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 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #pragma ident "%Z%%M% %I% %E% SMI" 27 28 #include <sys/zfs_context.h> 29 30 int taskq_now; 31 32 typedef struct task { 33 struct task *task_next; 34 struct task *task_prev; 35 task_func_t *task_func; 36 void *task_arg; 37 } task_t; 38 39 #define TASKQ_ACTIVE 0x00010000 40 41 struct taskq { 42 kmutex_t tq_lock; 43 krwlock_t tq_threadlock; 44 kcondvar_t tq_dispatch_cv; 45 kcondvar_t tq_wait_cv; 46 thread_t *tq_threadlist; 47 int tq_flags; 48 int tq_active; 49 int tq_nthreads; 50 int tq_nalloc; 51 int tq_minalloc; 52 int tq_maxalloc; 53 task_t *tq_freelist; 54 task_t tq_task; 55 }; 56 57 static task_t * 58 task_alloc(taskq_t *tq, int tqflags) 59 { 60 task_t *t; 61 62 if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) { 63 tq->tq_freelist = t->task_next; 64 } else { 65 mutex_exit(&tq->tq_lock); 66 if (tq->tq_nalloc >= tq->tq_maxalloc) { 67 if (!(tqflags & KM_SLEEP)) { 68 mutex_enter(&tq->tq_lock); 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. 77 */ 78 delay(hz); 79 } 80 t = kmem_alloc(sizeof (task_t), tqflags); 81 mutex_enter(&tq->tq_lock); 82 if (t != NULL) 83 tq->tq_nalloc++; 84 } 85 return (t); 86 } 87 88 static void 89 task_free(taskq_t *tq, task_t *t) 90 { 91 if (tq->tq_nalloc <= tq->tq_minalloc) { 92 t->task_next = tq->tq_freelist; 93 tq->tq_freelist = t; 94 } else { 95 tq->tq_nalloc--; 96 mutex_exit(&tq->tq_lock); 97 kmem_free(t, sizeof (task_t)); 98 mutex_enter(&tq->tq_lock); 99 } 100 } 101 102 taskqid_t 103 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags) 104 { 105 task_t *t; 106 107 if (taskq_now) { 108 func(arg); 109 return (1); 110 } 111 112 mutex_enter(&tq->tq_lock); 113 ASSERT(tq->tq_flags & TASKQ_ACTIVE); 114 if ((t = task_alloc(tq, tqflags)) == NULL) { 115 mutex_exit(&tq->tq_lock); 116 return (0); 117 } 118 t->task_next = &tq->tq_task; 119 t->task_prev = tq->tq_task.task_prev; 120 t->task_next->task_prev = t; 121 t->task_prev->task_next = t; 122 t->task_func = func; 123 t->task_arg = arg; 124 cv_signal(&tq->tq_dispatch_cv); 125 mutex_exit(&tq->tq_lock); 126 return (1); 127 } 128 129 void 130 taskq_wait(taskq_t *tq) 131 { 132 mutex_enter(&tq->tq_lock); 133 while (tq->tq_task.task_next != &tq->tq_task || tq->tq_active != 0) 134 cv_wait(&tq->tq_wait_cv, &tq->tq_lock); 135 mutex_exit(&tq->tq_lock); 136 } 137 138 static void * 139 taskq_thread(void *arg) 140 { 141 taskq_t *tq = arg; 142 task_t *t; 143 144 mutex_enter(&tq->tq_lock); 145 while (tq->tq_flags & TASKQ_ACTIVE) { 146 if ((t = tq->tq_task.task_next) == &tq->tq_task) { 147 if (--tq->tq_active == 0) 148 cv_broadcast(&tq->tq_wait_cv); 149 cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock); 150 tq->tq_active++; 151 continue; 152 } 153 t->task_prev->task_next = t->task_next; 154 t->task_next->task_prev = t->task_prev; 155 mutex_exit(&tq->tq_lock); 156 157 rw_enter(&tq->tq_threadlock, RW_READER); 158 t->task_func(t->task_arg); 159 rw_exit(&tq->tq_threadlock); 160 161 mutex_enter(&tq->tq_lock); 162 task_free(tq, t); 163 } 164 tq->tq_nthreads--; 165 cv_broadcast(&tq->tq_wait_cv); 166 mutex_exit(&tq->tq_lock); 167 return (NULL); 168 } 169 170 /*ARGSUSED*/ 171 taskq_t * 172 taskq_create(const char *name, int nthreads, pri_t pri, 173 int minalloc, int maxalloc, uint_t flags) 174 { 175 taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP); 176 int t; 177 178 rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL); 179 mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL); 180 cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL); 181 cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL); 182 tq->tq_flags = flags | TASKQ_ACTIVE; 183 tq->tq_active = nthreads; 184 tq->tq_nthreads = nthreads; 185 tq->tq_minalloc = minalloc; 186 tq->tq_maxalloc = maxalloc; 187 tq->tq_task.task_next = &tq->tq_task; 188 tq->tq_task.task_prev = &tq->tq_task; 189 tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP); 190 191 if (flags & TASKQ_PREPOPULATE) { 192 mutex_enter(&tq->tq_lock); 193 while (minalloc-- > 0) 194 task_free(tq, task_alloc(tq, KM_SLEEP)); 195 mutex_exit(&tq->tq_lock); 196 } 197 198 for (t = 0; t < nthreads; t++) 199 (void) thr_create(0, 0, taskq_thread, 200 tq, THR_BOUND, &tq->tq_threadlist[t]); 201 202 return (tq); 203 } 204 205 void 206 taskq_destroy(taskq_t *tq) 207 { 208 int t; 209 int nthreads = tq->tq_nthreads; 210 211 taskq_wait(tq); 212 213 mutex_enter(&tq->tq_lock); 214 215 tq->tq_flags &= ~TASKQ_ACTIVE; 216 cv_broadcast(&tq->tq_dispatch_cv); 217 218 while (tq->tq_nthreads != 0) 219 cv_wait(&tq->tq_wait_cv, &tq->tq_lock); 220 221 tq->tq_minalloc = 0; 222 while (tq->tq_nalloc != 0) { 223 ASSERT(tq->tq_freelist != NULL); 224 task_free(tq, task_alloc(tq, KM_SLEEP)); 225 } 226 227 mutex_exit(&tq->tq_lock); 228 229 for (t = 0; t < nthreads; t++) 230 (void) thr_join(tq->tq_threadlist[t], NULL, NULL); 231 232 kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t)); 233 234 rw_destroy(&tq->tq_threadlock); 235 mutex_destroy(&tq->tq_lock); 236 cv_destroy(&tq->tq_dispatch_cv); 237 cv_destroy(&tq->tq_wait_cv); 238 239 kmem_free(tq, sizeof (taskq_t)); 240 } 241 242 int 243 taskq_member(taskq_t *tq, void *t) 244 { 245 int i; 246 247 if (taskq_now) 248 return (1); 249 250 for (i = 0; i < tq->tq_nthreads; i++) 251 if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t) 252 return (1); 253 254 return (0); 255 } 256