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 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 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 tq->tq_freelist = t->tqent_next; 66 } else { 67 if (tq->tq_nalloc >= tq->tq_maxalloc) { 68 if (!(tqflags & KM_SLEEP)) 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. If we have tasks 77 * complete before one second timeout expires then 78 * taskq_ent_free will signal us and we will 79 * immediately retry the allocation. 80 */ 81 tq->tq_maxalloc_wait++; 82 rv = cv_timedwait(&tq->tq_maxalloc_cv, 83 &tq->tq_lock, ddi_get_lbolt() + hz); 84 tq->tq_maxalloc_wait--; 85 if (rv > 0) 86 goto again; /* signaled */ 87 } 88 mutex_exit(&tq->tq_lock); 89 90 t = kmem_alloc(sizeof (taskq_ent_t), tqflags); 91 92 mutex_enter(&tq->tq_lock); 93 if (t != NULL) 94 tq->tq_nalloc++; 95 } 96 return (t); 97 } 98 99 static void 100 task_free(taskq_t *tq, taskq_ent_t *t) 101 { 102 if (tq->tq_nalloc <= tq->tq_minalloc) { 103 t->tqent_next = tq->tq_freelist; 104 tq->tq_freelist = t; 105 } else { 106 tq->tq_nalloc--; 107 mutex_exit(&tq->tq_lock); 108 kmem_free(t, sizeof (taskq_ent_t)); 109 mutex_enter(&tq->tq_lock); 110 } 111 112 if (tq->tq_maxalloc_wait) 113 cv_signal(&tq->tq_maxalloc_cv); 114 } 115 116 taskqid_t 117 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags) 118 { 119 taskq_ent_t *t; 120 121 if (taskq_now) { 122 func(arg); 123 return (1); 124 } 125 126 mutex_enter(&tq->tq_lock); 127 ASSERT(tq->tq_flags & TASKQ_ACTIVE); 128 if ((t = task_alloc(tq, tqflags)) == NULL) { 129 mutex_exit(&tq->tq_lock); 130 return (0); 131 } 132 if (tqflags & TQ_FRONT) { 133 t->tqent_next = tq->tq_task.tqent_next; 134 t->tqent_prev = &tq->tq_task; 135 } else { 136 t->tqent_next = &tq->tq_task; 137 t->tqent_prev = tq->tq_task.tqent_prev; 138 } 139 t->tqent_next->tqent_prev = t; 140 t->tqent_prev->tqent_next = t; 141 t->tqent_func = func; 142 t->tqent_arg = arg; 143 t->tqent_flags = 0; 144 cv_signal(&tq->tq_dispatch_cv); 145 mutex_exit(&tq->tq_lock); 146 return (1); 147 } 148 149 void 150 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags, 151 taskq_ent_t *t) 152 { 153 ASSERT(func != NULL); 154 ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC)); 155 156 /* 157 * Mark it as a prealloc'd task. This is important 158 * to ensure that we don't free it later. 159 */ 160 t->tqent_flags |= TQENT_FLAG_PREALLOC; 161 /* 162 * Enqueue the task to the underlying queue. 163 */ 164 mutex_enter(&tq->tq_lock); 165 166 if (flags & TQ_FRONT) { 167 t->tqent_next = tq->tq_task.tqent_next; 168 t->tqent_prev = &tq->tq_task; 169 } else { 170 t->tqent_next = &tq->tq_task; 171 t->tqent_prev = tq->tq_task.tqent_prev; 172 } 173 t->tqent_next->tqent_prev = t; 174 t->tqent_prev->tqent_next = t; 175 t->tqent_func = func; 176 t->tqent_arg = arg; 177 cv_signal(&tq->tq_dispatch_cv); 178 mutex_exit(&tq->tq_lock); 179 } 180 181 void 182 taskq_wait(taskq_t *tq) 183 { 184 mutex_enter(&tq->tq_lock); 185 while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0) 186 cv_wait(&tq->tq_wait_cv, &tq->tq_lock); 187 mutex_exit(&tq->tq_lock); 188 } 189 190 static void * 191 taskq_thread(void *arg) 192 { 193 taskq_t *tq = arg; 194 taskq_ent_t *t; 195 boolean_t prealloc; 196 197 mutex_enter(&tq->tq_lock); 198 while (tq->tq_flags & TASKQ_ACTIVE) { 199 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) { 200 if (--tq->tq_active == 0) 201 cv_broadcast(&tq->tq_wait_cv); 202 cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock); 203 tq->tq_active++; 204 continue; 205 } 206 t->tqent_prev->tqent_next = t->tqent_next; 207 t->tqent_next->tqent_prev = t->tqent_prev; 208 t->tqent_next = NULL; 209 t->tqent_prev = NULL; 210 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC; 211 mutex_exit(&tq->tq_lock); 212 213 rw_enter(&tq->tq_threadlock, RW_READER); 214 t->tqent_func(t->tqent_arg); 215 rw_exit(&tq->tq_threadlock); 216 217 mutex_enter(&tq->tq_lock); 218 if (!prealloc) 219 task_free(tq, t); 220 } 221 tq->tq_nthreads--; 222 cv_broadcast(&tq->tq_wait_cv); 223 mutex_exit(&tq->tq_lock); 224 return (NULL); 225 } 226 227 /*ARGSUSED*/ 228 taskq_t * 229 taskq_create(const char *name, int nthreads, pri_t pri, 230 int minalloc, int maxalloc, uint_t flags) 231 { 232 taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP); 233 int t; 234 235 if (flags & TASKQ_THREADS_CPU_PCT) { 236 int pct; 237 ASSERT3S(nthreads, >=, 0); 238 ASSERT3S(nthreads, <=, 100); 239 pct = MIN(nthreads, 100); 240 pct = MAX(pct, 0); 241 242 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100; 243 nthreads = MAX(nthreads, 1); /* need at least 1 thread */ 244 } else { 245 ASSERT3S(nthreads, >=, 1); 246 } 247 248 rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL); 249 mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL); 250 cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL); 251 cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL); 252 cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL); 253 (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN + 1); 254 tq->tq_flags = flags | TASKQ_ACTIVE; 255 tq->tq_active = nthreads; 256 tq->tq_nthreads = nthreads; 257 tq->tq_minalloc = minalloc; 258 tq->tq_maxalloc = maxalloc; 259 tq->tq_task.tqent_next = &tq->tq_task; 260 tq->tq_task.tqent_prev = &tq->tq_task; 261 tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP); 262 263 if (flags & TASKQ_PREPOPULATE) { 264 mutex_enter(&tq->tq_lock); 265 while (minalloc-- > 0) 266 task_free(tq, task_alloc(tq, KM_SLEEP)); 267 mutex_exit(&tq->tq_lock); 268 } 269 270 for (t = 0; t < nthreads; t++) 271 (void) thr_create(0, 0, taskq_thread, 272 tq, THR_BOUND, &tq->tq_threadlist[t]); 273 274 return (tq); 275 } 276 277 void 278 taskq_destroy(taskq_t *tq) 279 { 280 int t; 281 int nthreads = tq->tq_nthreads; 282 283 taskq_wait(tq); 284 285 mutex_enter(&tq->tq_lock); 286 287 tq->tq_flags &= ~TASKQ_ACTIVE; 288 cv_broadcast(&tq->tq_dispatch_cv); 289 290 while (tq->tq_nthreads != 0) 291 cv_wait(&tq->tq_wait_cv, &tq->tq_lock); 292 293 tq->tq_minalloc = 0; 294 while (tq->tq_nalloc != 0) { 295 ASSERT(tq->tq_freelist != NULL); 296 task_free(tq, task_alloc(tq, KM_SLEEP)); 297 } 298 299 mutex_exit(&tq->tq_lock); 300 301 for (t = 0; t < nthreads; t++) 302 (void) thr_join(tq->tq_threadlist[t], NULL, NULL); 303 304 kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t)); 305 306 rw_destroy(&tq->tq_threadlock); 307 mutex_destroy(&tq->tq_lock); 308 cv_destroy(&tq->tq_dispatch_cv); 309 cv_destroy(&tq->tq_wait_cv); 310 cv_destroy(&tq->tq_maxalloc_cv); 311 312 kmem_free(tq, sizeof (taskq_t)); 313 } 314 315 int 316 taskq_member(taskq_t *tq, void *t) 317 { 318 int i; 319 320 if (taskq_now) 321 return (1); 322 323 for (i = 0; i < tq->tq_nthreads; i++) 324 if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t) 325 return (1); 326 327 return (0); 328 } 329 330 void 331 system_taskq_init(void) 332 { 333 system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512, 334 TASKQ_DYNAMIC | TASKQ_PREPOPULATE); 335 } 336 337 void 338 system_taskq_fini(void) 339 { 340 taskq_destroy(system_taskq); 341 system_taskq = NULL; /* defensive */ 342 } 343