\n", 274 lp->cnt_max / 1000, lp->cnt_tot / 1000, 275 lp->cnt_wait / 1000, lp->cnt_cur, 276 lp->cnt_cur == 0 ? (uintmax_t)0 : 277 lp->cnt_tot / (lp->cnt_cur * 1000), 278 lp->cnt_cur == 0 ? (uintmax_t)0 : 279 lp->cnt_wait / (lp->cnt_cur * 1000), 280 (uintmax_t)0, lp->cnt_contest_locking, 281 p, lp->line, lp->class->lc_name, lp->name); 282} 283 284static void 285lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash, 286 int spin, int t) 287{ 288 struct lock_prof_type *type; 289 struct lock_prof *l; 290 int cpu; 291 292 dst->file = match->file; 293 dst->line = match->line; 294 dst->class = match->class; 295 dst->name = match->name; 296 297 for (cpu = 0; cpu <= mp_maxid; cpu++) { 298 if (lp_cpu[cpu] == NULL) 299 continue; 300 type = &lp_cpu[cpu]->lpc_types[spin]; 301 SLIST_FOREACH(l, &type->lpt_hash[hash], link) { 302 if (l->ticks == t) 303 continue; 304 if (l->file != match->file || l->line != match->line || 305 l->name != match->name) 306 continue; 307 l->ticks = t; 308 if (l->cnt_max > dst->cnt_max) 309 dst->cnt_max = l->cnt_max; 310 dst->cnt_tot += l->cnt_tot; 311 dst->cnt_wait += l->cnt_wait; 312 dst->cnt_cur += l->cnt_cur; 313 dst->cnt_contest_locking += l->cnt_contest_locking; 314 } 315 } 316 317} 318 319static void 320lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin, 321 int t) 322{ 323 struct lock_prof *l; 324 int i; 325 326 for (i = 0; i < LPROF_HASH_SIZE; ++i) { 327 SLIST_FOREACH(l, &type->lpt_hash[i], link) { 328 struct lock_prof lp = {}; 329 330 if (l->ticks == t) 331 continue; 332 lock_prof_sum(l, &lp, i, spin, t); 333 lock_prof_output(&lp, sb); 334 if (sbuf_overflowed(sb)) 335 return; 336 } 337 } 338} 339 340static int 341dump_lock_prof_stats(SYSCTL_HANDLER_ARGS) 342{ 343 static int multiplier = 1; 344 struct sbuf *sb; 345 int error, cpu, t; 346 int enabled; 347 348retry_sbufops: 349 sb = sbuf_new(NULL, NULL, LPROF_SBUF_SIZE * multiplier, SBUF_FIXEDLEN); 350 sbuf_printf(sb, "\n%6s %12s %12s %11s %5s %5s %12s %12s %s\n", 351 "max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name"); 352 enabled = lock_prof_enable; 353 lock_prof_enable = 0; 354 pause("lpreset", hz / 10); 355 t = ticks; 356 for (cpu = 0; cpu <= mp_maxid; cpu++) { 357 if (lp_cpu[cpu] == NULL) 358 continue; 359 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t); 360 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t); 361 if (sbuf_overflowed(sb)) { 362 sbuf_delete(sb); 363 multiplier++; 364 goto retry_sbufops; 365 } 366 } 367 lock_prof_enable = enabled; 368 369 sbuf_finish(sb); 370 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 371 sbuf_delete(sb); 372 return (error); 373} 374 375static int 376enable_lock_prof(SYSCTL_HANDLER_ARGS) 377{ 378 int error, v; 379 380 v = lock_prof_enable; 381 error = sysctl_handle_int(oidp, &v, v, req); 382 if (error) 383 return (error); 384 if (req->newptr == NULL) 385 return (error); 386 if (v == lock_prof_enable) 387 return (0); 388 if (v == 1) 389 lock_prof_reset(); 390 lock_prof_enable = !!v; 391 392 return (0); 393} 394 395static int 396reset_lock_prof_stats(SYSCTL_HANDLER_ARGS) 397{ 398 int error, v; 399 400 v = 0; 401 error = sysctl_handle_int(oidp, &v, 0, req); 402 if (error) 403 return (error); 404 if (req->newptr == NULL) 405 return (error); 406 if (v == 0) 407 return (0); 408 lock_prof_reset(); 409 410 return (0); 411} 412 413static struct lock_prof * 414lock_profile_lookup(struct lock_object *lo, int spin, const char *file, 415 int line) 416{ 417 const char *unknown = "(unknown)"; 418 struct lock_prof_type *type; 419 struct lock_prof *lp; 420 struct lphead *head; 421 const char *p; 422 u_int hash; 423 424 p = file; 425 if (p == NULL || *p == '\0') 426 p = unknown; 427 hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line; 428 hash &= LPROF_HASH_MASK; 429 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 430 head = &type->lpt_hash[hash]; 431 SLIST_FOREACH(lp, head, link) { 432 if (lp->line == line && lp->file == p && 433 lp->name == lo->lo_name) 434 return (lp); 435 436 } 437 lp = SLIST_FIRST(&type->lpt_lpalloc); 438 if (lp == NULL) { 439 lock_prof_rejected++; 440 return (lp); 441 } 442 SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link); 443 lp->file = p; 444 lp->line = line; 445 lp->class = LOCK_CLASS(lo); 446 lp->name = lo->lo_name; 447 SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link); 448 return (lp); 449} 450 451static struct lock_profile_object * 452lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file, 453 int line) 454{ 455 struct lock_profile_object *l; 456 struct lock_prof_type *type; 457 struct lpohead *head; 458 459 head = &curthread->td_lprof[spin]; 460 LIST_FOREACH(l, head, lpo_link) 461 if (l->lpo_obj == lo && l->lpo_file == file && 462 l->lpo_line == line) 463 return (l); 464 critical_enter(); 465 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 466 l = LIST_FIRST(&type->lpt_lpoalloc); 467 if (l == NULL) { 468 lock_prof_rejected++; 469 critical_exit(); 470 return (NULL); 471 } 472 LIST_REMOVE(l, lpo_link); 473 critical_exit(); 474 l->lpo_obj = lo; 475 l->lpo_file = file; 476 l->lpo_line = line; 477 l->lpo_cnt = 0; 478 LIST_INSERT_HEAD(head, l, lpo_link); 479 480 return (l); 481} 482 483void 484lock_profile_obtain_lock_success(struct lock_object *lo, int contested, 485 uint64_t waittime, const char *file, int line) 486{ 487 static int lock_prof_count; 488 struct lock_profile_object *l; 489 int spin; 490 491 /* don't reset the timer when/if recursing */ 492 if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) 493 return; 494 if (lock_prof_skipcount && 495 (++lock_prof_count % lock_prof_skipcount) != 0) 496 return; 497 spin = LOCK_CLASS(lo) == &lock_class_mtx_spin; 498 if (spin && lock_prof_skipspin == 1) 499 return; 500 l = lock_profile_object_lookup(lo, spin, file, line); 501 if (l == NULL) 502 return; 503 l->lpo_cnt++; 504 if (++l->lpo_ref > 1) 505 return; 506 l->lpo_contest_locking = contested; 507 l->lpo_acqtime = nanoseconds(); 508 if (waittime && (l->lpo_acqtime > waittime)) 509 l->lpo_waittime = l->lpo_acqtime - waittime; 510 else 511 l->lpo_waittime = 0; 512} 513 514void 515lock_profile_release_lock(struct lock_object *lo) 516{ 517 struct lock_profile_object *l; 518 struct lock_prof_type *type; 519 struct lock_prof *lp; 520 u_int64_t holdtime; 521 struct lpohead *head; 522 int spin; 523 524 if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) 525 return; 526 spin = LOCK_CLASS(lo) == &lock_class_mtx_spin; 527 head = &curthread->td_lprof[spin]; 528 critical_enter(); 529 LIST_FOREACH(l, head, lpo_link) 530 if (l->lpo_obj == lo) 531 break; 532 if (l == NULL) 533 goto out; 534 if (--l->lpo_ref > 0) 535 goto out; 536 lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line); 537 if (lp == NULL) 538 goto release; 539 holdtime = nanoseconds() - l->lpo_acqtime; 540 if (holdtime < 0) 541 goto release; 542 /* 543 * Record if the lock has been held longer now than ever 544 * before. 545 */ 546 if (holdtime > lp->cnt_max) 547 lp->cnt_max = holdtime; 548 lp->cnt_tot += holdtime; 549 lp->cnt_wait += l->lpo_waittime; 550 lp->cnt_contest_locking += l->lpo_contest_locking; 551 lp->cnt_cur += l->lpo_cnt; 552release: 553 LIST_REMOVE(l, lpo_link); 554 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 555 LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link); 556out: 557 critical_exit(); 558} 559 560SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging"); 561SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL, "lock profiling"); 562SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW, 563 &lock_prof_skipspin, 0, "Skip profiling on spinlocks."); 564SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW, 565 &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions."); 566SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD, 567 &lock_prof_rejected, 0, "Number of rejected profiling records"); 568SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD, 569 NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics"); 570SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW, 571 NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics"); 572SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW, 573 NULL, 0, enable_lock_prof, "I", "Enable lock profiling"); 574 575#endif 576