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8fda74a5
PB
1/*
2 * rcutorture.c: simple user-level performance/stress test of RCU.
3 *
4 * Usage:
5 * ./rcu <nreaders> rperf [ <seconds> ]
6 * Run a read-side performance test with the specified
7 * number of readers for <seconds> seconds.
8 * ./rcu <nupdaters> uperf [ <seconds> ]
9 * Run an update-side performance test with the specified
10 * number of updaters and specified duration.
11 * ./rcu <nreaders> perf [ <seconds> ]
12 * Run a combined read/update performance test with the specified
13 * number of readers and one updater and specified duration.
14 *
15 * The above tests produce output as follows:
16 *
17 * n_reads: 46008000 n_updates: 146026 nreaders: 2 nupdaters: 1 duration: 1
18 * ns/read: 43.4707 ns/update: 6848.1
19 *
20 * The first line lists the total number of RCU reads and updates executed
21 * during the test, the number of reader threads, the number of updater
22 * threads, and the duration of the test in seconds. The second line
23 * lists the average duration of each type of operation in nanoseconds,
24 * or "nan" if the corresponding type of operation was not performed.
25 *
26 * ./rcu <nreaders> stress [ <seconds> ]
27 * Run a stress test with the specified number of readers and
28 * one updater.
29 *
30 * This test produces output as follows:
31 *
32 * n_reads: 114633217 n_updates: 3903415 n_mberror: 0
33 * rcu_stress_count: 114618391 14826 0 0 0 0 0 0 0 0 0
34 *
35 * The first line lists the number of RCU read and update operations
36 * executed, followed by the number of memory-ordering violations
37 * (which will be zero in a correct RCU implementation). The second
38 * line lists the number of readers observing progressively more stale
39 * data. A correct RCU implementation will have all but the first two
40 * numbers non-zero.
41 *
42 * This program is free software; you can redistribute it and/or modify
43 * it under the terms of the GNU General Public License as published by
44 * the Free Software Foundation; either version 2 of the License, or
45 * (at your option) any later version.
46 *
47 * This program is distributed in the hope that it will be useful,
48 * but WITHOUT ANY WARRANTY; without even the implied warranty of
49 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
50 * GNU General Public License for more details.
51 *
52 * You should have received a copy of the GNU General Public License
53 * along with this program; if not, write to the Free Software
54 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
55 *
56 * Copyright (c) 2008 Paul E. McKenney, IBM Corporation.
57 */
58
59/*
60 * Test variables.
61 */
62
681c28a3 63#include "qemu/osdep.h"
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PB
64#include "qemu/atomic.h"
65#include "qemu/rcu.h"
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PB
66#include "qemu/thread.h"
67
8fda74a5
PB
68int nthreadsrunning;
69
70#define GOFLAG_INIT 0
71#define GOFLAG_RUN 1
72#define GOFLAG_STOP 2
73
74static volatile int goflag = GOFLAG_INIT;
75
76#define RCU_READ_RUN 1000
77
78#define NR_THREADS 100
79static QemuThread threads[NR_THREADS];
80static struct rcu_reader_data *data[NR_THREADS];
81static int n_threads;
82
ea70ccff
AB
83/*
84 * Statistical counts
85 *
86 * These are the sum of local counters at the end of a run.
87 * Updates are protected by a mutex.
88 */
89static QemuMutex counts_mutex;
90long long n_reads = 0LL;
91long n_updates = 0L;
92
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PB
93static void create_thread(void *(*func)(void *))
94{
95 if (n_threads >= NR_THREADS) {
96 fprintf(stderr, "Thread limit of %d exceeded!\n", NR_THREADS);
97 exit(-1);
98 }
99 qemu_thread_create(&threads[n_threads], "test", func, &data[n_threads],
100 QEMU_THREAD_JOINABLE);
101 n_threads++;
102}
103
104static void wait_all_threads(void)
105{
106 int i;
107
108 for (i = 0; i < n_threads; i++) {
109 qemu_thread_join(&threads[i]);
110 }
111 n_threads = 0;
112}
113
114/*
115 * Performance test.
