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1/*
2 * Read-Copy Update module-based performance-test facility
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, you can access it online at
16 * http://www.gnu.org/licenses/gpl-2.0.html.
17 *
18 * Copyright (C) IBM Corporation, 2015
19 *
20 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
21 */
22#include <linux/types.h>
23#include <linux/kernel.h>
24#include <linux/init.h>
25#include <linux/module.h>
26#include <linux/kthread.h>
27#include <linux/err.h>
28#include <linux/spinlock.h>
29#include <linux/smp.h>
30#include <linux/rcupdate.h>
31#include <linux/interrupt.h>
32#include <linux/sched.h>
33#include <uapi/linux/sched/types.h>
34#include <linux/atomic.h>
35#include <linux/bitops.h>
36#include <linux/completion.h>
37#include <linux/moduleparam.h>
38#include <linux/percpu.h>
39#include <linux/notifier.h>
40#include <linux/reboot.h>
41#include <linux/freezer.h>
42#include <linux/cpu.h>
43#include <linux/delay.h>
44#include <linux/stat.h>
45#include <linux/srcu.h>
46#include <linux/slab.h>
47#include <asm/byteorder.h>
48#include <linux/torture.h>
49#include <linux/vmalloc.h>
50
51#include "rcu.h"
52
53MODULE_LICENSE("GPL");
54MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
55
56#define PERF_FLAG "-perf:"
57#define PERFOUT_STRING(s) \
58 pr_alert("%s" PERF_FLAG " %s\n", perf_type, s)
59#define VERBOSE_PERFOUT_STRING(s) \
60 do { if (verbose) pr_alert("%s" PERF_FLAG " %s\n", perf_type, s); } while (0)
61#define VERBOSE_PERFOUT_ERRSTRING(s) \
62 do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0)
63
64/*
65 * The intended use cases for the nreaders and nwriters module parameters
66 * are as follows:
67 *
68 * 1. Specify only the nr_cpus kernel boot parameter. This will
69 * set both nreaders and nwriters to the value specified by
70 * nr_cpus for a mixed reader/writer test.
71 *
72 * 2. Specify the nr_cpus kernel boot parameter, but set
73 * rcuperf.nreaders to zero. This will set nwriters to the
74 * value specified by nr_cpus for an update-only test.
75 *
76 * 3. Specify the nr_cpus kernel boot parameter, but set
77 * rcuperf.nwriters to zero. This will set nreaders to the
78 * value specified by nr_cpus for a read-only test.
79 *
80 * Various other use cases may of course be specified.
81 */
82
83torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
84torture_param(int, gp_async_max, 1000, "Max # outstanding waits per reader");
85torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
86torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
87torture_param(int, nreaders, -1, "Number of RCU reader threads");
88torture_param(int, nwriters, -1, "Number of RCU updater threads");
89torture_param(bool, shutdown, !IS_ENABLED(MODULE),
90 "Shutdown at end of performance tests.");
91torture_param(bool, verbose, true, "Enable verbose debugging printk()s");
92torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
93
94static char *perf_type = "rcu";
95module_param(perf_type, charp, 0444);
96MODULE_PARM_DESC(perf_type, "Type of RCU to performance-test (rcu, rcu_bh, ...)");
97
98static int nrealreaders;
99static int nrealwriters;
100static struct task_struct **writer_tasks;
101static struct task_struct **reader_tasks;
102static struct task_struct *shutdown_task;
103
104static u64 **writer_durations;
105static int *writer_n_durations;
106static atomic_t n_rcu_perf_reader_started;
107static atomic_t n_rcu_perf_writer_started;
108static atomic_t n_rcu_perf_writer_finished;
109static wait_queue_head_t shutdown_wq;
110static u64 t_rcu_perf_writer_started;
111static u64 t_rcu_perf_writer_finished;
112static unsigned long b_rcu_perf_writer_started;
113static unsigned long b_rcu_perf_writer_finished;
114static DEFINE_PER_CPU(atomic_t, n_async_inflight);
115
116static int rcu_perf_writer_state;
117#define RTWS_INIT 0
118#define RTWS_ASYNC 1
119#define RTWS_BARRIER 2
120#define RTWS_EXP_SYNC 3
121#define RTWS_SYNC 4
122#define RTWS_IDLE 5
123#define RTWS_STOPPING 6
124
125#define MAX_MEAS 10000
126#define MIN_MEAS 100
127
128/*
129 * Operations vector for selecting different types of tests.
