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 #include <linux/sched/debug.h>
43
44 #include "rcu.h"
45
46 MODULE_DESCRIPTION("Read-Copy Update module-based scalability-test facility");
47 MODULE_LICENSE("GPL");
48 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
49
50 #define SCALE_FLAG "-scale:"
51 #define SCALEOUT_STRING(s) \
52 pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s)
53 #define VERBOSE_SCALEOUT_STRING(s) \
54 do { if (verbose) pr_alert("%s" SCALE_FLAG " %s\n", scale_type, s); } while (0)
55 #define SCALEOUT_ERRSTRING(s) \
56 pr_alert("%s" SCALE_FLAG "!!! %s\n", scale_type, s)
57
58 /*
59 * The intended use cases for the nreaders and nwriters module parameters
60 * are as follows:
61 *
62 * 1. Specify only the nr_cpus kernel boot parameter. This will
63 * set both nreaders and nwriters to the value specified by
64 * nr_cpus for a mixed reader/writer test.
65 *
66 * 2. Specify the nr_cpus kernel boot parameter, but set
67 * rcuscale.nreaders to zero. This will set nwriters to the
68 * value specified by nr_cpus for an update-only test.
69 *
70 * 3. Specify the nr_cpus kernel boot parameter, but set
71 * rcuscale.nwriters to zero. This will set nreaders to the
72 * value specified by nr_cpus for a read-only test.
73 *
74 * Various other use cases may of course be specified.
75 *
76 * Note that this test's readers are intended only as a test load for
77 * the writers. The reader scalability statistics will be overly
78 * pessimistic due to the per-critical-section interrupt disabling,
79 * test-end checks, and the pair of calls through pointers.
80 */
81
82 torture_param(bool, gp_async, false, "Use asynchronous GP wait primitives");
83 torture_param(int, gp_async_max, 1000, "Max # outstanding waits per writer");
84 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
85 torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
86 torture_param(int, minruntime, 0, "Minimum run time (s)");
87 torture_param(int, nreaders, -1, "Number of RCU reader threads");
88 torture_param(int, nwriters, -1, "Number of RCU updater threads");
89 torture_param(int, shutdown_secs, !IS_MODULE(CONFIG_RCU_SCALE_TEST) * 300,
90 "Shutdown at end of scalability tests or at specified timeout (s).");
91 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
92 torture_param(int, writer_holdoff, 0, "Holdoff (us) between GPs, zero to disable");
93 torture_param(int, writer_holdoff_jiffies, 0, "Holdoff (jiffies) between GPs, zero to disable");
94 torture_param(int, kfree_rcu_test, 0, "Do we run a kfree_rcu() scale test?");
95 torture_param(int, kfree_mult, 1, "Multiple of kfree_obj size to allocate.");
96 torture_param(int, kfree_by_call_rcu, 0, "Use call_rcu() to emulate kfree_rcu()?");
97
98 static char *scale_type = "rcu";
99 module_param(scale_type, charp, 0444);
100 MODULE_PARM_DESC(scale_type, "Type of RCU to scalability-test (rcu, srcu, ...)");
101
102 // Structure definitions for custom fixed-per-task allocator.
103 struct writer_mblock {
104 struct rcu_head wmb_rh;
105 struct llist_node wmb_node;
106 struct writer_freelist *wmb_wfl;
107 };
108
109 struct writer_freelist {
110 struct llist_head ws_lhg;
111 atomic_t ws_inflight;
112 struct llist_head ____cacheline_internodealigned_in_smp ws_lhp;
113 struct writer_mblock *ws_mblocks;
114 };
115
116 static int nrealreaders;
117 static int nrealwriters;
118 static struct task_struct **writer_tasks;
119 static struct task_struct **reader_tasks;
120
121 static u64 **writer_durations;
122 static bool *writer_done;
123 static struct writer_freelist *writer_freelists;
124 static int *writer_n_durations;
125 static atomic_t n_rcu_scale_reader_started;
126 static atomic_t n_rcu_scale_writer_started;
127 static atomic_t n_rcu_scale_writer_finished;
128 static u64 t_rcu_scale_writer_started;
129 static u64 t_rcu_scale_writer_finished;
130 static unsigned long b_rcu_gp_test_started;
131 static unsigned long b_rcu_gp_test_finished;
132
133 #define MAX_MEAS 10000
134 #define MIN_MEAS 100
135
136 /*
137 * Operations vector for selecting different types of tests.
138 */
139
140 struct rcu_scale_ops {
141 int ptype;
142 void (*init)(void);
143 void (*cleanup)(void);
144 int (*readlock)(void);
145 void (*readunlock)(int idx);
146 unsigned long (*get_gp_seq)(void);
147 unsigned long (*gp_diff)(unsigned long new, unsigned long old);
148 unsigned long (*exp_completed)(void);
149 void (*async)(struct rcu_head *head, rcu_callback_t func);
150 void (*gp_barrier)(void);
151 void (*sync)(void);
152 void (*exp_sync)(void);
153 struct task_struct *(*rso_gp_kthread)(void);
154 void (*stats)(void);
155 const char *name;
156 };
157
158 static struct rcu_scale_ops *cur_ops;
159
160 /*
161 * Definitions for rcu scalability testing.
