lib/libzpool/taskq.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25 /*
  26  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
  27  * Copyright 2012 Garrett D'Amore <garrett@damore.org>.  All rights reserved.
  28  * Copyright (c) 2014 by Delphix. All rights reserved.
  29  */
  30
  31 #include <sys/zfs_context.h>
  32
  33 int taskq_now;
  34 taskq_t *system_taskq;
  35 taskq_t *system_delay_taskq;
  36
  37 static pthread_key_t taskq_tsd;
  38
  39 #define TASKQ_ACTIVE    0x00010000
  40
  41 static taskq_ent_t *
  42 task_alloc(taskq_t *tq, int tqflags)
  43 {
  44         taskq_ent_t *t;
  45         int rv;
  46
  47 again:  if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
  48                 ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
  49                 tq->tq_freelist = t->tqent_next;
  50         } else {
  51                 if (tq->tq_nalloc >= tq->tq_maxalloc) {
  52                         if (!(tqflags & KM_SLEEP))
  53                                 return (NULL);
  54
  55                         /*
  56                          * We don't want to exceed tq_maxalloc, but we can't
  57                          * wait for other tasks to complete (and thus free up
  58                          * task structures) without risking deadlock with
  59                          * the caller.  So, we just delay for one second
  60                          * to throttle the allocation rate. If we have tasks
  61                          * complete before one second timeout expires then
  62                          * taskq_ent_free will signal us and we will
  63                          * immediately retry the allocation.
  64                          */
  65                         tq->tq_maxalloc_wait++;
  66                         rv = cv_timedwait(&tq->tq_maxalloc_cv,
  67                             &tq->tq_lock, ddi_get_lbolt() + hz);
  68                         tq->tq_maxalloc_wait--;
  69                         if (rv > 0)
  70                                 goto again;             /* signaled */
  71                 }
  72                 mutex_exit(&tq->tq_lock);
  73
  74                 t = kmem_alloc(sizeof (taskq_ent_t), tqflags);
  75
  76                 mutex_enter(&tq->tq_lock);
  77                 if (t != NULL) {
  78                         /* Make sure we start without any flags */
  79                         t->tqent_flags = 0;
  80                         tq->tq_nalloc++;
  81                 }
  82         }
  83         return (t);
  84 }
  85
  86 static void
  87 task_free(taskq_t *tq, taskq_ent_t *t)
  88 {
  89         if (tq->tq_nalloc <= tq->tq_minalloc) {
  90                 t->tqent_next = tq->tq_freelist;
  91                 tq->tq_freelist = t;
  92         } else {
  93                 tq->tq_nalloc--;
  94                 mutex_exit(&tq->tq_lock);
  95                 kmem_free(t, sizeof (taskq_ent_t));
  96                 mutex_enter(&tq->tq_lock);
  97         }
  98
  99         if (tq->tq_maxalloc_wait)
 100                 cv_signal(&tq->tq_maxalloc_cv);
 101 }
 102
 103 taskqid_t
 104 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
 105 {
 106         taskq_ent_t *t;
 107
 108         if (taskq_now) {
 109                 func(arg);
 110                 return (1);
 111         }
 112
 113         mutex_enter(&tq->tq_lock);
 114         ASSERT(tq->tq_flags & TASKQ_ACTIVE);
 115         if ((t = task_alloc(tq, tqflags)) == NULL) {
 116                 mutex_exit(&tq->tq_lock);
 117                 return (0);
 118         }
 119         if (tqflags & TQ_FRONT) {
 120                 t->tqent_next = tq->tq_task.tqent_next;
 121                 t->tqent_prev = &tq->tq_task;
 122         } else {
 123                 t->tqent_next = &tq->tq_task;
 124                 t->tqent_prev = tq->tq_task.tqent_prev;
 125         }
 126         t->tqent_next->tqent_prev = t;
 127         t->tqent_prev->tqent_next = t;
 128         t->tqent_func = func;
 129         t->tqent_arg = arg;
 130         t->tqent_flags = 0;
 131         cv_signal(&tq->tq_dispatch_cv);
 132         mutex_exit(&tq->tq_lock);
 133         return (1);
 134 }
 135
 136 taskqid_t
 137 taskq_dispatch_delay(taskq_t *tq,  task_func_t func, void *arg, uint_t tqflags,
 138     clock_t expire_time)
 139 {
 140         return (0);
 141 }
 142
 143 int
 144 taskq_empty_ent(taskq_ent_t *t)
 145 {
 146         return (t->tqent_next == NULL);
 147 }
 148
 149 void
 150 taskq_init_ent(taskq_ent_t *t)
 151 {
 152         t->tqent_next = NULL;
 153         t->tqent_prev = NULL;
 154         t->tqent_func = NULL;
 155         t->tqent_arg = NULL;
 156         t->tqent_flags = 0;
 157 }
 158
 159 void
 160 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
 161     taskq_ent_t *t)
 162 {
 163         ASSERT(func != NULL);
 164
 165         /*
 166          * Mark it as a prealloc'd task.  This is important
 167          * to ensure that we don't free it later.
