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         (void) tq, (void) func, (void) arg, (void) tqflags, (void) expire_time;
 141         return (0);
 142 }
 143
 144 int
 145 taskq_empty_ent(taskq_ent_t *t)
 146 {
 147         return (t->tqent_next == NULL);
 148 }
 149
 150 void
 151 taskq_init_ent(taskq_ent_t *t)
 152 {
 153         t->tqent_next = NULL;
 154         t->tqent_prev = NULL;
 155         t->tqent_func = NULL;
 156         t->tqent_arg = NULL;
 157         t->tqent_flags = 0;
 158 }
 159
 160 void
 161 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
 162     taskq_ent_t *t)
 163 {
 164         ASSERT(func != NULL);
 165
 166         /*
 167          * Mark it as a prealloc'd task.  This is important
 168          * to ensure that we don't free it later.
 169          */
 170         t->tqent_flags |= TQENT_FLAG_PREALLOC;
 171         /*
 172          * Enqueue the task to the underlying queue.
 173          */
 174         mutex_enter(&tq->tq_lock);
 175
 176         if (flags & TQ_FRONT) {
 177                 t->tqent_next = tq->tq_task.tqent_next;
 178                 t->tqent_prev = &tq->tq_task;
 179         } else {
 180                 t->tqent_next = &tq->tq_task;
 181                 t->tqent_prev = tq->tq_task.tqent_prev;
 182         }
 183         t->tqent_next->tqent_prev = t;
 184         t->tqent_prev->tqent_next = t;
 185         t->tqent_func = func;
 186         t->tqent_arg = arg;
 187         cv_signal(&tq->tq_dispatch_cv);
 188         mutex_exit(&tq->tq_lock);
 189 }
 190
 191 void
 192 taskq_wait(taskq_t *tq)
 193 {
 194         mutex_enter(&tq->tq_lock);
 195         while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
 196                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 197         mutex_exit(&tq->tq_lock);
 198 }
 199
 200 void
 201 taskq_wait_id(taskq_t *tq, taskqid_t id)
 202 {
 203         (void) id;
 204         taskq_wait(tq);
 205 }
 206
 207 void
 208 taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
 209 {
 210         (void) id;
 211         taskq_wait(tq);
 212 }
 213
 214 static __attribute__((noreturn)) void
 215 taskq_thread(void *arg)
 216 {
 217         taskq_t *tq = arg;
 218         taskq_ent_t *t;
 219         boolean_t prealloc;
 220
 221         VERIFY0(pthread_setspecific(taskq_tsd, tq));
 222
 223         mutex_enter(&tq->tq_lock);
 224         while (tq->tq_flags & TASKQ_ACTIVE) {
 225                 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
 226                         if (--tq->tq_active == 0)
 227                                 cv_broadcast(&tq->tq_wait_cv);
 228                         cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
 229                         tq->tq_active++;
 230                         continue;
 231                 }
 232                 t->tqent_prev->tqent_next = t->tqent_next;
 233                 t->tqent_next->tqent_prev = t->tqent_prev;
 234                 t->tqent_next = NULL;
 235                 t->tqent_prev = NULL;
 236                 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
 237                 mutex_exit(&tq->tq_lock);
 238
 239                 rw_enter(&tq->tq_threadlock, RW_READER);
 240                 t->tqent_func(t->tqent_arg);
 241                 rw_exit(&tq->tq_threadlock);
 242
 243                 mutex_enter(&tq->tq_lock);
 244                 if (!prealloc)
 245                         task_free(tq, t);
 246         }
 247         tq->tq_nthreads--;
 248         cv_broadcast(&tq->tq_wait_cv);
 249         mutex_exit(&tq->tq_lock);
 250         thread_exit();
 251 }
 252
 253 taskq_t *
 254 taskq_create(const char *name, int nthreads, pri_t pri,
 255     int minalloc, int maxalloc, uint_t flags)
 256 {
 257         (void) pri;
 258         taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
 259         int t;
 260
 261         if (flags & TASKQ_THREADS_CPU_PCT) {
 262                 int pct;
 263                 ASSERT3S(nthreads, >=, 0);