162 */
163
rcu_scale_read_lock(void)164 static int rcu_scale_read_lock(void) __acquires(RCU)
165 {
166 rcu_read_lock();
167 return 0;
168 }
169
rcu_scale_read_unlock(int idx)170 static void rcu_scale_read_unlock(int idx) __releases(RCU)
171 {
172 rcu_read_unlock();
173 }
174
rcu_no_completed(void)175 static unsigned long __maybe_unused rcu_no_completed(void)
176 {
177 return 0;
178 }
179
rcu_sync_scale_init(void)180 static void rcu_sync_scale_init(void)
181 {
182 }
183
184 static struct rcu_scale_ops rcu_ops = {
185 .ptype = RCU_FLAVOR,
186 .init = rcu_sync_scale_init,
187 .readlock = rcu_scale_read_lock,
188 .readunlock = rcu_scale_read_unlock,
189 .get_gp_seq = rcu_get_gp_seq,
190 .gp_diff = rcu_seq_diff,
191 .exp_completed = rcu_exp_batches_completed,
192 .async = call_rcu_hurry,
193 .gp_barrier = rcu_barrier,
194 .sync = synchronize_rcu,
195 .exp_sync = synchronize_rcu_expedited,
196 .name = "rcu"
197 };
198
199 /*
200 * Definitions for srcu scalability testing.
201 */
202
203 DEFINE_STATIC_SRCU(srcu_ctl_scale);
204 static struct srcu_struct *srcu_ctlp = &srcu_ctl_scale;
205
srcu_scale_read_lock(void)206 static int srcu_scale_read_lock(void) __acquires(srcu_ctlp)
207 {
208 return srcu_read_lock(srcu_ctlp);
209 }
210
srcu_scale_read_unlock(int idx)211 static void srcu_scale_read_unlock(int idx) __releases(srcu_ctlp)
212 {
213 srcu_read_unlock(srcu_ctlp, idx);
214 }
215
srcu_scale_completed(void)216 static unsigned long srcu_scale_completed(void)
217 {
218 return srcu_batches_completed(srcu_ctlp);
219 }
220
srcu_call_rcu(struct rcu_head * head,rcu_callback_t func)221 static void srcu_call_rcu(struct rcu_head *head, rcu_callback_t func)
222 {
223 call_srcu(srcu_ctlp, head, func);
224 }
225
srcu_rcu_barrier(void)226 static void srcu_rcu_barrier(void)
227 {
228 srcu_barrier(srcu_ctlp);
229 }
230
srcu_scale_synchronize(void)231 static void srcu_scale_synchronize(void)
232 {
233 synchronize_srcu(srcu_ctlp);
234 }
235
srcu_scale_stats(void)236 static void srcu_scale_stats(void)
237 {
238 srcu_torture_stats_print(srcu_ctlp, scale_type, SCALE_FLAG);
239 }
240
srcu_scale_synchronize_expedited(void)241 static void srcu_scale_synchronize_expedited(void)
242 {
243 synchronize_srcu_expedited(srcu_ctlp);
244 }
245
246 static struct rcu_scale_ops srcu_ops = {
247 .ptype = SRCU_FLAVOR,
248 .init = rcu_sync_scale_init,
249 .readlock = srcu_scale_read_lock,
250 .readunlock = srcu_scale_read_unlock,
251 .get_gp_seq = srcu_scale_completed,
252 .gp_diff = rcu_seq_diff,
253 .exp_completed = srcu_scale_completed,
254 .async = srcu_call_rcu,
255 .gp_barrier = srcu_rcu_barrier,
256 .sync = srcu_scale_synchronize,
257 .exp_sync = srcu_scale_synchronize_expedited,
258 .stats = srcu_scale_stats,
259 .name = "srcu"
260 };
261
262 static struct srcu_struct srcud;
263
srcu_sync_scale_init(void)264 static void srcu_sync_scale_init(void)
265 {
266 srcu_ctlp = &srcud;
267 init_srcu_struct(srcu_ctlp);
268 }
269
srcu_sync_scale_cleanup(void)270 static void srcu_sync_scale_cleanup(void)
271 {
272 cleanup_srcu_struct(srcu_ctlp);
273 }
274
275 static struct rcu_scale_ops srcud_ops = {
276 .ptype = SRCU_FLAVOR,
277 .init = srcu_sync_scale_init,
278 .cleanup = srcu_sync_scale_cleanup,
279 .readlock = srcu_scale_read_lock,
280 .readunlock = srcu_scale_read_unlock,
281 .get_gp_seq = srcu_scale_completed,
282 .gp_diff = rcu_seq_diff,
283 .exp_completed = srcu_scale_completed,
284 .async = srcu_call_rcu,
285 .gp_barrier = srcu_rcu_barrier,
286 .sync = srcu_scale_synchronize,
287 .exp_sync = srcu_scale_synchronize_expedited,
288 .stats = srcu_scale_stats,
289 .name = "srcud"
290 };
291
292 #ifdef CONFIG_TASKS_RCU
293
294 /*
295 * Definitions for RCU-tasks scalability testing.
296 */
297
tasks_scale_read_lock(void)298 static int tasks_scale_read_lock(void)
299 {
300 return 0;
301 }
302
tasks_scale_read_unlock(int idx)303 static void tasks_scale_read_unlock(int idx)
304 {
305 }
306
rcu_tasks_scale_stats(void)307 static void rcu_tasks_scale_stats(void)
308 {
309 rcu_tasks_torture_stats_print(scale_type, SCALE_FLAG);
310 }
311
312 static struct rcu_scale_ops tasks_ops = {
313 .ptype = RCU_TASKS_FLAVOR,
314 .init = rcu_sync_scale_init,
315 .readlock = tasks_scale_read_lock,
316 .readunlock = tasks_scale_read_unlock,
317 .get_gp_seq = rcu_no_completed,
318 .gp_diff = rcu_seq_diff,
319 .async = call_rcu_tasks,
320 .gp_barrier = rcu_barrier_tasks,
321 .sync = synchronize_rcu_tasks,
322 .exp_sync = synchronize_rcu_tasks,
323 .rso_gp_kthread = get_rcu_tasks_gp_kthread,
324 .stats = IS_ENABLED(CONFIG_TINY_RCU) ? NULL : rcu_tasks_scale_stats,
325 .name = "tasks"
326 };
327
328 #define TASKS_OPS &tasks_ops,
329
330 #else // #ifdef CONFIG_TASKS_RCU
331
332 #define TASKS_OPS
333
334 #endif // #else // #ifdef CONFIG_TASKS_RCU
335
336 #ifdef CONFIG_TASKS_RUDE_RCU
337
338 /*
339 * Definitions for RCU-tasks-rude scalability testing.