130 */
131
132struct rcu_perf_ops {
133 int ptype;
134 void (*init)(void);
135 void (*cleanup)(void);
136 int (*readlock)(void);
137 void (*readunlock)(int idx);
138 unsigned long (*started)(void);
139 unsigned long (*completed)(void);
140 unsigned long (*exp_completed)(void);
141 void (*async)(struct rcu_head *head, rcu_callback_t func);
142 void (*gp_barrier)(void);
143 void (*sync)(void);
144 void (*exp_sync)(void);
145 const char *name;
146};
147
148static struct rcu_perf_ops *cur_ops;
149
150/*
151 * Definitions for rcu perf testing.
152 */
153
154static int rcu_perf_read_lock(void) __acquires(RCU)
155{
156 rcu_read_lock();
157 return 0;
158}
159
160static void rcu_perf_read_unlock(int idx) __releases(RCU)
161{
162 rcu_read_unlock();
163}
164
165static unsigned long __maybe_unused rcu_no_completed(void)
166{
167 return 0;
168}
169
170static void rcu_sync_perf_init(void)
171{
172}
173
174static struct rcu_perf_ops rcu_ops = {
175 .ptype = RCU_FLAVOR,
176 .init = rcu_sync_perf_init,
177 .readlock = rcu_perf_read_lock,
178 .readunlock = rcu_perf_read_unlock,
179 .started = rcu_batches_started,
180 .completed = rcu_batches_completed,
181 .exp_completed = rcu_exp_batches_completed,
182 .async = call_rcu,
183 .gp_barrier = rcu_barrier,
184 .sync = synchronize_rcu,
185 .exp_sync = synchronize_rcu_expedited,
186 .name = "rcu"
187};
188
189/*
190 * Definitions for rcu_bh perf testing.
191 */
192
193static int rcu_bh_perf_read_lock(void) __acquires(RCU_BH)
194{
195 rcu_read_lock_bh();
196 return 0;
197}
198
199static void rcu_bh_perf_read_unlock(int idx) __releases(RCU_BH)
200{
201 rcu_read_unlock_bh();
202}
203
204static struct rcu_perf_ops rcu_bh_ops = {
205 .ptype = RCU_BH_FLAVOR,
206 .init = rcu_sync_perf_init,
207 .readlock = rcu_bh_perf_read_lock,
208 .readunlock = rcu_bh_perf_read_unlock,
209 .started = rcu_batches_started_bh,
210 .completed = rcu_batches_completed_bh,
211 .exp_completed = rcu_exp_batches_completed_sched,
212 .async = call_rcu_bh,
213 .gp_barrier = rcu_barrier_bh,
214 .sync = synchronize_rcu_bh,
215 .exp_sync = synchronize_rcu_bh_expedited,
216 .name = "rcu_bh"
217};
218
219/*
220 * Definitions for srcu perf testing.
