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 #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         kthread_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                 ASSERT(!(t->tqent_flags & TQENT_FLAG_PREALLOC));
  66                 tq->tq_freelist = t->tqent_next;
  67         } else {
  68                 if (tq->tq_nalloc >= tq->tq_maxalloc) {
  69                         if (!(tqflags & KM_SLEEP))
  70                                 return (NULL);
  71
  72                         /*
  73                          * We don't want to exceed tq_maxalloc, but we can't
  74                          * wait for other tasks to complete (and thus free up
  75                          * task structures) without risking deadlock with
  76                          * the caller.  So, we just delay for one second
  77                          * to throttle the allocation rate. If we have tasks
  78                          * complete before one second timeout expires then
  79                          * taskq_ent_free will signal us and we will
  80                          * immediately retry the allocation.
  81                          */
  82                         tq->tq_maxalloc_wait++;
  83                         rv = cv_timedwait(&tq->tq_maxalloc_cv,
  84                             &tq->tq_lock, ddi_get_lbolt() + hz);
  85                         tq->tq_maxalloc_wait--;
  86                         if (rv > 0)
  87                                 goto again;             /* signaled */
  88                 }
  89                 mutex_exit(&tq->tq_lock);
  90
  91                 t = kmem_alloc(sizeof (taskq_ent_t), tqflags);
  92
  93                 mutex_enter(&tq->tq_lock);
  94                 if (t != NULL) {
  95                         /* Make sure we start without any flags */
  96                         t->tqent_flags = 0;
  97                         tq->tq_nalloc++;
  98                 }
  99         }
 100         return (t);
 101 }
 102
 103 static void
 104 task_free(taskq_t *tq, taskq_ent_t *t)
 105 {
 106         if (tq->tq_nalloc <= tq->tq_minalloc) {
 107                 t->tqent_next = tq->tq_freelist;
 108                 tq->tq_freelist = t;
 109         } else {
 110                 tq->tq_nalloc--;
 111                 mutex_exit(&tq->tq_lock);
 112                 kmem_free(t, sizeof (taskq_ent_t));
 113                 mutex_enter(&tq->tq_lock);
 114         }
 115
 116         if (tq->tq_maxalloc_wait)
 117                 cv_signal(&tq->tq_maxalloc_cv);
 118 }
 119
 120 taskqid_t
 121 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
 122 {
 123         taskq_ent_t *t;
 124
 125         if (taskq_now) {
 126                 func(arg);
 127                 return (1);
 128         }
 129
 130         mutex_enter(&tq->tq_lock);
 131         ASSERT(tq->tq_flags & TASKQ_ACTIVE);
 132         if ((t = task_alloc(tq, tqflags)) == NULL) {
 133                 mutex_exit(&tq->tq_lock);
 134                 return (0);
 135         }
 136         if (tqflags & TQ_FRONT) {
 137                 t->tqent_next = tq->tq_task.tqent_next;
 138                 t->tqent_prev = &tq->tq_task;
 139         } else {
 140                 t->tqent_next = &tq->tq_task;
 141                 t->tqent_prev = tq->tq_task.tqent_prev;
 142         }
 143         t->tqent_next->tqent_prev = t;
 144         t->tqent_prev->tqent_next = t;
 145         t->tqent_func = func;
 146         t->tqent_arg = arg;
 147         t->tqent_flags = 0;
 148         cv_signal(&tq->tq_dispatch_cv);
 149         mutex_exit(&tq->tq_lock);
 150         return (1);
 151 }
 152
 153 taskqid_t
 154 taskq_dispatch_delay(taskq_t *tq,  task_func_t func, void *arg, uint_t tqflags,
 155     clock_t expire_time)
 156 {
 157         return (0);
 158 }
 159
 160 int
 161 taskq_empty_ent(taskq_ent_t *t)
 162 {
 163         return (t->tqent_next == NULL);
 164 }
 165
 166 void
 167 taskq_init_ent(taskq_ent_t *t)
 168 {
 169         t->tqent_next = NULL;
 170         t->tqent_prev = NULL;
 171         t->tqent_func = NULL;
 172         t->tqent_arg = NULL;
 173         t->tqent_flags = 0;
 174 }
 175
 176 void
 177 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
 178     taskq_ent_t *t)
 179 {
 180         ASSERT(func != NULL);
 181         ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC));
 182
 183         /*
 184          * Mark it as a prealloc'd task.  This is important
 185          * to ensure that we don't free it later.
 186          */
 187         t->tqent_flags |= TQENT_FLAG_PREALLOC;
 188         /*
 189          * Enqueue the task to the underlying queue.