340 */
341
tasks_rude_scale_read_lock(void)342 static int tasks_rude_scale_read_lock(void)
343 {
344 return 0;
345 }
346
tasks_rude_scale_read_unlock(int idx)347 static void tasks_rude_scale_read_unlock(int idx)
348 {
349 }
350
rcu_tasks_rude_scale_stats(void)351 static void rcu_tasks_rude_scale_stats(void)
352 {
353 rcu_tasks_rude_torture_stats_print(scale_type, SCALE_FLAG);
354 }
355
356 static struct rcu_scale_ops tasks_rude_ops = {
357 .ptype = RCU_TASKS_RUDE_FLAVOR,
358 .init = rcu_sync_scale_init,
359 .readlock = tasks_rude_scale_read_lock,
360 .readunlock = tasks_rude_scale_read_unlock,
361 .get_gp_seq = rcu_no_completed,
362 .gp_diff = rcu_seq_diff,
363 .sync = synchronize_rcu_tasks_rude,
364 .exp_sync = synchronize_rcu_tasks_rude,
365 .rso_gp_kthread = get_rcu_tasks_rude_gp_kthread,
366 .stats = IS_ENABLED(CONFIG_TINY_RCU) ? NULL : rcu_tasks_rude_scale_stats,
367 .name = "tasks-rude"
368 };
369
370 #define TASKS_RUDE_OPS &tasks_rude_ops,
371
372 #else // #ifdef CONFIG_TASKS_RUDE_RCU
373
374 #define TASKS_RUDE_OPS
375
376 #endif // #else // #ifdef CONFIG_TASKS_RUDE_RCU
377
378 #ifdef CONFIG_TASKS_TRACE_RCU
379
380 /*
381 * Definitions for RCU-tasks-trace scalability testing.
382 */
383
tasks_trace_scale_read_lock(void)384 static int tasks_trace_scale_read_lock(void)
385 {
386 rcu_read_lock_trace();
387 return 0;
388 }
389
tasks_trace_scale_read_unlock(int idx)390 static void tasks_trace_scale_read_unlock(int idx)
391 {
392 rcu_read_unlock_trace();
393 }
394
395 static struct rcu_scale_ops tasks_tracing_ops = {
396 .ptype = RCU_TASKS_FLAVOR,
397 .init = rcu_sync_scale_init,
398 .readlock = tasks_trace_scale_read_lock,
399 .readunlock = tasks_trace_scale_read_unlock,
400 .get_gp_seq = rcu_no_completed,
401 .gp_diff = rcu_seq_diff,
402 .async = call_rcu_tasks_trace,
403 .gp_barrier = rcu_barrier_tasks_trace,
404 .sync = synchronize_rcu_tasks_trace,
405 .exp_sync = synchronize_rcu_tasks_trace,
406 .name = "tasks-tracing"
407 };
408
409 #define TASKS_TRACING_OPS &tasks_tracing_ops,
410
411 #else // #ifdef CONFIG_TASKS_TRACE_RCU
412
413 #define TASKS_TRACING_OPS
414
415 #endif // #else // #ifdef CONFIG_TASKS_TRACE_RCU
416
rcuscale_seq_diff(unsigned long new,unsigned long old)417 static unsigned long rcuscale_seq_diff(unsigned long new, unsigned long old)
418 {
419 if (!cur_ops->gp_diff)
420 return new - old;
421 return cur_ops->gp_diff(new, old);
422 }
423
424 /*
425 * If scalability tests complete, wait for shutdown to commence.
426 */
rcu_scale_wait_shutdown(void)427 static void rcu_scale_wait_shutdown(void)
428 {
429 cond_resched_tasks_rcu_qs();
430 if (atomic_read(&n_rcu_scale_writer_finished) < nrealwriters)
431 return;
432 while (!torture_must_stop())
433 schedule_timeout_uninterruptible(1);
434 }
435
436 /*
437 * RCU scalability reader kthread. Repeatedly does empty RCU read-side
438 * critical section, minimizing update-side interference. However, the
439 * point of this test is not to evaluate reader scalability, but instead
440 * to serve as a test load for update-side scalability testing.
441 */
442 static int
rcu_scale_reader(void * arg)443 rcu_scale_reader(void *arg)
444 {
445 unsigned long flags;
446 int idx;
447 long me = (long)arg;
448
449 VERBOSE_SCALEOUT_STRING("rcu_scale_reader task started");
450 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
451 set_user_nice(current, MAX_NICE);
452 atomic_inc(&n_rcu_scale_reader_started);
453
454 do {
455 local_irq_save(flags);
456 idx = cur_ops->readlock();
457 cur_ops->readunlock(idx);
458 local_irq_restore(flags);
459 rcu_scale_wait_shutdown();
460 } while (!torture_must_stop());
461 torture_kthread_stopping("rcu_scale_reader");
462 return 0;
463 }
464
465 /*
466 * Allocate a writer_mblock structure for the specified rcu_scale_writer
467 * task.
