qemu

rcutorture.c (12940B)

---

 /*
  * rcutorture.c: simple user-level performance/stress test of RCU.
  *
  * Usage:
  *     ./rcu <nreaders> rperf [ <seconds> ]
  *         Run a read-side performance test with the specified
  *         number of readers for <seconds> seconds.
  *     ./rcu <nupdaters> uperf [ <seconds> ]
  *         Run an update-side performance test with the specified
  *         number of updaters and specified duration.
  *     ./rcu <nreaders> perf [ <seconds> ]
  *         Run a combined read/update performance test with the specified
  *         number of readers and one updater and specified duration.
  *
  * The above tests produce output as follows:
  *
  * n_reads: 46008000  n_updates: 146026  nreaders: 2  nupdaters: 1 duration: 1
  * ns/read: 43.4707  ns/update: 6848.1
  *
  * The first line lists the total number of RCU reads and updates executed
  * during the test, the number of reader threads, the number of updater
  * threads, and the duration of the test in seconds.  The second line
  * lists the average duration of each type of operation in nanoseconds,
  * or "nan" if the corresponding type of operation was not performed.
  *
  *     ./rcu <nreaders> stress [ <seconds> ]
  *         Run a stress test with the specified number of readers and
  *         one updater.
  *
  * This test produces output as follows:
  *
  * n_reads: 114633217  n_updates: 3903415  n_mberror: 0
  * rcu_stress_count: 114618391 14826 0 0 0 0 0 0 0 0 0
  *
  * The first line lists the number of RCU read and update operations
  * executed, followed by the number of memory-ordering violations
  * (which will be zero in a correct RCU implementation).  The second
  * line lists the number of readers observing progressively more stale
  * data.  A correct RCU implementation will have all but the first two
  * numbers non-zero.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  *
  * Copyright (c) 2008 Paul E. McKenney, IBM Corporation.
  */
 
 /*
  * Test variables.
  */
 
 #include "qemu/osdep.h"
 #include "qemu/atomic.h"
 #include "qemu/rcu.h"
 #include "qemu/thread.h"
 
 int nthreadsrunning;
 
 #define GOFLAG_INIT 0
 #define GOFLAG_RUN  1
 #define GOFLAG_STOP 2
 
 static volatile int goflag = GOFLAG_INIT;
 
 #define RCU_READ_RUN 1000
 
 #define NR_THREADS 100
 static QemuThread threads[NR_THREADS];
 static struct rcu_reader_data *data[NR_THREADS];
 static int n_threads;
 
 /*
  * Statistical counts
  *
  * These are the sum of local counters at the end of a run.
  * Updates are protected by a mutex.
  */
 static QemuMutex counts_mutex;
 long long n_reads = 0LL;
 long n_updates = 0L;
 
 static void create_thread(void *(*func)(void *))
 {
     if (n_threads >= NR_THREADS) {
         fprintf(stderr, "Thread limit of %d exceeded!\n", NR_THREADS);
         exit(-1);
     }
     qemu_thread_create(&threads[n_threads], "test", func, &data[n_threads],
                        QEMU_THREAD_JOINABLE);
     n_threads++;
 }
 
 static void wait_all_threads(void)
 {
     int i;
 
     for (i = 0; i < n_threads; i++) {
         qemu_thread_join(&threads[i]);
     }
     n_threads = 0;
 }
 
 /*
  * Performance test.
  */
 
 static void *rcu_read_perf_test(void *arg)
 {
     int i;
     long long n_reads_local = 0;
 
     rcu_register_thread();
 
     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     qatomic_inc(&nthreadsrunning);
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
     }
     while (goflag == GOFLAG_RUN) {
         for (i = 0; i < RCU_READ_RUN; i++) {
             rcu_read_lock();
             rcu_read_unlock();
         }
         n_reads_local += RCU_READ_RUN;
     }
     qemu_mutex_lock(&counts_mutex);
     n_reads += n_reads_local;
     qemu_mutex_unlock(&counts_mutex);
 
     rcu_unregister_thread();
     return NULL;
 }
 
 static void *rcu_update_perf_test(void *arg)
 {
     long long n_updates_local = 0;
 
     rcu_register_thread();
 