 264                 ASSERT3S(nthreads, <=, 100);
 265                 pct = MIN(nthreads, 100);
 266                 pct = MAX(pct, 0);
 267
 268                 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
 269                 nthreads = MAX(nthreads, 1);    /* need at least 1 thread */
 270         } else {
 271                 ASSERT3S(nthreads, >=, 1);
 272         }
 273
 274         rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
 275         mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
 276         cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
 277         cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
 278         cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
 279         (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN);
 280         tq->tq_flags = flags | TASKQ_ACTIVE;
 281         tq->tq_active = nthreads;
 282         tq->tq_nthreads = nthreads;
 283         tq->tq_minalloc = minalloc;
 284         tq->tq_maxalloc = maxalloc;
 285         tq->tq_task.tqent_next = &tq->tq_task;
 286         tq->tq_task.tqent_prev = &tq->tq_task;
 287         tq->tq_threadlist = kmem_alloc(nthreads * sizeof (kthread_t *),
 288             KM_SLEEP);
 289
 290         if (flags & TASKQ_PREPOPULATE) {
 291                 mutex_enter(&tq->tq_lock);
 292                 while (minalloc-- > 0)
 293                         task_free(tq, task_alloc(tq, KM_SLEEP));
 294                 mutex_exit(&tq->tq_lock);
 295         }
 296
 297         for (t = 0; t < nthreads; t++)
 298                 VERIFY((tq->tq_threadlist[t] = thread_create(NULL, 0,
 299                     taskq_thread, tq, 0, &p0, TS_RUN, pri)) != NULL);
 300
 301         return (tq);
 302 }
 303
 304 void
 305 taskq_destroy(taskq_t *tq)
 306 {
 307         int nthreads = tq->tq_nthreads;
 308
 309         taskq_wait(tq);
 310
 311         mutex_enter(&tq->tq_lock);
 312
 313         tq->tq_flags &= ~TASKQ_ACTIVE;
 314         cv_broadcast(&tq->tq_dispatch_cv);
 315
 316         while (tq->tq_nthreads != 0)
 317                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 318
 319         tq->tq_minalloc = 0;
 320         while (tq->tq_nalloc != 0) {
 321                 ASSERT(tq->tq_freelist != NULL);
 322                 task_free(tq, task_alloc(tq, KM_SLEEP));
 323         }
 324
 325         mutex_exit(&tq->tq_lock);
 326
 327         kmem_free(tq->tq_threadlist, nthreads * sizeof (kthread_t *));
 328
 329         rw_destroy(&tq->tq_threadlock);
 330         mutex_destroy(&tq->tq_lock);
 331         cv_destroy(&tq->tq_dispatch_cv);
 332         cv_destroy(&tq->tq_wait_cv);
 333         cv_destroy(&tq->tq_maxalloc_cv);
 334
 335         kmem_free(tq, sizeof (taskq_t));
 336 }
 337
 338 int
 339 taskq_member(taskq_t *tq, kthread_t *t)
 340 {
 341         int i;
 342
 343         if (taskq_now)
 344                 return (1);
 345
 346         for (i = 0; i < tq->tq_nthreads; i++)
 347                 if (tq->tq_threadlist[i] == t)
 348                         return (1);
 349
 350         return (0);
 351 }
 352
 353 taskq_t *
 354 taskq_of_curthread(void)
 355 {
 356         return (pthread_getspecific(taskq_tsd));
 357 }
 358
 359 int
 360 taskq_cancel_id(taskq_t *tq, taskqid_t id)
 361 {
 362         (void) tq, (void) id;
 363         return (ENOENT);
 364 }
 365
 366 void
 367 system_taskq_init(void)
 368 {
 369         VERIFY0(pthread_key_create(&taskq_tsd, NULL));
 370         system_taskq = taskq_create("system_taskq", 64, maxclsyspri, 4, 512,
 371             TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 372         system_delay_taskq = taskq_create("delay_taskq", 4, maxclsyspri, 4,
 373             512, TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 374 }
 375
 376 void
 377 system_taskq_fini(void)
 378 {
 379         taskq_destroy(system_taskq);
 380         system_taskq = NULL; /* defensive */
 381         taskq_destroy(system_delay_taskq);
 382         system_delay_taskq = NULL;
 383         VERIFY0(pthread_key_delete(taskq_tsd));
 384 }