468 */
rcu_scale_alloc(long me)469 static struct writer_mblock *rcu_scale_alloc(long me)
470 {
471 struct llist_node *llnp;
472 struct writer_freelist *wflp;
473 struct writer_mblock *wmbp;
474
475 if (WARN_ON_ONCE(!writer_freelists))
476 return NULL;
477 wflp = &writer_freelists[me];
478 if (llist_empty(&wflp->ws_lhp)) {
479 // ->ws_lhp is private to its rcu_scale_writer task.
480 wmbp = container_of(llist_del_all(&wflp->ws_lhg), struct writer_mblock, wmb_node);
481 wflp->ws_lhp.first = &wmbp->wmb_node;
482 }
483 llnp = llist_del_first(&wflp->ws_lhp);
484 if (!llnp)
485 return NULL;
486 return container_of(llnp, struct writer_mblock, wmb_node);
487 }
488
489 /*
490 * Free a writer_mblock structure to its rcu_scale_writer task.
491 */
rcu_scale_free(struct writer_mblock * wmbp)492 static void rcu_scale_free(struct writer_mblock *wmbp)
493 {
494 struct writer_freelist *wflp;
495
496 if (!wmbp)
497 return;
498 wflp = wmbp->wmb_wfl;
499 llist_add(&wmbp->wmb_node, &wflp->ws_lhg);
500 }
501
502 /*
503 * Callback function for asynchronous grace periods from rcu_scale_writer().
504 */
rcu_scale_async_cb(struct rcu_head * rhp)505 static void rcu_scale_async_cb(struct rcu_head *rhp)
506 {
507 struct writer_mblock *wmbp = container_of(rhp, struct writer_mblock, wmb_rh);
508 struct writer_freelist *wflp = wmbp->wmb_wfl;
509
510 atomic_dec(&wflp->ws_inflight);
511 rcu_scale_free(wmbp);
512 }
513
514 static void rcu_scale_cleanup(void);
515
516 /*
517 * RCU scale writer kthread. Repeatedly does a grace period.
518 */
519 static int
rcu_scale_writer(void * arg)520 rcu_scale_writer(void *arg)
521 {
522 int i = 0;
523 int i_max;
524 unsigned long jdone;
525 long me = (long)arg;
526 bool selfreport = false;
527 bool started = false, done = false, alldone = false;
528 u64 t;
529 DEFINE_TORTURE_RANDOM(tr);
530 u64 *wdp;
531 u64 *wdpp = writer_durations[me];
532 struct writer_freelist *wflp = &writer_freelists[me];
533 struct writer_mblock *wmbp = NULL;
534
535 VERBOSE_SCALEOUT_STRING("rcu_scale_writer task started");
536 WARN_ON(!wdpp);
537 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
538 current->flags |= PF_NO_SETAFFINITY;
539 sched_set_fifo_low(current);
540
541 if (holdoff)
542 schedule_timeout_idle(holdoff * HZ);
543
544 /*
545 * Wait until rcu_end_inkernel_boot() is called for normal GP tests
546 * so that RCU is not always expedited for normal GP tests.
547 * The system_state test is approximate, but works well in practice.
548 */
549 while (!gp_exp && system_state != SYSTEM_RUNNING)
550 schedule_timeout_uninterruptible(1);
551
552 t = ktime_get_mono_fast_ns();
553 if (atomic_inc_return(&n_rcu_scale_writer_started) >= nrealwriters) {
554 t_rcu_scale_writer_started = t;
555 if (gp_exp) {
556 b_rcu_gp_test_started =
557 cur_ops->exp_completed() / 2;
558 } else {
559 b_rcu_gp_test_started = cur_ops->get_gp_seq();
560 }
561 }
562
563 jdone = jiffies + minruntime * HZ;
564 do {
565 bool gp_succeeded = false;
566
567 if (writer_holdoff)
568 udelay(writer_holdoff);
569 if (writer_holdoff_jiffies)
570 schedule_timeout_idle(torture_random(&tr) % writer_holdoff_jiffies + 1);
571 wdp = &wdpp[i];
572 *wdp = ktime_get_mono_fast_ns();
573 if (gp_async && !WARN_ON_ONCE(!cur_ops->async)) {
574 if (!wmbp)
575 wmbp = rcu_scale_alloc(me);
576 if (wmbp && atomic_read(&wflp->ws_inflight) < gp_async_max) {
577 atomic_inc(&wflp->ws_inflight);
578 cur_ops->async(&wmbp->wmb_rh, rcu_scale_async_cb);
579 wmbp = NULL;
580 gp_succeeded = true;
581 } else if (!kthread_should_stop()) {
582 cur_ops->gp_barrier();
583 } else {
584 rcu_scale_free(wmbp); /* Because we are stopping. */
585 wmbp = NULL;
586 }
587 } else if (gp_exp) {
588 cur_ops->exp_sync();
589 gp_succeeded = true;
590 } else {
591 cur_ops->sync();
592 gp_succeeded = true;
593 }
594 t = ktime_get_mono_fast_ns();
595 *wdp = t - *wdp;
596 i_max = i;
597 if (!started &&
598 atomic_read(&n_rcu_scale_writer_started) >= nrealwriters)
599 started = true;
600 if (!done && i >= MIN_MEAS && time_after(jiffies, jdone)) {
601 done = true;
602 WRITE_ONCE(writer_done[me], true);
603 sched_set_normal(current, 0);
604 pr_alert("%s%s rcu_scale_writer %ld has %d measurements\n",
605 scale_type, SCALE_FLAG, me, MIN_MEAS);
606 if (atomic_inc_return(&n_rcu_scale_writer_finished) >=
607 nrealwriters) {
608 schedule_timeout_interruptible(10);
609 rcu_ftrace_dump(DUMP_ALL);
610 SCALEOUT_STRING("Test complete");
611 t_rcu_scale_writer_finished = t;
612 if (gp_exp) {
613 b_rcu_gp_test_finished =
614 cur_ops->exp_completed() / 2;
615 } else {
616 b_rcu_gp_test_finished =
617 cur_ops->get_gp_seq();
618 }
619 if (shutdown_secs) {
620 writer_tasks[me] = NULL;
621 smp_mb(); /* Assign before wake. */
622 rcu_scale_cleanup();
623 kernel_power_off();
624 }
625 }
626 }
627 if (done && !alldone &&
