xref: /openbmc/linux/kernel/rcu/rcuscale.c (revision 2d56271f)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Read-Copy Update module-based scalability-test facility
4  *
5  * Copyright (C) IBM Corporation, 2015
6  *
7  * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
8  */
9 
10 #define pr_fmt(fmt) fmt
11 
12 #include <linux/types.h>
13 #include <linux/kernel.h>
14 #include <linux/init.h>
15 #include <linux/mm.h>
16 #include <linux/module.h>
17 #include <linux/kthread.h>
18 #include <linux/err.h>
19 #include <linux/spinlock.h>
20 #include <linux/smp.h>
21 #include <linux/rcupdate.h>
22 #include <linux/interrupt.h>
23 #include <linux/sched.h>
24 #include <uapi/linux/sched/types.h>
25 #include <linux/atomic.h>
26 #include <linux/bitops.h>
27 #include <linux/completion.h>
28 #include <linux/moduleparam.h>
29 #include <linux/percpu.h>
30 #include <linux/notifier.h>
31 #include <linux/reboot.h>
32 #include <linux/freezer.h>
33 #include <linux/cpu.h>
34 #include <linux/delay.h>
35 #include <linux/stat.h>
36 #include <linux/srcu.h>
37 #include <linux/slab.h>
38 #include <asm/byteorder.h>
39 #include <linux/torture.h>
40 #include <linux/vmalloc.h>
41 #include <linux/rcupdate_trace.h>
42 
43 #include "rcu.h"
44 
45 MODULE_LICENSE("GPL");
46 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
47 
48 #define SCALE_FLAG "-scale:"
49 #define SCALEOUT_STRING(s) \
50 	pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s)
51 #define VERBOSE_SCALEOUT_STRING(s) \
52 	do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0)
53 #define SCALEOUT_ERRSTRING(s) \
54 	pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s)
55 
56 /*
57  * The intended use cases for the nreaders and nwriters module parameters
58  * are as follows:
59  *
60  * 1.	Specify only the nr_cpus kernel boot parameter.  This will
61  *	set both nreaders and nwriters to the value specified by
62  *	nr_cpus for a mixed reader/writer test.
63  *
64  * 2.	Specify the nr_cpus kernel boot parameter, but set
65  *	rcuscale.nreaders to zero.  This will set nwriters to the
66  *	value specified by nr_cpus for an update-only test.
67  *
68  * 3.	Specify the nr_cpus kernel boot parameter, but set
69  *	rcuscale.nwriters to zero.  This will set nreaders to the
70  *	value specified by nr_cpus for a read-only test.
71  *
72  * Various other use cases may of course be specified.
73  *
74  * Note that this test's readers are intended only as a test load for
75  * the writers.  The reader scalability statistics will be overly
76  * pessimistic due to the per-critical-section interrupt disabling,
77  * test-end checks, and the pair of calls through pointers.
78  */
79 
80 #ifdef MODULE
81 # define RCUSCALE_SHUTDOWN 0
82 #else
83 # define RCUSCALE_SHUTDOWN 1
84 #endif
85 
86 torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
87 torture_param(int, gp_async_max, 1000, "Max # outstanding waits per writer");
88 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
89 torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
90 torture_param(int, minruntime, 0, "Minimum run time (s)");
91 torture_param(int, nreaders, -1, "Number of RCU reader threads");
92 torture_param(int, nwriters, -1, "Number of RCU updater threads");
93 torture_param(bool, shutdown, RCUSCALE_SHUTDOWN,
94 	      "Shutdown at end of scalability tests.");
95 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
96 torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
97 torture_param(int, writer_holdoff_jiffies, 0, "Holdoff (jiffies) between GPs, zero to disable");
98 torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?");
99 torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
100 torture_param(int, kfree_by_call_rcu, 0, "Use call_rcu() to emulate kfree_rcu()?");
101 
102 static char *scale_type = "rcu";
103 module_param(scale_type, charp, 0444);
104 MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)");
105 
106 static int nrealreaders;
107 static int nrealwriters;
108 static struct task_struct **writer_tasks;
109 static struct task_struct **reader_tasks;
110 static struct task_struct *shutdown_task;
111 
112 static u64 **writer_durations;
113 static int *writer_n_durations;
114 static atomic_t n_rcu_scale_reader_started;
115 static atomic_t n_rcu_scale_writer_started;
116 static atomic_t n_rcu_scale_writer_finished;
117 static wait_queue_head_t shutdown_wq;
118 static u64 t_rcu_scale_writer_started;
119 static u64 t_rcu_scale_writer_finished;
120 static unsigned long b_rcu_gp_test_started;
121 static unsigned long b_rcu_gp_test_finished;
122 static DEFINE_PER_CPU(atomic_t, n_async_inflight);
123 
124 #define MAX_MEAS 10000
125 #define MIN_MEAS 100
126 
127 /*
128  * Operations vector for selecting different types of tests.