 168          */
 169         t->tqent_flags |= TQENT_FLAG_PREALLOC;
 170         /*
 171          * Enqueue the task to the underlying queue.
 172          */
 173         mutex_enter(&tq->tq_lock);
 174
 175         if (flags & TQ_FRONT) {
 176                 t->tqent_next = tq->tq_task.tqent_next;
 177                 t->tqent_prev = &tq->tq_task;
 178         } else {
 179                 t->tqent_next = &tq->tq_task;
 180                 t->tqent_prev = tq->tq_task.tqent_prev;
 181         }
 182         t->tqent_next->tqent_prev = t;
 183         t->tqent_prev->tqent_next = t;
 184         t->tqent_func = func;
 185         t->tqent_arg = arg;
 186         cv_signal(&tq->tq_dispatch_cv);
 187         mutex_exit(&tq->tq_lock);
 188 }
 189
 190 void
 191 taskq_wait(taskq_t *tq)
 192 {
 193         mutex_enter(&tq->tq_lock);
 194         while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
 195                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 196         mutex_exit(&tq->tq_lock);
 197 }
 198
 199 void
 200 taskq_wait_id(taskq_t *tq, taskqid_t id)
 201 {
 202         taskq_wait(tq);
 203 }
 204
 205 void
 206 taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
 207 {
 208         taskq_wait(tq);
 209 }
 210
 211 static void
 212 taskq_thread(void *arg)
 213 {
 214         taskq_t *tq = arg;
 215         taskq_ent_t *t;
 216         boolean_t prealloc;
 217
 218         VERIFY0(pthread_setspecific(taskq_tsd, tq));
 219
 220         mutex_enter(&tq->tq_lock);
 221         while (tq->tq_flags & TASKQ_ACTIVE) {
 222                 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
 223                         if (--tq->tq_active == 0)
 224                                 cv_broadcast(&tq->tq_wait_cv);
 225                         cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
 226                         tq->tq_active++;
 227                         continue;
 228                 }
 229                 t->tqent_prev->tqent_next = t->tqent_next;
 230                 t->tqent_next->tqent_prev = t->tqent_prev;
 231                 t->tqent_next = NULL;
 232                 t->tqent_prev = NULL;
 233                 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
 234                 mutex_exit(&tq->tq_lock);
 235
 236                 rw_enter(&tq->tq_threadlock, RW_READER);
 237                 t->tqent_func(t->tqent_arg);
 238                 rw_exit(&tq->tq_threadlock);
 239
 240                 mutex_enter(&tq->tq_lock);
 241                 if (!prealloc)
 242                         task_free(tq, t);
 243         }
 244         tq->tq_nthreads--;
 245         cv_broadcast(&tq->tq_wait_cv);
 246         mutex_exit(&tq->tq_lock);
 247         thread_exit();
 248 }
 249
 250 /*ARGSUSED*/
 251 taskq_t *
 252 taskq_create(const char *name, int nthreads, pri_t pri,
 253     int minalloc, int maxalloc, uint_t flags)
 254 {
 255         taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
 256         int t;
 257
 258         if (flags & TASKQ_THREADS_CPU_PCT) {
 259                 int pct;
 260                 ASSERT3S(nthreads, >=, 0);
 261                 ASSERT3S(nthreads, <=, 100);
 262                 pct = MIN(nthreads, 100);
 263                 pct = MAX(pct, 0);
 264
 265                 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
 266                 nthreads = MAX(nthreads, 1);    /* need at least 1 thread */
 267         } else {
 268                 ASSERT3S(nthreads, >=, 1);
 269         }
 270
 271         rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