628 atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters)
629 alldone = true;
630 if (done && !alldone && time_after(jiffies, jdone + HZ * 60)) {
631 static atomic_t dumped;
632 int i;
633
634 if (!atomic_xchg(&dumped, 1)) {
635 for (i = 0; i < nrealwriters; i++) {
636 if (writer_done[i])
637 continue;
638 pr_info("%s: Task %ld flags writer %d:\n", __func__, me, i);
639 sched_show_task(writer_tasks[i]);
640 }
641 if (cur_ops->stats)
642 cur_ops->stats();
643 }
644 }
645 if (!selfreport && time_after(jiffies, jdone + HZ * (70 + me))) {
646 pr_info("%s: Writer %ld self-report: started %d done %d/%d->%d i %d jdone %lu.\n",
647 __func__, me, started, done, writer_done[me], atomic_read(&n_rcu_scale_writer_finished), i, jiffies - jdone);
648 selfreport = true;
649 }
650 if (gp_succeeded && started && !alldone && i < MAX_MEAS - 1)
651 i++;
652 rcu_scale_wait_shutdown();
653 } while (!torture_must_stop());
654 if (gp_async && cur_ops->async) {
655 rcu_scale_free(wmbp);
656 cur_ops->gp_barrier();
657 }
658 writer_n_durations[me] = i_max + 1;
659 torture_kthread_stopping("rcu_scale_writer");
660 return 0;
661 }
662
663 static void
rcu_scale_print_module_parms(struct rcu_scale_ops * cur_ops,const char * tag)664 rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
665 {
666 pr_alert("%s" SCALE_FLAG
667 "--- %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_secs=%d\n",
668 scale_type, tag, gp_async, gp_async_max, gp_exp, holdoff, minruntime, nrealreaders, nrealwriters, writer_holdoff, writer_holdoff_jiffies, verbose, shutdown_secs);
669 }
670
671 /*
672 * Return the number if non-negative. If -1, the number of CPUs.
673 * If less than -1, that much less than the number of CPUs, but
674 * at least one.
675 */
compute_real(int n)676 static int compute_real(int n)
677 {
678 int nr;
679
680 if (n >= 0) {
681 nr = n;
682 } else {
683 nr = num_online_cpus() + 1 + n;
684 if (nr <= 0)
685 nr = 1;
686 }
687 return nr;
688 }
689
690 /*
691 * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
692 * of iterations and measure total time and number of GP for all iterations to complete.
693 */
694
695 torture_param(int, kfree_nthreads, -1, "Number of threads running loops of kfree_rcu().");
696 torture_param(int, kfree_alloc_num, 8000, "Number of allocations and frees done in an iteration.");
697 torture_param(int, kfree_loops, 10, "Number of loops doing kfree_alloc_num allocations and frees.");
698 torture_param(bool, kfree_rcu_test_double, false, "Do we run a kfree_rcu() double-argument scale test?");
699 torture_param(bool, kfree_rcu_test_single, false, "Do we run a kfree_rcu() single-argument scale test?");
700
701 static struct task_struct **kfree_reader_tasks;
702 static int kfree_nrealthreads;
703 static atomic_t n_kfree_scale_thread_started;
704 static atomic_t n_kfree_scale_thread_ended;
705 static struct task_struct *kthread_tp;
706 static u64 kthread_stime;
707
708 struct kfree_obj {
709 char kfree_obj[8];
710 struct rcu_head rh;
711 };
712
713 /* Used if doing RCU-kfree'ing via call_rcu(). */
kfree_call_rcu(struct rcu_head * rh)714 static void kfree_call_rcu(struct rcu_head *rh)
715 {
716 struct kfree_obj *obj = container_of(rh, struct kfree_obj, rh);
717
718 kfree(obj);
719 }
720
721 static void kfree_scale_cleanup(void);
722
723 static int
kfree_scale_thread(void * arg)724 kfree_scale_thread(void *arg)
725 {
726 int i, loop = 0;
727 long me = (long)arg;
728 struct kfree_obj *alloc_ptr;
729 u64 start_time, end_time;
730 long long mem_begin, mem_during = 0;
731 bool kfree_rcu_test_both;
732 DEFINE_TORTURE_RANDOM(tr);
733
734 VERBOSE_SCALEOUT_STRING("kfree_scale_thread task started");
735 set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
736 set_user_nice(current, MAX_NICE);
737 kfree_rcu_test_both = (kfree_rcu_test_single == kfree_rcu_test_double);
738
739 start_time = ktime_get_mono_fast_ns();
740
741 if (atomic_inc_return(&n_kfree_scale_thread_started) >= kfree_nrealthreads) {
742 if (gp_exp)
743 b_rcu_gp_test_started = cur_ops->exp_completed() / 2;
744 else
745 b_rcu_gp_test_started = cur_ops->get_gp_seq();
746 }
747
748 do {
749 if (!mem_during) {
750 mem_during = mem_begin = si_mem_available();
751 } else if (loop % (kfree_loops / 4) == 0) {
752 mem_during = (mem_during + si_mem_available()) / 2;
753 }
754
755 for (i = 0; i < kfree_alloc_num; i++) {
756 alloc_ptr = kzalloc_objs(struct kfree_obj, kfree_mult);
757 if (!alloc_ptr)
758 return -ENOMEM;
759
760 if (kfree_by_call_rcu) {
761 call_rcu(&(alloc_ptr->rh), kfree_call_rcu);
762 continue;
763 }
764
765 // By default kfree_rcu_test_single and kfree_rcu_test_double are
766 // initialized to false. If both have the same value (false or true)
767 // both are randomly tested, otherwise only the one with value true
768 // is tested.
