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 #define TASKQ_ACTIVE    0x00010000
  38
  39 static taskq_ent_t *
  40 task_alloc(taskq_t *tq, int tqflags)
  41 {
  42         taskq_ent_t *t;
  43         int rv;
  44
  45 again:  if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
  46                 ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
  47                 tq->tq_freelist = t->tqent_next;
  48         } else {
  49                 if (tq->tq_nalloc >= tq->tq_maxalloc) {
  50                         if (!(tqflags & KM_SLEEP))
  51                                 return (NULL);
  52
  53                         /*
  54                          * We don't want to exceed tq_maxalloc, but we can't
  55                          * wait for other tasks to complete (and thus free up
  56                          * task structures) without risking deadlock with
  57                          * the caller.  So, we just delay for one second
  58                          * to throttle the allocation rate. If we have tasks
  59                          * complete before one second timeout expires then
  60                          * taskq_ent_free will signal us and we will
  61                          * immediately retry the allocation.
  62                          */
  63                         tq->tq_maxalloc_wait++;
  64                         rv = cv_timedwait(&tq->tq_maxalloc_cv,
  65                             &tq->tq_lock, ddi_get_lbolt() + hz);
  66                         tq->tq_maxalloc_wait--;
  67                         if (rv > 0)
  68                                 goto again;             /* signaled */
  69                 }
  70                 mutex_exit(&tq->tq_lock);
  71
  72                 t = kmem_alloc(sizeof (taskq_ent_t), tqflags);
  73
  74                 mutex_enter(&tq->tq_lock);
  75                 if (t != NULL) {
  76                         /* Make sure we start without any flags */
  77                         t->tqent_flags = 0;
  78                         tq->tq_nalloc++;
  79                 }
  80         }
  81         return (t);
  82 }
  83
  84 static void
  85 task_free(taskq_t *tq, taskq_ent_t *t)
  86 {
  87         if (tq->tq_nalloc <= tq->tq_minalloc) {
  88                 t->tqent_next = tq->tq_freelist;
  89                 tq->tq_freelist = t;
  90         } else {
  91                 tq->tq_nalloc--;
  92                 mutex_exit(&tq->tq_lock);
  93                 kmem_free(t, sizeof (taskq_ent_t));
  94                 mutex_enter(&tq->tq_lock);
  95         }
  96
  97         if (tq->tq_maxalloc_wait)
  98                 cv_signal(&tq->tq_maxalloc_cv);
  99 }
 100
 101 taskqid_t
 102 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
 103 {
 104         taskq_ent_t *t;
 105
 106         if (taskq_now) {
 107                 func(arg);
 108                 return (1);
 109         }
 110
 111         mutex_enter(&tq->tq_lock);
 112         ASSERT(tq->tq_flags & TASKQ_ACTIVE);
 113         if ((t = task_alloc(tq, tqflags)) == NULL) {
 114                 mutex_exit(&tq->tq_lock);
 115                 return (0);
 116         }
 117         if (tqflags & TQ_FRONT) {
 118                 t->tqent_next = tq->tq_task.tqent_next;
 119                 t->tqent_prev = &tq->tq_task;
 120         } else {
 121                 t->tqent_next = &tq->tq_task;
 122                 t->tqent_prev = tq->tq_task.tqent_prev;
 123         }
 124         t->tqent_next->tqent_prev = t;
 125         t->tqent_prev->tqent_next = t;
 126         t->tqent_func = func;
 127         t->tqent_arg = arg;
 128         t->tqent_flags = 0;
 129         cv_signal(&tq->tq_dispatch_cv);
 130         mutex_exit(&tq->tq_lock);
 131         return (1);
 132 }
 133
 134 taskqid_t
 135 taskq_dispatch_delay(taskq_t *tq,  task_func_t func, void *arg, uint_t tqflags,
 136     clock_t expire_time)
 137 {
 138         return (0);
 139 }
 140
 141 int
 142 taskq_empty_ent(taskq_ent_t *t)
 143 {
 144         return (t->tqent_next == NULL);
 145 }
 146
 147 void
 148 taskq_init_ent(taskq_ent_t *t)
 149 {
 150         t->tqent_next = NULL;
 151         t->tqent_prev = NULL;
 152         t->tqent_func = NULL;
 153         t->tqent_arg = NULL;
 154         t->tqent_flags = 0;
 155 }
 156
 157 void
 158 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
 159     taskq_ent_t *t)
 160 {
 161         ASSERT(func != NULL);
 162
 163         /*
 164          * Mark it as a prealloc'd task.  This is important
 165          * to ensure that we don't free it later.
