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, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include <sys/zfs_context.h>
  30
  31 int taskq_now;
  32
  33 typedef struct task {
  34         struct task     *task_next;
  35         struct task     *task_prev;
  36         task_func_t     *task_func;
  37         void            *task_arg;
  38 } task_t;
  39
  40 #define TASKQ_ACTIVE    0x00010000
  41
  42 struct taskq {
  43         kmutex_t        tq_lock;
  44         krwlock_t       tq_threadlock;
  45         kcondvar_t      tq_dispatch_cv;
  46         kcondvar_t      tq_wait_cv;
  47         thread_t        *tq_threadlist;
  48         int             tq_flags;
  49         int             tq_active;
  50         int             tq_nthreads;
  51         int             tq_nalloc;
  52         int             tq_minalloc;
  53         int             tq_maxalloc;
  54         task_t          *tq_freelist;
  55         task_t          tq_task;
  56 };
  57
  58 static task_t *
  59 task_alloc(taskq_t *tq, int tqflags)
  60 {
  61         task_t *t;
  62
  63         if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
  64                 tq->tq_freelist = t->task_next;
  65         } else {
  66                 mutex_exit(&tq->tq_lock);
  67                 if (tq->tq_nalloc >= tq->tq_maxalloc) {
  68                         if (!(tqflags & KM_SLEEP)) {
  69                                 mutex_enter(&tq->tq_lock);
  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.
  78                          */
  79                         delay(hz);
  80                 }
  81                 t = kmem_alloc(sizeof (task_t), tqflags);
  82                 mutex_enter(&tq->tq_lock);
  83                 if (t != NULL)
  84                         tq->tq_nalloc++;
  85         }
  86         return (t);
  87 }
  88
  89 static void
  90 task_free(taskq_t *tq, task_t *t)
  91 {
  92         if (tq->tq_nalloc <= tq->tq_minalloc) {
  93                 t->task_next = tq->tq_freelist;
  94                 tq->tq_freelist = t;
  95         } else {
  96                 tq->tq_nalloc--;
  97                 mutex_exit(&tq->tq_lock);
  98                 kmem_free(t, sizeof (task_t));
  99                 mutex_enter(&tq->tq_lock);
 100         }
 101 }
 102
 103 taskqid_t
 104 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
 105 {
 106         task_t *t;
 107
 108         if (taskq_now) {
 109                 func(arg);
 110                 return (1);
 111         }
 112
 113         mutex_enter(&tq->tq_lock);
 114         ASSERT(tq->tq_flags & TASKQ_ACTIVE);
 115         if ((t = task_alloc(tq, tqflags)) == NULL) {
 116                 mutex_exit(&tq->tq_lock);
 117                 return (0);
 118         }
 119         t->task_next = &tq->tq_task;
 120         t->task_prev = tq->tq_task.task_prev;
 121         t->task_next->task_prev = t;
 122         t->task_prev->task_next = t;
 123         t->task_func = func;
 124         t->task_arg = arg;
 125         cv_signal(&tq->tq_dispatch_cv);
 126         mutex_exit(&tq->tq_lock);
 127         return (1);
 128 }
 129
 130 void
 131 taskq_wait(taskq_t *tq)
 132 {
 133         mutex_enter(&tq->tq_lock);
 134         while (tq->tq_task.task_next != &tq->tq_task || tq->tq_active != 0)
 135                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 136         mutex_exit(&tq->tq_lock);
 137 }
 138
 139 static void *
 140 taskq_thread(void *arg)
 141 {
 142         taskq_t *tq = arg;
 143         task_t *t;
 144
 145         mutex_enter(&tq->tq_lock);
 146         while (tq->tq_flags & TASKQ_ACTIVE) {
 147                 if ((t = tq->tq_task.task_next) == &tq->tq_task) {
 148                         if (--tq->tq_active == 0)
 149                                 cv_broadcast(&tq->tq_wait_cv);
 150                         cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
 151                         tq->tq_active++;
 152                         continue;
 153                 }
 154                 t->task_prev->task_next = t->task_next;
 155                 t->task_next->task_prev = t->task_prev;
 156                 mutex_exit(&tq->tq_lock);
 157
 158                 rw_enter(&tq->tq_threadlock, RW_READER);
 159                 t->task_func(t->task_arg);
 160                 rw_exit(&tq->tq_threadlock);
 161
 162                 mutex_enter(&tq->tq_lock);
 163                 task_free(tq, t);
 164         }
 165         tq->tq_nthreads--;
 166         cv_broadcast(&tq->tq_wait_cv);
 167         mutex_exit(&tq->tq_lock);
 168         return (NULL);
 169 }
 170
 171 /*ARGSUSED*/
 172 taskq_t *
 173 taskq_create(const char *name, int nthreads, pri_t pri,
 174         int minalloc, int maxalloc, uint_t flags)
 175 {
 176         taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
 177         int t;
 178
 179         rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
 180         tq->tq_flags = flags | TASKQ_ACTIVE;
 181         tq->tq_active = nthreads;
 182         tq->tq_nthreads = nthreads;
 183         tq->tq_minalloc = minalloc;
 184         tq->tq_maxalloc = maxalloc;
 185         tq->tq_task.task_next = &tq->tq_task;
 186         tq->tq_task.task_prev = &tq->tq_task;
 187         tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP);
 188
 189         if (flags & TASKQ_PREPOPULATE) {
 190                 mutex_enter(&tq->tq_lock);
 191                 while (minalloc-- > 0)
 192                         task_free(tq, task_alloc(tq, KM_SLEEP));
 193                 mutex_exit(&tq->tq_lock);
 194         }
 195
 196         for (t = 0; t < nthreads; t++)
 197                 (void) thr_create(0, 0, taskq_thread,
 198                     tq, THR_BOUND, &tq->tq_threadlist[t]);
 199
 200         return (tq);
 201 }
 202
 203 void
 204 taskq_destroy(taskq_t *tq)
 205 {
 206         int t;
 207         int nthreads = tq->tq_nthreads;
 208
 209         taskq_wait(tq);
 210
 211         mutex_enter(&tq->tq_lock);
 212
 213         tq->tq_flags &= ~TASKQ_ACTIVE;
 214         cv_broadcast(&tq->tq_dispatch_cv);
 215
 216         while (tq->tq_nthreads != 0)
 217                 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
 218
 219         tq->tq_minalloc = 0;
 220         while (tq->tq_nalloc != 0) {
 221                 ASSERT(tq->tq_freelist != NULL);
 222                 task_free(tq, task_alloc(tq, KM_SLEEP));
 223         }
 224
 225         mutex_exit(&tq->tq_lock);
 226
 227         for (t = 0; t < nthreads; t++)
 228                 (void) thr_join(tq->tq_threadlist[t], NULL, NULL);
 229
 230         kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t));
 231
 232         rw_destroy(&tq->tq_threadlock);
 233
 234         kmem_free(tq, sizeof (taskq_t));
 235 }
 236
 237 int
 238 taskq_member(taskq_t *tq, void *t)
 239 {
 240         int i;
 241
 242         if (taskq_now)
 243                 return (1);
 244
 245         for (i = 0; i < tq->tq_nthreads; i++)
 246                 if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t)
 247                         return (1);
 248
 249         return (0);
 250 }