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 <[email protected]>. 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 *
task_alloc(taskq_t * tq,int tqflags)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 #ifdef __FreeBSD__
83 rv = cv_timedwait(&tq->tq_maxalloc_cv,
84 &tq->tq_lock, hz);
85 #else
86 rv = cv_timedwait(&tq->tq_maxalloc_cv,
87 &tq->tq_lock, ddi_get_lbolt() + hz);
88 #endif
89 tq->tq_maxalloc_wait--;
90 if (rv > 0)
91 goto again; /* signaled */
92 }
93 mutex_exit(&tq->tq_lock);
94
95 t = kmem_alloc(sizeof (taskq_ent_t), tqflags & KM_SLEEP);
96
97 mutex_enter(&tq->tq_lock);
98 if (t != NULL)
99 tq->tq_nalloc++;
100 }
101 return (t);
102 }
103
104 static void
task_free(taskq_t * tq,taskq_ent_t * t)105 task_free(taskq_t *tq, taskq_ent_t *t)
106 {
107 if (tq->tq_nalloc <= tq->tq_minalloc) {
108 t->tqent_next = tq->tq_freelist;
109 tq->tq_freelist = t;
110 } else {
111 tq->tq_nalloc--;
112 mutex_exit(&tq->tq_lock);
113 kmem_free(t, sizeof (taskq_ent_t));
114 mutex_enter(&tq->tq_lock);
115 }
116
117 if (tq->tq_maxalloc_wait)
118 cv_signal(&tq->tq_maxalloc_cv);
119 }
120
121 taskqid_t
taskq_dispatch(taskq_t * tq,task_func_t func,void * arg,uint_t tqflags)122 taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
123 {
124 taskq_ent_t *t;
125
126 if (taskq_now) {
127 func(arg);
128 return (1);
129 }
130
131 mutex_enter(&tq->tq_lock);
132 ASSERT(tq->tq_flags & TASKQ_ACTIVE);
133 if ((t = task_alloc(tq, tqflags)) == NULL) {
134 mutex_exit(&tq->tq_lock);
135 return (0);
136 }
137 if (tqflags & TQ_FRONT) {
138 t->tqent_next = tq->tq_task.tqent_next;
139 t->tqent_prev = &tq->tq_task;
140 } else {
141 t->tqent_next = &tq->tq_task;
142 t->tqent_prev = tq->tq_task.tqent_prev;
143 }
144 t->tqent_next->tqent_prev = t;
145 t->tqent_prev->tqent_next = t;
146 t->tqent_func = func;
147 t->tqent_arg = arg;
148 t->tqent_flags = 0;
149 cv_signal(&tq->tq_dispatch_cv);
150 mutex_exit(&tq->tq_lock);
151 return (1);
152 }
153
154 void
taskq_dispatch_ent(taskq_t * tq,task_func_t func,void * arg,uint_t flags,taskq_ent_t * t)155 taskq_dispatch_ent(taskq_t *tq, task_func_t func, void *arg, uint_t flags,
156 taskq_ent_t *t)
157 {
158 ASSERT(func != NULL);
159 ASSERT(!(tq->tq_flags & TASKQ_DYNAMIC));
160
161 /*
162 * Mark it as a prealloc'd task. This is important
163 * to ensure that we don't free it later.
164 */
165 t->tqent_flags |= TQENT_FLAG_PREALLOC;
166 /*
167 * Enqueue the task to the underlying queue.
168 */
169 mutex_enter(&tq->tq_lock);
170
171 if (flags & TQ_FRONT) {
172 t->tqent_next = tq->tq_task.tqent_next;
173 t->tqent_prev = &tq->tq_task;
174 } else {
175 t->tqent_next = &tq->tq_task;
176 t->tqent_prev = tq->tq_task.tqent_prev;
177 }
178 t->tqent_next->tqent_prev = t;
179 t->tqent_prev->tqent_next = t;
180 t->tqent_func = func;
181 t->tqent_arg = arg;
182 cv_signal(&tq->tq_dispatch_cv);
183 mutex_exit(&tq->tq_lock);
184 }
185
186 void
taskq_wait(taskq_t * tq)187 taskq_wait(taskq_t *tq)
188 {
189 mutex_enter(&tq->tq_lock);
190 while (tq->tq_task.tqent_next != &tq->tq_task || tq->tq_active != 0)
191 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
192 mutex_exit(&tq->tq_lock);
193 }
194
195 void
taskq_wait_id(taskq_t * tq,taskqid_t id)196 taskq_wait_id(taskq_t *tq, taskqid_t id)
197 {
198 taskq_wait(tq);
199 }
200
201 static void *
taskq_thread(void * arg)202 taskq_thread(void *arg)
203 {
204 taskq_t *tq = arg;
205 taskq_ent_t *t;
206 boolean_t prealloc;
207
208 mutex_enter(&tq->tq_lock);
209 while (tq->tq_flags & TASKQ_ACTIVE) {
210 if ((t = tq->tq_task.tqent_next) == &tq->tq_task) {
211 if (--tq->tq_active == 0)
212 cv_broadcast(&tq->tq_wait_cv);
213 cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
214 tq->tq_active++;
215 continue;
216 }