     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     qatomic_inc(&nthreadsrunning);
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
     }
     while (goflag == GOFLAG_RUN) {
         synchronize_rcu();
         n_updates_local++;
     }
     qemu_mutex_lock(&counts_mutex);
     n_updates += n_updates_local;
     qemu_mutex_unlock(&counts_mutex);
 
     rcu_unregister_thread();
     return NULL;
 }
 
 static void perftestinit(void)
 {
     nthreadsrunning = 0;
 }
 
 static void perftestrun(int nthreads, int duration, int nreaders, int nupdaters)
 {
     while (qatomic_read(&nthreadsrunning) < nthreads) {
         g_usleep(1000);
     }
     goflag = GOFLAG_RUN;
     g_usleep(duration * G_USEC_PER_SEC);
     goflag = GOFLAG_STOP;
     wait_all_threads();
     printf("n_reads: %lld  n_updates: %ld  nreaders: %d  nupdaters: %d duration: %d\n",
            n_reads, n_updates, nreaders, nupdaters, duration);
     printf("ns/read: %g  ns/update: %g\n",
            ((duration * 1000*1000*1000.*(double)nreaders) /
         (double)n_reads),
            ((duration * 1000*1000*1000.*(double)nupdaters) /
         (double)n_updates));
     exit(0);
 }
 
 static void perftest(int nreaders, int duration)
 {
     int i;
 
     perftestinit();
     for (i = 0; i < nreaders; i++) {
         create_thread(rcu_read_perf_test);
     }
     create_thread(rcu_update_perf_test);
     perftestrun(i + 1, duration, nreaders, 1);
 }
 
 static void rperftest(int nreaders, int duration)
 {
     int i;
 
     perftestinit();
     for (i = 0; i < nreaders; i++) {
         create_thread(rcu_read_perf_test);
     }
     perftestrun(i, duration, nreaders, 0);
 }
 
 static void uperftest(int nupdaters, int duration)
 {
     int i;
 
     perftestinit();
     for (i = 0; i < nupdaters; i++) {
         create_thread(rcu_update_perf_test);
     }
     perftestrun(i, duration, 0, nupdaters);
 }
 
 /*
  * Stress test.
  */
 
 #define RCU_STRESS_PIPE_LEN 10
 
 struct rcu_stress {
     int age;  /* how many update cycles while not rcu_stress_current */
     int mbtest;
 };
 
 struct rcu_stress rcu_stress_array[RCU_STRESS_PIPE_LEN] = { { 0 } };
 struct rcu_stress *rcu_stress_current;
 int n_mberror;
 
 /* Updates protected by counts_mutex */
 long long rcu_stress_count[RCU_STRESS_PIPE_LEN + 1];
 
 
 static void *rcu_read_stress_test(void *arg)
 {
     int i;
     struct rcu_stress *p;
     int pc;
     long long n_reads_local = 0;
     long long rcu_stress_local[RCU_STRESS_PIPE_LEN + 1] = { 0 };
     volatile int garbage = 0;
 
     rcu_register_thread();
 
     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
     }
     while (goflag == GOFLAG_RUN) {
         rcu_read_lock();
         p = qatomic_rcu_read(&rcu_stress_current);
         if (qatomic_read(&p->mbtest) == 0) {
             n_mberror++;
         }
         rcu_read_lock();
         for (i = 0; i < 100; i++) {
             garbage++;
         }
         rcu_read_unlock();
         pc = qatomic_read(&p->age);
         rcu_read_unlock();
         if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) {
             pc = RCU_STRESS_PIPE_LEN;
         }
         rcu_stress_local[pc]++;
         n_reads_local++;
     }
     qemu_mutex_lock(&counts_mutex);
     n_reads += n_reads_local;
     for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++) {
         rcu_stress_count[i] += rcu_stress_local[i];
     }
     qemu_mutex_unlock(&counts_mutex);
 
     rcu_unregister_thread();
     return NULL;
 }
 
 /*
  * Stress Test Updater
  *
  * The updater cycles around updating rcu_stress_current to point at
  * one of the rcu_stress_array_entries and resets it's age. It
  * then increments the age of all the other entries. The age
  * will be read under an rcu_read_lock() and distribution of values
  * calculated. The final result gives an indication of how many
  * previously current rcu_stress entries are in flight until the RCU
  * cycle complete.
  */
 static void *rcu_update_stress_test(void *arg)
 {
     int i, rcu_stress_idx = 0;
     struct rcu_stress *cp = qatomic_read(&rcu_stress_current);
 
     rcu_register_thread();
     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
 
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
     }
 
     while (goflag == GOFLAG_RUN) {
         struct rcu_stress *p;
         rcu_stress_idx++;
         if (rcu_stress_idx >= RCU_STRESS_PIPE_LEN) {
             rcu_stress_idx = 0;
         }
         p = &rcu_stress_array[rcu_stress_idx];
         /* catching up with ourselves would be a bug */
         assert(p != cp);
         qatomic_set(&p->mbtest, 0);
         smp_mb();
         qatomic_set(&p->age, 0);
         qatomic_set(&p->mbtest, 1);
         qatomic_rcu_set(&rcu_stress_current, p);
         cp = p;
         /*
          * New RCU structure is now live, update pipe counts on old
          * ones.
          */
         for (i = 0; i < RCU_STRESS_PIPE_LEN; i++) {
             if (i != rcu_stress_idx) {
                 qatomic_set(&rcu_stress_array[i].age,
                            rcu_stress_array[i].age + 1);
             }
         }
         synchronize_rcu();
         n_updates++;
     }
 
     rcu_unregister_thread();
     return NULL;
 }
 
 static void *rcu_fake_update_stress_test(void *arg)
 {
     rcu_register_thread();
 
