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 2009 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #include <sys/zfs_context.h> 27 28 int taskq_now; 29 taskq_t *system_taskq; 30 31 typedef struct task { 32 struct task *task_next; 33 struct task *task_prev; 34 task_func_t *task_func; 35 void *task_arg; 36 } task_t; 37 38 #define TASKQ_ACTIVE 0x00010000 39 40 struct taskq { 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 task_t *tq_freelist; 53 task_t tq_task; 54 }; 55 56 static task_t * 57 task_alloc(taskq_t *tq, int tqflags) 58 { 59 task_t *t; 60 61 if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) { 62 tq->tq_freelist = t->task_next; 63 } else { 64 mutex_exit(&tq->tq_lock); 65 if (tq->tq_nalloc >= tq->tq_maxalloc) { 66 if (!(tqflags & KM_SLEEP)) { 67 mutex_enter(&tq->tq_lock); 68 return (NULL); 69 } 70 /* 71 * We don't want to exceed tq_maxalloc, but we can't 72 * wait for other tasks to complete (and thus free up 73 * task structures) without risking deadlock with 74 * the caller. So, we just delay for one second 75 * to throttle the allocation rate. 76 */ 77 delay(hz); 78 } 79 t = kmem_alloc(sizeof (task_t), tqflags); 80 mutex_enter(&tq->tq_lock); 81 if (t != NULL) 82 tq->tq_nalloc++; 83 } 84 return (t); 85 } 86 87 static void 88 task_free(taskq_t *tq, task_t *t) 89 { 90 if (tq->tq_nalloc <= tq->tq_minalloc) { 91 t->task_next = tq->tq_freelist; 92 tq->tq_freelist = t; 93 } else { 94 tq->tq_nalloc--; 95 mutex_exit(&tq->tq_lock); 96 kmem_free(t, sizeof (task_t)); 97 mutex_enter(&tq->tq_lock); 98 } 99 } 100 101 taskqid_t 102 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags) 103 { 104 task_t *t; 105 106 if (taskq_now) { 107 func(arg); 108 return (1); 109 } 110 111 mutex_enter(&tq->tq_lock); 112 ASSERT(tq->tq_flags & TASKQ_ACTIVE); 113 if ((t = task_alloc(tq, tqflags)) == NULL) { 114 mutex_exit(&tq->tq_lock); 115 return (0); 116 } 117 t->task_next = &tq->tq_task; 118 t->task_prev = tq->tq_task.task_prev; 119 t->task_next->task_prev = t; 120 t->task_prev->task_next = t; 121 t->task_func = func; 122 t->task_arg = arg; 123 cv_signal(&tq->tq_dispatch_cv); 124 mutex_exit(&tq->tq_lock); 125 return (1); 126 } 127 128 void 129 taskq_wait(taskq_t *tq) 130 { 131 mutex_enter(&tq->tq_lock); 132 while (tq->tq_task.task_next != &tq->tq_task || tq->tq_active != 0) 133 cv_wait(&tq->tq_wait_cv, &tq->tq_lock); 134 mutex_exit(&tq->tq_lock); 135 } 136 137 static void * 138 taskq_thread(void *arg) 139 { 140 taskq_t *tq = arg; 141 task_t *t; 142 143 mutex_enter(&tq->tq_lock); 144 while (tq->tq_flags & TASKQ_ACTIVE) { 145 if ((t = tq->tq_task.task_next) == &tq->tq_task) { 146 if (--tq->tq_active == 0) 147 cv_broadcast(&tq->tq_wait_cv); 148 cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock); 149 tq->tq_active++; 150 continue; 151 } 152 t->task_prev->task_next = t->task_next; 153 t->task_next->task_prev = t->task_prev; 154 mutex_exit(&tq->tq_lock); 155 156 rw_enter(&tq->tq_threadlock, RW_READER); 157 t->task_func(t->task_arg); 158 rw_exit(&tq->tq_threadlock); 159 160 