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 * Copyright (c) 2017, Joyent, Inc.
30 */
31
32 #include <sys/zfs_context.h>
33
34 int taskq_now;
35 taskq_t *system_taskq;
36
37 #define TASKQ_ACTIVE 0x00010000
38 #define TASKQ_NAMELEN 31
39
40 struct taskq {
41 char tq_name[TASKQ_NAMELEN + 1];
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 kcondvar_t tq_maxalloc_cv;
54 int tq_maxalloc_wait;
55 taskq_ent_t *tq_freelist;
56 taskq_ent_t tq_task;
57 };
58
59 static taskq_ent_t *
60 task_alloc(taskq_t *tq, int tqflags)
61 {
62 taskq_ent_t *t;
63 int rv;
64
65 again: if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
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 tq->tq_nalloc++;
96 }
97 return (t);
98 }
99
100 static void
101 task_free(taskq_t *tq, taskq_ent_t *t)
102 {
103 if (tq->tq_nalloc <= tq->tq_minalloc) {
104 t->tqent_next = tq->tq_freelist;
105 tq->tq_freelist = t;
106 } else {
107 tq->tq_nalloc--;
108 mutex_exit(&tq->tq_lock);
109 kmem_free(t, sizeof (taskq_ent_t));
110 mutex_enter(&tq->tq_lock);
111 }
112
113 if (tq->tq_maxalloc_wait)
114 cv_signal(&tq->tq_maxalloc_cv);
115 }
116
117 taskqid_t
118 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
119 {
120 taskq_ent_t *t;
121
122 if (taskq_now) {
123 func(arg);
124 return (1);
125 }
126
127 mutex_enter(&tq->tq_lock);
128 ASSERT(tq->tq_flags & TASKQ_ACTIVE);
129 if ((t = task_alloc(tq, tqflags)) == NULL) {
130 mutex_exit(&tq->tq_lock);
131 return (0);
132 }
133 if (tqflags & TQ_FRONT) {
134 t->tqent_next = tq->tq_task.tqent_next;
135 t->tqent_prev = &tq->tq_task;
136 } else {
137 t->tqent_next = &tq->tq_task;
138 t->tqent_prev = tq->tq_task.tqent_prev;
139 }
140 t->tqent_next->tqent_prev = t;
141 t->tqent_prev->tqent_next = t;
142 t->tqent_func = func;
143 t->tqent_arg = arg;
144 t->tqent_flags = 0;
145 cv_signal(&tq->tq_dispatch_cv);
146 mutex_exit(&tq->tq_lock);
147 return (1);
148 }
149
150 void
151 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
152 taskq_ent_t *t)
153 {
154 ASSERT(func != NULL);
155 ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC));
156
157 /*
158 * Mark it as a prealloc'd task. This is important
159 * to ensure that we don't free it later.
160 */
161 t->tqent_flags |= TQENT_FLAG_PREALLOC;
162 /*
163 * Enqueue the task to the underlying queue.
164 */
165 mutex_enter(&tq->tq_lock);
166
167 if (flags & TQ_FRONT) {
168 t->tqent_next = tq->tq_task.tqent_next;
169 t->tqent_prev = &tq->tq_task;
170 } else {
171 t->tqent_next = &tq->tq_task;
172 t->tqent_prev = tq->tq_task.tqent_prev;
173 }
174 t->tqent_next->tqent_prev = t;
175 t->tqent_prev->tqent_next = t;
176 t->tqent_func = func;
177 t->tqent_arg = arg;
178 cv_signal(&tq->tq_dispatch_cv);
179 mutex_exit(&tq->tq_lock);
180 }
181
182 boolean_t
183 taskq_empty(taskq_t *tq)
184 {
185 boolean_t rv;
186
187 mutex_enter(&tq->tq_lock);
188 rv = (tq->tq_task.tqent_next == &tq->tq_task) && (tq->tq_active == 0);
189 mutex_exit(&tq->tq_lock);
190
191 return (rv);
192 }
193
194 void
195 taskq_wait(taskq_t *tq)
196 {
197 mutex_enter(&tq->tq_lock);
198 while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
199 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
200 mutex_exit(&tq->tq_lock);
201 }
202
203 static void *
204 taskq_thread(void *arg)
205 {
206 taskq_t *tq = arg;
207 taskq_ent_t *t;
208 boolean_t prealloc;
209
210 mutex_enter(&tq->tq_lock);
211 while (tq->tq_flags & TASKQ_ACTIVE) {
212 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
213 if (--tq->tq_active == 0)
214 cv_broadcast(&tq->tq_wait_cv);
215 cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
216 tq->tq_active++;
