sys/kern/subr_taskqueue.c

   1 /*-
   2  * Copyright (c) 2000 Doug Rabson
   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  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/kern/subr_taskqueue.c,v 1.69 2012/08/28 13:35:37 jhb Exp $"
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/queue.h>
  31 #include <sys/systm.h>
  32 #include <sys/kernel.h>
  33 #include <sys/taskqueue.h>
  34 #include <sys/interrupt.h>
  35 #include <sys/lock.h>
  36 #include <sys/malloc.h>
  37 #include <sys/kthread.h>
  38 #include <sys/spinlock.h>
  39 #include <sys/spinlock2.h>
  40 #include <sys/serialize.h>
  41 #include <sys/proc.h>
  42
  43 MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
  44
  45 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
  46 static struct lock      taskqueue_queues_lock;
  47 static struct spinlock  taskqueue_queues_spin;
  48
  49 struct taskqueue {
  50         STAILQ_ENTRY(taskqueue) tq_link;
  51         STAILQ_HEAD(, task)     tq_queue;
  52         const char              *tq_name;
  53         /* NOTE: tq must be locked before calling tq_enqueue */
  54         taskqueue_enqueue_fn    tq_enqueue;
  55         void                    *tq_context;
  56
  57         struct task             *tq_running;
  58         struct spinlock         tq_lock;
  59         struct thread           **tq_threads;
  60         int                     tq_tcount;
  61         int                     tq_flags;
  62         int                     tq_callouts;
  63 };
  64
  65 #define TQ_FLAGS_ACTIVE         (1 << 0)
  66 #define TQ_FLAGS_BLOCKED        (1 << 1)
  67 #define TQ_FLAGS_PENDING        (1 << 2)
  68
  69 #define DT_CALLOUT_ARMED        (1 << 0)
  70
  71 void
  72 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
  73     int priority, task_fn_t func, void *context)
  74 {
  75
  76         TASK_INIT(&timeout_task->t, priority, func, context);
  77         callout_init_mp(&timeout_task->c);
  78         timeout_task->t.ta_queue = queue;
  79         timeout_task->f = 0;
  80 }
  81
  82 static void taskqueue_run(struct taskqueue *queue, int lock_held);
  83
  84 static __inline void
  85 TQ_LOCK_INIT(struct taskqueue *tq)
  86 {
  87         spin_init(&tq->tq_lock, "tqlock");
  88 }
  89
  90 static __inline void
  91 TQ_LOCK_UNINIT(struct taskqueue *tq)
  92 {
  93         spin_uninit(&tq->tq_lock);
  94 }
  95
  96 static __inline void
  97 TQ_LOCK(struct taskqueue *tq)
  98 {
  99         spin_lock(&tq->tq_lock);
 100 }
 101
 102 static __inline void
 103 TQ_UNLOCK(struct taskqueue *tq)
 104 {
 105         spin_unlock(&tq->tq_lock);
 106 }
 107
 108 static __inline void
 109 TQ_SLEEP(struct taskqueue *tq, void *ident, const char *wmesg)
 110 {
 111         ssleep(ident, &tq->tq_lock, 0, wmesg, 0);
 112 }
 113
 114 struct taskqueue *
 115 taskqueue_create(const char *name, int mflags,
 116                  taskqueue_enqueue_fn enqueue, void *context)
 117 {
 118         struct taskqueue *queue;
 119
 120         queue = kmalloc(sizeof(*queue), M_TASKQUEUE, mflags | M_ZERO);
 121         if (!queue)
 122                 return NULL;
 123         STAILQ_INIT(&queue->tq_queue);
 124         queue->tq_name = name;
 125         queue->tq_enqueue = enqueue;
 126         queue->tq_context = context;
 127         queue->tq_flags |= TQ_FLAGS_ACTIVE;
 128         TQ_LOCK_INIT(queue);
 129
 130         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 131         STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
 132         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 133
 134         return queue;
 135 }
 136
 137 /* NOTE: tq must be locked */
 138 static void
 139 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
 140 {
 141         while (tq->tq_tcount > 0) {
 142                 /* Unlock spinlock before wakeup() */
 143                 TQ_UNLOCK(tq);
 144                 wakeup(tq);
 145                 TQ_LOCK(tq);
 146                 TQ_SLEEP(tq, pp, "taskqueue_terminate");
 147         }
 148 }
 149
 150 void
 151 taskqueue_free(struct taskqueue *queue)
 152 {
 153         TQ_LOCK(queue);
 154         queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
 155         taskqueue_run(queue, 1);
 156         taskqueue_terminate(queue->tq_threads, queue);
 157         TQ_UNLOCK(queue);
 158
 159         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 160         STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
 161         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 162
 163         TQ_LOCK_UNINIT(queue);
 164
 165         kfree(queue, M_TASKQUEUE);