     *(struct rcu_reader_data **)arg = get_ptr_rcu_reader();
     while (goflag == GOFLAG_INIT) {
         g_usleep(1000);
     }
     while (goflag == GOFLAG_RUN) {
         synchronize_rcu();
         g_usleep(1000);
     }
 
     rcu_unregister_thread();
     return NULL;
 }
 
 static void stresstest(int nreaders, int duration)
 {
     int i;
 
     rcu_stress_current = &rcu_stress_array[0];
     rcu_stress_current->age = 0;
     rcu_stress_current->mbtest = 1;
     for (i = 0; i < nreaders; i++) {
         create_thread(rcu_read_stress_test);
     }
     create_thread(rcu_update_stress_test);
     for (i = 0; i < 5; i++) {
         create_thread(rcu_fake_update_stress_test);
     }
     goflag = GOFLAG_RUN;
     g_usleep(duration * G_USEC_PER_SEC);
     goflag = GOFLAG_STOP;
     wait_all_threads();
     printf("n_reads: %lld  n_updates: %ld  n_mberror: %d\n",
            n_reads, n_updates, n_mberror);
     printf("rcu_stress_count:");
     for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++) {
         printf(" %lld", rcu_stress_count[i]);
     }
     printf("\n");
     exit(0);
 }
 
 /* GTest interface */
 
 static void gtest_stress(int nreaders, int duration)
 {
     int i;
 
     rcu_stress_current = &rcu_stress_array[0];
     rcu_stress_current->age = 0;
     rcu_stress_current->mbtest = 1;
     for (i = 0; i < nreaders; i++) {
         create_thread(rcu_read_stress_test);
     }
     create_thread(rcu_update_stress_test);
     for (i = 0; i < 5; i++) {
         create_thread(rcu_fake_update_stress_test);
     }
     goflag = GOFLAG_RUN;
     g_usleep(duration * G_USEC_PER_SEC);
     goflag = GOFLAG_STOP;
     wait_all_threads();
     g_assert_cmpint(n_mberror, ==, 0);
     for (i = 2; i <= RCU_STRESS_PIPE_LEN; i++) {
         g_assert_cmpint(rcu_stress_count[i], ==, 0);
     }
 }
 
 static void gtest_stress_1_1(void)
 {
     gtest_stress(1, 1);
 }
 
 static void gtest_stress_10_1(void)
 {
     gtest_stress(10, 1);
 }
 
 static void gtest_stress_1_5(void)
 {
     gtest_stress(1, 5);
 }
 
 static void gtest_stress_10_5(void)
 {
     gtest_stress(10, 5);
 }
 
 /*
  * Mainprogram.
  */
 
 static void usage(int argc, char *argv[])
 {
     fprintf(stderr, "Usage: %s [nreaders [ [r|u]perf | stress [duration]]\n",
             argv[0]);
     exit(-1);
 }
 
 int main(int argc, char *argv[])
 {
     int nreaders = 1;
     int duration = 1;
 
     qemu_mutex_init(&counts_mutex);
     if (argc >= 2 && argv[1][0] == '-') {
         g_test_init(&argc, &argv, NULL);
         if (g_test_quick()) {
             g_test_add_func("/rcu/torture/1reader", gtest_stress_1_1);
             g_test_add_func("/rcu/torture/10readers", gtest_stress_10_1);
         } else {
             g_test_add_func("/rcu/torture/1reader", gtest_stress_1_5);
             g_test_add_func("/rcu/torture/10readers", gtest_stress_10_5);
         }
         return g_test_run();
     }
 
     if (argc >= 2) {
         nreaders = strtoul(argv[1], NULL, 0);
     }
     if (argc > 3) {
         duration = strtoul(argv[3], NULL, 0);
     }
     if (argc < 3 || strcmp(argv[2], "stress") == 0) {
         stresstest(nreaders, duration);
     } else if (strcmp(argv[2], "rperf") == 0) {
         rperftest(nreaders, duration);
     } else if (strcmp(argv[2], "uperf") == 0) {
         uperftest(nreaders, duration);
     } else if (strcmp(argv[2], "perf") == 0) {
         perftest(nreaders, duration);
     }
     usage(argc, argv);
     return 0;
 }