129  */
130 
131 struct rcu_scale_ops {
132 	int ptype;
133 	void (*init)(void);
134 	void (*cleanup)(void);
135 	int (*readlock)(void);
136 	void (*readunlock)(int idx);
137 	unsigned long (*get_gp_seq)(void);
138 	unsigned long (*gp_diff)(unsigned long new, unsigned long old);
139 	unsigned long (*exp_completed)(void);
140 	void (*async)(struct rcu_head *head, rcu_callback_t func);
141 	void (*gp_barrier)(void);
142 	void (*sync)(void);
143 	void (*exp_sync)(void);
144 	struct task_struct *(*rso_gp_kthread)(void);
145 	const char *name;
146 };
147 
148 static struct rcu_scale_ops *cur_ops;
149 
150 /*
151  * Definitions for rcu scalability testing.
152  */
153 
rcu_scale_read_lock(void)154 static int rcu_scale_read_lock(void) __acquires(RCU)
155 {
156 	rcu_read_lock();
157 	return 0;
158 }
159 
rcu_scale_read_unlock(int idx)160 static void rcu_scale_read_unlock(int idx) __releases(RCU)
161 {
162 	rcu_read_unlock();
163 }
164 
rcu_no_completed(void)165 static unsigned long __maybe_unused rcu_no_completed(void)
166 {
167 	return 0;
168 }
169 
rcu_sync_scale_init(void)170 static void rcu_sync_scale_init(void)
171 {
172 }
173 
174 static struct rcu_scale_ops rcu_ops = {
175 	.ptype		= RCU_FLAVOR,
176 	.init		= rcu_sync_scale_init,
177 	.readlock	= rcu_scale_read_lock,
178 	.readunlock	= rcu_scale_read_unlock,
179 	.get_gp_seq	= rcu_get_gp_seq,
180 	.gp_diff	= rcu_seq_diff,
181 	.exp_completed	= rcu_exp_batches_completed,
182 	.async		= call_rcu_hurry,
183 	.gp_barrier	= rcu_barrier,
184 	.sync		= synchronize_rcu,
185 	.exp_sync	= synchronize_rcu_expedited,
186 	.name		= "rcu"
187 };
188 
189 /*
190  * Definitions for srcu scalability testing.
191  */
192 
193 DEFINE_STATIC_SRCU(srcu_ctl_scale);
194 static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale;
195 
srcu_scale_read_lock(void)196 static int srcu_scale_read_lock(void) __acquires(srcu_ctlp)
197 {
198 	return srcu_read_lock(srcu_ctlp);
199 }
200 
srcu_scale_read_unlock(int idx)201 static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp)
202 {
203 	srcu_read_unlock(srcu_ctlp, idx);
204 }
205 
srcu_scale_completed(void)206 static unsigned long srcu_scale_completed(void)
207 {
208 	return srcu_batches_completed(srcu_ctlp);
209 }
210 
srcu_call_rcu(struct rcu_head * head,rcu_callback_t func)211 static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
212 {
213 	call_srcu(srcu_ctlp, head, func);
214 }
215 
srcu_rcu_barrier(void)216 static void srcu_rcu_barrier(void)
217 {
218 	srcu_barrier(srcu_ctlp);
219 }
220 
srcu_scale_synchronize(void)221 static void srcu_scale_synchronize(void)
222 {
223 	synchronize_srcu(srcu_ctlp);
224 }
225 
srcu_scale_synchronize_expedited(void)226 static void srcu_scale_synchronize_expedited(void)
227 {
228 	synchronize_srcu_expedited(srcu_ctlp);
229 }
230 
231 static struct rcu_scale_ops srcu_ops = {
232 	.ptype		= SRCU_FLAVOR,
233 	.init		= rcu_sync_scale_init,
234 	.readlock	= srcu_scale_read_lock,
235 	.readunlock	= srcu_scale_read_unlock,
236 	.get_gp_seq	= srcu_scale_completed,
237 	.gp_diff	= rcu_seq_diff,
238 	.exp_completed	= srcu_scale_completed,
239 	.async		= srcu_call_rcu,
240 	.gp_barrier	= srcu_rcu_barrier,
241 	.sync		= srcu_scale_synchronize,
242 	.exp_sync	= srcu_scale_synchronize_expedited,
243 	.name		= "srcu"
244 };
245 
246 static struct srcu_struct srcud;
247 
srcu_sync_scale_init(void)248 static void srcu_sync_scale_init(void)
249 {
250 	srcu_ctlp = &srcud;
251 	init_srcu_struct(srcu_ctlp);
252 }
253 
srcu_sync_scale_cleanup(void)254 static void srcu_sync_scale_cleanup(void)
255 {
256 	cleanup_srcu_struct(srcu_ctlp);
257 }
258 
259 static struct rcu_scale_ops srcud_ops = {
260 	.ptype		= SRCU_FLAVOR,
261 	.init		= srcu_sync_scale_init,
262 	.cleanup	= srcu_sync_scale_cleanup,
263 	.readlock	= srcu_scale_read_lock,
264 	.readunlock	= srcu_scale_read_unlock,
265 	.get_gp_seq	= srcu_scale_completed,
266 	.gp_diff	= rcu_seq_diff,
267 	.exp_completed	= srcu_scale_completed,
268 	.async		= srcu_call_rcu,
269 	.gp_barrier	= srcu_rcu_barrier,
270 	.sync		= srcu_scale_synchronize,
271 	.exp_sync	= srcu_scale_synchronize_expedited,
272 	.name		= "srcud"
273 };
274 
275 #ifdef CONFIG_TASKS_RCU
276 
277 /*
278  * Definitions for RCU-tasks scalability testing.
