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 }