116 */
117
118static void *rcu_read_perf_test(void *arg)
119{
120 int i;
121 long long n_reads_local = 0;
122
123 rcu_register_thread();
124
125 *(struct rcu_reader_data **)arg = &rcu_reader;
126 atomic_inc(&nthreadsrunning);
127 while (goflag == GOFLAG_INIT) {
128 g_usleep(1000);
129 }
130 while (goflag == GOFLAG_RUN) {
131 for (i = 0; i < RCU_READ_RUN; i++) {
132 rcu_read_lock();
133 rcu_read_unlock();
134 }
135 n_reads_local += RCU_READ_RUN;
136 }
8a5956ad
PB
137 qemu_mutex_lock(&counts_mutex);
138 n_reads += n_reads_local;
139 qemu_mutex_unlock(&counts_mutex);
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140
141 rcu_unregister_thread();
142 return NULL;
143}
144
145static void *rcu_update_perf_test(void *arg)
146{
147 long long n_updates_local = 0;
148
149 rcu_register_thread();
150
151 *(struct rcu_reader_data **)arg = &rcu_reader;
152 atomic_inc(&nthreadsrunning);
153 while (goflag == GOFLAG_INIT) {
154 g_usleep(1000);
155 }
156 while (goflag == GOFLAG_RUN) {
157 synchronize_rcu();
158 n_updates_local++;
159 }
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PB
160 qemu_mutex_lock(&counts_mutex);
161 n_updates += n_updates_local;
162 qemu_mutex_unlock(&counts_mutex);
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163
164 rcu_unregister_thread();
165 return NULL;
166}
167
168static void perftestinit(void)
169{
170 nthreadsrunning = 0;
171}
172
173static void perftestrun(int nthreads, int duration, int nreaders, int nupdaters)
174{
175 while (atomic_read(&nthreadsrunning) < nthreads) {
176 g_usleep(1000);
177 }
178 goflag = GOFLAG_RUN;
179 g_usleep(duration * G_USEC_PER_SEC);
180 goflag = GOFLAG_STOP;
181 wait_all_threads();
182 printf("n_reads: %lld n_updates: %ld nreaders: %d nupdaters: %d duration: %d\n",
183 n_reads, n_updates, nreaders, nupdaters, duration);
184 printf("ns/read: %g ns/update: %g\n",
185 ((duration * 1000*1000*1000.*(double)nreaders) /
186 (double)n_reads),
187 ((duration * 1000*1000*1000.*(double)nupdaters) /
188 (double)n_updates));
189 exit(0);
190}
191
192static void perftest(int nreaders, int duration)
193{
194 int i;
195
196 perftestinit();
197 for (i = 0; i < nreaders; i++) {
198 create_thread(rcu_read_perf_test);
199 }
200 create_thread(rcu_update_perf_test);
201 perftestrun(i + 1, duration, nreaders, 1);
202}
203
204static void rperftest(int nreaders, int duration)
205{
206 int i;
207
208 perftestinit();
209 for (i = 0; i < nreaders; i++) {
210 create_thread(rcu_read_perf_test);
211 }
212 perftestrun(i, duration, nreaders, 0);
213}
214
215static void uperftest(int nupdaters, int duration)
216{
217 int i;
218
219 perftestinit();
220 for (i = 0; i < nupdaters; i++) {
221 create_thread(rcu_update_perf_test);
222 }
223 perftestrun(i, duration, 0, nupdaters);
224}
225
226/*
227 * Stress test.
