1 /*
2 * GPL HEADER START
3 *
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; If not, see
18 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
19 *
20 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
21 * CA 95054 USA or visit www.sun.com if you need additional information or
22 * have any questions.
23 *
24 * GPL HEADER END
25 */
26 /*
27 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
29 *
30 * Copyright (c) 2011, 2012, Intel Corporation.
31 */
32 /*
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
35 *
36 * libcfs/libcfs/workitem.c
37 *
38 * Author: Isaac Huang <isaac@clusterfs.com>
39 * Liang Zhen <zhen.liang@sun.com>
40 */
41
42 #define DEBUG_SUBSYSTEM S_LNET
43
44 #include "../../include/linux/libcfs/libcfs.h"
45
46 #define CFS_WS_NAME_LEN 16
47
48 typedef struct cfs_wi_sched {
49 struct list_head ws_list; /* chain on global list */
50 /** serialised workitems */
51 spinlock_t ws_lock;
52 /** where schedulers sleep */
53 wait_queue_head_t ws_waitq;
54 /** concurrent workitems */
55 struct list_head ws_runq;
56 /** rescheduled running-workitems, a workitem can be rescheduled
57 * while running in wi_action(), but we don't to execute it again
58 * unless it returns from wi_action(), so we put it on ws_rerunq
59 * while rescheduling, and move it to runq after it returns
60 * from wi_action() */
61 struct list_head ws_rerunq;
62 /** CPT-table for this scheduler */
63 struct cfs_cpt_table *ws_cptab;
64 /** CPT id for affinity */
65 int ws_cpt;
66 /** number of scheduled workitems */
67 int ws_nscheduled;
68 /** started scheduler thread, protected by cfs_wi_data::wi_glock */
69 unsigned int ws_nthreads:30;
70 /** shutting down, protected by cfs_wi_data::wi_glock */
71 unsigned int ws_stopping:1;
72 /** serialize starting thread, protected by cfs_wi_data::wi_glock */
73 unsigned int ws_starting:1;
74 /** scheduler name */
75 char ws_name[CFS_WS_NAME_LEN];
76 } cfs_wi_sched_t;
77
78 static struct cfs_workitem_data {
79 /** serialize */
80 spinlock_t wi_glock;
81 /** list of all schedulers */
82 struct list_head wi_scheds;
83 /** WI module is initialized */
84 int wi_init;
85 /** shutting down the whole WI module */
86 int wi_stopping;
87 } cfs_wi_data;
88
89 static inline void
cfs_wi_sched_lock(cfs_wi_sched_t * sched)90 cfs_wi_sched_lock(cfs_wi_sched_t *sched)
91 {
92 spin_lock(&sched->ws_lock);
93 }
94
95 static inline void
cfs_wi_sched_unlock(cfs_wi_sched_t * sched)96 cfs_wi_sched_unlock(cfs_wi_sched_t *sched)
97 {
98 spin_unlock(&sched->ws_lock);
99 }
100
101 static inline int
cfs_wi_sched_cansleep(cfs_wi_sched_t * sched)102 cfs_wi_sched_cansleep(cfs_wi_sched_t *sched)
103 {
104 cfs_wi_sched_lock(sched);
105 if (sched->ws_stopping) {
106 cfs_wi_sched_unlock(sched);
107 return 0;
108 }
109
110 if (!list_empty(&sched->ws_runq)) {
111 cfs_wi_sched_unlock(sched);
112 return 0;
113 }
114 cfs_wi_sched_unlock(sched);
115 return 1;
116 }
117
118
119 /* XXX:
120 * 0. it only works when called from wi->wi_action.
121 * 1. when it returns no one shall try to schedule the workitem.
