zfs/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
  36 #define TASKQ_ACTIVE    0x00010000
  37
  38 static taskq_ent_t *
  39 task_alloc(taskq_t *tq, int tqflags)
  40 {
  41         taskq_ent_t *t;
  42         int rv;
  43
  44 again:  if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
  45                 ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
  46                 tq->tq_freelist = t->tqent_next;
  47         } else {
  48                 if (tq->tq_nalloc >= tq->tq_maxalloc) {
  49                         if (!(tqflags & KM_SLEEP))
  50                                 return (NULL);
  51
  52                         /*
  53                          * We don't want to exceed tq_maxalloc, but we can't
  54                          * wait for other tasks to complete (and thus free up
  55                          * task structures) without risking deadlock with
  56                          * the caller.  So, we just delay for one second
  57                          * to throttle the allocation rate. If we have tasks
  58                          * complete before one second timeout expires then
  59                          * taskq_ent_free will signal us and we will
  60                          * immediately retry the allocation.
  61                          */
  62                         tq->tq_maxalloc_wait++;
  63                         rv = cv_timedwait(&tq->tq_maxalloc_cv,
  64                             &tq->tq_lock, ddi_get_lbolt() + hz);
  65                         tq->tq_maxalloc_wait--;
  66                         if (rv > 0)
  67                                 goto again;             /* signaled */
  68                 }
  69                 mutex_exit(&tq->tq_lock);
  70
  71                 t = kmem_alloc(sizeof (taskq_ent_t), tqflags);
  72
  73                 mutex_enter(&tq->tq_lock);
  74                 if (t != NULL) {
  75                         /* Make sure we start without any flags */
  76                         t->tqent_flags = 0;
  77                         tq->tq_nalloc++;
  78                 }
  79         }
  80         return (t);
  81 }
  82
  83 static void
  84 task_free(taskq_t *tq, taskq_ent_t *t)
  85 {
  86         if (tq->tq_nalloc <= tq->tq_minalloc) {
  87                 t->tqent_next = tq->tq_freelist;
  88                 tq->tq_freelist = t;
  89         } else {
  90                 tq->tq_nalloc--;
  91                 mutex_exit(&tq->tq_lock);
  92                 kmem_free(t, sizeof (taskq_ent_t));
  93                 mutex_enter(&tq->tq_lock);
  94         }
  95
  96         if (tq->tq_maxalloc_wait)
  97                 cv_signal(&tq->tq_maxalloc_cv);
  98 }
  99
 100 taskqid_t
 101 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
 102 {
 103         taskq_ent_t *t;
 104
 105         if (taskq_now) {
 106                 func(arg);
 107                 return (1);
 108         }
 109
 110         mutex_enter(&tq->tq_lock);
 111         ASSERT(tq->tq_flags & TASKQ_ACTIVE);
 112         if ((t = task_alloc(tq, tqflags)) == NULL) {
 113                 mutex_exit(&tq->tq_lock);
 114                 return (0);
 115         }
 116         if (tqflags & TQ_FRONT) {
 117                 t->tqent_next = tq->tq_task.tqent_next;
 118                 t->tqent_prev = &tq->tq_task;
 119         } else {
 120                 t->tqent_next = &tq->tq_task;
 121                 t->tqent_prev = tq->tq_task.tqent_prev;
 122         }
 123         t->tqent_next->tqent_prev = t;
 124         t->tqent_prev->tqent_next = t;
 125         t->tqent_func = func;
 126         t->tqent_arg = arg;
 127         t->tqent_flags = 0;
 128         cv_signal(&tq->tq_dispatch_cv);
 129         mutex_exit(&tq->tq_lock);
 130         return (1);
 131 }
 132
 133 taskqid_t
 134 taskq_dispatch_delay(taskq_t *tq,  task_func_t func, void *arg, uint_t tqflags,
 135     clock_t expire_time)
 136 {
 137         return (0);
 138 }
 139
 140 int
 141 taskq_empty_ent(taskq_ent_t *t)
 142 {
 143         return (t->tqent_next == NULL);
 144 }
 145
 146 void
 147 taskq_init_ent(taskq_ent_t *t)
 148 {
 149         t->tqent_next = NULL;
 150         t->tqent_prev = NULL;
 151         t->tqent_func = NULL;
 152         t->tqent_arg = NULL;
 153         t->tqent_flags = 0;
 154 }
 155
 156 void
 157 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
 158     taskq_ent_t *t)
 159 {
 160         ASSERT(func != NULL);
 161
 162         /*
 163          * Mark it as a prealloc'd task.  This is important
 164          * to ensure that we don't free it later.
 165          */
 166         t->tqent_flags |= TQENT_FLAG_PREALLOC;
 167         /*
 168          * Enqueue the task to the underlying queue.