221 */
222
223DEFINE_STATIC_SRCU(srcu_ctl_perf);
224static struct srcu_struct *srcu_ctlp = &srcu_ctl_perf;
225
226static int srcu_perf_read_lock(void) __acquires(srcu_ctlp)
227{
228 return srcu_read_lock(srcu_ctlp);
229}
230
231static void srcu_perf_read_unlock(int idx) __releases(srcu_ctlp)
232{
233 srcu_read_unlock(srcu_ctlp, idx);
234}
235
236static unsigned long srcu_perf_completed(void)
237{
238 return srcu_batches_completed(srcu_ctlp);
239}
240
241static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
242{
243 call_srcu(srcu_ctlp, head, func);
244}
245
246static void srcu_rcu_barrier(void)
247{
248 srcu_barrier(srcu_ctlp);
249}
250
251static void srcu_perf_synchronize(void)
252{
253 synchronize_srcu(srcu_ctlp);
254}
255
256static void srcu_perf_synchronize_expedited(void)
257{
258 synchronize_srcu_expedited(srcu_ctlp);
259}
260
261static struct rcu_perf_ops srcu_ops = {
262 .ptype = SRCU_FLAVOR,
263 .init = rcu_sync_perf_init,
264 .readlock = srcu_perf_read_lock,
265 .readunlock = srcu_perf_read_unlock,
266 .started = NULL,
267 .completed = srcu_perf_completed,
268 .exp_completed = srcu_perf_completed,
269 .async = srcu_call_rcu,
270 .gp_barrier = srcu_rcu_barrier,
271 .sync = srcu_perf_synchronize,
272 .exp_sync = srcu_perf_synchronize_expedited,
273 .name = "srcu"
274};
275
276static struct srcu_struct srcud;
277
278static void srcu_sync_perf_init(void)
279{
280 srcu_ctlp = &srcud;
281 init_srcu_struct(srcu_ctlp);
282}
283
284static void srcu_sync_perf_cleanup(void)
285{
286 cleanup_srcu_struct(srcu_ctlp);
287}
288
289static struct rcu_perf_ops srcud_ops = {
290 .ptype = SRCU_FLAVOR,
291 .init = srcu_sync_perf_init,
292 .cleanup = srcu_sync_perf_cleanup,
293 .readlock = srcu_perf_read_lock,
294 .readunlock = srcu_perf_read_unlock,
295 .started = NULL,
296 .completed = srcu_perf_completed,
297 .exp_completed = srcu_perf_completed,
298 .async = srcu_call_rcu,
299 .gp_barrier = srcu_rcu_barrier,
300 .sync = srcu_perf_synchronize,
301 .exp_sync = srcu_perf_synchronize_expedited,
302 .name = "srcud"
303};
304
305/*
306 * Definitions for sched perf testing.
307 */
308
309static int sched_perf_read_lock(void)
310{
311 preempt_disable();
312 return 0;
313}
314
315static void sched_perf_read_unlock(int idx)
316{
317 preempt_enable();
318}
319
320static struct rcu_perf_ops sched_ops = {
321 .ptype = RCU_SCHED_FLAVOR,
322 .init = rcu_sync_perf_init,
323 .readlock = sched_perf_read_lock,
324 .readunlock = sched_perf_read_unlock,
325 .started = rcu_batches_started_sched,
326 .completed = rcu_batches_completed_sched,
327 .exp_completed = rcu_exp_batches_completed_sched,
328 .async = call_rcu_sched,
329 .gp_barrier = rcu_barrier_sched,
330 .sync = synchronize_sched,
331 .exp_sync = synchronize_sched_expedited,
332 .name = "sched"
333};
334
335/*
336 * Definitions for RCU-tasks perf testing.
337 */
338
339static int tasks_perf_read_lock(void)
340{
341 return 0;
342}
343
344static void tasks_perf_read_unlock(int idx)
345{
346}
347
348static struct rcu_perf_ops tasks_ops = {
349 .ptype = RCU_TASKS_FLAVOR,
350 .init = rcu_sync_perf_init,
351 .readlock = tasks_perf_read_lock,
352 .readunlock = tasks_perf_read_unlock,
353 .started = rcu_no_completed,
354 .completed = rcu_no_completed,
355 .async = call_rcu_tasks,
356 .gp_barrier = rcu_barrier_tasks,
357 .sync = synchronize_rcu_tasks,
358 .exp_sync = synchronize_rcu_tasks,
359 .name = "tasks"
360};
361
362static bool __maybe_unused torturing_tasks(void)
363{
364 return cur_ops == &tasks_ops;
365}
366
367/*
368 * If performance tests complete, wait for shutdown to commence.
369 */
370static void rcu_perf_wait_shutdown(void)
371{
372 cond_resched_rcu_qs();
373 if (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters)
374 return;
375 while (!torture_must_stop())
376 schedule_timeout_uninterruptible(1);
377}
378
379/*
380 * RCU perf reader kthread. Repeatedly does empty RCU read-side
381 * critical section, minimizing update-side interference.
