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b9b7581754
This gives much worse numbers for readers, especially if synchronize_rcu is made more expensive as is the case with --enable-membarrier. Before: $ tests/rcutorture 10 stress 10 n_reads: 98304 n_updates: 529 n_mberror: 0 rcu_stress_count: 98302 2 0 0 0 0 0 0 0 0 0 After: $ tests/rcutorture 10 stress 10 n_reads: 165158482 n_updates: 429 n_mberror: 0 rcu_stress_count: 165154364 4118 0 0 0 0 0 0 0 0 0 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
456 lines
12 KiB
C
456 lines
12 KiB
C
/*
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* rcutorture.c: simple user-level performance/stress test of RCU.
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*
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* Usage:
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* ./rcu <nreaders> rperf [ <seconds> ]
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* Run a read-side performance test with the specified
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* number of readers for <seconds> seconds.
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* ./rcu <nupdaters> uperf [ <seconds> ]
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* Run an update-side performance test with the specified
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* number of updaters and specified duration.
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* ./rcu <nreaders> perf [ <seconds> ]
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* Run a combined read/update performance test with the specified
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* number of readers and one updater and specified duration.
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*
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* The above tests produce output as follows:
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*
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* n_reads: 46008000 n_updates: 146026 nreaders: 2 nupdaters: 1 duration: 1
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* ns/read: 43.4707 ns/update: 6848.1
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*
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* The first line lists the total number of RCU reads and updates executed
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* during the test, the number of reader threads, the number of updater
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* threads, and the duration of the test in seconds. The second line
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* lists the average duration of each type of operation in nanoseconds,
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* or "nan" if the corresponding type of operation was not performed.
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*
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* ./rcu <nreaders> stress [ <seconds> ]
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* Run a stress test with the specified number of readers and
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* one updater.
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*
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* This test produces output as follows:
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*
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* n_reads: 114633217 n_updates: 3903415 n_mberror: 0
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* rcu_stress_count: 114618391 14826 0 0 0 0 0 0 0 0 0
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*
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* The first line lists the number of RCU read and update operations
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* executed, followed by the number of memory-ordering violations
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* (which will be zero in a correct RCU implementation). The second
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* line lists the number of readers observing progressively more stale
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* data. A correct RCU implementation will have all but the first two
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* numbers non-zero.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (c) 2008 Paul E. McKenney, IBM Corporation.
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*/
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/*
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* Test variables.
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*/
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#include "qemu/osdep.h"
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#include "qemu/atomic.h"
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#include "qemu/rcu.h"
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#include "qemu/thread.h"
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long long n_reads = 0LL;
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long n_updates = 0L;
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int nthreadsrunning;
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#define GOFLAG_INIT 0
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#define GOFLAG_RUN 1
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#define GOFLAG_STOP 2
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static volatile int goflag = GOFLAG_INIT;
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#define RCU_READ_RUN 1000
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#define NR_THREADS 100
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static QemuMutex counts_mutex;
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static QemuThread threads[NR_THREADS];
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static struct rcu_reader_data *data[NR_THREADS];
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static int n_threads;
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static void create_thread(void *(*func)(void *))
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{
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if (n_threads >= NR_THREADS) {
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fprintf(stderr, "Thread limit of %d exceeded!\n", NR_THREADS);
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exit(-1);
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}
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qemu_thread_create(&threads[n_threads], "test", func, &data[n_threads],
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QEMU_THREAD_JOINABLE);
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n_threads++;
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}
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static void wait_all_threads(void)
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{
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int i;
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for (i = 0; i < n_threads; i++) {
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qemu_thread_join(&threads[i]);
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}
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n_threads = 0;
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}
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/*
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* Performance test.