279  */
280 
tasks_scale_read_lock(void)281 static int tasks_scale_read_lock(void)
282 {
283 	return 0;
284 }
285 
tasks_scale_read_unlock(int idx)286 static void tasks_scale_read_unlock(int idx)
287 {
288 }
289 
290 static struct rcu_scale_ops tasks_ops = {
291 	.ptype		= RCU_TASKS_FLAVOR,
292 	.init		= rcu_sync_scale_init,
293 	.readlock	= tasks_scale_read_lock,
294 	.readunlock	= tasks_scale_read_unlock,
295 	.get_gp_seq	= rcu_no_completed,
296 	.gp_diff	= rcu_seq_diff,
297 	.async		= call_rcu_tasks,
298 	.gp_barrier	= rcu_barrier_tasks,
299 	.sync		= synchronize_rcu_tasks,
300 	.exp_sync	= synchronize_rcu_tasks,
301 	.rso_gp_kthread	= get_rcu_tasks_gp_kthread,
302 	.name		= "tasks"
303 };
304 
305 #define TASKS_OPS &tasks_ops,
306 
307 #else // #ifdef CONFIG_TASKS_RCU
308 
309 #define TASKS_OPS
310 
311 #endif // #else // #ifdef CONFIG_TASKS_RCU
312 
313 #ifdef CONFIG_TASKS_RUDE_RCU
314 
315 /*
316  * Definitions for RCU-tasks-rude scalability testing.
317  */
318 
tasks_rude_scale_read_lock(void)319 static int tasks_rude_scale_read_lock(void)
320 {
321 	return 0;
322 }
323 
tasks_rude_scale_read_unlock(int idx)324 static void tasks_rude_scale_read_unlock(int idx)
325 {
326 }
327 
328 static struct rcu_scale_ops tasks_rude_ops = {
329 	.ptype		= RCU_TASKS_RUDE_FLAVOR,
330 	.init		= rcu_sync_scale_init,
331 	.readlock	= tasks_rude_scale_read_lock,
332 	.readunlock	= tasks_rude_scale_read_unlock,
333 	.get_gp_seq	= rcu_no_completed,
334 	.gp_diff	= rcu_seq_diff,
335 	.async		= call_rcu_tasks_rude,
336 	.gp_barrier	= rcu_barrier_tasks_rude,
337 	.sync		= synchronize_rcu_tasks_rude,
338 	.exp_sync	= synchronize_rcu_tasks_rude,
339 	.rso_gp_kthread	= get_rcu_tasks_rude_gp_kthread,
340 	.name		= "tasks-rude"
341 };
342 
343 #define TASKS_RUDE_OPS &tasks_rude_ops,
344 
345 #else // #ifdef CONFIG_TASKS_RUDE_RCU
346 
347 #define TASKS_RUDE_OPS
348 
349 #endif // #else // #ifdef CONFIG_TASKS_RUDE_RCU
350 
351 #ifdef CONFIG_TASKS_TRACE_RCU
352 
353 /*
354  * Definitions for RCU-tasks-trace scalability testing.
355  */
356 
tasks_trace_scale_read_lock(void)357 static int tasks_trace_scale_read_lock(void)
358 {
359 	rcu_read_lock_trace();
360 	return 0;
361 }
362 
tasks_trace_scale_read_unlock(int idx)363 static void tasks_trace_scale_read_unlock(int idx)
364 {
365 	rcu_read_unlock_trace();
366 }
367 
368 static struct rcu_scale_ops tasks_tracing_ops = {
369 	.ptype		= RCU_TASKS_FLAVOR,
370 	.init		= rcu_sync_scale_init,
371 	.readlock	= tasks_trace_scale_read_lock,
372 	.readunlock	= tasks_trace_scale_read_unlock,
373 	.get_gp_seq	= rcu_no_completed,
374 	.gp_diff	= rcu_seq_diff,
375 	.async		= call_rcu_tasks_trace,
376 	.gp_barrier	= rcu_barrier_tasks_trace,
377 	.sync		= synchronize_rcu_tasks_trace,
378 	.exp_sync	= synchronize_rcu_tasks_trace,
379 	.rso_gp_kthread	= get_rcu_tasks_trace_gp_kthread,
380 	.name		= "tasks-tracing"
381 };
382 
383 #define TASKS_TRACING_OPS &tasks_tracing_ops,
384 
385 #else // #ifdef CONFIG_TASKS_TRACE_RCU
386 
387 #define TASKS_TRACING_OPS
388 
389 #endif // #else // #ifdef CONFIG_TASKS_TRACE_RCU
390 
rcuscale_seq_diff(unsigned long new,unsigned long old)391 static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
392 {
393 	if (!cur_ops->gp_diff)
394 		return new - old;
395 	return cur_ops->gp_diff(new, old);
396 }
397 
398 /*
399  * If scalability tests complete, wait for shutdown to commence.