mutex_enter(&tq->tq_lock); 161 task_free(tq, t); 162 } 163 tq->tq_nthreads--; 164 cv_broadcast(&tq->tq_wait_cv); 165 mutex_exit(&tq->tq_lock); 166 return (NULL); 167 } 168 169 /*ARGSUSED*/ 170 taskq_t * 171 taskq_create(const char *name, int nthreads, pri_t pri, 172 int minalloc, int maxalloc, uint_t flags) 173 { 174 taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP); 175 int t; 176 177 if (flags & TASKQ_THREADS_CPU_PCT) { 178 int pct; 179 ASSERT3S(nthreads, >=, 0); 180 ASSERT3S(nthreads, <=, 100); 181 pct = MIN(nthreads, 100); 182 pct = MAX(pct, 0); 183 184 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100; 185 nthreads = MAX(nthreads, 1); /* need at least 1 thread */ 186 } else { 187 ASSERT3S(nthreads, >=, 1); 188 } 189 190 rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL); 191 mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL); 192 cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL); 193 cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL); 194 tq->tq_flags = flags | TASKQ_ACTIVE; 195 tq->tq_active = nthreads; 196 tq->tq_nthreads = nthreads; 197 tq->tq_minalloc = minalloc; 198 tq->tq_maxalloc = maxalloc; 199 tq->tq_task.task_next = &tq->tq_task; 200 tq->tq_task.task_prev = &tq->tq_task; 201 tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP); 202 203 if (flags & TASKQ_PREPOPULATE) { 204 mutex_enter(&tq->tq_lock); 205 while (minalloc-- > 0) 206 task_free(tq, task_alloc(tq, KM_SLEEP)); 207 mutex_exit(&tq->tq_lock); 208 } 209 210 for (t = 0; t < nthreads; t++) 211 (void) thr_create(0, 0, taskq_thread, 212 tq, THR_BOUND, &tq->tq_threadlist[t]); 213 214 return (tq); 215 } 216 217 void 218 taskq_destroy(taskq_t *tq) 219 { 220 int t; 221 int nthreads = tq->tq_nthreads; 222 223 taskq_wait(tq); 224 225 mutex_enter(&tq->tq_lock); 226 227 tq->tq_flags &= ~TASKQ_ACTIVE; 228 cv_broadcast(&tq->tq_dispatch_cv); 229 230 while (tq->tq_nthreads != 0) 231 cv_wait(&tq->tq_wait_cv, &tq->tq_lock); 232 233 tq->tq_minalloc = 0; 234 while (tq->tq_nalloc != 0) { 235 ASSERT(tq->tq_freelist != NULL); 236 task_free(tq, task_alloc(tq, KM_SLEEP)); 237 } 238 239 mutex_exit(&tq->tq_lock); 240 241 for (t = 0; t < nthreads; t++) 242 (void) thr_join(tq->tq_threadlist[t], NULL, NULL); 243 244 kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t)); 245 246 rw_destroy(&tq->tq_threadlock); 247 mutex_destroy(&tq->tq_lock); 248 cv_destroy(&tq->tq_dispatch_cv); 249 cv_destroy(&tq->tq_wait_cv); 250 251 kmem_free(tq, sizeof (taskq_t)); 252 } 253 254 int 255 taskq_member(taskq_t *tq, void *t) 256 { 257 int i; 258 259 if (taskq_now) 260 return (1); 261 262 for (i = 0; i < tq->tq_nthreads; i++) 263 if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t) 264 return (1); 265 266 return (0); 267 } 268 269 void 270 system_taskq_init(void) 271 { 272 system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512, 273 TASKQ_DYNAMIC | TASKQ_PREPOPULATE); 274 } 275 276 void 277 system_taskq_fini(void) 278 { 279 taskq_destroy(system_taskq); 280 system_taskq = NULL; /* defensive */ 281 } 282