 166          */
 167         t->tqent_flags |= TQENT_FLAG_PREALLOC;
 168         /*
 169          * Enqueue the task to the underlying queue.
 170          */
 171         mutex_enter(&tq->tq_lock);
 172
 173         if (flags & TQ_FRONT) {
 174                 t->tqent_next = tq->tq_task.tqent_next;
 175                 t->tqent_prev = &tq->tq_task;
 176         } else {
 177                 t->tqent_next = &tq->tq_task;
 178                 t->tqent_prev = tq->tq_task.tqent_prev;
 179         }
 180         t->tqent_next->tqent_prev = t;
 181         t->tqent_prev->tqent_next = t;
 182         t->tqent_func = func;
 183         t->tqent_arg = arg;
 184         cv_signal(&tq->tq_dispatch_cv);
 185         mutex_exit(&tq->tq_lock);
 186 }
 187
 188 void
 189 taskq_wait(taskq_t *tq)
 190 {
 191         mutex_enter(&tq->tq_lock);
 192         while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
 193                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 194         mutex_exit(&tq->tq_lock);
 195 }
 196
 197 void
 198 taskq_wait_id(taskq_t *tq, taskqid_t id)
 199 {
 200         taskq_wait(tq);
 201 }
 202
 203 void
 204 taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
 205 {
 206         taskq_wait(tq);
 207 }
 208
 209 static void
 210 taskq_thread(void *arg)
 211 {
 212         taskq_t *tq = arg;
 213         taskq_ent_t *t;
 214         boolean_t prealloc;
 215
 216         mutex_enter(&tq->tq_lock);
 217         while (tq->tq_flags & TASKQ_ACTIVE) {
 218                 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
 219                         if (--tq->tq_active == 0)
 220                                 cv_broadcast(&tq->tq_wait_cv);
 221                         cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
 222                         tq->tq_active++;
 223                         continue;
 224                 }
 225                 t->tqent_prev->tqent_next = t->tqent_next;
 226                 t->tqent_next->tqent_prev = t->tqent_prev;
 227                 t->tqent_next = NULL;
 228                 t->tqent_prev = NULL;
 229                 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
 230                 mutex_exit(&tq->tq_lock);
 231
 232                 rw_enter(&tq->tq_threadlock, RW_READER);
 233                 t->tqent_func(t->tqent_arg);
 234                 rw_exit(&tq->tq_threadlock);
 235
 236                 mutex_enter(&tq->tq_lock);
 237                 if (!prealloc)
 238                         task_free(tq, t);
 239         }
 240         tq->tq_nthreads--;
 241         cv_broadcast(&tq->tq_wait_cv);
 242         mutex_exit(&tq->tq_lock);
 243         thread_exit();
 244 }
 245
 246 /*ARGSUSED*/
 247 taskq_t *
 248 taskq_create(const char *name, int nthreads, pri_t pri,
 249     int minalloc, int maxalloc, uint_t flags)
 250 {
 251         taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
 252         int t;
 253
 254         if (flags & TASKQ_THREADS_CPU_PCT) {
 255                 int pct;
 256                 ASSERT3S(nthreads, >=, 0);
 257                 ASSERT3S(nthreads, <=, 100);
 258                 pct = MIN(nthreads, 100);
 259                 pct = MAX(pct, 0);
 260
 261                 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
 262                 nthreads = MAX(nthreads, 1);    /* need at least 1 thread */
 263         } else {
 264                 ASSERT3S(nthreads, >=, 1);