122 */
123 void
cfs_wi_exit(struct cfs_wi_sched * sched,cfs_workitem_t * wi)124 cfs_wi_exit(struct cfs_wi_sched *sched, cfs_workitem_t *wi)
125 {
126 LASSERT(!in_interrupt()); /* because we use plain spinlock */
127 LASSERT(!sched->ws_stopping);
128
129 cfs_wi_sched_lock(sched);
130
131 LASSERT(wi->wi_running);
132 if (wi->wi_scheduled) { /* cancel pending schedules */
133 LASSERT(!list_empty(&wi->wi_list));
134 list_del_init(&wi->wi_list);
135
136 LASSERT(sched->ws_nscheduled > 0);
137 sched->ws_nscheduled--;
138 }
139
140 LASSERT(list_empty(&wi->wi_list));
141
142 wi->wi_scheduled = 1; /* LBUG future schedule attempts */
143 cfs_wi_sched_unlock(sched);
144
145 return;
146 }
147 EXPORT_SYMBOL(cfs_wi_exit);
148
149 /**
150 * cancel schedule request of workitem \a wi
151 */
152 int
cfs_wi_deschedule(struct cfs_wi_sched * sched,cfs_workitem_t * wi)153 cfs_wi_deschedule(struct cfs_wi_sched *sched, cfs_workitem_t *wi)
154 {
155 int rc;
156
157 LASSERT(!in_interrupt()); /* because we use plain spinlock */
158 LASSERT(!sched->ws_stopping);
159
160 /*
161 * return 0 if it's running already, otherwise return 1, which
162 * means the workitem will not be scheduled and will not have
163 * any race with wi_action.
164 */
165 cfs_wi_sched_lock(sched);
166
167 rc = !(wi->wi_running);
168
169 if (wi->wi_scheduled) { /* cancel pending schedules */
170 LASSERT(!list_empty(&wi->wi_list));
171 list_del_init(&wi->wi_list);
172
173 LASSERT(sched->ws_nscheduled > 0);
174 sched->ws_nscheduled--;
175
176 wi->wi_scheduled = 0;
177 }
178
179 LASSERT (list_empty(&wi->wi_list));
180
181 cfs_wi_sched_unlock(sched);
182 return rc;
183 }
184 EXPORT_SYMBOL(cfs_wi_deschedule);
185
186 /*
187 * Workitem scheduled with (serial == 1) is strictly serialised not only with
188 * itself, but also with others scheduled this way.
189 *
190 * Now there's only one static serialised queue, but in the future more might
191 * be added, and even dynamic creation of serialised queues might be supported.
192 */
193 void
cfs_wi_schedule(struct cfs_wi_sched * sched,cfs_workitem_t * wi)194 cfs_wi_schedule(struct cfs_wi_sched *sched, cfs_workitem_t *wi)
195 {
196 LASSERT(!in_interrupt()); /* because we use plain spinlock */
197 LASSERT(!sched->ws_stopping);
198
199 cfs_wi_sched_lock(sched);
200
201 if (!wi->wi_scheduled) {
202 LASSERT (list_empty(&wi->wi_list));
203
204 wi->wi_scheduled = 1;
205 sched->ws_nscheduled++;
206 if (!wi->wi_running) {
207 list_add_tail(&wi->wi_list, &sched->ws_runq);
208 wake_up(&sched->ws_waitq);
209 } else {
210 list_add(&wi->wi_list, &sched->ws_rerunq);
211 }
212 }
213
214 LASSERT (!list_empty(&wi->wi_list));
215 cfs_wi_sched_unlock(sched);
216 return;
217 }
218 EXPORT_SYMBOL(cfs_wi_schedule);
219
220
221 static int
cfs_wi_scheduler(void * arg)222 cfs_wi_scheduler (void *arg)
223 {
224 struct cfs_wi_sched *sched = (cfs_wi_sched_t *)arg;
225
226 cfs_block_allsigs();
227
228 /* CPT affinity scheduler? */
229 if (sched->ws_cptab != NULL)
230 cfs_cpt_bind(sched->ws_cptab, sched->ws_cpt);
231
232 spin_lock(&cfs_wi_data.wi_glock);
233
234 LASSERT(sched->ws_starting == 1);
235 sched->ws_starting--;
236 sched->ws_nthreads++;
237