769 if ((kfree_rcu_test_single && !kfree_rcu_test_double) ||
770 (kfree_rcu_test_both && torture_random(&tr) & 0x800))
771 kfree_rcu_mightsleep(alloc_ptr);
772 else
773 kfree_rcu(alloc_ptr, rh);
774 }
775
776 cond_resched();
777 } while (!torture_must_stop() && ++loop < kfree_loops);
778
779 if (atomic_inc_return(&n_kfree_scale_thread_ended) >= kfree_nrealthreads) {
780 end_time = ktime_get_mono_fast_ns();
781
782 if (gp_exp)
783 b_rcu_gp_test_finished = cur_ops->exp_completed() / 2;
784 else
785 b_rcu_gp_test_finished = cur_ops->get_gp_seq();
786
787 pr_alert("Total time taken by all kfree'ers: %llu ns, loops: %d, batches: %ld, memory footprint: %lldMB\n",
788 (unsigned long long)(end_time - start_time), kfree_loops,
789 rcuscale_seq_diff(b_rcu_gp_test_finished, b_rcu_gp_test_started),
790 PAGES_TO_MB(mem_begin - mem_during));
791
792 if (shutdown_secs) {
793 kfree_reader_tasks[me] = NULL;
794 smp_mb(); /* Assign before wake. */
795 kfree_scale_cleanup();
796 kernel_power_off();
797 }
798 }
799
800 torture_kthread_stopping("kfree_scale_thread");
801 return 0;
802 }
803
804 static void
kfree_scale_cleanup(void)805 kfree_scale_cleanup(void)
806 {
807 int i;
808
809 if (torture_cleanup_begin())
810 return;
811
812 if (kfree_reader_tasks) {
813 for (i = 0; i < kfree_nrealthreads; i++)
814 torture_stop_kthread(kfree_scale_thread,
815 kfree_reader_tasks[i]);
816 kfree(kfree_reader_tasks);
817 kfree_reader_tasks = NULL;
818 }
819
820 torture_cleanup_end();
821 }
822
823 // Used if doing RCU-kfree'ing via call_rcu().
824 static unsigned long jiffies_at_lazy_cb;
825 static struct rcu_head lazy_test1_rh;
826 static int rcu_lazy_test1_cb_called;
call_rcu_lazy_test1(struct rcu_head * rh)827 static void call_rcu_lazy_test1(struct rcu_head *rh)
828 {
829 jiffies_at_lazy_cb = jiffies;
830 WRITE_ONCE(rcu_lazy_test1_cb_called, 1);
831 }
832
833 static int __init
kfree_scale_init(void)834 kfree_scale_init(void)
835 {
836 int firsterr = 0;
837 long i;
838 unsigned long jif_start;
839 unsigned long orig_jif;
840
841 pr_alert("%s" SCALE_FLAG
842 "--- 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",
843 scale_type, kfree_mult, kfree_by_call_rcu, kfree_nthreads, kfree_alloc_num, kfree_loops, kfree_rcu_test_double, kfree_rcu_test_single);
844
845 // Also, do a quick self-test to ensure laziness is as much as
846 // expected.
847 if (kfree_by_call_rcu && !IS_ENABLED(CONFIG_RCU_LAZY)) {
848 pr_alert("CONFIG_RCU_LAZY is disabled, falling back to kfree_rcu() for delayed RCU kfree'ing\n");
849 kfree_by_call_rcu = 0;
850 }
851
852 if (kfree_by_call_rcu) {
853 /* do a test to check the timeout. */
854 orig_jif = rcu_get_jiffies_lazy_flush();
855
856 rcu_set_jiffies_lazy_flush(2 * HZ);
857 rcu_barrier();
858
859 jif_start = jiffies;
860 jiffies_at_lazy_cb = 0;
861 call_rcu(&lazy_test1_rh, call_rcu_lazy_test1);
862
863 smp_cond_load_relaxed(&rcu_lazy_test1_cb_called, VAL == 1);
864
865 rcu_set_jiffies_lazy_flush(orig_jif);
866
867 if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start < 2 * HZ)) {
868 pr_alert("ERROR: call_rcu() CBs are not being lazy as expected!\n");
869 firsterr = -1;
870 goto unwind;
871 }
872
873 if (WARN_ON_ONCE(jiffies_at_lazy_cb - jif_start > 3 * HZ)) {
874 pr_alert("ERROR: call_rcu() CBs are being too lazy!\n");
875 firsterr = -1;
876 goto unwind;
877 }
878 }
879
880 kfree_nrealthreads = compute_real(kfree_nthreads);
881 /* Start up the kthreads. */
882 if (shutdown_secs) {
883 firsterr = torture_shutdown_init(shutdown_secs, kfree_scale_cleanup);
884 if (torture_init_error(firsterr))
885 goto unwind;
886 }
887
888 pr_alert("kfree object size=%zu, kfree_by_call_rcu=%d\n",
889 kfree_mult * sizeof(struct kfree_obj),
890 kfree_by_call_rcu);
891
892 kfree_reader_tasks = kzalloc_objs(kfree_reader_tasks[0],
893 kfree_nrealthreads);
894 if (kfree_reader_tasks == NULL) {
895 firsterr = -ENOMEM;
896 goto unwind;
897 }
898
899 for (i = 0; i < kfree_nrealthreads; i++) {
900 firsterr = torture_create_kthread(kfree_scale_thread, (void *)i,
901 kfree_reader_tasks[i]);
902 if (torture_init_error(firsterr))
903 goto unwind;
904 }
905
906 while (atomic_read(&n_kfree_scale_thread_started) < kfree_nrealthreads)
907 schedule_timeout_uninterruptible(1);
908
909 torture_init_end();
910 return 0;
911
912 unwind:
913 torture_init_end();
914 kfree_scale_cleanup();
915 return firsterr;
916 }
917
918 static void
rcu_scale_cleanup(void)919 rcu_scale_cleanup(void)
920 {
921 int i;
922 int j;
923 int ngps = 0;
924 u64 *wdp;
925 u64 *wdpp;
926
927 /*
928 * Would like warning at start, but everything is expedited
929 * during the mid-boot phase, so have to wait till the end.
