Fix occasional hangs on mutexes
[fio.git] / workqueue.c
CommitLineData
a9da8ab2 1/*
51575029 2 * Generic workqueue offload mechanism
a9da8ab2
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3 *
4 * Copyright (C) 2015 Jens Axboe <axboe@kernel.dk>
5 *
6 */
7#include <unistd.h>
8
9#include "fio.h"
a9da8ab2
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10#include "flist.h"
11#include "workqueue.h"
a47591e4 12#include "smalloc.h"
a9da8ab2 13
a9da8ab2
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14enum {
15 SW_F_IDLE = 1 << 0,
16 SW_F_RUNNING = 1 << 1,
17 SW_F_EXIT = 1 << 2,
18 SW_F_EXITED = 1 << 3,
19 SW_F_ACCOUNTED = 1 << 4,
20 SW_F_ERROR = 1 << 5,
21};
22
23static struct submit_worker *__get_submit_worker(struct workqueue *wq,
24 unsigned int start,
25 unsigned int end,
26 struct submit_worker **best)
27{
28 struct submit_worker *sw = NULL;
29
30 while (start <= end) {
31 sw = &wq->workers[start];
32 if (sw->flags & SW_F_IDLE)
33 return sw;
34 if (!(*best) || sw->seq < (*best)->seq)
35 *best = sw;
36 start++;
37 }
38
39 return NULL;
40}
41
42static struct submit_worker *get_submit_worker(struct workqueue *wq)
43{
44 unsigned int next = wq->next_free_worker;
45 struct submit_worker *sw, *best = NULL;
46
47 assert(next < wq->max_workers);
48
49 sw = __get_submit_worker(wq, next, wq->max_workers - 1, &best);
50 if (!sw && next)
51 sw = __get_submit_worker(wq, 0, next - 1, &best);
52
53 /*
54 * No truly idle found, use best match
55 */
56 if (!sw)
57 sw = best;
58
59 if (sw->index == wq->next_free_worker) {
60 if (sw->index + 1 < wq->max_workers)
61 wq->next_free_worker = sw->index + 1;
62 else
63 wq->next_free_worker = 0;
64 }
65
66 return sw;
67}
68
1391052a 69static bool all_sw_idle(struct workqueue *wq)
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70{
71 int i;
72
73 for (i = 0; i < wq->max_workers; i++) {
74 struct submit_worker *sw = &wq->workers[i];
75
76 if (!(sw->flags & SW_F_IDLE))
1391052a 77 return false;
a9da8ab2
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78 }
79
1391052a 80 return true;
a9da8ab2
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81}
82
83/*
84 * Must be serialized wrt workqueue_enqueue() by caller
85 */
86void workqueue_flush(struct workqueue *wq)
87{
88 wq->wake_idle = 1;
89
90 while (!all_sw_idle(wq)) {
91 pthread_mutex_lock(&wq->flush_lock);
92 pthread_cond_wait(&wq->flush_cond, &wq->flush_lock);
93 pthread_mutex_unlock(&wq->flush_lock);
94 }
95
96 wq->wake_idle = 0;
97}
98
99/*
b07f6ad1 100 * Must be serialized by caller. Returns true for queued, false for busy.
a9da8ab2 101 */
26de50cf 102void workqueue_enqueue(struct workqueue *wq, struct workqueue_work *work)
a9da8ab2
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103{
104 struct submit_worker *sw;
105
106 sw = get_submit_worker(wq);
26de50cf
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107 assert(sw);
108
109 pthread_mutex_lock(&sw->lock);
110 flist_add_tail(&work->list, &sw->work_list);
111 sw->seq = ++wq->work_seq;
112 sw->flags &= ~SW_F_IDLE;
113 pthread_mutex_unlock(&sw->lock);
a9da8ab2 114
26de50cf 115 pthread_cond_signal(&sw->cond);
a9da8ab2
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116}
117
118static void handle_list(struct submit_worker *sw, struct flist_head *list)
119{
120 struct workqueue *wq = sw->wq;
88271841 121 struct workqueue_work *work;
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122
123 while (!flist_empty(list)) {
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124 work = flist_first_entry(list, struct workqueue_work, list);
125 flist_del_init(&work->list);
ee2b6d6e 126 wq->ops.fn(sw, work);
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127 }
128}
129
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130static void *worker_thread(void *data)
131{
132 struct submit_worker *sw = data;
133 struct workqueue *wq = sw->wq;
f6496ba7 134 unsigned int eflags = 0, ret = 0;
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135 FLIST_HEAD(local_list);
136
24660963
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137 sk_out_assign(sw->sk_out);
138
f6496ba7
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139 if (wq->ops.nice) {
140 if (nice(wq->ops.nice) < 0) {
141 log_err("workqueue: nice %s\n", strerror(errno));
142 ret = 1;
143 }
144 }
145
146 if (!ret)
147 ret = workqueue_init_worker(sw);
148
a9da8ab2
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149 pthread_mutex_lock(&sw->lock);
150 sw->flags |= SW_F_RUNNING;
151 if (ret)
152 sw->flags |= SW_F_ERROR;
153 pthread_mutex_unlock(&sw->lock);
154
155 pthread_mutex_lock(&wq->flush_lock);
156 pthread_cond_signal(&wq->flush_cond);
157 pthread_mutex_unlock(&wq->flush_lock);
158
159 if (sw->flags & SW_F_ERROR)
160 goto done;
161
162 while (1) {
163 pthread_mutex_lock(&sw->lock);
164
165 if (flist_empty(&sw->work_list)) {
166 if (sw->flags & SW_F_EXIT) {
167 pthread_mutex_unlock(&sw->lock);
168 break;
169 }
170
ee2b6d6e 171 if (workqueue_pre_sleep_check(sw)) {
a9da8ab2 172 pthread_mutex_unlock(&sw->lock);
ee2b6d6e 173 workqueue_pre_sleep(sw);
a9da8ab2
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174 pthread_mutex_lock(&sw->lock);
175 }
176
177 /*
178 * We dropped and reaquired the lock, check
179 * state again.