400  */
rcu_scale_wait_shutdown(void)401 static void rcu_scale_wait_shutdown(void)
402 {
403 	cond_resched_tasks_rcu_qs();
404 	if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
405 		return;
406 	while (!torture_must_stop())
407 		schedule_timeout_uninterruptible(1);
408 }
409 
410 /*
411  * RCU scalability reader kthread.  Repeatedly does empty RCU read-side
412  * critical section, minimizing update-side interference.  However, the
413  * point of this test is not to evaluate reader scalability, but instead
414  * to serve as a test load for update-side scalability testing.
415  */
416 static int
rcu_scale_reader(void * arg)417 rcu_scale_reader(void *arg)
418 {
419 	unsigned long flags;
420 	int idx;
421 	long me = (long)arg;
422 
423 	VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
424 	set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
425 	set_user_nice(current, MAX_NICE);
426 	atomic_inc(&n_rcu_scale_reader_started);
427 
428 	do {
429 		local_irq_save(flags);
430 		idx = cur_ops->readlock();
431 		cur_ops->readunlock(idx);
432 		local_irq_restore(flags);
433 		rcu_scale_wait_shutdown();
434 	} while (!torture_must_stop());
435 	torture_kthread_stopping("rcu_scale_reader");
436 	return 0;
437 }
438 
439 /*
440  * Callback function for asynchronous grace periods from rcu_scale_writer().
441  */
rcu_scale_async_cb(struct rcu_head * rhp)442 static void rcu_scale_async_cb(struct rcu_head *rhp)
443 {
444 	atomic_dec(this_cpu_ptr(&n_async_inflight));
445 	kfree(rhp);
446 }
447 
448 /*
449  * RCU scale writer kthread.  Repeatedly does a grace period.
450  */
451 static int
rcu_scale_writer(void * arg)452 rcu_scale_writer(void *arg)
453 {
454 	int i = 0;
455 	int i_max;
456 	unsigned long jdone;
457 	long me = (long)arg;
458 	struct rcu_head *rhp = NULL;
459 	bool started = false, done = false, alldone = false;
460 	u64 t;
461 	DEFINE_TORTURE_RANDOM(tr);
462 	u64 *wdp;
463 	u64 *wdpp = writer_durations[me];
464 
465 	VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
466 	WARN_ON(!wdpp);
467 	set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
468 	current->flags |= PF_NO_SETAFFINITY;
469 	sched_set_fifo_low(current);
470 
471 	if (holdoff)
472 		schedule_timeout_idle(holdoff * HZ);
473 
474 	/*
475 	 * Wait until rcu_end_inkernel_boot() is called for normal GP tests
476 	 * so that RCU is not always expedited for normal GP tests.
477 	 * The system_state test is approximate, but works well in practice.
478 	 */
479 	while (!gp_exp && system_state != SYSTEM_RUNNING)
480 		schedule_timeout_uninterruptible(1);
481 
482 	t = ktime_get_mono_fast_ns();
483 	if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
484 		t_rcu_scale_writer_started = t;
485 		if (gp_exp) {
486 			b_rcu_gp_test_started =
487 				cur_ops->exp_completed() / 2;
488 		} else {
489 			b_rcu_gp_test_started = cur_ops->get_gp_seq();
490 		}
491 	}
492 
493 	jdone = jiffies + minruntime * HZ;
494 	do {
495 		if (writer_holdoff)
496 			udelay(writer_holdoff);
497 		if (writer_holdoff_jiffies)
498 			schedule_timeout_idle(torture_random(&tr) % writer_holdoff_jiffies + 1);
499 		wdp = &wdpp[i];
500 		*wdp = ktime_get_mono_fast_ns();
501 		if (gp_async && !WARN_ON_ONCE(!cur_ops->async)) {
502 retry:
503 			if (!rhp)
504 				rhp = kmalloc(sizeof(*rhp), GFP_KERNEL);
505 			if (rhp && atomic_read(this_cpu_ptr(&n_async_inflight)) < gp_async_max) {
506 				atomic_inc(this_cpu_ptr(&n_async_inflight));
507 				cur_ops->async(rhp, rcu_scale_async_cb);
508 				rhp = NULL;
509 			} else if (!kthread_should_stop()) {
510 				cur_ops->gp_barrier();
511 				goto retry;
512 			} else {
513 				kfree(rhp); /* Because we are stopping. */
514 			}
515 		} else if (gp_exp) {
516 			cur_ops->exp_sync();
517 		} else {
518 			cur_ops->sync();
519 		}
520 		t = ktime_get_mono_fast_ns();
521 		*wdp = t - *wdp;
522 		i_max = i;
523 		if (!started &&
524 		    atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
525 			started = true;
526 		if (!done && i >= MIN_MEAS && time_after(jiffies, jdone)) {
527 			done = true;
528 			sched_set_normal(current, 0);
529 			pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
530 				 scale_type, SCALE_FLAG, me, MIN_MEAS);
531 			if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
532 			    nrealwriters) {
533 				schedule_timeout_interruptible(10);
534 				rcu_ftrace_dump(DUMP_ALL);
535 				SCALEOUT_STRING("Test complete");
536 				t_rcu_scale_writer_finished = t;
