/*
* 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 = &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 = &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 = &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 = &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 = &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;
}