 166 }
 167
 168 struct taskqueue *
 169 taskqueue_find(const char *name)
 170 {
 171         struct taskqueue *queue;
 172
 173         lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
 174         STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
 175                 if (!strcmp(queue->tq_name, name)) {
 176                         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 177                         return queue;
 178                 }
 179         }
 180         lockmgr(&taskqueue_queues_lock, LK_RELEASE);
 181         return NULL;
 182 }
 183
 184 /*
 185  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
 186  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
 187  * So either use a throwaway task which will only be enqueued once, or
 188  * use one task per CPU!
 189  */
 190 static int
 191 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
 192 {
 193         struct task *ins;
 194         struct task *prev;
 195
 196         /*
 197          * Don't allow new tasks on a queue which is being freed.
 198          */
 199         if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0)
 200                 return EPIPE;
 201
 202         /*
 203          * Count multiple enqueues.
 204          */
 205         if (task->ta_pending) {
 206                 KKASSERT(queue == task->ta_queue);
 207                 task->ta_pending++;
 208                 return 0;
 209         }
 210         task->ta_queue = queue;
 211
 212         /*
 213          * Optimise the case when all tasks have the same priority.
 214          */
 215         prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
 216         if (!prev || prev->ta_priority >= task->ta_priority) {
 217                 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
 218         } else {
 219                 prev = NULL;
 220                 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
 221                      prev = ins, ins = STAILQ_NEXT(ins, ta_link))
 222                         if (ins->ta_priority < task->ta_priority)
 223                                 break;
 224
 225                 if (prev)
 226                         STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
 227                 else
 228                         STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
 229         }
 230
 231         task->ta_pending = 1;
 232         if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) {
 233                 if (queue->tq_enqueue)
 234                         queue->tq_enqueue(queue->tq_context);
 235         } else {
 236                 queue->tq_flags |= TQ_FLAGS_PENDING;
 237         }
 238
 239         return 0;
 240 }
 241
 242 /*
 243  * This version requires that the task not be moved between queues
 244  * in an uncontrolled fashion.
 245  */
 246 int
 247 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
 248 {
 249         int res;
 250
 251         TQ_LOCK(queue);
 252         res = taskqueue_enqueue_locked(queue, task);
 253         TQ_UNLOCK(queue);
 254
 255         return (res);
 256 }
 257
 258 /*
 259  * This version allows a task to be moved between queues in an uncontrolled
 260  * fashion.  (*qpp) is set to the queue the task is (possibly already)
 261  * enqueued on, or the specified queue if it is possible to move the task.
 262  */
 263 int
 264 taskqueue_enqueue_optq(struct taskqueue *queue, struct taskqueue **qpp,
 265                        struct task *task)
 266 {
 267         struct taskqueue *qtmp;
 268         int res;
 269
 270         /*
 271          * Interlock for task structure check, handle the case where we
 272          * are unable to safely shift the task to the specified queue.
 273          */
 274         for (;;) {
 275                 qtmp = task->ta_queue;
 276                 cpu_ccfence();
 277
 278                 if (qtmp == NULL) {
 279                         spin_lock(&taskqueue_queues_spin);
 280                         if (task->ta_queue == NULL)
 281                                 task->ta_queue = queue;
 282                         spin_unlock(&taskqueue_queues_spin);
 283                 } else {
 284                         TQ_LOCK(qtmp);
 285                         if (task->ta_queue == qtmp) {
 286                                 if (qtmp == queue)
 287                                         break;
 288
 289                                 /*
 290                                  * If qtmp is pending on a different queue
 291                                  * it must stay on that queue.