537 				if (gp_exp) {
538 					b_rcu_gp_test_finished =
539 						cur_ops->exp_completed() / 2;
540 				} else {
541 					b_rcu_gp_test_finished =
542 						cur_ops->get_gp_seq();
543 				}
544 				if (shutdown) {
545 					smp_mb(); /* Assign before wake. */
546 					wake_up(&shutdown_wq);
547 				}
548 			}
549 		}
550 		if (done && !alldone &&
551 		    atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
552 			alldone = true;
553 		if (started && !alldone && i < MAX_MEAS - 1)
554 			i++;
555 		rcu_scale_wait_shutdown();
556 	} while (!torture_must_stop());
557 	if (gp_async && cur_ops->async) {
558 		cur_ops->gp_barrier();
559 	}
560 	writer_n_durations[me] = i_max + 1;
561 	torture_kthread_stopping("rcu_scale_writer");
562 	return 0;
563 }
564 
565 static void
rcu_scale_print_module_parms(struct rcu_scale_ops * cur_ops,const char * tag)566 rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
567 {
568 	pr_alert("%s" SCALE_FLAG
569 		 "--- %s: gp_async=%d gp_async_max=%d gp_exp=%d holdoff=%d minruntime=%d nreaders=%d nwriters=%d writer_holdoff=%d writer_holdoff_jiffies=%d verbose=%d shutdown=%d\n",
570 		 scale_type, tag, gp_async, gp_async_max, gp_exp, holdoff, minruntime, nrealreaders, nrealwriters, writer_holdoff, writer_holdoff_jiffies, verbose, shutdown);
571 }
572 
573 /*
574  * Return the number if non-negative.  If -1, the number of CPUs.
575  * If less than -1, that much less than the number of CPUs, but
576  * at least one.
577  */
compute_real(int n)578 static int compute_real(int n)
579 {
580 	int nr;
581 
582 	if (n >= 0) {
583 		nr = n;
584 	} else {
585 		nr = num_online_cpus() + 1 + n;
586 		if (nr <= 0)
587 			nr = 1;
588 	}
589 	return nr;
590 }
591 
592 /*
593  * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
594  * of iterations and measure total time and number of GP for all iterations to complete.
595  */
596 
597 torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
598 torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
599 torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
600 torture_param(bool, kfree_rcu_test_double, false, "Do we run a kfree_rcu() double-argument scale test?");
601 torture_param(bool, kfree_rcu_test_single, false, "Do we run a kfree_rcu() single-argument scale test?");
602 
603 static struct task_struct **kfree_reader_tasks;
604 static int kfree_nrealthreads;
605 static atomic_t n_kfree_scale_thread_started;
606 static atomic_t n_kfree_scale_thread_ended;
607 static struct task_struct *kthread_tp;
608 static u64 kthread_stime;
609 
610 struct kfree_obj {
611 	char kfree_obj[8];
612 	struct rcu_head rh;
613 };
614 
615 /* Used if doing RCU-kfree'ing via call_rcu(). */
kfree_call_rcu(struct rcu_head * rh)616 static void kfree_call_rcu(struct rcu_head *rh)
617 {
618 	struct kfree_obj *obj = container_of(rh, struct kfree_obj, rh);
619 
620 	kfree(obj);
621 }
622 
623 static int
kfree_scale_thread(void * arg)624 kfree_scale_thread(void *arg)
625 {
626 	int i, loop = 0;
627 	long me = (long)arg;
628 	struct kfree_obj *alloc_ptr;
629 	u64 start_time, end_time;
630 	long long mem_begin, mem_during = 0;
631 	bool kfree_rcu_test_both;
632 	DEFINE_TORTURE_RANDOM(tr);
633 
634 	VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
635 	set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
636 	set_user_nice(current, MAX_NICE);
637 	kfree_rcu_test_both = (kfree_rcu_test_single == kfree_rcu_test_double);
638 
639 	start_time = ktime_get_mono_fast_ns();
640 
641 	if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) {
642 		if (gp_exp)
643 			b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
644 		else
645 			b_rcu_gp_test_started = cur_ops->get_gp_seq();
646 	}
647 
648 	do {
649 		if (!mem_during) {
650 			mem_during = mem_begin = si_mem_available();
651 		} else if (loop % (kfree_loops / 4) == 0) {
652 			mem_during = (mem_during + si_mem_available()) / 2;
653 		}
654 
655 		for (i = 0; i < kfree_alloc_num; i++) {
656 			alloc_ptr = kmalloc(kfree_mult * sizeof(struct kfree_obj), GFP_KERNEL);
657 			if (!alloc_ptr)
658 				return -ENOMEM;
659 
660 			if (kfree_by_call_rcu) {
661 				call_rcu(&(alloc_ptr->rh), kfree_call_rcu);
662 				continue;
663 			}
664 
665 			// By default kfree_rcu_test_single and kfree_rcu_test_double are
666 			// initialized to false. If both have the same value (false or true)
667 			// both are randomly tested, otherwise only the one with value true
668 			// is tested.