217 t->tqent_prev->tqent_next = t->tqent_next;
218 t->tqent_next->tqent_prev = t->tqent_prev;
219 t->tqent_next = NULL;
220 t->tqent_prev = NULL;
221 prealloc = t->tqent_flags & TQENT_FLAG_PREALLOC;
222 mutex_exit(&tq->tq_lock);
223
224 rw_enter(&tq->tq_threadlock, RW_READER);
225 t->tqent_func(t->tqent_arg);
226 rw_exit(&tq->tq_threadlock);
227
228 mutex_enter(&tq->tq_lock);
229 if (!prealloc)
230 task_free(tq, t);
231 }
232 tq->tq_nthreads--;
233 cv_broadcast(&tq->tq_wait_cv);
234 mutex_exit(&tq->tq_lock);
235 return (NULL);
236 }
237
238 /*ARGSUSED*/
239 taskq_t *
taskq_create(const char * name,int nthreads,pri_t pri,int minalloc,int maxalloc,uint_t flags)240 taskq_create(const char *name, int nthreads, pri_t pri,
241 int minalloc, int maxalloc, uint_t flags)
242 {
243 taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
244 int t;
245
246 if (flags & TASKQ_THREADS_CPU_PCT) {
247 int pct;
248 ASSERT3S(nthreads, >=, 0);
249 ASSERT3S(nthreads, <=, 100);
250 pct = MIN(nthreads, 100);
251 pct = MAX(pct, 0);
252
253 nthreads = (sysconf(_SC_NPROCESSORS_ONLN) * pct) / 100;
254 nthreads = MAX(nthreads, 1); /* need at least 1 thread */
255 } else {
256 ASSERT3S(nthreads, >=, 1);
257 }
258
259 rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
260 mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
261 cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
262 cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
263 cv_init(&tq->tq_maxalloc_cv, NULL, CV_DEFAULT, NULL);
264 (void) strncpy(tq->tq_name, name, TASKQ_NAMELEN + 1);
265 tq->tq_flags = flags | TASKQ_ACTIVE;
266 tq->tq_active = nthreads;
267 tq->tq_nthreads = nthreads;
268 tq->tq_minalloc = minalloc;
269 tq->tq_maxalloc = maxalloc;
270 tq->tq_task.tqent_next = &tq->tq_task;
271 tq->tq_task.tqent_prev = &tq->tq_task;
272 tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP);
273
274 if (flags & TASKQ_PREPOPULATE) {
275 mutex_enter(&tq->tq_lock);
276 while (minalloc-- > 0)
277 task_free(tq, task_alloc(tq, KM_SLEEP));
278 mutex_exit(&tq->tq_lock);
279 }
280
281 for (t = 0; t < nthreads; t++)
282 (void) thr_create(0, 0, taskq_thread,
283 tq, THR_BOUND, &tq->tq_threadlist[t]);
284
285 return (tq);
286 }
287
288 void
taskq_destroy(taskq_t * tq)289 taskq_destroy(taskq_t *tq)
290 {
291 int t;
292 int nthreads = tq->tq_nthreads;
293
294 taskq_wait(tq);
295
296 mutex_enter(&tq->tq_lock);
297
298 tq->tq_flags &= ~TASKQ_ACTIVE;
299 cv_broadcast(&tq->tq_dispatch_cv);
300
301 while (tq->tq_nthreads != 0)
302 cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
303
304 tq->tq_minalloc = 0;
305 while (tq->tq_nalloc != 0) {
306 ASSERT(tq->tq_freelist != NULL);
307 task_free(tq, task_alloc(tq, KM_SLEEP));
308 }
309
310 mutex_exit(&tq->tq_lock);
311
312 for (t = 0; t < nthreads; t++)
313 (void) thr_join(tq->tq_threadlist[t], NULL, NULL);
314
315 kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t));
316
317 rw_destroy(&tq->tq_threadlock);
318 mutex_destroy(&tq->tq_lock);
319 cv_destroy(&tq->tq_dispatch_cv);
320 cv_destroy(&tq->tq_wait_cv);
321 cv_destroy(&tq->tq_maxalloc_cv);
322
323 kmem_free(tq, sizeof (taskq_t));
324 }
325
326 int
taskq_member(taskq_t * tq,void * t)327 taskq_member(taskq_t *tq, void *t)
328 {
329 int i;
330
331 if (taskq_now)
332 return (1);
333
334 for (i = 0; i < tq->tq_nthreads; i++)
335 if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t)
336 return (1);
337
338 return (0);
339 }
340
341 void
system_taskq_init(void)342 system_taskq_init(void)
343 {
344 system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
345 TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
346 }
347
348 void
system_taskq_fini(void)349 system_taskq_fini(void)
350 {
351 taskq_destroy(system_taskq);
352 system_taskq = NULL; /* defensive */
353 }
354