 292                                  *
 293                                  * WARNING: Once ta_queue is reassigned
 294                                  *          our qtmp lock is no longer
 295                                  *          sufficient and we lose control
 296                                  *          of the task.
 297                                  */
 298                                 if (task->ta_pending) {
 299                                         task->ta_pending++;
 300                                         *qpp = qtmp;
 301                                         TQ_UNLOCK(qtmp);
 302                                         return 0;
 303                                 }
 304                                 cpu_sfence();
 305                                 task->ta_queue = queue;
 306                                 cpu_ccfence();
 307                         }
 308                         TQ_UNLOCK(qtmp);
 309                 }
 310                 /* retry */
 311         }
 312
 313         /*
 314          * The task is assigned to (queue), enqueue it there.
 315          */
 316         *qpp = queue;
 317         res = taskqueue_enqueue_locked(queue, task);
 318         TQ_UNLOCK(queue);
 319
 320         return (res);
 321 }
 322
 323 static void
 324 taskqueue_timeout_func(void *arg)
 325 {
 326         struct taskqueue *queue;
 327         struct timeout_task *timeout_task;
 328
 329         timeout_task = arg;
 330         queue = timeout_task->t.ta_queue;
 331
 332         TQ_LOCK(queue);
 333         KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
 334         timeout_task->f &= ~DT_CALLOUT_ARMED;
 335         queue->tq_callouts--;
 336         taskqueue_enqueue_locked(queue, &timeout_task->t);
 337         TQ_UNLOCK(queue);
 338 }
 339
 340 int
 341 taskqueue_enqueue_timeout(struct taskqueue *queue,
 342     struct timeout_task *timeout_task, int ticks)
 343 {
 344         int res;
 345
 346         TQ_LOCK(queue);
 347         KASSERT(timeout_task->t.ta_queue == NULL ||
 348                 timeout_task->t.ta_queue == queue,
 349                 ("Migrated queue"));
 350         timeout_task->t.ta_queue = queue;
 351         res = timeout_task->t.ta_pending;
 352         if (ticks == 0) {
 353                 taskqueue_enqueue_locked(queue, &timeout_task->t);
 354                 TQ_UNLOCK(queue);
 355         } else {
 356                 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 357                         res++;
 358                 } else {
 359                         queue->tq_callouts++;
 360                         timeout_task->f |= DT_CALLOUT_ARMED;
 361                 }
 362                 TQ_UNLOCK(queue);
 363                 callout_reset(&timeout_task->c, ticks, taskqueue_timeout_func,
 364                               timeout_task);
 365         }
 366         return (res);
 367 }
 368
 369 void
 370 taskqueue_block(struct taskqueue *queue)
 371 {
 372         TQ_LOCK(queue);
 373         queue->tq_flags |= TQ_FLAGS_BLOCKED;
 374         TQ_UNLOCK(queue);
 375 }
 376
 377 void
 378 taskqueue_unblock(struct taskqueue *queue)
 379 {
 380         TQ_LOCK(queue);
 381         queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
 382         if (queue->tq_flags & TQ_FLAGS_PENDING) {
 383                 queue->tq_flags &= ~TQ_FLAGS_PENDING;
 384                 if (queue->tq_enqueue)
 385                         queue->tq_enqueue(queue->tq_context);
 386         }
 387         TQ_UNLOCK(queue);
 388 }
 389
 390 static void
 391 taskqueue_run(struct taskqueue *queue, int lock_held)
 392 {
 393         struct task *task;
 394         int pending;
 395
 396         if (lock_held == 0)
 397                 TQ_LOCK(queue);
 398         while (STAILQ_FIRST(&queue->tq_queue)) {
 399                 /*
 400                  * Carefully remove the first task from the queue and
 401                  * zero its pending count.