669 			if ((kfree_rcu_test_single && !kfree_rcu_test_double) ||
670 					(kfree_rcu_test_both && torture_random(&tr) & 0x800))
671 				kfree_rcu_mightsleep(alloc_ptr);
672 			else
673 				kfree_rcu(alloc_ptr, rh);
674 		}
675 
676 		cond_resched();
677 	} while (!torture_must_stop() && ++loop < kfree_loops);
678 
679 	if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) {
680 		end_time = ktime_get_mono_fast_ns();
681 
682 		if (gp_exp)
683 			b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
684 		else
685 			b_rcu_gp_test_finished = cur_ops->get_gp_seq();
686 
687 		pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
688 		       (unsigned long long)(end_time - start_time), kfree_loops,
689 		       rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
690 		       (mem_begin - mem_during) >> (20 - PAGE_SHIFT));
691 
692 		if (shutdown) {
693 			smp_mb(); /* Assign before wake. */
694 			wake_up(&shutdown_wq);
695 		}
696 	}
697 
698 	torture_kthread_stopping("kfree_scale_thread");
699 	return 0;
700 }
701 
702 static void
kfree_scale_cleanup(void)703 kfree_scale_cleanup(void)
704 {
705 	int i;
706 
707 	if (torture_cleanup_begin())
708 		return;
709 
710 	if (kfree_reader_tasks) {
711 		for (i = 0; i < kfree_nrealthreads; i++)
712 			torture_stop_kthread(kfree_scale_thread,
713 					     kfree_reader_tasks[i]);
714 		kfree(kfree_reader_tasks);
715 	}
716 
717 	torture_cleanup_end();
718 }
719 
720 /*
721  * shutdown kthread.  Just waits to be awakened, then shuts down system.
722  */
723 static int
kfree_scale_shutdown(void * arg)724 kfree_scale_shutdown(void *arg)
725 {
726 	wait_event_idle(shutdown_wq,
727 			atomic_read(&n_kfree_scale_thread_ended) >= kfree_nrealthreads);
728 
729 	smp_mb(); /* Wake before output. */
730 
731 	kfree_scale_cleanup();
732 	kernel_power_off();
733 	return -EINVAL;
734 }
735 
736 // Used if doing RCU-kfree'ing via call_rcu().
737 static unsigned long jiffies_at_lazy_cb;
738 static struct rcu_head lazy_test1_rh;
739 static int rcu_lazy_test1_cb_called;
call_rcu_lazy_test1(struct rcu_head * rh)740 static void call_rcu_lazy_test1(struct rcu_head *rh)
741 {
742 	jiffies_at_lazy_cb = jiffies;
743 	WRITE_ONCE(rcu_lazy_test1_cb_called, 1);
744 }
745 
746 static int __init
kfree_scale_init(void)747 kfree_scale_init(void)
748 {
749 	int firsterr = 0;
750 	long i;
751 	unsigned long jif_start;
752 	unsigned long orig_jif;
753 
754 	pr_alert("%s" SCALE_FLAG
755 		 "--- kfree_rcu_test: kfree_mult=%d kfree_by_call_rcu=%d kfree_nthreads=%d kfree_alloc_num=%d kfree_loops=%d kfree_rcu_test_double=%d kfree_rcu_test_single=%d\n",
756 		 scale_type, kfree_mult, kfree_by_call_rcu, kfree_nthreads, kfree_alloc_num, kfree_loops, kfree_rcu_test_double, kfree_rcu_test_single);
757 
758 	// Also, do a quick self-test to ensure laziness is as much as
759 	// expected.