217 continue;
218 }
219 t->tqent_prev->tqent_next = t->tqent_next;
220 t->tqent_next->tqent_prev = t->tqent_prev;
221 t->tqent_next = NULL;
222 t->tqent_prev = NULL;
223 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
224 mutex_exit(&tq->tq_lock);
225
226 rw_enter(&tq->tq_threadlock, RW_READER);
227 t->tqent_func(t->tqent_arg);
228 rw_exit(&tq->tq_threadlock);
229
230 mutex_enter(&tq->tq_lock);
231 if (!prealloc)
232 task_free(tq, t);
233 }
234 tq->tq_nthreads--;
235 cv_broadcast(&tq->tq_wait_cv);
236 mutex_exit(&tq->tq_lock);
237 return (NULL);
238 }
239
240 /*ARGSUSED*/
241 taskq_t *
242 taskq_create(const char *name, int nthreads, pri_t pri,
243 int minalloc, int maxalloc, uint_t flags)
244 {
245 taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
246 int t;
247
248 if (flags & TASKQ_THREADS_CPU_PCT) {
249 int pct;
250 ASSERT3S(nthreads, >=, 0);
251 ASSERT3S(nthreads, <=, 100);
252 pct = MIN(nthreads, 100);
253 pct = MAX(pct, 0);
254
255 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
256 nthreads = MAX(nthreads, 1); /* need at least 1 thread */
257 } else {
258 ASSERT3S(nthreads, >=, 1);
259 }
260
261 rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
262 mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
263 cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
264 cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
265 cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
266 (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN + 1);
267 tq->tq_flags = flags | TASKQ_ACTIVE;
268 tq->tq_active = nthreads;
269 tq->tq_nthreads = nthreads;
270 tq->tq_minalloc = minalloc;
271 tq->tq_maxalloc = maxalloc;
272 tq->tq_task.tqent_next = &tq->tq_task;
273 tq->tq_task.tqent_prev = &tq->tq_task;
274 tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP);
275
276 if (flags & TASKQ_PREPOPULATE) {
277 mutex_enter(&tq->tq_lock);
278 while (minalloc-- > 0)
279 task_free(tq, task_alloc(tq, KM_SLEEP));
280 mutex_exit(&tq->tq_lock);
281 }
282
283 for (t = 0; t < nthreads; t++)
284 (void) thr_create(0, 0, taskq_thread,
285 tq, THR_BOUND, &tq->tq_threadlist[t]);
286
287 return (tq);
288 }
289
290 void
291 taskq_destroy(taskq_t *tq)
292 {
293 int t;
294 int nthreads = tq->tq_nthreads;
295
296 taskq_wait(tq);
297
298 mutex_enter(&tq->tq_lock);
299
300 tq->tq_flags &= ~TASKQ_ACTIVE;
301 cv_broadcast(&tq->tq_dispatch_cv);
302
303 while (tq->tq_nthreads != 0)
304 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
305
306 tq->tq_minalloc = 0;
307 while (tq->tq_nalloc != 0) {
308 ASSERT(tq->tq_freelist != NULL);
309 task_free(tq, task_alloc(tq, KM_SLEEP));
310 }
311
312 mutex_exit(&tq->tq_lock);
313
314 for (t = 0; t < nthreads; t++)
315 (void) thr_join(tq->tq_threadlist[t], NULL, NULL);
316
317 kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t));
318
319 rw_destroy(&tq->tq_threadlock);
320 mutex_destroy(&tq->tq_lock);
321 cv_destroy(&tq->tq_dispatch_cv);
322 cv_destroy(&tq->tq_wait_cv);
323 cv_destroy(&tq->tq_maxalloc_cv);
324
325 kmem_free(tq, sizeof (taskq_t));
326 }
327
328 int
329 taskq_member(taskq_t *tq, void *t)
330 {
331 int i;
332
333 if (taskq_now)
334 return (1);
335
336 for (i = 0; i < tq->tq_nthreads; i++)
337 if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t)
338 return (1);
339
340 return (0);
341 }
342
343 void
344 system_taskq_init(void)
345 {
346 system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
347 TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
348 }
349
350 void
351 system_taskq_fini(void)
352 {
353 taskq_destroy(system_taskq);
354 system_taskq = NULL; /* defensive */
355 }