 402                  */
 403                 task = STAILQ_FIRST(&queue->tq_queue);
 404                 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
 405                 pending = task->ta_pending;
 406                 task->ta_pending = 0;
 407                 queue->tq_running = task;
 408
 409                 TQ_UNLOCK(queue);
 410                 task->ta_func(task->ta_context, pending);
 411                 queue->tq_running = NULL;
 412                 wakeup(task);
 413                 TQ_LOCK(queue);
 414         }
 415         if (lock_held == 0)
 416                 TQ_UNLOCK(queue);
 417 }
 418
 419 static int
 420 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
 421     u_int *pendp)
 422 {
 423
 424         if (task->ta_pending > 0)
 425                 STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
 426         if (pendp != NULL)
 427                 *pendp = task->ta_pending;
 428         task->ta_pending = 0;
 429         return (task == queue->tq_running ? EBUSY : 0);
 430 }
 431
 432 int
 433 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
 434 {
 435         int error;
 436
 437         TQ_LOCK(queue);
 438         error = taskqueue_cancel_locked(queue, task, pendp);
 439         TQ_UNLOCK(queue);
 440
 441         return (error);
 442 }
 443
 444 int
 445 taskqueue_cancel_simple(struct task *task)
 446 {
 447         struct taskqueue *queue;
 448         int error;
 449
 450         for (;;) {
 451                 queue = task->ta_queue;
 452                 cpu_ccfence();
 453                 if (queue == NULL) {
 454                         error = 0;
 455                         break;
 456                 }
 457                 TQ_LOCK(queue);
 458                 if (queue == task->ta_queue) {
 459                         error = taskqueue_cancel_locked(queue, task, NULL);
 460                         TQ_UNLOCK(queue);
 461                         break;
 462                 }
 463                 TQ_UNLOCK(queue);
 464         }
 465         return error;
 466 }
 467
 468 int
 469 taskqueue_cancel_timeout(struct taskqueue *queue,
 470                          struct timeout_task *timeout_task, u_int *pendp)
 471 {
 472         u_int pending, pending1;
 473         int error;
 474
 475         pending = !!callout_stop(&timeout_task->c);
 476         TQ_LOCK(queue);
 477         error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
 478         if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
 479                 timeout_task->f &= ~DT_CALLOUT_ARMED;
 480                 queue->tq_callouts--;
 481         }
 482         TQ_UNLOCK(queue);
 483
 484         if (pendp != NULL)
 485                 *pendp = pending + pending1;
 486         return (error);
 487 }
 488
 489 void
 490 taskqueue_drain(struct taskqueue *queue, struct task *task)
 491 {
 492         TQ_LOCK(queue);
 493         while (task->ta_pending != 0 || task == queue->tq_running)
 494                 TQ_SLEEP(queue, task, "-");
 495         TQ_UNLOCK(queue);
 496 }
 497
 498 /*
 499  * Wait for the task to drain and return
 500  */
 501 void
 502 taskqueue_drain_simple(struct task *task)
 503 {
 504         struct taskqueue *queue;
 505
 506         for (;;) {
 507                 queue = task->ta_queue;
 508                 cpu_ccfence();
 509                 if (queue == NULL)
 510                         return;
 511                 TQ_LOCK(queue);
 512                 if (task->ta_pending == 0 && task != queue->tq_running) {
 513                         TQ_UNLOCK(queue);
 514                         return;
 515                 }
 516                 TQ_SLEEP(queue, task, "-");
 517                 TQ_UNLOCK(queue);
 518         }
 519 }
 520
 521 void
 522 taskqueue_drain_timeout(struct taskqueue *queue,
 523     struct timeout_task *timeout_task)
 524 {
 525         callout_cancel(&timeout_task->c);
 526         taskqueue_drain(queue, &timeout_task->t);
 527 }
 528
 529 static void
 530 taskqueue_swi_enqueue(void *context)
 531 {
 532         setsofttq();
 533 }
 534
 535 static void
 536 taskqueue_swi_run(void *arg, void *frame)
 537 {
 538         taskqueue_run(taskqueue_swi, 0);
 539 }
 540
 541 static void
 542 taskqueue_swi_mp_run(void *arg, void *frame)
 543 {
 544         taskqueue_run(taskqueue_swi_mp, 0);
 545 }
 546
 547 int
 548 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, int ncpu,
 549                         const char *fmt, ...)