 190          */
 191         mutex_enter(&tq->tq_lock);
 192
 193         if (flags & TQ_FRONT) {
 194                 t->tqent_next = tq->tq_task.tqent_next;
 195                 t->tqent_prev = &tq->tq_task;
 196         } else {
 197                 t->tqent_next = &tq->tq_task;
 198                 t->tqent_prev = tq->tq_task.tqent_prev;
 199         }
 200         t->tqent_next->tqent_prev = t;
 201         t->tqent_prev->tqent_next = t;
 202         t->tqent_func = func;
 203         t->tqent_arg = arg;
 204         cv_signal(&tq->tq_dispatch_cv);
 205         mutex_exit(&tq->tq_lock);
 206 }
 207
 208 void
 209 taskq_wait(taskq_t *tq)
 210 {
 211         mutex_enter(&tq->tq_lock);
 212         while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
 213                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 214         mutex_exit(&tq->tq_lock);
 215 }
 216
 217 void
 218 taskq_wait_id(taskq_t *tq, taskqid_t id)
 219 {
 220         taskq_wait(tq);
 221 }
 222
 223 void
 224 taskq_wait_outstanding(taskq_t *tq, taskqid_t id)
 225 {
 226         taskq_wait(tq);
 227 }
 228
 229 static void
 230 taskq_thread(void *arg)
 231 {
 232         taskq_t *tq = arg;
 233         taskq_ent_t *t;
 234         boolean_t prealloc;
 235
 236         mutex_enter(&tq->tq_lock);
 237         while (tq->tq_flags & TASKQ_ACTIVE) {
 238                 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
 239                         if (--tq->tq_active == 0)
 240                                 cv_broadcast(&tq->tq_wait_cv);
 241                         cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
 242                         tq->tq_active++;
 243                         continue;
 244                 }
 245                 t->tqent_prev->tqent_next = t->tqent_next;
 246                 t->tqent_next->tqent_prev = t->tqent_prev;
 247                 t->tqent_next = NULL;
 248                 t->tqent_prev = NULL;
 249                 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
 250                 mutex_exit(&tq->tq_lock);
 251
 252                 rw_enter(&tq->tq_threadlock, RW_READER);
 253                 t->tqent_func(t->tqent_arg);
 254                 rw_exit(&tq->tq_threadlock);
 255
 256                 mutex_enter(&tq->tq_lock);
 257                 if (!prealloc)
 258                         task_free(tq, t);
 259         }
 260         tq->tq_nthreads--;
 261         cv_broadcast(&tq->tq_wait_cv);
 262         mutex_exit(&tq->tq_lock);
 263         thread_exit();
 264 }
 265
 266 /*ARGSUSED*/
 267 taskq_t *
 268 taskq_create(const char *name, int nthreads, pri_t pri,
 269         int minalloc, int maxalloc, uint_t flags)
 270 {
 271         taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
 272         int t;
 273
 274         if (flags & TASKQ_THREADS_CPU_PCT) {
 275                 int pct;
 276                 ASSERT3S(nthreads, >=, 0);
 277                 ASSERT3S(nthreads, <=, 100);
 278                 pct = MIN(nthreads, 100);
 279                 pct = MAX(pct, 0);
 280
 281                 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
 282                 nthreads = MAX(nthreads, 1);    /* need at least 1 thread */
 283         } else {
 284                 ASSERT3S(nthreads, >=, 1);
 285         }
 286
 287         rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
 288         mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
 289         cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
 290         cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
 291         cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
 292         (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN + 1);
 293         tq->tq_flags = flags | TASKQ_ACTIVE;
 294         tq->tq_active = nthreads;
 295         tq->tq_nthreads = nthreads;
 296         tq->tq_minalloc = minalloc;
 297         tq->tq_maxalloc = maxalloc;
 298         tq->tq_task.tqent_next = &tq->tq_task;
 299         tq->tq_task.tqent_prev = &tq->tq_task;
 300         tq->tq_threadlist = kmem_alloc(nthreads * sizeof (kthread_t *),
 301             KM_SLEEP);
 302
 303         if (flags & TASKQ_PREPOPULATE) {
 304                 mutex_enter(&tq->tq_lock);
 305                 while (minalloc-- > 0)
 306                         task_free(tq, task_alloc(tq, KM_SLEEP));
 307                 mutex_exit(&tq->tq_lock);
 308         }
 309
 310         for (t = 0; t < nthreads; t++)
 311                 VERIFY((tq->tq_threadlist[t] = thread_create(NULL, 0,
 312                     taskq_thread, tq, TS_RUN, NULL, 0, 0)) != NULL);
 313
 314         return (tq);
 315 }
 316
 317 void
 318 taskq_destroy(taskq_t *tq)
 319 {
 320         int nthreads = tq->tq_nthreads;
 321
 322         taskq_wait(tq);
 323
 324         mutex_enter(&tq->tq_lock);
 325
 326         tq->tq_flags &= ~TASKQ_ACTIVE;
 327         cv_broadcast(&tq->tq_dispatch_cv);
 328
 329         while (tq->tq_nthreads != 0)
 330                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 331
 332         tq->tq_minalloc = 0;
 333         while (tq->tq_nalloc != 0) {
 334                 ASSERT(tq->tq_freelist != NULL);
 335                 task_free(tq, task_alloc(tq, KM_SLEEP));
 336         }
 337
 338         mutex_exit(&tq->tq_lock);
 339
 340         kmem_free(tq->tq_threadlist, nthreads * sizeof (kthread_t *));
 341
 342         rw_destroy(&tq->tq_threadlock);
 343         mutex_destroy(&tq->tq_lock);
 344         cv_destroy(&tq->tq_dispatch_cv);
 345         cv_destroy(&tq->tq_wait_cv);
 346         cv_destroy(&tq->tq_maxalloc_cv);
 347
 348         kmem_free(tq, sizeof (taskq_t));
 349 }
 350
 351 int
 352 taskq_member(taskq_t *tq, kthread_t *t)
 353 {
 354         int i;
 355
 356         if (taskq_now)
 357                 return (1);
 358
 359         for (i = 0; i < tq->tq_nthreads; i++)
 360                 if (tq->tq_threadlist[i] == t)
 361                         return (1);
 362
 363         return (0);
 364 }
 365
 366 int
 367 taskq_cancel_id(taskq_t *tq, taskqid_t id)
 368 {
 369         return (ENOENT);
 370 }
 371
 372 void
 373 system_taskq_init(void)
 374 {
 375         system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
 376             TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
 377 }
 378
 379 void
 380 system_taskq_fini(void)
 381 {
 382         taskq_destroy(system_taskq);
 383         system_taskq = NULL; /* defensive */
 384 }