tests/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, 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
  63 #include "qemu/osdep.h"
  64 #include "qemu/atomic.h"
  65 #include "qemu/rcu.h"
  66 #include "qemu/thread.h"
  67
  68 int nthreadsrunning;
  69
  70 #define GOFLAG_INIT 0
  71 #define GOFLAG_RUN  1
  72 #define GOFLAG_STOP 2
  73
  74 static volatile int goflag = GOFLAG_INIT;
  75
  76 #define RCU_READ_RUN 1000
  77
  78 #define NR_THREADS 100
  79 static QemuThread threads[NR_THREADS];
  80 static struct rcu_reader_data *data[NR_THREADS];
  81 static int n_threads;
  82
  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  */
  89 static QemuMutex counts_mutex;
  90 long long n_reads = 0LL;
  91 long n_updates = 0L;
  92
  93 static 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
 104 static 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
 118 static 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     }
 137     qemu_mutex_lock(&counts_mutex);
 138     n_reads += n_reads_local;
 139     qemu_mutex_unlock(&counts_mutex);
 140
 141     rcu_unregister_thread();
 142     return NULL;
 143 }
 144
 145 static 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     }
 160     qemu_mutex_lock(&counts_mutex);
 161     n_updates += n_updates_local;
 162     qemu_mutex_unlock(&counts_mutex);
 163
 164     rcu_unregister_thread();
 165     return NULL;
 166 }
 167
 168 static void perftestinit(void)
 169 {
 170     nthreadsrunning = 0;
 171 }
 172
 173 static 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
 192 static 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
 204 static 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
 215 static 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
 232 struct rcu_stress {
 233     int age;  /* how many update cycles while not rcu_stress_current */
 234     int mbtest;
 235 };
 236
 237 struct rcu_stress rcu_stress_array[RCU_STRESS_PIPE_LEN] = { { 0 } };
 238 struct rcu_stress *rcu_stress_current;
 239 int n_mberror;
 240
 241 /* Updates protected by counts_mutex */
 242 long long rcu_stress_count[RCU_STRESS_PIPE_LEN + 1];
 243
 244
 245 static void *rcu_read_stress_test(void *arg)
 246 {
 247     int i;
 248     struct rcu_stress *p;
 249     int pc;
 250     long long n_reads_local = 0;
 251     long long rcu_stress_local[RCU_STRESS_PIPE_LEN + 1] = { 0 };
 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);
 263         if (atomic_read(&p->mbtest) == 0) {
 264             n_mberror++;
 265         }
 266         rcu_read_lock();
 267         for (i = 0; i < 100; i++) {
 268             garbage++;
 269         }
 270         rcu_read_unlock();
 271         pc = atomic_read(&p->age);
 272         rcu_read_unlock();
 273         if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) {
 274             pc = RCU_STRESS_PIPE_LEN;
 275         }
 276         rcu_stress_local[pc]++;
 277         n_reads_local++;
 278     }
 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);
 285
 286     rcu_unregister_thread();
 287     return NULL;
 288 }
 289
 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  */
 301 static void *rcu_update_stress_test(void *arg)
 302 {
 303     int i, rcu_stress_idx = 0;
 304     struct rcu_stress *cp = atomic_read(&rcu_stress_current);
 305
 306     rcu_register_thread();
 307     *(struct rcu_reader_data **)arg = &rcu_reader;
 308
 309     while (goflag == GOFLAG_INIT) {
 310         g_usleep(1000);
 311     }
 312
 313     while (goflag == GOFLAG_RUN) {
 314         struct rcu_stress *p;
 315         rcu_stress_idx++;
 316         if (rcu_stress_idx >= RCU_STRESS_PIPE_LEN) {
 317             rcu_stress_idx = 0;
 318         }
 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);
 323         smp_mb();
 324         atomic_set(&p->age, 0);
 325         atomic_set(&p->mbtest, 1);
 326         atomic_rcu_set(&rcu_stress_current, p);
 327         cp = p;
 328         /*
 329          * New RCU structure is now live, update pipe counts on old
 330          * ones.
 331          */
 332         for (i = 0; i < RCU_STRESS_PIPE_LEN; i++) {
 333             if (i != rcu_stress_idx) {
 334                 atomic_set(&rcu_stress_array[i].age,
 335                            rcu_stress_array[i].age + 1);
 336             }
 337         }
 338         synchronize_rcu();
 339         n_updates++;
 340     }
 341
 342     rcu_unregister_thread();
 343     return NULL;
 344 }
 345
 346 static 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
 363 static void stresstest(int nreaders, int duration)
 364 {
 365     int i;
 366
 367     rcu_stress_current = &rcu_stress_array[0];
 368     rcu_stress_current->age = 0;
 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
 393 static void gtest_stress(int nreaders, int duration)
 394 {
 395     int i;
 396
 397     rcu_stress_current = &rcu_stress_array[0];
 398     rcu_stress_current->age = 0;
 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
 417 static void gtest_stress_1_1(void)
 418 {
 419     gtest_stress(1, 1);
 420 }
 421
 422 static void gtest_stress_10_1(void)
 423 {
 424     gtest_stress(10, 1);
 425 }
 426
 427 static void gtest_stress_1_5(void)
 428 {
 429     gtest_stress(1, 5);
 430 }
 431
 432 static void gtest_stress_10_5(void)
 433 {
 434     gtest_stress(10, 5);
 435 }
 436
 437 /*
 438  * Mainprogram.
 439  */
 440
 441 static void usage(int argc, char *argv[])
 442 {
 443     fprintf(stderr, "Usage: %s [nreaders [ [r|u]perf | stress [duration]]\n",
 444             argv[0]);
 445     exit(-1);
 446 }
 447
 448 int main(int argc, char *argv[])
 449 {
 450     int nreaders = 1;
 451     int duration = 1;
 452
 453     qemu_mutex_init(&counts_mutex);
 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 }