tests/unit/rcutorture.c

   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, see <https://www.gnu.org/licenses/>.
  54  *
  55  * Copyright (c) 2008 Paul E. McKenney, IBM Corporation.
  56  */
  57
  58 /*
  59  * Test variables.
  60  */
  61
  62 #include "qemu/osdep.h"
  63 #include "qemu/atomic.h"
  64 #include "qemu/rcu.h"
  65 #include "qemu/thread.h"
  66
  67 int nthreadsrunning;
  68
  69 #define GOFLAG_INIT 0
  70 #define GOFLAG_RUN  1
  71 #define GOFLAG_STOP 2
  72
  73 static volatile int goflag = GOFLAG_INIT;
  74
  75 #define RCU_READ_RUN 1000
  76
  77 #define NR_THREADS 100
  78 static QemuThread threads[NR_THREADS];
  79 static struct rcu_reader_data *data[NR_THREADS];
  80 static int n_threads;
  81
  82 /*
  83  * Statistical counts
  84  *
  85  * These are the sum of local counters at the end of a run.
  86  * Updates are protected by a mutex.
  87  */
  88 static QemuMutex counts_mutex;
  89 long long n_reads = 0LL;
  90 long n_updates = 0L;
  91
  92 static void create_thread(void *(*func)(void *))
  93 {
  94     if (n_threads >= NR_THREADS) {
  95         fprintf(stderr, "Thread limit of %d exceeded!\n", NR_THREADS);
  96         exit(-1);
  97     }
  98     qemu_thread_create(&threads[n_threads], "test", func, &data[n_threads],
  99                        QEMU_THREAD_JOINABLE);
 100     n_threads++;
 101 }
 102
 103 static void wait_all_threads(void)
 104 {
 105     int i;
 106
 107     for (i = 0; i < n_threads; i++) {
 108         qemu_thread_join(&threads[i]);
 109     }
 110     n_threads = 0;
 111 }
 112
 113 /*
 114  * Performance test.
 115  */
 116
 117 static void *rcu_read_perf_test(void *arg)
 118 {
 119     int i;
 120     long long n_reads_local = 0;
 121
 122     rcu_register_thread();
 123
 124     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
 125     qatomic_inc(&nthreadsrunning);
 126     while (goflag == GOFLAG_INIT) {
 127         g_usleep(1000);
 128     }
 129     while (goflag == GOFLAG_RUN) {
 130         for (i = 0; i < RCU_READ_RUN; i++) {
 131             rcu_read_lock();
 132             rcu_read_unlock();
 133         }
 134         n_reads_local += RCU_READ_RUN;
 135     }
 136     qemu_mutex_lock(&counts_mutex);
 137     n_reads += n_reads_local;
 138     qemu_mutex_unlock(&counts_mutex);
 139
 140     rcu_unregister_thread();
 141     return NULL;
 142 }
 143
 144 static void *rcu_update_perf_test(void *arg)
 145 {
 146     long long n_updates_local = 0;
 147
 148     rcu_register_thread();
 149
 150     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
 151     qatomic_inc(&nthreadsrunning);
 152     while (goflag == GOFLAG_INIT) {
 153         g_usleep(1000);
 154     }
 155     while (goflag == GOFLAG_RUN) {
 156         synchronize_rcu();
 157         n_updates_local++;
 158     }
 159     qemu_mutex_lock(&counts_mutex);
 160     n_updates += n_updates_local;
 161     qemu_mutex_unlock(&counts_mutex);
 162
 163     rcu_unregister_thread();
 164     return NULL;
 165 }
 166
 167 static void perftestinit(void)
 168 {
 169     nthreadsrunning = 0;
 170 }
 171
 172 static void perftestrun(int nthreads, int duration, int nreaders, int nupdaters)
 173 {
 174     while (qatomic_read(&nthreadsrunning) < nthreads) {
 175         g_usleep(1000);
 176     }
 177     goflag = GOFLAG_RUN;
 178     g_usleep(duration * G_USEC_PER_SEC);
 179     goflag = GOFLAG_STOP;
 180     wait_all_threads();
 181     printf("n_reads: %lld  n_updates: %ld  nreaders: %d  nupdaters: %d duration: %d\n",
 182            n_reads, n_updates, nreaders, nupdaters, duration);
 183     printf("ns/read: %g  ns/update: %g\n",
 184            ((duration * 1000*1000*1000.*(double)nreaders) /
 185         (double)n_reads),
 186            ((duration * 1000*1000*1000.*(double)nupdaters) /
 187         (double)n_updates));
 188     exit(0);
 189 }
 190
 191 static void perftest(int nreaders, int duration)
 192 {
 193     int i;
 194
 195     perftestinit();
 196     for (i = 0; i < nreaders; i++) {
 197         create_thread(rcu_read_perf_test);
 198     }
 199     create_thread(rcu_update_perf_test);
 200     perftestrun(i + 1, duration, nreaders, 1);
 201 }
 202
 203 static void rperftest(int nreaders, int duration)
 204 {
 205     int i;
 206
 207     perftestinit();
 208     for (i = 0; i < nreaders; i++) {
 209         create_thread(rcu_read_perf_test);
 210     }
 211     perftestrun(i, duration, nreaders, 0);
 212 }
 213
 214 static void uperftest(int nupdaters, int duration)
 215 {
 216     int i;
 217
 218     perftestinit();
 219     for (i = 0; i < nupdaters; i++) {
 220         create_thread(rcu_update_perf_test);
 221     }
 222     perftestrun(i, duration, 0, nupdaters);
 223 }
 224
 225 /*
 226  * Stress test.
