[Qemu-devel] [RFC PATCH 06/13] rcu: add rcutorture

[Paolo Bonzini]

A stress test program (works :)).  So far not ported to Windows.

Signed-off-by: Paolo Bonzini <address@hidden>
---
 rcutorture.c |  433 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 433 insertions(+), 0 deletions(-)
 create mode 100644 rcutorture.c

diff --git a/rcutorture.c b/rcutorture.c
new file mode 100644
index 0000000..33b258e
--- /dev/null
+++ b/rcutorture.c
@@ -0,0 +1,433 @@
+/*
+ * rcutorture.h: 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.
+ *             Thus "./rcu 16 rperf 2" would run 16 readers on even-numbered
+ *             CPUs from 0 to 30.
+ *     ./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.  None of the threads are affinitied to any
+ *             particular CPU.
+ *
+ * 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 <stdlib.h>
+#include <stdio.h>
+#include <pthread.h>
+#include "rcu.h"
+#include "compiler.h"
+#include "qemu-thread.h"
+
+#include "qemu-thread-posix.c"
+#include "rcu.c"
+
+long long n_reads = 0LL;
+long n_updates = 0L;
+int nthreadsrunning;
+
+char argsbuf[64];
+
+#define GOFLAG_INIT 0
+#define GOFLAG_RUN  1
+#define GOFLAG_STOP 2
+
+volatile int goflag = GOFLAG_INIT;
+
+#define RCU_READ_RUN 1000
+
+#define NR_THREADS 100
+static pthread_t threads[NR_THREADS];
+
+static void create_thread(void *(*func)(void *), void *arg)
+{
+       pthread_t tid;
+       int i;
+
+       if (pthread_create(&tid, NULL, func, arg) != 0) {
+               perror("create_thread:pthread_create");
+               exit(-1);
+       }
+       for (i = 0; i < NR_THREADS; i++) {
+               if (__sync_bool_compare_and_swap(&threads[i], 0, tid))
+                       break;
+       }
+       if (i >= NR_THREADS) {
+               fprintf(stderr, "Thread limit of %d exceeded!\n", NR_THREADS);
+               exit(-1);
+       }
+}
+
+static void wait_all_threads(void)
+{
+       int i;
+       void *vp;
+       pthread_t tid;
+
+       for (i = 1; i < NR_THREADS; i++) {
+               tid = threads[i];
+               if (tid != 0) {
+                       if (pthread_join(tid, &vp) != 0) {
+                               perror("wait_thread:pthread_join");
+                               exit(-1);
+                       }
+                       threads[i] = 0;
+               }
+       }
+}
+
+/*
+ * Performance test.
+ */
+
+void *rcu_read_perf_test(void *arg)
+{
+       int i;
+       long long n_reads_local = 0;
+
+       rcu_register_thread();
+       __sync_fetch_and_add(&nthreadsrunning, 1);
+       rcu_thread_offline();
+       while (goflag == GOFLAG_INIT)
+               poll(NULL, 0, 1);
+       rcu_thread_online();
+       while (goflag == GOFLAG_RUN) {
+               for (i = 0; i < RCU_READ_RUN; i++) {
+                       rcu_read_lock();
+                       rcu_read_unlock();
+               }
+               n_reads_local += RCU_READ_RUN;
+               rcu_quiescent_state();
+       }
+       __sync_fetch_and_add(&n_reads, n_reads_local);
+       rcu_unregister_thread();
+
+       return (NULL);
+}
+
+void *rcu_update_perf_test(void *arg)
+{
+       long long n_updates_local = 0;
+
+       __sync_fetch_and_add(&nthreadsrunning, 1);
+       while (goflag == GOFLAG_INIT)
+               poll(NULL, 0, 1);
+       while (goflag == GOFLAG_RUN) {
+               synchronize_rcu();
+               n_updates_local++;
+       }
+       __sync_fetch_and_add(&n_updates, n_updates_local);
+       return NULL;
+}
+
+void perftestinit(void)
+{
+       nthreadsrunning = 0;
+}
+
+void perftestrun(int nthreads, int duration, int nreaders, int nupdaters)
+{
+       int t;
+
+       while (ACCESS_ONCE(nthreadsrunning) < nthreads)
+               poll(NULL, 0, 1);
+       goflag = GOFLAG_RUN;
+       sleep(duration);
+       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);
+}
+
+void perftest(int nreaders, int duration)
+{
+       int i;
+
+       perftestinit();
+       for (i = 0; i < nreaders; i++) {
+               create_thread(rcu_read_perf_test, NULL);
+       }
+       create_thread(rcu_update_perf_test, NULL);
+       perftestrun(i + 1, duration, nreaders, 1);
+}
+
+void rperftest(int nreaders, int duration)
+{
+       int i;
+
+       perftestinit();
+       for (i = 0; i < nreaders; i++) {
+               create_thread(rcu_read_perf_test, NULL);
+       }
+       perftestrun(i, duration, nreaders, 0);
+}
+
+void uperftest(int nupdaters, int duration)
+{
+       int i;
+
+       perftestinit();
+       for (i = 0; i < nupdaters; i++) {
+               create_thread(rcu_update_perf_test, NULL);
+       }
+       perftestrun(i, duration, 0, nupdaters);
+}
+
+/*
+ * Stress test.
+ */
+
+#define RCU_STRESS_PIPE_LEN 10
+
+struct rcu_stress {
+       int pipe_count;
+       int mbtest;
+};
+
+struct rcu_stress rcu_stress_array[RCU_STRESS_PIPE_LEN] = { { 0 } };
+struct rcu_stress *rcu_stress_current;