180 */
181 if (!flist_empty(&sw->work_list))
182 goto handle_work;
183
184 if (sw->flags & SW_F_EXIT) {
185 pthread_mutex_unlock(&sw->lock);
186 break;
187 } else if (!(sw->flags & SW_F_IDLE)) {
188 sw->flags |= SW_F_IDLE;
189 wq->next_free_worker = sw->index;
190 if (wq->wake_idle)
191 pthread_cond_signal(&wq->flush_cond);
192 }
17ecadc3
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193 if (wq->ops.update_acct_fn)
194 wq->ops.update_acct_fn(sw);
195
a9da8ab2
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196 pthread_cond_wait(&sw->cond, &sw->lock);
197 } else {
198handle_work:
199 flist_splice_init(&sw->work_list, &local_list);
200 }
201 pthread_mutex_unlock(&sw->lock);
202 handle_list(sw, &local_list);
203 }
204
17ecadc3
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205 if (wq->ops.update_acct_fn)
206 wq->ops.update_acct_fn(sw);
a9da8ab2
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207
208done:
209 pthread_mutex_lock(&sw->lock);
210 sw->flags |= (SW_F_EXITED | eflags);
211 pthread_mutex_unlock(&sw->lock);
24660963 212 sk_out_drop();
a9da8ab2
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213 return NULL;
214}
215
c35c582d 216static void free_worker(struct submit_worker *sw, unsigned int *sum_cnt)
a9da8ab2 217{
ee2b6d6e 218 struct workqueue *wq = sw->wq;
a9da8ab2 219
c35c582d 220 workqueue_exit_worker(sw, sum_cnt);
a9da8ab2
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221
222 pthread_cond_destroy(&sw->cond);
223 pthread_mutex_destroy(&sw->lock);
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224
225 if (wq->ops.free_worker_fn)
226 wq->ops.free_worker_fn(sw);
a9da8ab2
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227}
228
229static void shutdown_worker(struct submit_worker *sw, unsigned int *sum_cnt)
230{
a9da8ab2 231 pthread_join(sw->thread, NULL);
c35c582d 232 free_worker(sw, sum_cnt);
a9da8ab2
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233}
234
235void workqueue_exit(struct workqueue *wq)
236{
237 unsigned int shutdown, sum_cnt = 0;
238 struct submit_worker *sw;
239 int i;
240
f8e266c9
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241 if (!wq->workers)
242 return;
243
a9da8ab2
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244 for (i = 0; i < wq->max_workers; i++) {
245 sw = &wq->workers[i];
246
247 pthread_mutex_lock(&sw->lock);
248 sw->flags |= SW_F_EXIT;
249 pthread_cond_signal(&sw->cond);
250 pthread_mutex_unlock(&sw->lock);
251 }
252
253 do {
254 shutdown = 0;
255 for (i = 0; i < wq->max_workers; i++) {
256 sw = &wq->workers[i];
257 if (sw->flags & SW_F_ACCOUNTED)
258 continue;
b7d0bbf1 259 pthread_mutex_lock(&sw->lock);
a9da8ab2 260 sw->flags |= SW_F_ACCOUNTED;
b7d0bbf1 261 pthread_mutex_unlock(&sw->lock);
a9da8ab2
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262 shutdown_worker(sw, &sum_cnt);
263 shutdown++;
264 }
265 } while (shutdown && shutdown != wq->max_workers);
266
a47591e4 267 sfree(wq->workers);
f8e266c9 268 wq->workers = NULL;
a9da8ab2
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269 pthread_mutex_destroy(&wq->flush_lock);
270 pthread_cond_destroy(&wq->flush_cond);
2a274336 271 pthread_mutex_destroy(&wq->stat_lock);
a9da8ab2
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272}
273
24660963
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274static int start_worker(struct workqueue *wq, unsigned int index,
275 struct sk_out *sk_out)
a9da8ab2
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276{
277 struct submit_worker *sw = &wq->workers[index];
278 int ret;
f9e5b5ee
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279 pthread_condattr_t cattr;
280 pthread_mutexattr_t mattr;
a9da8ab2
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281
282 INIT_FLIST_HEAD(&sw->work_list);
f9e5b5ee
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283 ret = pthread_condattr_init(&cattr);
284 if (ret)
285 return ret;
286 ret = pthread_mutexattr_init(&mattr);
287 if (ret)
288 return ret;
289#ifdef FIO_HAVE_PSHARED_MUTEX