930 */
931 if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
932 SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
933 if (rcu_gp_is_normal() && gp_exp)
934 SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
935 if (gp_exp && gp_async)
936 SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
937
938 // If built-in, just report all of the GP kthread's CPU time.
939 if (IS_BUILTIN(CONFIG_RCU_SCALE_TEST) && !kthread_tp && cur_ops->rso_gp_kthread)
940 kthread_tp = cur_ops->rso_gp_kthread();
941 if (kthread_tp) {
942 u32 ns;
943 u64 us;
944
945 kthread_stime = kthread_tp->stime - kthread_stime;
946 us = div_u64_rem(kthread_stime, 1000, &ns);
947 pr_info("rcu_scale: Grace-period kthread CPU time: %llu.%03u us\n", us, ns);
948 show_rcu_gp_kthreads();
949 }
950 if (kfree_rcu_test) {
951 kfree_scale_cleanup();
952 return;
953 }
954
955 if (torture_cleanup_begin())
956 return;
957 if (!cur_ops) {
958 torture_cleanup_end();
959 return;
960 }
961
962 if (reader_tasks) {
963 for (i = 0; i < nrealreaders; i++)
964 torture_stop_kthread(rcu_scale_reader,
965 reader_tasks[i]);
966 kfree(reader_tasks);
967 reader_tasks = NULL;
968 }
969
970 if (writer_tasks) {
971 for (i = 0; i < nrealwriters; i++) {
972 torture_stop_kthread(rcu_scale_writer,
973 writer_tasks[i]);
974 if (!writer_n_durations)
975 continue;
976 j = writer_n_durations[i];
977 pr_alert("%s%s writer %d gps: %d\n",
978 scale_type, SCALE_FLAG, i, j);
979 ngps += j;
980 }
981 pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
982 scale_type, SCALE_FLAG,
983 t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
984 t_rcu_scale_writer_finished -
985 t_rcu_scale_writer_started,
986 ngps,
987 rcuscale_seq_diff(b_rcu_gp_test_finished,
988 b_rcu_gp_test_started));
989 for (i = 0; i < nrealwriters; i++) {
990 if (!writer_durations)
991 break;
992 if (!writer_n_durations)
993 continue;
994 wdpp = writer_durations[i];
995 if (!wdpp)
996 continue;
997 for (j = 0; j < writer_n_durations[i]; j++) {
998 wdp = &wdpp[j];
999 pr_alert("%s%s %4d writer-duration: %5d %llu\n",
1000 scale_type, SCALE_FLAG,
1001 i, j, *wdp);
1002 if (j % 100 == 0)
1003 schedule_timeout_uninterruptible(1);
1004 }
1005 kfree(writer_durations[i]);
1006 if (writer_freelists) {
1007 int ctr = 0;
1008 struct llist_node *llnp;
1009 struct writer_freelist *wflp = &writer_freelists[i];
1010
1011 if (wflp->ws_mblocks) {
1012 llist_for_each(llnp, wflp->ws_lhg.first)
1013 ctr++;
1014 llist_for_each(llnp, wflp->ws_lhp.first)
1015 ctr++;
1016 WARN_ONCE(ctr != gp_async_max,
1017 "%s: ctr = %d gp_async_max = %d\n",
1018 __func__, ctr, gp_async_max);
1019 kfree(wflp->ws_mblocks);
1020 }
1021 }
1022 }
1023 kfree(writer_tasks);
1024 writer_tasks = NULL;
1025 kfree(writer_durations);
1026 writer_durations = NULL;
1027 kfree(writer_n_durations);
1028 writer_n_durations = NULL;
1029 kfree(writer_done);
1030 writer_done = NULL;
1031 kfree(writer_freelists);
1032 writer_freelists = NULL;
1033 }
1034
1035 /* Do torture-type-specific cleanup operations. */
1036 if (cur_ops->cleanup != NULL)
1037 cur_ops->cleanup();
1038
1039 torture_cleanup_end();
1040 }
1041
1042 static int __init
rcu_scale_init(void)1043 rcu_scale_init(void)
1044 {
1045 int firsterr = 0;
1046 long i;
1047 long j;
1048 static struct rcu_scale_ops *scale_ops[] = {
1049 &rcu_ops, &srcu_ops, &srcud_ops, TASKS_OPS TASKS_RUDE_OPS TASKS_TRACING_OPS
1050 };
1051
1052 if (!torture_init_begin(scale_type, verbose))
1053 return -EBUSY;
1054
1055 /* Process args and announce that the scalability'er is on the job. */
1056 for (i = 0; i < ARRAY_SIZE(scale_ops); i++) {
1057 cur_ops = scale_ops[i];
1058 if (strcmp(scale_type, cur_ops->name) == 0)
1059 break;