228 */
229
230#define RCU_STRESS_PIPE_LEN 10
231
232struct rcu_stress {
a74c82c8 233 int age; /* how many update cycles while not rcu_stress_current */
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234 int mbtest;
235};
236
237struct rcu_stress rcu_stress_array[RCU_STRESS_PIPE_LEN] = { { 0 } };
238struct rcu_stress *rcu_stress_current;
8fda74a5 239int n_mberror;
ea70ccff
AB
240
241/* Updates protected by counts_mutex */
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242long long rcu_stress_count[RCU_STRESS_PIPE_LEN + 1];
243
244
245static void *rcu_read_stress_test(void *arg)
246{
247 int i;
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PB
248 struct rcu_stress *p;
249 int pc;
250 long long n_reads_local = 0;
8a5956ad 251 long long rcu_stress_local[RCU_STRESS_PIPE_LEN + 1] = { 0 };
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PB
252 volatile int garbage = 0;
253
254 rcu_register_thread();
255
256 *(struct rcu_reader_data **)arg = &rcu_reader;
257 while (goflag == GOFLAG_INIT) {
258 g_usleep(1000);
259 }
260 while (goflag == GOFLAG_RUN) {
261 rcu_read_lock();
262 p = atomic_rcu_read(&rcu_stress_current);
a74c82c8 263 if (atomic_read(&p->mbtest) == 0) {
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264 n_mberror++;
265 }
d62cb4f2 266 rcu_read_lock();
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267 for (i = 0; i < 100; i++) {
268 garbage++;
269 }
d62cb4f2 270 rcu_read_unlock();
a74c82c8 271 pc = atomic_read(&p->age);
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PB
272 rcu_read_unlock();
273 if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) {
274 pc = RCU_STRESS_PIPE_LEN;
275 }
8a5956ad 276 rcu_stress_local[pc]++;
8fda74a5 277 n_reads_local++;
8fda74a5 278 }
8a5956ad
PB
279 qemu_mutex_lock(&counts_mutex);
280 n_reads += n_reads_local;
281 for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++) {
282 rcu_stress_count[i] += rcu_stress_local[i];
283 }
284 qemu_mutex_unlock(&counts_mutex);
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285
286 rcu_unregister_thread();
287 return NULL;
288}
289
a74c82c8
AB
290/*
291 * Stress Test Updater
292 *
293 * The updater cycles around updating rcu_stress_current to point at
294 * one of the rcu_stress_array_entries and resets it's age. It
295 * then increments the age of all the other entries. The age
296 * will be read under an rcu_read_lock() and distribution of values
297 * calculated. The final result gives an indication of how many
298 * previously current rcu_stress entries are in flight until the RCU
299 * cycle complete.
300 */
8fda74a5
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301static void *rcu_update_stress_test(void *arg)
302{
a74c82c8
AB
303 int i, rcu_stress_idx = 0;
304 struct rcu_stress *cp = atomic_read(&rcu_stress_current);
8fda74a5
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305
306 rcu_register_thread();
8fda74a5 307 *(struct rcu_reader_data **)arg = &rcu_reader;
a74c82c8 308
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309 while (goflag == GOFLAG_INIT) {
310 g_usleep(1000);
311 }
a74c82c8 312
8fda74a5 313 while (goflag == GOFLAG_RUN) {
a74c82c8
AB
314 struct rcu_stress *p;
315 rcu_stress_idx++;
316 if (rcu_stress_idx >= RCU_STRESS_PIPE_LEN) {
317 rcu_stress_idx = 0;
8fda74a5 318 }
a74c82c8
AB
319 p = &rcu_stress_array[rcu_stress_idx];
320 /* catching up with ourselves would be a bug */
321 assert(p != cp);
322 atomic_set(&p->mbtest, 0);
8fda74a5 323 smp_mb();
a74c82c8
AB
324 atomic_set(&p->age, 0);
325 atomic_set(&p->mbtest, 1);
8fda74a5 326 atomic_rcu_set(&rcu_stress_current, p);
a74c82c8
AB
327 cp = p;
328 /*
329 * New RCU structure is now live, update pipe counts on old
330 * ones.