760 	if (kfree_by_call_rcu && !IS_ENABLED(CONFIG_RCU_LAZY)) {
761 		pr_alert("CONFIG_RCU_LAZY is disabled, falling back to kfree_rcu() for delayed RCU kfree'ing\n");
762 		kfree_by_call_rcu = 0;
763 	}
764 
765 	if (kfree_by_call_rcu) {
766 		/* do a test to check the timeout. */
767 		orig_jif = rcu_lazy_get_jiffies_till_flush();
768 
769 		rcu_lazy_set_jiffies_till_flush(2 * HZ);
770 		rcu_barrier();
771 
772 		jif_start = jiffies;
773 		jiffies_at_lazy_cb = 0;
774 		call_rcu(&lazy_test1_rh, call_rcu_lazy_test1);
775 
776 		smp_cond_load_relaxed(&rcu_lazy_test1_cb_called, VAL == 1);
777 
778 		rcu_lazy_set_jiffies_till_flush(orig_jif);
779 
780 		if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) {
781 			pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n");
782 			WARN_ON_ONCE(1);
783 			return -1;
784 		}
785 
786 		if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start > 3 * HZ)) {
787 			pr_alert("ERROR: call_rcu() CBs are being too lazy!\n");
788 			WARN_ON_ONCE(1);
789 			return -1;
790 		}
791 	}
792 
793 	kfree_nrealthreads = compute_real(kfree_nthreads);
794 	/* Start up the kthreads. */
795 	if (shutdown) {
796 		init_waitqueue_head(&shutdown_wq);
797 		firsterr = torture_create_kthread(kfree_scale_shutdown, NULL,
798 						  shutdown_task);
799 		if (torture_init_error(firsterr))
800 			goto unwind;
801 		schedule_timeout_uninterruptible(1);
802 	}
803 
804 	pr_alert("kfree object size=%zu, kfree_by_call_rcu=%d\n",
805 			kfree_mult * sizeof(struct kfree_obj),
806 			kfree_by_call_rcu);
807 
808 	kfree_reader_tasks = kcalloc(kfree_nrealthreads, sizeof(kfree_reader_tasks[0]),
809 			       GFP_KERNEL);
810 	if (kfree_reader_tasks == NULL) {
811 		firsterr = -ENOMEM;
812 		goto unwind;
813 	}
814 
815 	for (i = 0; i < kfree_nrealthreads; i++) {
816 		firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
817 						  kfree_reader_tasks[i]);
818 		if (torture_init_error(firsterr))
819 			goto unwind;
820 	}
821 
822 	while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
823 		schedule_timeout_uninterruptible(1);
824 
825 	torture_init_end();
826 	return 0;
827 
828 unwind:
829 	torture_init_end();
830 	kfree_scale_cleanup();
831 	return firsterr;
832 }
833 
834 static void
rcu_scale_cleanup(void)835 rcu_scale_cleanup(void)
836 {
837 	int i;
838 	int j;
839 	int ngps = 0;
840 	u64 *wdp;
841 	u64 *wdpp;
842 
843 	/*
844 	 * Would like warning at start, but everything is expedited
845 	 * during the mid-boot phase, so have to wait till the end.
846 	 */
847 	if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
848 		SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
849 	if (rcu_gp_is_normal() && gp_exp)
850 		SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
851 	if (gp_exp && gp_async)
852 		SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
853 
854 	// If built-in, just report all of the GP kthread's CPU time.
855 	if (IS_BUILTIN(CONFIG_RCU_SCALE_TEST) && !kthread_tp && cur_ops->rso_gp_kthread)
856 		kthread_tp = cur_ops->rso_gp_kthread();
857 	if (kthread_tp) {
858 		u32 ns;
859 		u64 us;
860 
861 		kthread_stime = kthread_tp->stime - kthread_stime;
862 		us = div_u64_rem(kthread_stime, 1000, &ns);
863 		pr_info("rcu_scale: Grace-period kthread CPU time: %llu.%03u us\n", us, ns);
864 		show_rcu_gp_kthreads();
865 	}
866 	if (kfree_rcu_test) {
867 		kfree_scale_cleanup();
868 		return;
869 	}
870 
871 	if (torture_cleanup_begin())
872 		return;
873 	if (!cur_ops) {
874 		torture_cleanup_end();
875 		return;
876 	}
877 
878 	if (reader_tasks) {
879 		for (i = 0; i < nrealreaders; i++)
880 			torture_stop_kthread(rcu_scale_reader,
881 					     reader_tasks[i]);
882 		kfree(reader_tasks);
883 	}
884 
885 	if (writer_tasks) {
886 		for (i = 0; i < nrealwriters; i++) {
887 			torture_stop_kthread(rcu_scale_writer,
888 					     writer_tasks[i]);
889 			if (!writer_n_durations)
890 				continue;
891 			j = writer_n_durations[i];
892 			pr_alert("%s%s writer %d gps: %d\n",
893 				 scale_type, SCALE_FLAG, i, j);
894 			ngps += j;
895 		}
896 		pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
897 			 scale_type, SCALE_FLAG,
898 			 t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
899 			 t_rcu_scale_writer_finished -
900 			 t_rcu_scale_writer_started,
901 			 ngps,
902 			 rcuscale_seq_diff(b_rcu_gp_test_finished,
903 					   b_rcu_gp_test_started));
904 		for (i = 0; i < nrealwriters; i++) {
905 			if (!writer_durations)
906 				break;
907 			if (!writer_n_durations)
908 				continue;
909 			wdpp = writer_durations[i];
910 			if (!wdpp)
911 				continue;
912 			for (j = 0; j < writer_n_durations[i]; j++) {
913 				wdp = &wdpp[j];
914 				pr_alert("%s%s %4d writer-duration: %5d %llu\n",
915 					scale_type, SCALE_FLAG,
916 					i, j, *wdp);
917 				if (j % 100 == 0)
918 					schedule_timeout_uninterruptible(1);
919 			}
920 			kfree(writer_durations[i]);
921 		}
922 		kfree(writer_tasks);
923 		kfree(writer_durations);
924 		kfree(writer_n_durations);
925 	}
926 
927 	/* Do torture-type-specific cleanup operations.  */
928 	if (cur_ops->cleanup != NULL)
929 		cur_ops->cleanup();
930 
931 	torture_cleanup_end();
932 }
933 
934 /*
935  * RCU scalability shutdown kthread.  Just waits to be awakened, then shuts
936  * down system.