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*/
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static void *rcu_read_perf_test(void *arg)
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{
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int i;
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long long n_reads_local = 0;
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rcu_register_thread();
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*(struct rcu_reader_data **)arg = &rcu_reader;
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atomic_inc(&nthreadsrunning);
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while (goflag == GOFLAG_INIT) {
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g_usleep(1000);
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}
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while (goflag == GOFLAG_RUN) {
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for (i = 0; i < RCU_READ_RUN; i++) {
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rcu_read_lock();
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rcu_read_unlock();
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}
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n_reads_local += RCU_READ_RUN;
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}
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qemu_mutex_lock(&counts_mutex);
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n_reads += n_reads_local;
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qemu_mutex_unlock(&counts_mutex);
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rcu_unregister_thread();
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return NULL;
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}
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static void *rcu_update_perf_test(void *arg)
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{
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long long n_updates_local = 0;
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rcu_register_thread();
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*(struct rcu_reader_data **)arg = &rcu_reader;
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atomic_inc(&nthreadsrunning);
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while (goflag == GOFLAG_INIT) {
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g_usleep(1000);
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}
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while (goflag == GOFLAG_RUN) {
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synchronize_rcu();
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n_updates_local++;
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}
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qemu_mutex_lock(&counts_mutex);
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n_updates += n_updates_local;
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qemu_mutex_unlock(&counts_mutex);
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rcu_unregister_thread();
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return NULL;
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}
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static void perftestinit(void)
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{
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nthreadsrunning = 0;
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}
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static void perftestrun(int nthreads, int duration, int nreaders, int nupdaters)
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{
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while (atomic_read(&nthreadsrunning) < nthreads) {
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g_usleep(1000);
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}
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goflag = GOFLAG_RUN;
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g_usleep(duration * G_USEC_PER_SEC);
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goflag = GOFLAG_STOP;
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wait_all_threads();
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printf("n_reads: %lld n_updates: %ld nreaders: %d nupdaters: %d duration: %d\n",
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n_reads, n_updates, nreaders, nupdaters, duration);
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printf("ns/read: %g ns/update: %g\n",
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((duration * 1000*1000*1000.*(double)nreaders) /
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(double)n_reads),
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((duration * 1000*1000*1000.*(double)nupdaters) /
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(double)n_updates));
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exit(0);
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}
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static void perftest(int nreaders, int duration)
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{
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int i;
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perftestinit();
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for (i = 0; i < nreaders; i++) {
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create_thread(rcu_read_perf_test);
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}
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create_thread(rcu_update_perf_test);
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perftestrun(i + 1, duration, nreaders, 1);
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}
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static void rperftest(int nreaders, int duration)
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{
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int i;
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perftestinit();
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for (i = 0; i < nreaders; i++) {
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create_thread(rcu_read_perf_test);
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}
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perftestrun(i, duration, nreaders, 0);
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}
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static void uperftest(int nupdaters, int duration)
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{
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int i;
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perftestinit();
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for (i = 0; i < nupdaters; i++) {
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create_thread(rcu_update_perf_test);
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}
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perftestrun(i, duration, 0, nupdaters);
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}
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/*
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* Stress test.
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*/
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#define RCU_STRESS_PIPE_LEN 10
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struct rcu_stress {
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int pipe_count;
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int mbtest;
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};
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struct rcu_stress rcu_stress_array[RCU_STRESS_PIPE_LEN] = { { 0 } };
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struct rcu_stress *rcu_stress_current;
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int rcu_stress_idx;
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int n_mberror;
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long long rcu_stress_count[RCU_STRESS_PIPE_LEN + 1];
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static void *rcu_read_stress_test(void *arg)
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{
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int i;
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struct rcu_stress *p;
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int pc;
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long long n_reads_local = 0;
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long long rcu_stress_local[RCU_STRESS_PIPE_LEN + 1] = { 0 };
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volatile int garbage = 0;
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rcu_register_thread();
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*(struct rcu_reader_data **)arg = &rcu_reader;
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while (goflag == GOFLAG_INIT) {
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g_usleep(1000);
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}
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while (goflag == GOFLAG_RUN) {
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rcu_read_lock();
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p = atomic_rcu_read(&rcu_stress_current);
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if (p->mbtest == 0) {
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n_mberror++;
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}
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rcu_read_lock();
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for (i = 0; i < 100; i++) {
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garbage++;
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}
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rcu_read_unlock();
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pc = p->pipe_count;
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rcu_read_unlock();
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if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) {
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pc = RCU_STRESS_PIPE_LEN;
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}
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rcu_stress_local[pc]++;
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n_reads_local++;
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}
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qemu_mutex_lock(&counts_mutex);
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n_reads += n_reads_local;
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for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++) {
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rcu_stress_count[i] += rcu_stress_local[i];
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}
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qemu_mutex_unlock(&counts_mutex);
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rcu_unregister_thread();
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return NULL;
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}
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static void *rcu_update_stress_test(void *arg)
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{
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int i;
