subr_lock.c revision 174629
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 174629 2007-12-15 23:13:31Z jeff $"); 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 const char *file; 154 const char *name; 155 int line; 156 int ticks; 157 const char *type; 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 for (cpu = 0; cpu <= mp_maxid; cpu++) { 253 lpc = lp_cpu[cpu]; 254 for (i = 0; i < LPROF_CACHE_SIZE; i++) { 255 LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link); 256 LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link); 257 } 258 bzero(lpc, sizeof(*lpc)); 259 lock_prof_init_type(&lpc->lpc_types[0]); 260 lock_prof_init_type(&lpc->lpc_types[1]); 261 } 262 lock_prof_enable = enabled; 263} 264 265static void 266lock_prof_output(struct lock_prof *lp, struct sbuf *sb) 267{ 268 const char *p; 269 270 for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3); 271 sbuf_printf(sb, 272 "%6ju %12ju %12ju %11ju %5ju %5ju %12ju %12ju %s:%d (%s:%s)\n", 273 lp->cnt_max / 1000, lp->cnt_tot / 1000, 274 lp->cnt_wait / 1000, lp->cnt_cur, 275 lp->cnt_cur == 0 ? (uintmax_t)0 : 276 lp->cnt_tot / (lp->cnt_cur * 1000), 277 lp->cnt_cur == 0 ? (uintmax_t)0 : 278 lp->cnt_wait / (lp->cnt_cur * 1000), 279 (uintmax_t)0, lp->cnt_contest_locking, 280 p, lp->line, lp->type, lp->name); 281} 282 283static void 284lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash, 285 int spin, int t) 286{ 287 struct lock_prof_type *type; 288 struct lock_prof *l; 289 int cpu; 290 291 dst->file = match->file; 292 dst->line = match->line; 293 dst->type = match->type; 294 dst->name = match->name; 295 296 for (cpu = 0; cpu <= mp_maxid; cpu++) { 297 if (lp_cpu[cpu] == NULL) 298 continue; 299 type = &lp_cpu[cpu]->lpc_types[spin]; 300 SLIST_FOREACH(l, &type->lpt_hash[hash], link) { 301 if (l->ticks == t) 302 continue; 303 if (l->file != match->file || l->line != match->line || 304 l->name != match->name || l->type != match->type) 305 continue; 306 l->ticks = t; 307 if (l->cnt_max > dst->cnt_max) 308 dst->cnt_max = l->cnt_max; 309 dst->cnt_tot += l->cnt_tot; 310 dst->cnt_wait += l->cnt_wait; 311 dst->cnt_cur += l->cnt_cur; 312 dst->cnt_contest_locking += l->cnt_contest_locking; 313 } 314 } 315 316} 317 318static void 319lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin, 320 int t) 321{ 322 struct lock_prof *l; 323 int i; 324 325 for (i = 0; i < LPROF_HASH_SIZE; ++i) { 326 SLIST_FOREACH(l, &type->lpt_hash[i], link) { 327 struct lock_prof lp = {}; 328 329 if (l->ticks == t) 330 continue; 331 lock_prof_sum(l, &lp, i, spin, t); 332 lock_prof_output(&lp, sb); 333 if (sbuf_overflowed(sb)) 334 return; 335 } 336 } 337} 338 339static int 340dump_lock_prof_stats(SYSCTL_HANDLER_ARGS) 341{ 342 static int multiplier = 1; 343 struct sbuf *sb; 344 int error, cpu, t; 345 346retry_sbufops: 347 sb = sbuf_new(NULL, NULL, LPROF_SBUF_SIZE * multiplier, SBUF_FIXEDLEN); 348 sbuf_printf(sb, "\n%6s %12s %12s %11s %5s %5s %12s %12s %s\n", 349 "max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name"); 350 t = ticks; 351 for (cpu = 0; cpu <= mp_maxid; cpu++) { 352 if (lp_cpu[cpu] == NULL) 353 continue; 354 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t); 355 lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t); 356 if (sbuf_overflowed(sb)) { 357 sbuf_delete(sb); 358 multiplier++; 359 goto retry_sbufops; 360 } 361 } 362 363 sbuf_finish(sb); 364 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); 365 sbuf_delete(sb); 366 return (error); 367} 368 369static int 370enable_lock_prof(SYSCTL_HANDLER_ARGS) 371{ 372 int error, v; 373 374 v = lock_prof_enable; 375 error = sysctl_handle_int(oidp, &v, v, req); 376 if (error) 377 return (error); 378 if (req->newptr == NULL) 379 return (error); 380 if (v == lock_prof_enable) 381 return (0); 382 if (v == 1) 383 lock_prof_reset(); 384 lock_prof_enable = !!v; 385 386 return (0); 387} 388 389static int 390reset_lock_prof_stats(SYSCTL_HANDLER_ARGS) 391{ 392 int error, v; 393 394 v = 0; 395 error = sysctl_handle_int(oidp, &v, 0, req); 396 if (error) 397 return (error); 398 if (req->newptr == NULL) 399 return (error); 400 if (v == 0) 401 return (0); 402 lock_prof_reset(); 403 404 return (0); 405} 406 407static struct lock_prof * 408lock_profile_lookup(struct lock_object *lo, int spin, const char *file, 409 int line) 410{ 411 const char *unknown = "(unknown)"; 412 struct lock_prof_type *type; 413 struct lock_prof *lp; 414 struct lphead *head; 415 const char *p; 416 u_int hash; 417 418 p = file; 419 if (p == NULL || *p == '\0') 420 p = unknown; 421 hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line; 422 hash &= LPROF_HASH_MASK; 423 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 424 head = &type->lpt_hash[hash]; 425 SLIST_FOREACH(lp, head, link) { 426 if (lp->line == line && lp->file == p && 427 lp->name == lo->lo_name) 428 return (lp); 429 430 } 431 lp = SLIST_FIRST(&type->lpt_lpalloc); 432 if (lp == NULL) { 433 lock_prof_rejected++; 434 return (lp); 435 } 436 SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link); 437 lp->file = p; 438 lp->line = line; 439 lp->type = lo->lo_type; 440 lp->name = lo->lo_name; 441 SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link); 442 return (lp); 443} 444 445static struct lock_profile_object * 446lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file, 447 int line) 448{ 449 struct lock_profile_object *l; 450 struct lock_prof_type *type; 451 struct lpohead *head; 452 453 head = &curthread->td_lprof[spin]; 454 LIST_FOREACH(l, head, lpo_link) 455 if (l->lpo_obj == lo && l->lpo_file == file && 456 l->lpo_line == line) 457 return (l); 458 critical_enter(); 459 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 460 l = LIST_FIRST(&type->lpt_lpoalloc); 461 if (l == NULL) { 462 lock_prof_rejected++; 463 critical_exit(); 464 return (NULL); 465 } 466 LIST_REMOVE(l, lpo_link); 467 critical_exit(); 468 l->lpo_obj = lo; 469 l->lpo_file = file; 470 l->lpo_line = line; 471 l->lpo_cnt = 0; 472 LIST_INSERT_HEAD(head, l, lpo_link); 473 474 return (l); 475} 476 477void 478lock_profile_obtain_lock_success(struct lock_object *lo, int contested, 479 uint64_t waittime, const char *file, int line) 480{ 481 static int lock_prof_count; 482 struct lock_profile_object *l; 483 int spin; 484 485 /* don't reset the timer when/if recursing */ 486 if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) 487 return; 488 if (lock_prof_skipcount && 489 (++lock_prof_count % lock_prof_skipcount) == 0) 490 return; 491 spin = LOCK_CLASS(lo) == &lock_class_mtx_spin; 492 if (spin && lock_prof_skipspin == 1) 493 return; 494 l = lock_profile_object_lookup(lo, spin, file, line); 495 if (l == NULL) 496 return; 497 l->lpo_cnt++; 498 if (++l->lpo_ref > 1) 499 return; 500 l->lpo_contest_locking = contested; 501 l->lpo_acqtime = nanoseconds(); 502 if (waittime && (l->lpo_acqtime > waittime)) 503 l->lpo_waittime = l->lpo_acqtime - waittime; 504 else 505 l->lpo_waittime = 0; 506} 507 508void 509lock_profile_release_lock(struct lock_object *lo) 510{ 511 struct lock_profile_object *l; 512 struct lock_prof_type *type; 513 struct lock_prof *lp; 514 u_int64_t holdtime; 515 struct lpohead *head; 516 int spin; 517 518 if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) 519 return; 520 spin = LOCK_CLASS(lo) == &lock_class_mtx_spin; 521 head = &curthread->td_lprof[spin]; 522 critical_enter(); 523 LIST_FOREACH(l, head, lpo_link) 524 if (l->lpo_obj == lo) 525 break; 526 if (l == NULL) 527 goto out; 528 if (--l->lpo_ref > 0) 529 goto out; 530 lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line); 531 if (lp == NULL) 532 goto release; 533 holdtime = nanoseconds() - l->lpo_acqtime; 534 if (holdtime < 0) 535 goto release; 536 /* 537 * Record if the lock has been held longer now than ever 538 * before. 539 */ 540 if (holdtime > lp->cnt_max) 541 lp->cnt_max = holdtime; 542 lp->cnt_tot += holdtime; 543 lp->cnt_wait += l->lpo_waittime; 544 lp->cnt_contest_locking += l->lpo_contest_locking; 545 lp->cnt_cur += l->lpo_cnt; 546release: 547 LIST_REMOVE(l, lpo_link); 548 type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; 549 LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link); 550out: 551 critical_exit(); 552} 553 554SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging"); 555SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL, "lock profiling"); 556SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW, 557 &lock_prof_skipspin, 0, "Skip profiling on spinlocks."); 558SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW, 559 &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions."); 560SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD, 561 &lock_prof_rejected, 0, "Number of rejected profiling records"); 562SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD, 563 NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics"); 564SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW, 565 NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics"); 566SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW, 567 NULL, 0, enable_lock_prof, "I", "Enable lock profiling"); 568 569#endif 570