331 */
8fda74a5
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332 for (i = 0; i < RCU_STRESS_PIPE_LEN; i++) {
333 if (i != rcu_stress_idx) {
a74c82c8
AB
334 atomic_set(&rcu_stress_array[i].age,
335 rcu_stress_array[i].age + 1);
8fda74a5
PB
336 }
337 }
338 synchronize_rcu();
339 n_updates++;
340 }
341
342 rcu_unregister_thread();
343 return NULL;
344}
345
346static void *rcu_fake_update_stress_test(void *arg)
347{
348 rcu_register_thread();
349
350 *(struct rcu_reader_data **)arg = &rcu_reader;
351 while (goflag == GOFLAG_INIT) {
352 g_usleep(1000);
353 }
354 while (goflag == GOFLAG_RUN) {
355 synchronize_rcu();
356 g_usleep(1000);
357 }
358
359 rcu_unregister_thread();
360 return NULL;
361}
362
363static void stresstest(int nreaders, int duration)
364{
365 int i;
366
367 rcu_stress_current = &rcu_stress_array[0];
a74c82c8 368 rcu_stress_current->age = 0;
8fda74a5
PB
369 rcu_stress_current->mbtest = 1;
370 for (i = 0; i < nreaders; i++) {
371 create_thread(rcu_read_stress_test);
372 }
373 create_thread(rcu_update_stress_test);
374 for (i = 0; i < 5; i++) {
375 create_thread(rcu_fake_update_stress_test);
376 }
377 goflag = GOFLAG_RUN;
378 g_usleep(duration * G_USEC_PER_SEC);
379 goflag = GOFLAG_STOP;
380 wait_all_threads();
381 printf("n_reads: %lld n_updates: %ld n_mberror: %d\n",
382 n_reads, n_updates, n_mberror);
383 printf("rcu_stress_count:");
384 for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++) {
385 printf(" %lld", rcu_stress_count[i]);
386 }
387 printf("\n");
388 exit(0);
389}
390
391/* GTest interface */
392
393static void gtest_stress(int nreaders, int duration)
394{
395 int i;
396
397 rcu_stress_current = &rcu_stress_array[0];
a74c82c8 398 rcu_stress_current->age = 0;
8fda74a5
PB
399 rcu_stress_current->mbtest = 1;
400 for (i = 0; i < nreaders; i++) {
401 create_thread(rcu_read_stress_test);
402 }
403 create_thread(rcu_update_stress_test);
404 for (i = 0; i < 5; i++) {
405 create_thread(rcu_fake_update_stress_test);
406 }
407 goflag = GOFLAG_RUN;
408 g_usleep(duration * G_USEC_PER_SEC);
409 goflag = GOFLAG_STOP;
410 wait_all_threads();
411 g_assert_cmpint(n_mberror, ==, 0);
412 for (i = 2; i <= RCU_STRESS_PIPE_LEN; i++) {
413 g_assert_cmpint(rcu_stress_count[i], ==, 0);
414 }
415}
416
417static void gtest_stress_1_1(void)
418{
419 gtest_stress(1, 1);
420}
421
422static void gtest_stress_10_1(void)
423{
424 gtest_stress(10, 1);
425}
426
427static void gtest_stress_1_5(void)
428{
429 gtest_stress(1, 5);
430}
431
432static void gtest_stress_10_5(void)
433{
434 gtest_stress(10, 5);
435}
436
437/*
438 * Mainprogram.
439 */
440
441static void usage(int argc, char *argv[])
442{
804c9684
AB
443 fprintf(stderr, "Usage: %s [nreaders [ [r|u]perf | stress [duration]]\n",
444 argv[0]);
8fda74a5
PB
445 exit(-1);
446}
447
448int main(int argc, char *argv[])
449{
450 int nreaders = 1;
451 int duration = 1;
452
8a5956ad 453 qemu_mutex_init(&counts_mutex);
8fda74a5
PB
454 if (argc >= 2 && argv[1][0] == '-') {
455 g_test_init(&argc, &argv, NULL);
456 if (g_test_quick()) {
457 g_test_add_func("/rcu/torture/1reader", gtest_stress_1_1);
458 g_test_add_func("/rcu/torture/10readers", gtest_stress_10_1);
459 } else {
460 g_test_add_func("/rcu/torture/1reader", gtest_stress_1_5);
461 g_test_add_func("/rcu/torture/10readers", gtest_stress_10_5);
462 }
463 return g_test_run();
464 }
465
466 if (argc >= 2) {
467 nreaders = strtoul(argv[1], NULL, 0);
468 }
469 if (argc > 3) {
470 duration = strtoul(argv[3], NULL, 0);
471 }
472 if (argc < 3 || strcmp(argv[2], "stress") == 0) {
473 stresstest(nreaders, duration);
474 } else if (strcmp(argv[2], "rperf") == 0) {
475 rperftest(nreaders, duration);
476 } else if (strcmp(argv[2], "uperf") == 0) {
477 uperftest(nreaders, duration);
478 } else if (strcmp(argv[2], "perf") == 0) {
479 perftest(nreaders, duration);
480 }
481 usage(argc, argv);
482 return 0;
483}