 227  */
 228
 229 #define RCU_STRESS_PIPE_LEN 10
 230
 231 struct rcu_stress {
 232     int age;  /* how many update cycles while not rcu_stress_current */
 233     int mbtest;
 234 };
 235
 236 struct rcu_stress rcu_stress_array[RCU_STRESS_PIPE_LEN] = { { 0 } };
 237 struct rcu_stress *rcu_stress_current;
 238 int n_mberror;
 239
 240 /* Updates protected by counts_mutex */
 241 long long rcu_stress_count[RCU_STRESS_PIPE_LEN + 1];
 242
 243
 244 static void *rcu_read_stress_test(void *arg)
 245 {
 246     int i;
 247     struct rcu_stress *p;
 248     int pc;
 249     long long n_reads_local = 0;
 250     long long rcu_stress_local[RCU_STRESS_PIPE_LEN + 1] = { 0 };
 251     volatile int garbage = 0;
 252
 253     rcu_register_thread();
 254
 255     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
 256     while (goflag == GOFLAG_INIT) {
 257         g_usleep(1000);
 258     }
 259     while (goflag == GOFLAG_RUN) {
 260         rcu_read_lock();
 261         p = qatomic_rcu_read(&rcu_stress_current);
 262         if (qatomic_read(&p->mbtest) == 0) {
 263             n_mberror++;
 264         }
 265         rcu_read_lock();
 266         for (i = 0; i < 100; i++) {
 267             garbage++;
 268         }
 269         rcu_read_unlock();
 270         pc = qatomic_read(&p->age);
 271         rcu_read_unlock();
 272         if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) {
 273             pc = RCU_STRESS_PIPE_LEN;
 274         }
 275         rcu_stress_local[pc]++;
 276         n_reads_local++;
 277     }
 278     qemu_mutex_lock(&counts_mutex);
 279     n_reads += n_reads_local;
 280     for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++) {
 281         rcu_stress_count[i] += rcu_stress_local[i];
 282     }
 283     qemu_mutex_unlock(&counts_mutex);
 284
 285     rcu_unregister_thread();
 286     return NULL;
 287 }
 288
 289 /*
 290  * Stress Test Updater
 291  *
 292  * The updater cycles around updating rcu_stress_current to point at
 293  * one of the rcu_stress_array_entries and resets it's age. It
 294  * then increments the age of all the other entries. The age
 295  * will be read under an rcu_read_lock() and distribution of values
 296  * calculated. The final result gives an indication of how many
 297  * previously current rcu_stress entries are in flight until the RCU
 298  * cycle complete.
 299  */
 300 static void *rcu_update_stress_test(void *arg)
 301 {
 302     int i, rcu_stress_idx = 0;
 303     struct rcu_stress *cp = qatomic_read(&rcu_stress_current);
 304
 305     rcu_register_thread();
 306     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
 307
 308     while (goflag == GOFLAG_INIT) {
 309         g_usleep(1000);
 310     }
 311
 312     while (goflag == GOFLAG_RUN) {
 313         struct rcu_stress *p;
 314         rcu_stress_idx++;
 315         if (rcu_stress_idx >= RCU_STRESS_PIPE_LEN) {
 316             rcu_stress_idx = 0;
 317         }
 318         p = &rcu_stress_array[rcu_stress_idx];
 319         /* catching up with ourselves would be a bug */
 320         assert(p != cp);
 321         qatomic_set(&p->mbtest, 0);
 322         smp_mb();
 323         qatomic_set(&p->age, 0);
 324         qatomic_set(&p->mbtest, 1);
 325         qatomic_rcu_set(&rcu_stress_current, p);
 326         cp = p;
 327         /*
 328          * New RCU structure is now live, update pipe counts on old
 329          * ones.