+int rcu_stress_idx = 0;
+
+int n_mberror = 0;
+long long rcu_stress_count[RCU_STRESS_PIPE_LEN + 1];
+
+int garbage = 0;
+
+void *rcu_read_stress_test(void *arg)
+{
+       int i;
+       int itercnt = 0;
+       struct rcu_stress *p;
+       int pc;
+       long long n_reads_local;
+
+       rcu_register_thread();
+       rcu_thread_offline();
+       while (goflag == GOFLAG_INIT)
+               poll(NULL, 0, 1);
+       rcu_thread_online();
+       while (goflag == GOFLAG_RUN) {
+               rcu_read_lock();
+               p = rcu_dereference(rcu_stress_current);
+               if (p->mbtest == 0)
+                       n_mberror++;
+               rcu_read_lock();
+               for (i = 0; i < 100; i++)
+                       garbage++;
+               rcu_read_unlock();
+               pc = p->pipe_count;
+               rcu_read_unlock();
+               if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0))
+                       pc = RCU_STRESS_PIPE_LEN;
+               __sync_fetch_and_add(&rcu_stress_count[pc], 1);
+               n_reads_local++;
+               rcu_quiescent_state();
+               if ((++itercnt % 0x1000) == 0) {
+                       synchronize_rcu();
+               }
+       }
+       __sync_fetch_and_add(&n_reads, n_reads_local);
+       rcu_thread_offline();
+       rcu_unregister_thread();
+
+       return (NULL);
+}
+
+#if 0
+void rcu_update_stress_test_rcu(struct rcu_head *head)
+{
+       if (pthread_mutex_lock(&call_rcu_test_mutex) != 0) {
+               perror("pthread_mutex_lock");
+               exit(-1);
+       }
+       if (pthread_cond_signal(&call_rcu_test_cond) != 0) {
+               perror("pthread_cond_signal");
+               exit(-1);
+       }
+       if (pthread_mutex_unlock(&call_rcu_test_mutex) != 0) {
+               perror("pthread_mutex_unlock");
+               exit(-1);
+       }
+}
+#endif
+
+void *rcu_update_stress_test(void *arg)
+{
+       int i;
+       struct rcu_stress *p;
+#if 0
+       struct rcu_head rh;
+#endif
+
+       while (goflag == GOFLAG_INIT)
+               poll(NULL, 0, 1);
+       while (goflag == GOFLAG_RUN) {
+               i = rcu_stress_idx + 1;
+               if (i >= RCU_STRESS_PIPE_LEN)
+                       i = 0;
+               p = &rcu_stress_array[i];
+               p->mbtest = 0;
+               __sync_synchronize();
+               p->pipe_count = 0;
+               p->mbtest = 1;
+               rcu_assign_pointer(rcu_stress_current, p);
+               rcu_stress_idx = i;
+               for (i = 0; i < RCU_STRESS_PIPE_LEN; i++)
+                       if (i != rcu_stress_idx)
+                               rcu_stress_array[i].pipe_count++;
+#if 0
+               if (n_updates & 0x1)
+                       synchronize_rcu();
+               else {
+                       if (pthread_mutex_lock(&call_rcu_test_mutex) != 0) {
+                               perror("pthread_mutex_lock");
+                               exit(-1);
+                       }
+                       call_rcu(&rh, rcu_update_stress_test_rcu);
+                       if (pthread_cond_wait(&call_rcu_test_cond,
+                                             &call_rcu_test_mutex) != 0) {
+                               perror("pthread_cond_wait");
+                               exit(-1);
+                       }
+                       if (pthread_mutex_unlock(&call_rcu_test_mutex) != 0) {
+                               perror("pthread_mutex_unlock");
+                               exit(-1);
+                       }
+               }
+#else
+                       synchronize_rcu();
+#endif
+               n_updates++;
+       }
+       return NULL;
+}
+
+void *rcu_fake_update_stress_test(void *arg)
+{
+       while (goflag == GOFLAG_INIT)
+               poll(NULL, 0, 1);
+       while (goflag == GOFLAG_RUN) {
+               synchronize_rcu();
+               poll(NULL, 0, 1);
+       }
+       return NULL;
+}
+
+void stresstest(int nreaders, int duration)
+{
+       int i;
+       int t;
+       long long *p;
+       long long sum;
+
+       rcu_stress_current = &rcu_stress_array[0];
+       rcu_stress_current->pipe_count = 0;
+       rcu_stress_current->mbtest = 1;
+       for (i = 0; i < nreaders; i++)
+               create_thread(rcu_read_stress_test, NULL);
+       create_thread(rcu_update_stress_test, NULL);
+       for (i = 0; i < 5; i++)
+               create_thread(rcu_fake_update_stress_test, NULL);
+       goflag = GOFLAG_RUN;
+       sleep(duration);
+       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);
+}
+
+/*
+ * Mainprogram.
+ */
+
+void usage(int argc, char *argv[])
+{
+       fprintf(stderr, "Usage: %s [nreaders [ perf | stress ] ]\n", argv[0]);
+       exit(-1);
+}
+
+int main(int argc, char *argv[])
+{
+       int nreaders = 1;
+       int duration = 1;
+
+       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;
+}
-- 
1.7.6