cddl/contrib/opensolaris/lib/libzpool/common/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 #define TASKQ_NAMELEN   31
  38
  39 struct taskq {
  40         char            tq_name[TASKQ_NAMELEN + 1];
  41         kmutex_t        tq_lock;
  42         krwlock_t       tq_threadlock;
  43         kcondvar_t      tq_dispatch_cv;
  44         kcondvar_t      tq_wait_cv;
  45         thread_t        *tq_threadlist;
  46         int             tq_flags;
  47         int             tq_active;
  48         int             tq_nthreads;
  49         int             tq_nalloc;
  50         int             tq_minalloc;
  51         int             tq_maxalloc;
  52         kcondvar_t      tq_maxalloc_cv;
  53         int             tq_maxalloc_wait;
  54         taskq_ent_t     *tq_freelist;
  55         taskq_ent_t     tq_task;
  56 };
  57
  58 static taskq_ent_t *
  59 task_alloc(taskq_t *tq, int tqflags)
  60 {
  61         taskq_ent_t *t;
  62         int rv;
  63
  64 again:  if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
  65                 tq->tq_freelist = t->tqent_next;
  66         } else {
  67                 if (tq->tq_nalloc >= tq->tq_maxalloc) {
  68                         if (!(tqflags & KM_SLEEP))
  69                                 return (NULL);
  70
  71                         /*
  72                          * We don't want to exceed tq_maxalloc, but we can't
  73                          * wait for other tasks to complete (and thus free up
  74                          * task structures) without risking deadlock with
  75                          * the caller.  So, we just delay for one second
  76                          * to throttle the allocation rate. If we have tasks
  77                          * complete before one second timeout expires then
  78                          * taskq_ent_free will signal us and we will
  79                          * immediately retry the allocation.
  80                          */
  81                         tq->tq_maxalloc_wait++;
  82 #ifdef __FreeBSD__
  83                         rv = cv_timedwait(&tq->tq_maxalloc_cv,
  84                             &tq->tq_lock, hz);
  85 #else
  86                         rv = cv_timedwait(&tq->tq_maxalloc_cv,
  87                             &tq->tq_lock, ddi_get_lbolt() + hz);
  88 #endif
  89                         tq->tq_maxalloc_wait--;
  90                         if (rv > 0)
  91                                 goto again;             /* signaled */
  92                 }
  93                 mutex_exit(&tq->tq_lock);
  94
  95                 t = kmem_alloc(sizeof (taskq_ent_t), tqflags & KM_SLEEP);
  96
  97                 mutex_enter(&tq->tq_lock);
  98                 if (t != NULL)
  99                         tq->tq_nalloc++;
 100         }
 101         return (t);
 102 }
 103
 104 static void
 105 task_free(taskq_t *tq, taskq_ent_t *t)
 106 {
 107         if (tq->tq_nalloc <= tq->tq_minalloc) {
 108                 t->tqent_next = tq->tq_freelist;
 109                 tq->tq_freelist = t;
 110         } else {
 111                 tq->tq_nalloc--;
 112                 mutex_exit(&tq->tq_lock);
 113                 kmem_free(t, sizeof (taskq_ent_t));
 114                 mutex_enter(&tq->tq_lock);
 115         }
 116
 117         if (tq->tq_maxalloc_wait)
 118                 cv_signal(&tq->tq_maxalloc_cv);
 119 }
 120
 121 taskqid_t
 122 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
 123 {
 124         taskq_ent_t *t;
 125
 126         if (taskq_now) {
 127                 func(arg);
 128                 return (1);
 129         }
 130
 131         mutex_enter(&tq->tq_lock);
 132         ASSERT(tq->tq_flags & TASKQ_ACTIVE);
 133         if ((t = task_alloc(tq, tqflags)) == NULL) {
 134                 mutex_exit(&tq->tq_lock);
 135                 return (0);
 136         }
 137         if (tqflags & TQ_FRONT) {
 138                 t->tqent_next = tq->tq_task.tqent_next;
 139                 t->tqent_prev = &tq->tq_task;
 140         } else {
 141                 t->tqent_next = &tq->tq_task;
 142                 t->tqent_prev = tq->tq_task.tqent_prev;
 143         }
 144         t->tqent_next->tqent_prev = t;
 145         t->tqent_prev->tqent_next = t;
 146         t->tqent_func = func;
 147         t->tqent_arg = arg;
 148         t->tqent_flags = 0;
 149         cv_signal(&tq->tq_dispatch_cv);
 150         mutex_exit(&tq->tq_lock);
 151         return (1);
 152 }
 153
 154 void
 155 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
 156     taskq_ent_t *t)
 157 {
 158         ASSERT(func != NULL);
 159         ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC));
 160
 161         /*
 162          * Mark it as a prealloc'd task.  This is important
 163          * to ensure that we don't free it later.
 164          */
 165         t->tqent_flags |= TQENT_FLAG_PREALLOC;
 166         /*
 167          * Enqueue the task to the underlying queue.