 272         mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
 273         cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
 274         cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
 275         cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
 276         (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN);
 277         tq->tq_flags = flags | TASKQ_ACTIVE;
 278         tq->tq_active = nthreads;
 279         tq->tq_nthreads = nthreads;
 280         tq->tq_minalloc = minalloc;
 281         tq->tq_maxalloc = maxalloc;
 282         tq->tq_task.tqent_next = &tq->tq_task;
 283         tq->tq_task.tqent_prev = &tq->tq_task;
 284         tq->tq_threadlist = kmem_alloc(nthreads * sizeof (kthread_t *),
 285             KM_SLEEP);
 286
 287         if (flags & TASKQ_PREPOPULATE) {
 288                 mutex_enter(&tq->tq_lock);
 289                 while (minalloc-- > 0)
 290                         task_free(tq, task_alloc(tq, KM_SLEEP));
 291                 mutex_exit(&tq->tq_lock);
 292         }
 293
 294         for (t = 0; t < nthreads; t++)
 295                 VERIFY((tq->tq_threadlist[t] = thread_create(NULL, 0,
 296                     taskq_thread, tq, 0, &p0, TS_RUN, pri)) != NULL);
 297
 298         return (tq);
 299 }
 300
 301 void
 302 taskq_destroy(taskq_t *tq)
 303 {
 304         int nthreads = tq->tq_nthreads;
 305
 306         taskq_wait(tq);
 307
 308         mutex_enter(&tq->tq_lock);
 309
 310         tq->tq_flags &= ~TASKQ_ACTIVE;
 311         cv_broadcast(&tq->tq_dispatch_cv);
 312
 313         while (tq->tq_nthreads != 0)
 314                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 315
 316         tq->tq_minalloc = 0;
 317         while (tq->tq_nalloc != 0) {
 318                 ASSERT(tq->tq_freelist != NULL);
 319                 task_free(tq, task_alloc(tq, KM_SLEEP));
 320         }
 321
 322         mutex_exit(&tq->tq_lock);
 323
 324         kmem_free(tq->tq_threadlist, nthreads * sizeof (kthread_t *));
 325
 326         rw_destroy(&tq->tq_threadlock);
 327         mutex_destroy(&tq->tq_lock);
 328         cv_destroy(&tq->tq_dispatch_cv);
 329         cv_destroy(&tq->tq_wait_cv);
 330         cv_destroy(&tq->tq_maxalloc_cv);
 331
 332         kmem_free(tq, sizeof (taskq_t));
 333 }
 334
 335 int
 336 taskq_member(taskq_t *tq, kthread_t *t)
 337 {
 338         int i;
 339
 340         if (taskq_now)
 341                 return (1);
 342
 343         for (i = 0; i < tq->tq_nthreads; i++)
 344                 if (tq->tq_threadlist[i] == t)
 345                         return (1);
 346
 347         return (0);
 348 }
 349
 350 taskq_t *
 351 taskq_of_curthread(void)
 352 {
 353         return (pthread_getspecific(taskq_tsd));
 354 }
 355
 356 int
 357 taskq_cancel_id(taskq_t *tq, taskqid_t id)
 358 {
 359         return (ENOENT);
 360 }
 361
 362 void
 363 system_taskq_init(void)
 364 {
 365         VERIFY0(pthread_key_create(&taskq_tsd, NULL));
 366         system_taskq = taskq_create("system_taskq", 64, maxclsyspri, 4, 512,
 367             TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 368         system_delay_taskq = taskq_create("delay_taskq", 4, maxclsyspri, 4,
 369             512, TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 370 }
 371
 372 void
 373 system_taskq_fini(void)
 374 {
 375         taskq_destroy(system_taskq);
 376         system_taskq = NULL; /* defensive */
 377         taskq_destroy(system_delay_taskq);
 378         system_delay_taskq = NULL;
 379         VERIFY0(pthread_key_delete(taskq_tsd));
 380 }