382 */
383static int
384rcu_perf_reader(void *arg)
385{
386 unsigned long flags;
387 int idx;
388 long me = (long)arg;
389
390 VERBOSE_PERFOUT_STRING("rcu_perf_reader task started");
391 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
392 set_user_nice(current, MAX_NICE);
393 atomic_inc(&n_rcu_perf_reader_started);
394
395 do {
396 local_irq_save(flags);
397 idx = cur_ops->readlock();
398 cur_ops->readunlock(idx);
399 local_irq_restore(flags);
400 rcu_perf_wait_shutdown();
401 } while (!torture_must_stop());
402 torture_kthread_stopping("rcu_perf_reader");
403 return 0;
404}
405
406/*
407 * Callback function for asynchronous grace periods from rcu_perf_writer().
408 */
409static void rcu_perf_async_cb(struct rcu_head *rhp)
410{
411 atomic_dec(this_cpu_ptr(&n_async_inflight));
412 kfree(rhp);
413}
414
415/*
416 * RCU perf writer kthread. Repeatedly does a grace period.
417 */
418static int
419rcu_perf_writer(void *arg)
420{
421 int i = 0;
422 int i_max;
423 long me = (long)arg;
424 struct rcu_head *rhp = NULL;
425 struct sched_param sp;
426 bool started = false, done = false, alldone = false;
427 u64 t;
428 u64 *wdp;
429 u64 *wdpp = writer_durations[me];
430
431 VERBOSE_PERFOUT_STRING("rcu_perf_writer task started");
432 WARN_ON(!wdpp);
433 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
434 sp.sched_priority = 1;
435 sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
436
437 if (holdoff)
438 schedule_timeout_uninterruptible(holdoff * HZ);
439
440 t = ktime_get_mono_fast_ns();
441 if (atomic_inc_return(&n_rcu_perf_writer_started) >= nrealwriters) {
442 t_rcu_perf_writer_started = t;
443 if (gp_exp) {
444 b_rcu_perf_writer_started =
445 cur_ops->exp_completed() / 2;
446 } else {
447 b_rcu_perf_writer_started =
448 cur_ops->completed();
449 }
450 }
451
452 do {
453 if (writer_holdoff)
454 udelay(writer_holdoff);
455 wdp = &wdpp[i];
456 *wdp = ktime_get_mono_fast_ns();
457 if (gp_async) {
458retry:
459 if (!rhp)
460 rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
461 if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
462 rcu_perf_writer_state = RTWS_ASYNC;
463 atomic_inc(this_cpu_ptr(&n_async_inflight));
464 cur_ops->async(rhp, rcu_perf_async_cb);
465 rhp = NULL;
466 } else if (!kthread_should_stop()) {
467 rcu_perf_writer_state = RTWS_BARRIER;
468 cur_ops->gp_barrier();
469 goto retry;
470 } else {
471 kfree(rhp); /* Because we are stopping. */
472 }
473 } else if (gp_exp) {
474 rcu_perf_writer_state = RTWS_EXP_SYNC;
475 cur_ops->exp_sync();
476 } else {
477 rcu_perf_writer_state = RTWS_SYNC;
478 cur_ops->sync();
479 }
480 rcu_perf_writer_state = RTWS_IDLE;
481 t = ktime_get_mono_fast_ns();
482 *wdp = t - *wdp;
483 i_max = i;
484 if (!started &&
485 atomic_read(&n_rcu_perf_writer_started) >= nrealwriters)
486 started = true;
487 if (!done && i >= MIN_MEAS) {
488 done = true;
489 sp.sched_priority = 0;
490 sched_setscheduler_nocheck(current,
491 SCHED_NORMAL, &sp);
492 pr_alert("%s%s rcu_perf_writer %ld has %d measurements\n",
493 perf_type, PERF_FLAG, me, MIN_MEAS);
494 if (atomic_inc_return(&n_rcu_perf_writer_finished) >=
495 nrealwriters) {
496 schedule_timeout_interruptible(10);
497 rcu_ftrace_dump(DUMP_ALL);
498 PERFOUT_STRING("Test complete");
499 t_rcu_perf_writer_finished = t;
500 if (gp_exp) {
501 b_rcu_perf_writer_finished =
502 cur_ops->exp_completed() / 2;
503 } else {
504 b_rcu_perf_writer_finished =
505 cur_ops->completed();