 550 {
 551         __va_list ap;
 552         struct thread *td;
 553         struct taskqueue *tq;
 554         int i, error, cpu;
 555         char ktname[MAXCOMLEN];
 556
 557         tq = *tqp;
 558         cpu = ncpu;
 559
 560         /* catch call argument mistakes */
 561         KKASSERT(pri > 0 && pri < TDPRI_MAX);
 562         KKASSERT(tq->tq_enqueue == taskqueue_thread_enqueue);
 563
 564         if (count <= 0)
 565                 return EINVAL;
 566
 567         __va_start(ap, fmt);
 568         kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
 569         __va_end(ap);
 570
 571         tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
 572             M_WAITOK | M_ZERO);
 573
 574         for (i = 0; i < count; i++) {
 575                 /*
 576                  * If no specific cpu was specified and more than one thread
 577                  * is to be created, we distribute the threads amongst all
 578                  * cpus.
 579                  */
 580                 if ((ncpu <= -1) && (count > 1))
 581                         cpu = i % ncpus;
 582
 583                 if (count == 1) {
 584                         error = lwkt_create(taskqueue_thread_loop, tqp,
 585                                             &tq->tq_threads[i], NULL,
 586                                             TDF_NOSTART, cpu,
 587                                             "%s", ktname);
 588                 } else {
 589                         error = lwkt_create(taskqueue_thread_loop, tqp,
 590                                             &tq->tq_threads[i], NULL,
 591                                             TDF_NOSTART, cpu,
 592                                             "%s_%d", ktname, i);
 593                 }
 594                 if (error) {
 595                         kprintf("%s: lwkt_create(%s): error %d", __func__,
 596                             ktname, error);
 597                         tq->tq_threads[i] = NULL;
 598                 } else {
 599                         td = tq->tq_threads[i];
 600                         lwkt_setpri_initial(td, pri);
 601                         lwkt_schedule(td);
 602                         tq->tq_tcount++;
 603                 }
 604         }
 605
 606         return 0;
 607 }
 608
 609 void
 610 taskqueue_thread_loop(void *arg)
 611 {
 612         struct taskqueue **tqp, *tq;
 613
 614         tqp = arg;
 615         tq = *tqp;
 616         TQ_LOCK(tq);
 617         while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
 618                 taskqueue_run(tq, 1);
 619                 TQ_SLEEP(tq, tq, "tqthr");
 620         }
 621
 622         /* rendezvous with thread that asked us to terminate */
 623         tq->tq_tcount--;
 624         TQ_UNLOCK(tq);
 625         wakeup_one(tq->tq_threads);
 626         lwkt_exit();
 627 }
 628
 629 /* NOTE: tq must be locked */
 630 void
 631 taskqueue_thread_enqueue(void *context)
 632 {
 633         struct taskqueue **tqp, *tq;
 634
 635         tqp = context;
 636         tq = *tqp;
 637
 638         /* Unlock spinlock before wakeup_one() */
 639         TQ_UNLOCK(tq);
 640         wakeup_one(tq);
 641         TQ_LOCK(tq);
 642 }
 643
 644 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
 645          register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL, -1));
 646 /*
 647  * XXX: possibly use a different SWI_TQ_MP or so.
 648  * related: sys/interrupt.h
 649  * related: platform/XXX/isa/ipl_funcs.c
 650  */
 651 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
 652     register_swi_mp(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL,
 653                     -1));
 654
 655 struct taskqueue *taskqueue_thread[MAXCPU];
 656
 657 static void
 658 taskqueue_init(void)
 659 {
 660         int cpu;
 661
 662         lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
 663         spin_init(&taskqueue_queues_spin, "tqspin");
 664         STAILQ_INIT(&taskqueue_queues);
 665
 666         for (cpu = 0; cpu < ncpus; cpu++) {
 667                 taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
 668                     taskqueue_thread_enqueue, &taskqueue_thread[cpu]);
 669                 taskqueue_start_threads(&taskqueue_thread[cpu], 1,
 670                     TDPRI_KERN_DAEMON, cpu, "taskq_cpu %d", cpu);
 671         }
 672 }
 673
 674 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_FIRST, taskqueue_init, NULL);