238 spin_unlock(&cfs_wi_data.wi_glock);
239
240 cfs_wi_sched_lock(sched);
241
242 while (!sched->ws_stopping) {
243 int nloops = 0;
244 int rc;
245 cfs_workitem_t *wi;
246
247 while (!list_empty(&sched->ws_runq) &&
248 nloops < CFS_WI_RESCHED) {
249 wi = list_entry(sched->ws_runq.next,
250 cfs_workitem_t, wi_list);
251 LASSERT(wi->wi_scheduled && !wi->wi_running);
252
253 list_del_init(&wi->wi_list);
254
255 LASSERT(sched->ws_nscheduled > 0);
256 sched->ws_nscheduled--;
257
258 wi->wi_running = 1;
259 wi->wi_scheduled = 0;
260
261
262 cfs_wi_sched_unlock(sched);
263 nloops++;
264
265 rc = (*wi->wi_action) (wi);
266
267 cfs_wi_sched_lock(sched);
268 if (rc != 0) /* WI should be dead, even be freed! */
269 continue;
270
271 wi->wi_running = 0;
272 if (list_empty(&wi->wi_list))
273 continue;
274
275 LASSERT(wi->wi_scheduled);
276 /* wi is rescheduled, should be on rerunq now, we
277 * move it to runq so it can run action now */
278 list_move_tail(&wi->wi_list, &sched->ws_runq);
279 }
280
281 if (!list_empty(&sched->ws_runq)) {
282 cfs_wi_sched_unlock(sched);
283 /* don't sleep because some workitems still
284 * expect me to come back soon */
285 cond_resched();
286 cfs_wi_sched_lock(sched);
287 continue;
288 }
289
290 cfs_wi_sched_unlock(sched);
291 rc = wait_event_interruptible_exclusive(sched->ws_waitq,
292 !cfs_wi_sched_cansleep(sched));
293 cfs_wi_sched_lock(sched);
294 }
295
296 cfs_wi_sched_unlock(sched);
297
298 spin_lock(&cfs_wi_data.wi_glock);
299 sched->ws_nthreads--;
300 spin_unlock(&cfs_wi_data.wi_glock);
301
302 return 0;
303 }
304
305
306 void
cfs_wi_sched_destroy(struct cfs_wi_sched * sched)307 cfs_wi_sched_destroy(struct cfs_wi_sched *sched)
308 {
309 int i;
310
311 LASSERT(cfs_wi_data.wi_init);
312 LASSERT(!cfs_wi_data.wi_stopping);
313
314 spin_lock(&cfs_wi_data.wi_glock);
315 if (sched->ws_stopping) {
316 CDEBUG(D_INFO, "%s is in progress of stopping\n",
317 sched->ws_name);
318 spin_unlock(&cfs_wi_data.wi_glock);
319 return;
320 }
321
322 LASSERT(!list_empty(&sched->ws_list));
323 sched->ws_stopping = 1;
324
325 spin_unlock(&cfs_wi_data.wi_glock);
326
327 i = 2;
328 wake_up_all(&sched->ws_waitq);
329
330 spin_lock(&cfs_wi_data.wi_glock);
331 while (sched->ws_nthreads > 0) {
332 CDEBUG(IS_PO2(++i) ? D_WARNING : D_NET,
333 "waiting for %d threads of WI sched[%s] to terminate\n",
334 sched->ws_nthreads, sched->ws_name);
335
336 spin_unlock(&cfs_wi_data.wi_glock);
337 set_current_state(TASK_UNINTERRUPTIBLE);
338 schedule_timeout(cfs_time_seconds(1) / 20);
339 spin_lock(&cfs_wi_data.wi_glock);
340 }
341
342 list_del(&sched->ws_list);
343
344 spin_unlock(&cfs_wi_data.wi_glock);
345 LASSERT(sched->ws_nscheduled == 0);
346
347 LIBCFS_FREE(sched, sizeof(*sched));
348 }
349 EXPORT_SYMBOL(cfs_wi_sched_destroy);
350
351 int
cfs_wi_sched_create(char * name,struct cfs_cpt_table * cptab,int cpt,int nthrs,struct cfs_wi_sched ** sched_pp)352 cfs_wi_sched_create(char *name, struct cfs_cpt_table *cptab,
353 int cpt, int nthrs, struct cfs_wi_sched **sched_pp)
354 {
355 struct cfs_wi_sched *sched;
356 int rc;
357
358 LASSERT(cfs_wi_data.wi_init);
359 LASSERT(!cfs_wi_data.wi_stopping);
360 LASSERT(cptab == NULL || cpt == CFS_CPT_ANY ||