290 ret = pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
291 if (ret)
292 return ret;
293 ret = pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
294 if (ret)
295 return ret;
296#endif
297 pthread_cond_init(&sw->cond, &cattr);
298 pthread_mutex_init(&sw->lock, &mattr);
a9da8ab2
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299 sw->wq = wq;
300 sw->index = index;
24660963 301 sw->sk_out = sk_out;
a9da8ab2 302
ee2b6d6e
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303 if (wq->ops.alloc_worker_fn) {
304 ret = wq->ops.alloc_worker_fn(sw);
305 if (ret)
306 return ret;
307 }
308
a9da8ab2
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309 ret = pthread_create(&sw->thread, NULL, worker_thread, sw);
310 if (!ret) {
311 pthread_mutex_lock(&sw->lock);
312 sw->flags = SW_F_IDLE;
313 pthread_mutex_unlock(&sw->lock);
314 return 0;
315 }
316
c35c582d 317 free_worker(sw, NULL);
a9da8ab2
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318 return 1;
319}
320
321int workqueue_init(struct thread_data *td, struct workqueue *wq,
24660963
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322 struct workqueue_ops *ops, unsigned int max_workers,
323 struct sk_out *sk_out)
a9da8ab2
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324{
325 unsigned int running;
326 int i, error;
f9e5b5ee
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327 int ret;
328 pthread_condattr_t cattr;
329 pthread_mutexattr_t mattr;
a9da8ab2 330
24660963 331 wq->max_workers = max_workers;
a9da8ab2 332 wq->td = td;
5bb79f69 333 wq->ops = *ops;
a9da8ab2
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334 wq->work_seq = 0;
335 wq->next_free_worker = 0;
f9e5b5ee
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336
337 ret = pthread_condattr_init(&cattr);
338 if (ret) {
339 td_verror(td, ret, "pthread_condattr_init");
340 goto err;
341 }
342 ret = pthread_mutexattr_init(&mattr);
343 if (ret) {
344 td_verror(td, ret, "pthread_mutexattr_init");
345 goto err;
346 }
347#ifdef FIO_HAVE_PSHARED_MUTEX
348 ret = pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
349 if (ret) {
350 td_verror(td, ret, "pthread_condattr_setpshared");
351 goto err;
352 }
353 ret = pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
354 if (ret) {
355 td_verror(td, ret, "pthread_mutexattr_setpshared");
356 goto err;
357 }
358#endif
359 pthread_cond_init(&wq->flush_cond, &cattr);
360 pthread_mutex_init(&wq->flush_lock, &mattr);
361 pthread_mutex_init(&wq->stat_lock, &mattr);
a9da8ab2 362
a47591e4 363 wq->workers = smalloc(wq->max_workers * sizeof(struct submit_worker));
a9da8ab2
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364
365 for (i = 0; i < wq->max_workers; i++)
24660963 366 if (start_worker(wq, i, sk_out))
a9da8ab2
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367 break;
368
369 wq->max_workers = i;
bddc8d16
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370 if (!wq->max_workers)
371 goto err;
a9da8ab2
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372
373 /*
374 * Wait for them all to be started and initialized
375 */
376 error = 0;
377 do {
378 struct submit_worker *sw;
379
380 running = 0;
381 pthread_mutex_lock(&wq->flush_lock);
382 for (i = 0; i < wq->max_workers; i++) {
383 sw = &wq->workers[i];
384 pthread_mutex_lock(&sw->lock);
385 if (sw->flags & SW_F_RUNNING)
386 running++;
387 if (sw->flags & SW_F_ERROR)
388 error++;
389 pthread_mutex_unlock(&sw->lock);
390 }
391
392 if (error || running == wq->max_workers) {
393 pthread_mutex_unlock(&wq->flush_lock);
394 break;
395 }
396
397 pthread_cond_wait(&wq->flush_cond, &wq->flush_lock);
398 pthread_mutex_unlock(&wq->flush_lock);
399 } while (1);
400
bddc8d16
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401 if (!error)
402 return 0;
a9da8ab2 403
bddc8d16
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404err:
405 log_err("Can't create rate workqueue\n");
406 td_verror(td, ESRCH, "workqueue_init");
407 workqueue_exit(wq);
408 return 1;
a9da8ab2 409}