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  */
  28
  29 #include <sys/zfs_context.h>
  30
  31 int taskq_now;
  32 taskq_t *system_taskq;
  33
  34 #define TASKQ_ACTIVE    0x00010000
  35
  36 struct taskq {
  37         kmutex_t        tq_lock;
  38         krwlock_t       tq_threadlock;
  39         kcondvar_t      tq_dispatch_cv;
  40         kcondvar_t      tq_wait_cv;
  41         thread_t        *tq_threadlist;
  42         int             tq_flags;
  43         int             tq_active;
  44         int             tq_nthreads;
  45         int             tq_nalloc;
  46         int             tq_minalloc;
  47         int             tq_maxalloc;
  48         kcondvar_t      tq_maxalloc_cv;
  49         int             tq_maxalloc_wait;
  50         taskq_ent_t     *tq_freelist;
  51         taskq_ent_t     tq_task;
  52 };
  53
  54 static taskq_ent_t *
  55 task_alloc(taskq_t *tq, int tqflags)
  56 {
  57         taskq_ent_t *t;
  58         int rv;
  59
  60 again:  if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
  61                 tq->tq_freelist = t->tqent_next;
  62         } else {
  63                 if (tq->tq_nalloc >= tq->tq_maxalloc) {
  64                         if (!(tqflags & KM_SLEEP))
  65                                 return (NULL);
  66
  67                         /*
  68                          * We don't want to exceed tq_maxalloc, but we can't
  69                          * wait for other tasks to complete (and thus free up
  70                          * task structures) without risking deadlock with
  71                          * the caller.  So, we just delay for one second
  72                          * to throttle the allocation rate. If we have tasks
  73                          * complete before one second timeout expires then
  74                          * taskq_ent_free will signal us and we will
  75                          * immediately retry the allocation.
  76                          */
  77                         tq->tq_maxalloc_wait++;
  78                         rv = cv_timedwait(&tq->tq_maxalloc_cv,
  79                             &tq->tq_lock, ddi_get_lbolt() + hz);
  80                         tq->tq_maxalloc_wait--;
  81                         if (rv > 0)
  82                                 goto again;             /* signaled */
  83                 }
  84                 mutex_exit(&tq->tq_lock);
  85
  86                 t = kmem_alloc(sizeof (taskq_ent_t), tqflags & KM_SLEEP);
  87
  88                 mutex_enter(&tq->tq_lock);
  89                 if (t != NULL)
  90                         tq->tq_nalloc++;
  91         }
  92         return (t);
  93 }
  94
  95 static void
  96 task_free(taskq_t *tq, taskq_ent_t *t)
  97 {
  98         if (tq->tq_nalloc <= tq->tq_minalloc) {
  99                 t->tqent_next = tq->tq_freelist;
 100                 tq->tq_freelist = t;
 101         } else {
 102                 tq->tq_nalloc--;
 103                 mutex_exit(&tq->tq_lock);
 104                 kmem_free(t, sizeof (taskq_ent_t));
 105                 mutex_enter(&tq->tq_lock);
 106         }
 107
 108         if (tq->tq_maxalloc_wait)
 109                 cv_signal(&tq->tq_maxalloc_cv);
 110 }
 111
 112 taskqid_t
 113 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
 114 {
 115         taskq_ent_t *t;
 116
 117         if (taskq_now) {
 118                 func(arg);
 119                 return (1);
 120         }
 121
 122         mutex_enter(&tq->tq_lock);
 123         ASSERT(tq->tq_flags & TASKQ_ACTIVE);
 124         if ((t = task_alloc(tq, tqflags)) == NULL) {
 125                 mutex_exit(&tq->tq_lock);
 126                 return (0);
 127         }
 128         if (tqflags & TQ_FRONT) {
 129                 t->tqent_next = tq->tq_task.tqent_next;
 130                 t->tqent_prev = &tq->tq_task;
 131         } else {
 132                 t->tqent_next = &tq->tq_task;
 133                 t->tqent_prev = tq->tq_task.tqent_prev;
 134         }
 135         t->tqent_next->tqent_prev = t;
 136         t->tqent_prev->tqent_next = t;
 137         t->tqent_func = func;
 138         t->tqent_arg = arg;
 139         cv_signal(&tq->tq_dispatch_cv);
 140         mutex_exit(&tq->tq_lock);
 141         return (1);
 142 }
 143
 144 void
 145 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
 146     taskq_ent_t *t)
 147 {
 148         ASSERT(func != NULL);
 149         ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC));
 150
 151         /*
 152          * Mark it as a prealloc'd task.  This is important
 153          * to ensure that we don't free it later.
 154          */
 155         t->tqent_flags |= TQENT_FLAG_PREALLOC;
 156         /*
 157          * Enqueue the task to the underlying queue.