361 (cpt >= 0 && cpt < cfs_cpt_number(cptab)));
362
363 LIBCFS_ALLOC(sched, sizeof(*sched));
364 if (sched == NULL)
365 return -ENOMEM;
366
367 strncpy(sched->ws_name, name, CFS_WS_NAME_LEN);
368 sched->ws_name[CFS_WS_NAME_LEN - 1] = '\0';
369 sched->ws_cptab = cptab;
370 sched->ws_cpt = cpt;
371
372 spin_lock_init(&sched->ws_lock);
373 init_waitqueue_head(&sched->ws_waitq);
374 INIT_LIST_HEAD(&sched->ws_runq);
375 INIT_LIST_HEAD(&sched->ws_rerunq);
376 INIT_LIST_HEAD(&sched->ws_list);
377
378 rc = 0;
379 while (nthrs > 0) {
380 char name[16];
381 struct task_struct *task;
382
383 spin_lock(&cfs_wi_data.wi_glock);
384 while (sched->ws_starting > 0) {
385 spin_unlock(&cfs_wi_data.wi_glock);
386 schedule();
387 spin_lock(&cfs_wi_data.wi_glock);
388 }
389
390 sched->ws_starting++;
391 spin_unlock(&cfs_wi_data.wi_glock);
392
393 if (sched->ws_cptab != NULL && sched->ws_cpt >= 0) {
394 snprintf(name, sizeof(name), "%s_%02d_%02u",
395 sched->ws_name, sched->ws_cpt,
396 sched->ws_nthreads);
397 } else {
398 snprintf(name, sizeof(name), "%s_%02u",
399 sched->ws_name, sched->ws_nthreads);
400 }
401
402 task = kthread_run(cfs_wi_scheduler, sched, "%s", name);
403 if (!IS_ERR(task)) {
404 nthrs--;
405 continue;
406 }
407 rc = PTR_ERR(task);
408
409 CERROR("Failed to create thread for WI scheduler %s: %d\n",
410 name, rc);
411
412 spin_lock(&cfs_wi_data.wi_glock);
413
414 /* make up for cfs_wi_sched_destroy */
415 list_add(&sched->ws_list, &cfs_wi_data.wi_scheds);
416 sched->ws_starting--;
417
418 spin_unlock(&cfs_wi_data.wi_glock);
419
420 cfs_wi_sched_destroy(sched);
421 return rc;
422 }
423 spin_lock(&cfs_wi_data.wi_glock);
424 list_add(&sched->ws_list, &cfs_wi_data.wi_scheds);
425 spin_unlock(&cfs_wi_data.wi_glock);
426
427 *sched_pp = sched;
428 return 0;
429 }
430 EXPORT_SYMBOL(cfs_wi_sched_create);
431
432 int
cfs_wi_startup(void)433 cfs_wi_startup(void)
434 {
435 memset(&cfs_wi_data, 0, sizeof(cfs_wi_data));
436
437 spin_lock_init(&cfs_wi_data.wi_glock);
438 INIT_LIST_HEAD(&cfs_wi_data.wi_scheds);
439 cfs_wi_data.wi_init = 1;
440
441 return 0;
442 }
443
444 void
cfs_wi_shutdown(void)445 cfs_wi_shutdown (void)
446 {
447 struct cfs_wi_sched *sched;
448
449 spin_lock(&cfs_wi_data.wi_glock);
450 cfs_wi_data.wi_stopping = 1;
451 spin_unlock(&cfs_wi_data.wi_glock);
452
453 /* nobody should contend on this list */
454 list_for_each_entry(sched, &cfs_wi_data.wi_scheds, ws_list) {
455 sched->ws_stopping = 1;
456 wake_up_all(&sched->ws_waitq);
457 }
458
459 list_for_each_entry(sched, &cfs_wi_data.wi_scheds, ws_list) {
460 spin_lock(&cfs_wi_data.wi_glock);
461
462 while (sched->ws_nthreads != 0) {
463 spin_unlock(&cfs_wi_data.wi_glock);
464 set_current_state(TASK_UNINTERRUPTIBLE);
465 schedule_timeout(cfs_time_seconds(1) / 20);
466 spin_lock(&cfs_wi_data.wi_glock);
467 }
468 spin_unlock(&cfs_wi_data.wi_glock);
469 }
470 while (!list_empty(&cfs_wi_data.wi_scheds)) {
471 sched = list_entry(cfs_wi_data.wi_scheds.next,
472 struct cfs_wi_sched, ws_list);
473 list_del(&sched->ws_list);
474 LIBCFS_FREE(sched, sizeof(*sched));
475 }
476
477 cfs_wi_data.wi_stopping = 0;
478 cfs_wi_data.wi_init = 0;
479 }
480