506 }
507 if (shutdown) {
508 smp_mb(); /* Assign before wake. */
509 wake_up(&shutdown_wq);
510 }
511 }
512 }
513 if (done && !alldone &&
514 atomic_read(&n_rcu_perf_writer_finished) >= nrealwriters)
515 alldone = true;
516 if (started && !alldone && i < MAX_MEAS - 1)
517 i++;
518 rcu_perf_wait_shutdown();
519 } while (!torture_must_stop());
520 if (gp_async) {
521 rcu_perf_writer_state = RTWS_BARRIER;
522 cur_ops->gp_barrier();
523 }
524 rcu_perf_writer_state = RTWS_STOPPING;
525 writer_n_durations[me] = i_max;
526 torture_kthread_stopping("rcu_perf_writer");
527 return 0;
528}
529
530static inline void
531rcu_perf_print_module_parms(struct rcu_perf_ops *cur_ops, const char *tag)
532{
533 pr_alert("%s" PERF_FLAG
534 "--- %s: nreaders=%d nwriters=%d verbose=%d shutdown=%d\n",
535 perf_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
536}
537
538static void
539rcu_perf_cleanup(void)
540{
541 int i;
542 int j;
543 int ngps = 0;
544 u64 *wdp;
545 u64 *wdpp;
546
547 /*
548 * Would like warning at start, but everything is expedited
549 * during the mid-boot phase, so have to wait till the end.
550 */
551 if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
552 VERBOSE_PERFOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
553 if (rcu_gp_is_normal() && gp_exp)
554 VERBOSE_PERFOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
555 if (gp_exp && gp_async)
556 VERBOSE_PERFOUT_ERRSTRING("No expedited async GPs, so went with async!");
557
558 if (torture_cleanup_begin())
559 return;
560
561 if (reader_tasks) {
562 for (i = 0; i < nrealreaders; i++)
563 torture_stop_kthread(rcu_perf_reader,
564 reader_tasks[i]);
565 kfree(reader_tasks);
566 }
567
568 if (writer_tasks) {
569 for (i = 0; i < nrealwriters; i++) {
570 torture_stop_kthread(rcu_perf_writer,
571 writer_tasks[i]);
572 if (!writer_n_durations)
573 continue;
574 j = writer_n_durations[i];
575 pr_alert("%s%s writer %d gps: %d\n",
576 perf_type, PERF_FLAG, i, j);
577 ngps += j;
578 }
579 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
580 perf_type, PERF_FLAG,
581 t_rcu_perf_writer_started, t_rcu_perf_writer_finished,
582 t_rcu_perf_writer_finished -
583 t_rcu_perf_writer_started,
584 ngps,
585 b_rcu_perf_writer_finished -
586 b_rcu_perf_writer_started);
587 for (i = 0; i < nrealwriters; i++) {
588 if (!writer_durations)
589 break;
590 if (!writer_n_durations)
591 continue;
592 wdpp = writer_durations[i];
593 if (!wdpp)
594 continue;
595 for (j = 0; j <= writer_n_durations[i]; j++) {
596 wdp = &wdpp[j];
597 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
598 perf_type, PERF_FLAG,
599 i, j, *wdp);
600 if (j % 100 == 0)
601 schedule_timeout_uninterruptible(1);
602 }
603 kfree(writer_durations[i]);
604 }
605 kfree(writer_tasks);
606 kfree(writer_durations);
607 kfree(writer_n_durations);
608 }
609
610 /* Do flavor-specific cleanup operations. */
611 if (cur_ops->cleanup != NULL)
612 cur_ops->cleanup();
613
614 torture_cleanup_end();
615}
616
617/*
618 * Return the number if non-negative. If -1, the number of CPUs.
619 * If less than -1, that much less than the number of CPUs, but
620 * at least one.
621 */
622static int compute_real(int n)
623{
624 int nr;
625
626 if (n >= 0) {
627 nr = n;
628 } else {
629 nr = num_online_cpus() + 1 + n;
630 if (nr <= 0)
631 nr = 1;
632 }
633 return nr;
634}
635
636/*
637 * RCU perf shutdown kthread. Just waits to be awakened, then shuts
638 * down system.