 168          */
 169         mutex_enter(&tq->tq_lock);
 170
 171         if (flags & TQ_FRONT) {
 172                 t->tqent_next = tq->tq_task.tqent_next;
 173                 t->tqent_prev = &tq->tq_task;
 174         } else {
 175                 t->tqent_next = &tq->tq_task;
 176                 t->tqent_prev = tq->tq_task.tqent_prev;
 177         }
 178         t->tqent_next->tqent_prev = t;
 179         t->tqent_prev->tqent_next = t;
 180         t->tqent_func = func;
 181         t->tqent_arg = arg;
 182         cv_signal(&tq->tq_dispatch_cv);
 183         mutex_exit(&tq->tq_lock);
 184 }
 185
 186 void
 187 taskq_wait(taskq_t *tq)
 188 {
 189         mutex_enter(&tq->tq_lock);
 190         while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
 191                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 192         mutex_exit(&tq->tq_lock);
 193 }
 194
 195 void
 196 taskq_wait_id(taskq_t *tq, taskqid_t id)
 197 {
 198         taskq_wait(tq);
 199 }
 200
 201 static void *
 202 taskq_thread(void *arg)
 203 {
 204         taskq_t *tq = arg;
 205         taskq_ent_t *t;
 206         boolean_t prealloc;
 207
 208         mutex_enter(&tq->tq_lock);
 209         while (tq->tq_flags & TASKQ_ACTIVE) {
 210                 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
 211                         if (--tq->tq_active == 0)
 212                                 cv_broadcast(&tq->tq_wait_cv);
 213                         cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
 214                         tq->tq_active++;
 215                         continue;
 216                 }
 217                 t->tqent_prev->tqent_next = t->tqent_next;
 218                 t->tqent_next->tqent_prev = t->tqent_prev;
 219                 t->tqent_next = NULL;
 220                 t->tqent_prev = NULL;
 221                 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
 222                 mutex_exit(&tq->tq_lock);
 223
 224                 rw_enter(&tq->tq_threadlock, RW_READER);
 225                 t->tqent_func(t->tqent_arg);
 226                 rw_exit(&tq->tq_threadlock);
 227
 228                 mutex_enter(&tq->tq_lock);
 229                 if (!prealloc)
 230                         task_free(tq, t);
 231         }
 232         tq->tq_nthreads--;
 233         cv_broadcast(&tq->tq_wait_cv);
 234         mutex_exit(&tq->tq_lock);
 235         return (NULL);
 236 }
 237
 238 /*ARGSUSED*/
 239 taskq_t *
 240 taskq_create(const char *name, int nthreads, pri_t pri,
 241         int minalloc, int maxalloc, uint_t flags)
 242 {
 243         taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
 244         int t;
 245
 246         if (flags & TASKQ_THREADS_CPU_PCT) {
 247                 int pct;
 248                 ASSERT3S(nthreads, >=, 0);
 249                 ASSERT3S(nthreads, <=, 100);
 250                 pct = MIN(nthreads, 100);
 251                 pct = MAX(pct, 0);
 252
 253                 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
 254                 nthreads = MAX(nthreads, 1);    /* need at least 1 thread */
 255         } else {
 256                 ASSERT3S(nthreads, >=, 1);
 257         }
 258
 259         rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
 260         mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
 261         cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
 262         cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
 263         cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
 264         (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN + 1);
 265         tq->tq_flags = flags | TASKQ_ACTIVE;
 266         tq->tq_active = nthreads;
 267         tq->tq_nthreads = nthreads;
 268         tq->tq_minalloc = minalloc;
 269         tq->tq_maxalloc = maxalloc;
 270         tq->tq_task.tqent_next = &tq->tq_task;
 271         tq->tq_task.tqent_prev = &tq->tq_task;
 272         tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP);
 273
 274         if (flags & TASKQ_PREPOPULATE) {
 275                 mutex_enter(&tq->tq_lock);
 276                 while (minalloc-- > 0)
 277                         task_free(tq, task_alloc(tq, KM_SLEEP));
 278                 mutex_exit(&tq->tq_lock);
 279         }
 280
 281         for (t = 0; t < nthreads; t++)
 282                 (void) thr_create(0, 0, taskq_thread,
 283                     tq, THR_BOUND, &tq->tq_threadlist[t]);
 284
 285         return (tq);
 286 }
 287
 288 void
 289 taskq_destroy(taskq_t *tq)
 290 {
 291         int t;
 292         int nthreads = tq->tq_nthreads;
 293
 294         taskq_wait(tq);
 295
 296         mutex_enter(&tq->tq_lock);
 297
 298         tq->tq_flags &= ~TASKQ_ACTIVE;
 299         cv_broadcast(&tq->tq_dispatch_cv);
 300
 301         while (tq->tq_nthreads != 0)
 302                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 303
 304         tq->tq_minalloc = 0;
 305         while (tq->tq_nalloc != 0) {
 306                 ASSERT(tq->tq_freelist != NULL);
 307                 task_free(tq, task_alloc(tq, KM_SLEEP));
 308         }
 309
 310         mutex_exit(&tq->tq_lock);
 311
 312         for (t = 0; t < nthreads; t++)
 313                 (void) thr_join(tq->tq_threadlist[t], NULL, NULL);
 314
 315         kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t));
 316
 317         rw_destroy(&tq->tq_threadlock);
 318         mutex_destroy(&tq->tq_lock);
 319         cv_destroy(&tq->tq_dispatch_cv);
 320         cv_destroy(&tq->tq_wait_cv);
 321         cv_destroy(&tq->tq_maxalloc_cv);
 322
 323         kmem_free(tq, sizeof (taskq_t));
 324 }
 325
 326 int
 327 taskq_member(taskq_t *tq, void *t)
 328 {
 329         int i;
 330
 331         if (taskq_now)
 332                 return (1);
 333
 334         for (i = 0; i < tq->tq_nthreads; i++)
 335                 if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t)
 336                         return (1);
 337
 338         return (0);
 339 }
 340
 341 void
 342 system_taskq_init(void)
 343 {
 344         system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
 345             TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 346 }
 347
 348 void
 349 system_taskq_fini(void)
 350 {
 351         taskq_destroy(system_taskq);
 352         system_taskq = NULL; /* defensive */
 353 }