937  */
938 static int
rcu_scale_shutdown(void * arg)939 rcu_scale_shutdown(void *arg)
940 {
941 	wait_event_idle(shutdown_wq, atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
942 	smp_mb(); /* Wake before output. */
943 	rcu_scale_cleanup();
944 	kernel_power_off();
945 	return -EINVAL;
946 }
947 
948 static int __init
rcu_scale_init(void)949 rcu_scale_init(void)
950 {
951 	long i;
952 	int firsterr = 0;
953 	static struct rcu_scale_ops *scale_ops[] = {
954 		&rcu_ops, &srcu_ops, &srcud_ops, TASKS_OPS TASKS_RUDE_OPS TASKS_TRACING_OPS
955 	};
956 
957 	if (!torture_init_begin(scale_type, verbose))
958 		return -EBUSY;
959 
960 	/* Process args and announce that the scalability'er is on the job. */
961 	for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
962 		cur_ops = scale_ops[i];
963 		if (strcmp(scale_type, cur_ops->name) == 0)
964 			break;
965 	}
966 	if (i == ARRAY_SIZE(scale_ops)) {
967 		pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
968 		pr_alert("rcu-scale types:");
969 		for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
970 			pr_cont(" %s", scale_ops[i]->name);
971 		pr_cont("\n");
972 		firsterr = -EINVAL;
973 		cur_ops = NULL;
974 		goto unwind;
975 	}
976 	if (cur_ops->init)
977 		cur_ops->init();
978 
979 	if (cur_ops->rso_gp_kthread) {
980 		kthread_tp = cur_ops->rso_gp_kthread();
981 		if (kthread_tp)
982 			kthread_stime = kthread_tp->stime;
983 	}
984 	if (kfree_rcu_test)
985 		return kfree_scale_init();
986 
987 	nrealwriters = compute_real(nwriters);
988 	nrealreaders = compute_real(nreaders);
989 	atomic_set(&n_rcu_scale_reader_started, 0);
990 	atomic_set(&n_rcu_scale_writer_started, 0);
991 	atomic_set(&n_rcu_scale_writer_finished, 0);
992 	rcu_scale_print_module_parms(cur_ops, "Start of test");
993 
994 	/* Start up the kthreads. */
995 
996 	if (shutdown) {
997 		init_waitqueue_head(&shutdown_wq);
998 		firsterr = torture_create_kthread(rcu_scale_shutdown, NULL,
999 						  shutdown_task);
1000 		if (torture_init_error(firsterr))
1001 			goto unwind;
1002 		schedule_timeout_uninterruptible(1);
1003 	}
1004 	reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
1005 			       GFP_KERNEL);
1006 	if (reader_tasks == NULL) {
1007 		SCALEOUT_ERRSTRING("out of memory");
1008 		firsterr = -ENOMEM;
1009 		goto unwind;
1010 	}
1011 	for (i = 0; i < nrealreaders; i++) {
1012 		firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
1013 						  reader_tasks[i]);
1014 		if (torture_init_error(firsterr))
1015 			goto unwind;
1016 	}
1017 	while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
1018 		schedule_timeout_uninterruptible(1);
1019 	writer_tasks = kcalloc(nrealwriters, sizeof(reader_tasks[0]),
1020 			       GFP_KERNEL);
1021 	writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations),
1022 				   GFP_KERNEL);
1023 	writer_n_durations =
1024 		kcalloc(nrealwriters, sizeof(*writer_n_durations),
1025 			GFP_KERNEL);
1026 	if (!writer_tasks || !writer_durations || !writer_n_durations) {
1027 		SCALEOUT_ERRSTRING("out of memory");
1028 		firsterr = -ENOMEM;
1029 		goto unwind;
1030 	}
1031 	for (i = 0; i < nrealwriters; i++) {
1032 		writer_durations[i] =
1033 			kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
1034 				GFP_KERNEL);
1035 		if (!writer_durations[i]) {
1036 			firsterr = -ENOMEM;
1037 			goto unwind;
1038 		}
1039 		firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
1040 						  writer_tasks[i]);
1041 		if (torture_init_error(firsterr))
1042 			goto unwind;
1043 	}
1044 	torture_init_end();
1045 	return 0;
1046 
1047 unwind:
1048 	torture_init_end();
1049 	rcu_scale_cleanup();
1050 	if (shutdown) {
1051 		WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
1052 		kernel_power_off();
1053 	}
1054 	return firsterr;
1055 }
1056 
1057 module_init(rcu_scale_init);
1058 module_exit(rcu_scale_cleanup);
1059