 158          */
 159         mutex_enter(&tq->tq_lock);
 160
 161         if (flags & TQ_FRONT) {
 162                 t->tqent_next = tq->tq_task.tqent_next;
 163                 t->tqent_prev = &tq->tq_task;
 164         } else {
 165                 t->tqent_next = &tq->tq_task;
 166                 t->tqent_prev = tq->tq_task.tqent_prev;
 167         }
 168         t->tqent_next->tqent_prev = t;
 169         t->tqent_prev->tqent_next = t;
 170         t->tqent_func = func;
 171         t->tqent_arg = arg;
 172         cv_signal(&tq->tq_dispatch_cv);
 173         mutex_exit(&tq->tq_lock);
 174 }
 175
 176 void
 177 taskq_wait(taskq_t *tq)
 178 {
 179         mutex_enter(&tq->tq_lock);
 180         while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
 181                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 182         mutex_exit(&tq->tq_lock);
 183 }
 184
 185 static void *
 186 taskq_thread(void *arg)
 187 {
 188         taskq_t *tq = arg;
 189         taskq_ent_t *t;
 190         boolean_t prealloc;
 191
 192         mutex_enter(&tq->tq_lock);
 193         while (tq->tq_flags & TASKQ_ACTIVE) {
 194                 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
 195                         if (--tq->tq_active == 0)
 196                                 cv_broadcast(&tq->tq_wait_cv);
 197                         cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
 198                         tq->tq_active++;
 199                         continue;
 200                 }
 201                 t->tqent_prev->tqent_next = t->tqent_next;
 202                 t->tqent_next->tqent_prev = t->tqent_prev;
 203                 t->tqent_next = NULL;
 204                 t->tqent_prev = NULL;
 205                 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
 206                 mutex_exit(&tq->tq_lock);
 207
 208                 rw_enter(&tq->tq_threadlock, RW_READER);
 209                 t->tqent_func(t->tqent_arg);
 210                 rw_exit(&tq->tq_threadlock);
 211
 212                 mutex_enter(&tq->tq_lock);
 213                 if (!prealloc)
 214                         task_free(tq, t);
 215         }
 216         tq->tq_nthreads--;
 217         cv_broadcast(&tq->tq_wait_cv);
 218         mutex_exit(&tq->tq_lock);
 219         return (NULL);
 220 }
 221
 222 /*ARGSUSED*/
 223 taskq_t *
 224 taskq_create(const char *name, int nthreads, pri_t pri,
 225         int minalloc, int maxalloc, uint_t flags)
 226 {
 227         taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
 228         int t;
 229
 230         if (flags & TASKQ_THREADS_CPU_PCT) {
 231                 int pct;
 232                 ASSERT3S(nthreads, >=, 0);
 233                 ASSERT3S(nthreads, <=, 100);
 234                 pct = MIN(nthreads, 100);
 235                 pct = MAX(pct, 0);
 236
 237                 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
 238                 nthreads = MAX(nthreads, 1);    /* need at least 1 thread */
 239         } else {
 240                 ASSERT3S(nthreads, >=, 1);
 241         }
 242
 243         rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
 244         mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
 245         cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
 246         cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
 247         cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
 248         tq->tq_flags = flags | TASKQ_ACTIVE;
 249         tq->tq_active = nthreads;
 250         tq->tq_nthreads = nthreads;
 251         tq->tq_minalloc = minalloc;
 252         tq->tq_maxalloc = maxalloc;
 253         tq->tq_task.tqent_next = &tq->tq_task;
 254         tq->tq_task.tqent_prev = &tq->tq_task;
 255         tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP);
 256
 257         if (flags & TASKQ_PREPOPULATE) {
 258                 mutex_enter(&tq->tq_lock);
 259                 while (minalloc-- > 0)
 260                         task_free(tq, task_alloc(tq, KM_SLEEP));
 261                 mutex_exit(&tq->tq_lock);
 262         }
 263
 264         for (t = 0; t < nthreads; t++)
 265                 (void) thr_create(0, 0, taskq_thread,
 266                     tq, THR_BOUND, &tq->tq_threadlist[t]);
 267
 268         return (tq);
 269 }
 270
 271 void
 272 taskq_destroy(taskq_t *tq)
 273 {
 274         int t;
 275         int nthreads = tq->tq_nthreads;
 276
 277         taskq_wait(tq);
 278
 279         mutex_enter(&tq->tq_lock);
 280
 281         tq->tq_flags &= ~TASKQ_ACTIVE;
 282         cv_broadcast(&tq->tq_dispatch_cv);
 283
 284         while (tq->tq_nthreads != 0)
 285                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 286
 287         tq->tq_minalloc = 0;
 288         while (tq->tq_nalloc != 0) {
 289                 ASSERT(tq->tq_freelist != NULL);
 290                 task_free(tq, task_alloc(tq, KM_SLEEP));
 291         }
 292
 293         mutex_exit(&tq->tq_lock);
 294
 295         for (t = 0; t < nthreads; t++)
 296                 (void) thr_join(tq->tq_threadlist[t], NULL, NULL);
 297
 298         kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t));
 299
 300         rw_destroy(&tq->tq_threadlock);
 301         mutex_destroy(&tq->tq_lock);
 302         cv_destroy(&tq->tq_dispatch_cv);
 303         cv_destroy(&tq->tq_wait_cv);
 304         cv_destroy(&tq->tq_maxalloc_cv);
 305
 306         kmem_free(tq, sizeof (taskq_t));
 307 }
 308
 309 int
 310 taskq_member(taskq_t *tq, void *t)
 311 {
 312         int i;
 313
 314         if (taskq_now)
 315                 return (1);
 316
 317         for (i = 0; i < tq->tq_nthreads; i++)
 318                 if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t)
 319                         return (1);
 320
 321         return (0);
 322 }
 323
 324 void
 325 system_taskq_init(void)
 326 {
 327         system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
 328             TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 329 }
 330
 331 void
 332 system_taskq_fini(void)
 333 {
 334         taskq_destroy(system_taskq);
 335         system_taskq = NULL; /* defensive */
 336 }