 330          */
 331         for (i = 0; i < RCU_STRESS_PIPE_LEN; i++) {
 332             if (i != rcu_stress_idx) {
 333                 qatomic_set(&rcu_stress_array[i].age,
 334                            rcu_stress_array[i].age + 1);
 335             }
 336         }
 337         synchronize_rcu();
 338         n_updates++;
 339     }
 340
 341     rcu_unregister_thread();
 342     return NULL;
 343 }
 344
 345 static void *rcu_fake_update_stress_test(void *arg)
 346 {
 347     rcu_register_thread();
 348
 349     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
 350     while (goflag == GOFLAG_INIT) {
 351         g_usleep(1000);
 352     }
 353     while (goflag == GOFLAG_RUN) {
 354         synchronize_rcu();
 355         g_usleep(1000);
 356     }
 357
 358     rcu_unregister_thread();
 359     return NULL;
 360 }
 361
 362 static void stresstest(int nreaders, int duration)
 363 {
 364     int i;
 365
 366     rcu_stress_current = &rcu_stress_array[0];
 367     rcu_stress_current->age = 0;
 368     rcu_stress_current->mbtest = 1;
 369     for (i = 0; i < nreaders; i++) {
 370         create_thread(rcu_read_stress_test);
 371     }
 372     create_thread(rcu_update_stress_test);
 373     for (i = 0; i < 5; i++) {
 374         create_thread(rcu_fake_update_stress_test);
 375     }
 376     goflag = GOFLAG_RUN;
 377     g_usleep(duration * G_USEC_PER_SEC);
 378     goflag = GOFLAG_STOP;
 379     wait_all_threads();
 380     printf("n_reads: %lld  n_updates: %ld  n_mberror: %d\n",
 381            n_reads, n_updates, n_mberror);
 382     printf("rcu_stress_count:");
 383     for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++) {
 384         printf(" %lld", rcu_stress_count[i]);
 385     }
 386     printf("\n");
 387     exit(0);
 388 }
 389
 390 /* GTest interface */
 391
 392 static void gtest_stress(int nreaders, int duration)
 393 {
 394     int i;
 395
 396     rcu_stress_current = &rcu_stress_array[0];
 397     rcu_stress_current->age = 0;
 398     rcu_stress_current->mbtest = 1;
 399     for (i = 0; i < nreaders; i++) {
 400         create_thread(rcu_read_stress_test);
 401     }
 402     create_thread(rcu_update_stress_test);
 403     for (i = 0; i < 5; i++) {
 404         create_thread(rcu_fake_update_stress_test);
 405     }
 406     goflag = GOFLAG_RUN;
 407     g_usleep(duration * G_USEC_PER_SEC);
 408     goflag = GOFLAG_STOP;
 409     wait_all_threads();
 410     g_assert_cmpint(n_mberror, ==, 0);
 411     for (i = 2; i <= RCU_STRESS_PIPE_LEN; i++) {
 412         g_assert_cmpint(rcu_stress_count[i], ==, 0);
 413     }
 414 }
 415
 416 static void gtest_stress_1_1(void)
 417 {
 418     gtest_stress(1, 1);
 419 }
 420
 421 static void gtest_stress_10_1(void)
 422 {
 423     gtest_stress(10, 1);
 424 }
 425
 426 static void gtest_stress_1_5(void)
 427 {
 428     gtest_stress(1, 5);
 429 }
 430
 431 static void gtest_stress_10_5(void)
 432 {
 433     gtest_stress(10, 5);
 434 }
 435
 436 /*
 437  * Mainprogram.
 438  */
 439
 440 static void usage(int argc, char *argv[])
 441 {
 442     fprintf(stderr, "Usage: %s [nreaders [ [r|u]perf | stress [duration]]\n",
 443             argv[0]);
 444     exit(-1);
 445 }
 446
 447 int main(int argc, char *argv[])
 448 {
 449     int nreaders = 1;
 450     int duration = 1;
 451
 452     qemu_mutex_init(&counts_mutex);
 453     if (argc >= 2 && argv[1][0] == '-') {
 454         g_test_init(&argc, &argv, NULL);
 455         if (g_test_quick()) {
 456             g_test_add_func("/rcu/torture/1reader", gtest_stress_1_1);
 457             g_test_add_func("/rcu/torture/10readers", gtest_stress_10_1);
 458         } else {
 459             g_test_add_func("/rcu/torture/1reader", gtest_stress_1_5);
 460             g_test_add_func("/rcu/torture/10readers", gtest_stress_10_5);
 461         }
 462         return g_test_run();
 463     }
 464
 465     if (argc >= 2) {
 466         nreaders = strtoul(argv[1], NULL, 0);
 467     }
 468     if (argc > 3) {
 469         duration = strtoul(argv[3], NULL, 0);
 470     }
 471     if (argc < 3 || strcmp(argv[2], "stress") == 0) {
 472         stresstest(nreaders, duration);
 473     } else if (strcmp(argv[2], "rperf") == 0) {
 474         rperftest(nreaders, duration);
 475     } else if (strcmp(argv[2], "uperf") == 0) {
 476         uperftest(nreaders, duration);
 477     } else if (strcmp(argv[2], "perf") == 0) {
 478         perftest(nreaders, duration);
 479     }
 480     usage(argc, argv);
 481     return 0;
 482 }