1060 }
1061 if (i == ARRAY_SIZE(scale_ops)) {
1062 pr_alert("rcu-scale: invalid scale type: \"%s\"\n", scale_type);
1063 pr_alert("rcu-scale types:");
1064 for (i = 0; i < ARRAY_SIZE(scale_ops); i++)
1065 pr_cont(" %s", scale_ops[i]->name);
1066 pr_cont("\n");
1067 firsterr = -EINVAL;
1068 cur_ops = NULL;
1069 goto unwind;
1070 }
1071 if (cur_ops->init)
1072 cur_ops->init();
1073
1074 if (cur_ops->rso_gp_kthread) {
1075 kthread_tp = cur_ops->rso_gp_kthread();
1076 if (kthread_tp)
1077 kthread_stime = kthread_tp->stime;
1078 }
1079 if (kfree_rcu_test)
1080 return kfree_scale_init();
1081
1082 nrealwriters = compute_real(nwriters);
1083 nrealreaders = compute_real(nreaders);
1084 atomic_set(&n_rcu_scale_reader_started, 0);
1085 atomic_set(&n_rcu_scale_writer_started, 0);
1086 atomic_set(&n_rcu_scale_writer_finished, 0);
1087 rcu_scale_print_module_parms(cur_ops, "Start of test");
1088
1089 /* Start up the kthreads. */
1090
1091 if (shutdown_secs) {
1092 firsterr = torture_shutdown_init(shutdown_secs, rcu_scale_cleanup);
1093 if (torture_init_error(firsterr))
1094 goto unwind;
1095 }
1096 reader_tasks = kzalloc_objs(reader_tasks[0], nrealreaders);
1097 if (reader_tasks == NULL) {
1098 SCALEOUT_ERRSTRING("out of memory");
1099 firsterr = -ENOMEM;
1100 goto unwind;
1101 }
1102 for (i = 0; i < nrealreaders; i++) {
1103 firsterr = torture_create_kthread(rcu_scale_reader, (void *)i,
1104 reader_tasks[i]);
1105 if (torture_init_error(firsterr))
1106 goto unwind;
1107 }
1108 while (atomic_read(&n_rcu_scale_reader_started) < nrealreaders)
1109 schedule_timeout_uninterruptible(1);
1110 writer_tasks = kzalloc_objs(writer_tasks[0], nrealwriters);
1111 writer_durations = kcalloc(nrealwriters, sizeof(*writer_durations), GFP_KERNEL);
1112 writer_n_durations = kzalloc_objs(*writer_n_durations, nrealwriters);
1113 writer_done = kzalloc_objs(writer_done[0], nrealwriters);
1114 if (gp_async) {
1115 if (gp_async_max <= 0) {
1116 pr_warn("%s: gp_async_max = %d must be greater than zero.\n",
1117 __func__, gp_async_max);
1118 WARN_ON_ONCE(IS_BUILTIN(CONFIG_RCU_TORTURE_TEST));
1119 firsterr = -EINVAL;
1120 goto unwind;
1121 }
1122 writer_freelists = kzalloc_objs(writer_freelists[0],
1123 nrealwriters);
1124 }
1125 if (!writer_tasks || !writer_durations || !writer_n_durations || !writer_done ||
1126 (gp_async && !writer_freelists)) {
1127 SCALEOUT_ERRSTRING("out of memory");
1128 firsterr = -ENOMEM;
1129 goto unwind;
1130 }
1131 for (i = 0; i < nrealwriters; i++) {
1132 writer_durations[i] =
1133 kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
1134 GFP_KERNEL);
1135 if (!writer_durations[i]) {
1136 firsterr = -ENOMEM;
1137 goto unwind;
1138 }
1139 if (writer_freelists) {
1140 struct writer_freelist *wflp = &writer_freelists[i];
1141
1142 init_llist_head(&wflp->ws_lhg);
1143 init_llist_head(&wflp->ws_lhp);
1144 wflp->ws_mblocks = kzalloc_objs(wflp->ws_mblocks[0],
1145 gp_async_max);
1146 if (!wflp->ws_mblocks) {
1147 firsterr = -ENOMEM;
1148 goto unwind;
1149 }
1150 for (j = 0; j < gp_async_max; j++) {
1151 struct writer_mblock *wmbp = &wflp->ws_mblocks[j];
1152
1153 wmbp->wmb_wfl = wflp;
1154 llist_add(&wmbp->wmb_node, &wflp->ws_lhp);
1155 }
1156 }
1157 firsterr = torture_create_kthread(rcu_scale_writer, (void *)i,
1158 writer_tasks[i]);
1159 if (torture_init_error(firsterr))
1160 goto unwind;
1161 }
1162 torture_init_end();
1163 return 0;
1164
1165 unwind:
1166 torture_init_end();
1167 rcu_scale_cleanup();
1168 if (shutdown_secs) {
1169 WARN_ON(!IS_MODULE(CONFIG_RCU_SCALE_TEST));
1170 kernel_power_off();
1171 }
1172 return firsterr;
1173 }
1174
1175 module_init(rcu_scale_init);
1176 module_exit(rcu_scale_cleanup);
1177