 169          */
 170         mutex_enter(&tq->tq_lock);
 171
 172         if (flags & TQ_FRONT) {
 173                 t->tqent_next = tq->tq_task.tqent_next;
 174                 t->tqent_prev = &tq->tq_task;
 175         } else {
 176                 t->tqent_next = &tq->tq_task;
 177                 t->tqent_prev = tq->tq_task.tqent_prev;
 178         }
 179         t->tqent_next->tqent_prev = t;
 180         t->tqent_prev->tqent_next = t;
 181         t->tqent_func = func;
 182         t->tqent_arg = arg;
 183         cv_signal(&tq->tq_dispatch_cv);
 184         mutex_exit(&tq->tq_lock);
 185 }
 186
 187 void
 188 taskq_wait(taskq_t *tq)
 189 {
 190         mutex_enter(&tq->tq_lock);
 191         while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
 192                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 193         mutex_exit(&tq->tq_lock);
 194 }
 195
 196 void
 197 taskq_wait_id(taskq_t *tq, taskqid_t id)
 198 {
 199         taskq_wait(tq);
 200 }
 201
 202 void
 203 taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
 204 {
 205         taskq_wait(tq);
 206 }
 207
 208 static void
 209 taskq_thread(void *arg)
 210 {
 211         taskq_t *tq = arg;
 212         taskq_ent_t *t;
 213         boolean_t prealloc;
 214
 215         mutex_enter(&tq->tq_lock);
 216         while (tq->tq_flags & TASKQ_ACTIVE) {
 217                 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
 218                         if (--tq->tq_active == 0)
 219                                 cv_broadcast(&tq->tq_wait_cv);
 220                         cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
 221                         tq->tq_active++;
 222                         continue;
 223                 }
 224                 t->tqent_prev->tqent_next = t->tqent_next;
 225                 t->tqent_next->tqent_prev = t->tqent_prev;
 226                 t->tqent_next = NULL;
 227                 t->tqent_prev = NULL;
 228                 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
 229                 mutex_exit(&tq->tq_lock);
 230
 231                 rw_enter(&tq->tq_threadlock, RW_READER);
 232                 t->tqent_func(t->tqent_arg);
 233                 rw_exit(&tq->tq_threadlock);
 234
 235                 mutex_enter(&tq->tq_lock);
 236                 if (!prealloc)
 237                         task_free(tq, t);
 238         }
 239         tq->tq_nthreads--;
 240         cv_broadcast(&tq->tq_wait_cv);
 241         mutex_exit(&tq->tq_lock);
 242         thread_exit();
 243 }
 244
 245 /*ARGSUSED*/
 246 taskq_t *
 247 taskq_create(const char *name, int nthreads, pri_t pri,
 248         int minalloc, int maxalloc, uint_t flags)
 249 {
 250         taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
 251         int t;
 252
 253         if (flags & TASKQ_THREADS_CPU_PCT) {
 254                 int pct;
 255                 ASSERT3S(nthreads, >=, 0);
 256                 ASSERT3S(nthreads, <=, 100);
 257                 pct = MIN(nthreads, 100);
 258                 pct = MAX(pct, 0);
 259
 260                 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
 261                 nthreads = MAX(nthreads, 1);    /* need at least 1 thread */
 262         } else {
 263                 ASSERT3S(nthreads, >=, 1);
 264         }
 265
 266         rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
 267         mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
 268         cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
 269         cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
 270         cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
 271         (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN);
 272         tq->tq_flags = flags | TASKQ_ACTIVE;
 273         tq->tq_active = nthreads;
 274         tq->tq_nthreads = nthreads;
 275         tq->tq_minalloc = minalloc;
 276         tq->tq_maxalloc = maxalloc;
 277         tq->tq_task.tqent_next = &tq->tq_task;
 278         tq->tq_task.tqent_prev = &tq->tq_task;
 279         tq->tq_threadlist = kmem_alloc(nthreads * sizeof (kthread_t *),
 280             KM_SLEEP);
 281
 282         if (flags & TASKQ_PREPOPULATE) {
 283                 mutex_enter(&tq->tq_lock);
 284                 while (minalloc-- > 0)
 285                         task_free(tq, task_alloc(tq, KM_SLEEP));
 286                 mutex_exit(&tq->tq_lock);
 287         }
 288
 289         for (t = 0; t < nthreads; t++)
 290                 VERIFY((tq->tq_threadlist[t] = thread_create(NULL, 0,
 291                     taskq_thread, tq, 0, &p0, TS_RUN, pri)) != NULL);
 292
 293         return (tq);
 294 }
 295
 296 void
 297 taskq_destroy(taskq_t *tq)
 298 {
 299         int nthreads = tq->tq_nthreads;
 300
 301         taskq_wait(tq);
 302
 303         mutex_enter(&tq->tq_lock);
 304
 305         tq->tq_flags &= ~TASKQ_ACTIVE;
 306         cv_broadcast(&tq->tq_dispatch_cv);
 307
 308         while (tq->tq_nthreads != 0)
 309                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 310
 311         tq->tq_minalloc = 0;
 312         while (tq->tq_nalloc != 0) {
 313                 ASSERT(tq->tq_freelist != NULL);
 314                 task_free(tq, task_alloc(tq, KM_SLEEP));
 315         }
 316
 317         mutex_exit(&tq->tq_lock);
 318
 319         kmem_free(tq->tq_threadlist, nthreads * sizeof (kthread_t *));
 320
 321         rw_destroy(&tq->tq_threadlock);
 322         mutex_destroy(&tq->tq_lock);
 323         cv_destroy(&tq->tq_dispatch_cv);
 324         cv_destroy(&tq->tq_wait_cv);
 325         cv_destroy(&tq->tq_maxalloc_cv);
 326
 327         kmem_free(tq, sizeof (taskq_t));
 328 }
 329
 330 int
 331 taskq_member(taskq_t *tq, kthread_t *t)
 332 {
 333         int i;
 334
 335         if (taskq_now)
 336                 return (1);
 337
 338         for (i = 0; i < tq->tq_nthreads; i++)
 339                 if (tq->tq_threadlist[i] == t)
 340                         return (1);
 341
 342         return (0);
 343 }
 344
 345 int
 346 taskq_cancel_id(taskq_t *tq, taskqid_t id)
 347 {
 348         return (ENOENT);
 349 }
 350
 351 void
 352 system_taskq_init(void)
 353 {
 354         system_taskq = taskq_create("system_taskq", 64, maxclsyspri, 4, 512,
 355             TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 356 }
 357
 358 void
 359 system_taskq_fini(void)
 360 {
 361         taskq_destroy(system_taskq);
 362         system_taskq = NULL; /* defensive */
 363 }