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struct rcu_stress *p;
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rcu_register_thread();
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*(struct rcu_reader_data **)arg = &rcu_reader;
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while (goflag == GOFLAG_INIT) {
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g_usleep(1000);
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}
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while (goflag == GOFLAG_RUN) {
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i = rcu_stress_idx + 1;
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if (i >= RCU_STRESS_PIPE_LEN) {
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i = 0;
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}
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p = &rcu_stress_array[i];
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p->mbtest = 0;
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smp_mb();
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p->pipe_count = 0;
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p->mbtest = 1;
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atomic_rcu_set(&rcu_stress_current, p);
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rcu_stress_idx = i;
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for (i = 0; i < RCU_STRESS_PIPE_LEN; i++) {
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if (i != rcu_stress_idx) {
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rcu_stress_array[i].pipe_count++;
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}
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}
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synchronize_rcu();
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n_updates++;
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}
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rcu_unregister_thread();
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return NULL;
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}
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static void *rcu_fake_update_stress_test(void *arg)
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{
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rcu_register_thread();
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*(struct rcu_reader_data **)arg = &rcu_reader;
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while (goflag == GOFLAG_INIT) {
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g_usleep(1000);
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}
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while (goflag == GOFLAG_RUN) {
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synchronize_rcu();
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g_usleep(1000);
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}
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rcu_unregister_thread();
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return NULL;
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}
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static void stresstest(int nreaders, int duration)
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{
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int i;
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rcu_stress_current = &rcu_stress_array[0];
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rcu_stress_current->pipe_count = 0;
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rcu_stress_current->mbtest = 1;
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for (i = 0; i < nreaders; i++) {
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create_thread(rcu_read_stress_test);
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}
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create_thread(rcu_update_stress_test);
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for (i = 0; i < 5; i++) {
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create_thread(rcu_fake_update_stress_test);
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}
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goflag = GOFLAG_RUN;
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g_usleep(duration * G_USEC_PER_SEC);
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goflag = GOFLAG_STOP;
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wait_all_threads();
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printf("n_reads: %lld n_updates: %ld n_mberror: %d\n",
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n_reads, n_updates, n_mberror);
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printf("rcu_stress_count:");
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for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++) {
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printf(" %lld", rcu_stress_count[i]);
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}
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printf("\n");
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exit(0);
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}
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/* GTest interface */
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static void gtest_stress(int nreaders, int duration)
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{
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int i;
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rcu_stress_current = &rcu_stress_array[0];
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rcu_stress_current->pipe_count = 0;
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rcu_stress_current->mbtest = 1;
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for (i = 0; i < nreaders; i++) {
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create_thread(rcu_read_stress_test);
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}
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create_thread(rcu_update_stress_test);
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for (i = 0; i < 5; i++) {
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create_thread(rcu_fake_update_stress_test);
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}
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goflag = GOFLAG_RUN;
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g_usleep(duration * G_USEC_PER_SEC);
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goflag = GOFLAG_STOP;
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wait_all_threads();
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g_assert_cmpint(n_mberror, ==, 0);
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for (i = 2; i <= RCU_STRESS_PIPE_LEN; i++) {
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g_assert_cmpint(rcu_stress_count[i], ==, 0);
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}
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}
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static void gtest_stress_1_1(void)
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{
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gtest_stress(1, 1);
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}
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static void gtest_stress_10_1(void)
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{
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gtest_stress(10, 1);
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}
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static void gtest_stress_1_5(void)
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{
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gtest_stress(1, 5);
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}
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static void gtest_stress_10_5(void)
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{
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gtest_stress(10, 5);
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}
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/*
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* Mainprogram.
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*/
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static void usage(int argc, char *argv[])
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{
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fprintf(stderr, "Usage: %s [nreaders [ perf | stress ] ]\n", argv[0]);
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exit(-1);
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}
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int main(int argc, char *argv[])
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{
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int nreaders = 1;
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int duration = 1;
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qemu_mutex_init(&counts_mutex);
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if (argc >= 2 && argv[1][0] == '-') {
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g_test_init(&argc, &argv, NULL);
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if (g_test_quick()) {
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g_test_add_func("/rcu/torture/1reader", gtest_stress_1_1);
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g_test_add_func("/rcu/torture/10readers", gtest_stress_10_1);
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} else {
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g_test_add_func("/rcu/torture/1reader", gtest_stress_1_5);
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g_test_add_func("/rcu/torture/10readers", gtest_stress_10_5);
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}
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return g_test_run();
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}
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if (argc >= 2) {
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nreaders = strtoul(argv[1], NULL, 0);
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}
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if (argc > 3) {
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duration = strtoul(argv[3], NULL, 0);
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}
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if (argc < 3 || strcmp(argv[2], "stress") == 0) {
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stresstest(nreaders, duration);
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} else if (strcmp(argv[2], "rperf") == 0) {
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rperftest(nreaders, duration);
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} else if (strcmp(argv[2], "uperf") == 0) {
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uperftest(nreaders, duration);
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} else if (strcmp(argv[2], "perf") == 0) {
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perftest(nreaders, duration);
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}
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usage(argc, argv);
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return 0;
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}
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