639 */
640static int
641rcu_perf_shutdown(void *arg)
642{
643 do {
644 wait_event(shutdown_wq,
645 atomic_read(&n_rcu_perf_writer_finished) >=
646 nrealwriters);
647 } while (atomic_read(&n_rcu_perf_writer_finished) < nrealwriters);
648 smp_mb(); /* Wake before output. */
649 rcu_perf_cleanup();
650 kernel_power_off();
651 return -EINVAL;
652}
653
654static int __init
655rcu_perf_init(void)
656{
657 long i;
658 int firsterr = 0;
659 static struct rcu_perf_ops *perf_ops[] = {
660 &rcu_ops, &rcu_bh_ops, &srcu_ops, &srcud_ops, &sched_ops,
661 &tasks_ops,
662 };
663
664 if (!torture_init_begin(perf_type, verbose))
665 return -EBUSY;
666
667 /* Process args and tell the world that the perf'er is on the job. */
668 for (i = 0; i < ARRAY_SIZE(perf_ops); i++) {
669 cur_ops = perf_ops[i];
670 if (strcmp(perf_type, cur_ops->name) == 0)
671 break;
672 }
673 if (i == ARRAY_SIZE(perf_ops)) {
674 pr_alert("rcu-perf: invalid perf type: \"%s\"\n",
675 perf_type);
676 pr_alert("rcu-perf types:");
677 for (i = 0; i < ARRAY_SIZE(perf_ops); i++)
678 pr_alert(" %s", perf_ops[i]->name);
679 pr_alert("\n");
680 firsterr = -EINVAL;
681 goto unwind;
682 }
683 if (cur_ops->init)
684 cur_ops->init();
685
686 nrealwriters = compute_real(nwriters);
687 nrealreaders = compute_real(nreaders);
688 atomic_set(&n_rcu_perf_reader_started, 0);
689 atomic_set(&n_rcu_perf_writer_started, 0);
690 atomic_set(&n_rcu_perf_writer_finished, 0);
691 rcu_perf_print_module_parms(cur_ops, "Start of test");
692
693 /* Start up the kthreads. */
694
695 if (shutdown) {
696 init_waitqueue_head(&shutdown_wq);
697 firsterr = torture_create_kthread(rcu_perf_shutdown, NULL,
698 shutdown_task);
699 if (firsterr)
700 goto unwind;
701 schedule_timeout_uninterruptible(1);
702 }
703 reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
704 GFP_KERNEL);
705 if (reader_tasks == NULL) {
706 VERBOSE_PERFOUT_ERRSTRING("out of memory");
707 firsterr = -ENOMEM;
708 goto unwind;
709 }
710 for (i = 0; i < nrealreaders; i++) {
711 firsterr = torture_create_kthread(rcu_perf_reader, (void *)i,
712 reader_tasks[i]);
713 if (firsterr)
714 goto unwind;
715 }
716 while (atomic_read(&n_rcu_perf_reader_started) < nrealreaders)
717 schedule_timeout_uninterruptible(1);
718 writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
719 GFP_KERNEL);
720 writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
721 GFP_KERNEL);
722 writer_n_durations =
723 kcalloc(nrealwriters, sizeof(*writer_n_durations),
724 GFP_KERNEL);
725 if (!writer_tasks || !writer_durations || !writer_n_durations) {
726 VERBOSE_PERFOUT_ERRSTRING("out of memory");
727 firsterr = -ENOMEM;
728 goto unwind;
729 }
730 for (i = 0; i < nrealwriters; i++) {
731 writer_durations[i] =
732 kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
733 GFP_KERNEL);
734 if (!writer_durations[i]) {
735 firsterr = -ENOMEM;
736 goto unwind;
737 }
738 firsterr = torture_create_kthread(rcu_perf_writer, (void *)i,
739 writer_tasks[i]);
740 if (firsterr)
741 goto unwind;
742 }
743 torture_init_end();
744 return 0;
745
746unwind:
747 torture_init_end();
748 rcu_perf_cleanup();
749 return firsterr;
750}
751
752module_init(rcu_perf_init);
753module_exit(rcu_perf_cleanup);