 265         }
 266
 267         rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
 268         mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
 269         cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
 270         cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
 271         cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
 272         (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN);
 273         tq->tq_flags = flags | TASKQ_ACTIVE;
 274         tq->tq_active = nthreads;
 275         tq->tq_nthreads = nthreads;
 276         tq->tq_minalloc = minalloc;
 277         tq->tq_maxalloc = maxalloc;
 278         tq->tq_task.tqent_next = &tq->tq_task;
 279         tq->tq_task.tqent_prev = &tq->tq_task;
 280         tq->tq_threadlist = kmem_alloc(nthreads * sizeof (kthread_t *),
 281             KM_SLEEP);
 282
 283         if (flags & TASKQ_PREPOPULATE) {
 284                 mutex_enter(&tq->tq_lock);
 285                 while (minalloc-- > 0)
 286                         task_free(tq, task_alloc(tq, KM_SLEEP));
 287                 mutex_exit(&tq->tq_lock);
 288         }
 289
 290         for (t = 0; t < nthreads; t++)
 291                 VERIFY((tq->tq_threadlist[t] = thread_create(NULL, 0,
 292                     taskq_thread, tq, 0, &p0, TS_RUN, pri)) != NULL);
 293
 294         return (tq);
 295 }
 296
 297 void
 298 taskq_destroy(taskq_t *tq)
 299 {
 300         int nthreads = tq->tq_nthreads;
 301
 302         taskq_wait(tq);
 303
 304         mutex_enter(&tq->tq_lock);
 305
 306         tq->tq_flags &= ~TASKQ_ACTIVE;
 307         cv_broadcast(&tq->tq_dispatch_cv);
 308
 309         while (tq->tq_nthreads != 0)
 310                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 311
 312         tq->tq_minalloc = 0;
 313         while (tq->tq_nalloc != 0) {
 314                 ASSERT(tq->tq_freelist != NULL);
 315                 task_free(tq, task_alloc(tq, KM_SLEEP));
 316         }
 317
 318         mutex_exit(&tq->tq_lock);
 319
 320         kmem_free(tq->tq_threadlist, nthreads * sizeof (kthread_t *));
 321
 322         rw_destroy(&tq->tq_threadlock);
 323         mutex_destroy(&tq->tq_lock);
 324         cv_destroy(&tq->tq_dispatch_cv);
 325         cv_destroy(&tq->tq_wait_cv);
 326         cv_destroy(&tq->tq_maxalloc_cv);
 327
 328         kmem_free(tq, sizeof (taskq_t));
 329 }
 330
 331 int
 332 taskq_member(taskq_t *tq, kthread_t *t)
 333 {
 334         int i;
 335
 336         if (taskq_now)
 337                 return (1);
 338
 339         for (i = 0; i < tq->tq_nthreads; i++)
 340                 if (tq->tq_threadlist[i] == t)
 341                         return (1);
 342
 343         return (0);
 344 }
 345
 346 int
 347 taskq_cancel_id(taskq_t *tq, taskqid_t id)
 348 {
 349         return (ENOENT);
 350 }
 351
 352 void
 353 system_taskq_init(void)
 354 {
 355         system_taskq = taskq_create("system_taskq", 64, maxclsyspri, 4, 512,
 356             TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 357         system_delay_taskq = taskq_create("delay_taskq", 4, maxclsyspri, 4,
 358             512, TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 359 }
 360
 361 void
 362 system_taskq_fini(void)
 363 {
 364         taskq_destroy(system_taskq);
 365         system_taskq = NULL; /* defensive */
 366         taskq_destroy(system_delay_taskq);
 367         system_delay_taskq = NULL;
 368 }