CodeSamples/defer/rcutorture.h

/*
 * rcutorture.h: simple user-level performance/stress test of RCU.
 *
 * Usage:
 * 	./rcu <nreaders> rperf [ <cpustride> ]
 * 		Run a read-side performance test with the specified
 * 		number of readers spaced by <cpustride>.
 * 		Thus "./rcu 16 rperf 2" would run 16 readers on even-numbered
 * 		CPUs from 0 to 30.
 * 	./rcu <nupdaters> uperf [ <cpustride> ]
 * 		Run an update-side performance test with the specified
 * 		number of updaters and specified CPU spacing.
 * 	./rcu <nreaders> perf [ <cpustride> ]
 * 		Run a combined read/update performance test with the specified
 * 		number of readers and one updater and specified CPU spacing.
 * 		The readers run on the low-numbered CPUs and the updater
 * 		of the highest-numbered CPU.
 *
 * 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
 * 		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.
 */

DEFINE_PER_THREAD(long long, n_reads_pt);
DEFINE_PER_THREAD(long long, n_updates_pt);

long long n_reads = 0LL;
long n_updates = 0L;
atomic_t nthreadsrunning;
char argsbuf[64];

#define GOFLAG_INIT 0
#define GOFLAG_RUN  1
#define GOFLAG_STOP 2

int goflag __attribute__((__aligned__(CACHE_LINE_SIZE))) = GOFLAG_INIT;

#define RCU_READ_RUN 1000

#ifdef RCU_READ_NESTABLE
#define rcu_read_lock_nest() rcu_read_lock()
#define rcu_read_unlock_nest() rcu_read_unlock()
#else /* #ifdef RCU_READ_NESTABLE */
#define rcu_read_lock_nest()
#define rcu_read_unlock_nest()
#endif /* #else #ifdef RCU_READ_NESTABLE */

#ifndef mark_rcu_quiescent_state
#define mark_rcu_quiescent_state() do ; while (0)
#endif /* #ifdef mark_rcu_quiescent_state */

#ifndef put_thread_offline
#define put_thread_offline()		do ; while (0)
#define put_thread_online()		do ; while (0)
#define put_thread_online_delay()	do ; while (0)
#else /* #ifndef put_thread_offline */
#define put_thread_online_delay()	synchronize_rcu()
#endif /* #else #ifndef put_thread_offline */

#ifndef NEED_REGISTER_THREAD
#define rcu_register_thread()		do ; while (0)
#define rcu_unregister_thread()		do ; while (0)
#endif /* #ifndef NEED_REGISTER_THREAD */

/*
 * Performance test.
 */

void *rcu_read_perf_test(void *arg)
{
	int i;
	int me = (long)arg;
	long long n_reads_local = 0;

	run_on(me);
	rcu_register_thread();
	atomic_inc(&nthreadsrunning);
	while (goflag == GOFLAG_INIT)
		poll(NULL, 0, 1);
	mark_rcu_quiescent_state();
	while (goflag == GOFLAG_RUN) {
		for (i = 0; i < RCU_READ_RUN; i++) {
			rcu_read_lock();
			/* rcu_read_lock_nest(); */
			/* rcu_read_unlock_nest(); */
			rcu_read_unlock();
		}
		n_reads_local += RCU_READ_RUN;
		mark_rcu_quiescent_state();
	}
	__get_thread_var(n_reads_pt) += n_reads_local;
	put_thread_offline();
	rcu_unregister_thread();

	return (NULL);
}

void *rcu_update_perf_test(void *arg)
{
	long long n_updates_local = 0;

	rcu_register_thread();
	atomic_inc(&nthreadsrunning);
	while (goflag == GOFLAG_INIT)
		poll(NULL, 0, 1);
	while (goflag == GOFLAG_RUN) {
		synchronize_rcu();
		n_updates_local++;
	}
	__get_thread_var(n_updates_pt) += n_updates_local;
	rcu_unregister_thread();
	return NULL;
}

void perftestinit(void)
{
	init_per_thread(n_reads_pt, 0LL);
	init_per_thread(n_updates_pt, 0LL);
	atomic_set(&nthreadsrunning, 0);
}

void perftestrun(int nthreads, int nreaders, int nupdaters)
{
	int t;
	int duration = 1;

	smp_mb();
	while (atomic_read(&nthreadsrunning) < nthreads)
		poll(NULL, 0, 1);
	goflag = GOFLAG_RUN;
	smp_mb();
	sleep(duration);
	smp_mb();
	goflag = GOFLAG_STOP;
	smp_mb();
	wait_all_threads();
	for_each_thread(t) {
		n_reads += per_thread(n_reads_pt, t);
		n_updates += per_thread(n_updates_pt, t);
	}
	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 cpustride)
{
	int i;
	long arg;

	perftestinit();
	for (i = 0; i < nreaders; i++) {
		arg = (long)(i * cpustride);
		create_thread(rcu_read_perf_test, (void *)arg);
	}
	arg = (long)(i * cpustride);
	create_thread(rcu_update_perf_test, (void *)arg);
	perftestrun(i + 1, nreaders, 1);
}

void rperftest(int nreaders, int cpustride)
{
	int i;
	long arg;

	perftestinit();
	init_per_thread(n_reads_pt, 0LL);
	for (i = 0; i < nreaders; i++) {
		arg = (long)(i * cpustride);
		create_thread(rcu_read_perf_test, (void *)arg);
	}
	perftestrun(i, nreaders, 0);
}

void uperftest(int nupdaters, int cpustride)
{
	int i;
	long arg;

	perftestinit();
	init_per_thread(n_reads_pt, 0LL);
	for (i = 0; i < nupdaters; i++) {
		arg = (long)(i * cpustride);
		create_thread(rcu_update_perf_test, (void *)arg);
	}
	perftestrun(i, 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;
DEFINE_PER_THREAD(long long [RCU_STRESS_PIPE_LEN + 1], rcu_stress_count);

int garbage = 0;

void *rcu_read_stress_test(void *arg)
{
	int i;
	int itercnt = 0;
	struct rcu_stress *p;
	int pc;

	while (goflag == GOFLAG_INIT)
		poll(NULL, 0, 1);
	rcu_register_thread();
	mark_rcu_quiescent_state();
	while (goflag == GOFLAG_RUN) {
		rcu_read_lock();
		p = rcu_dereference(rcu_stress_current);
		if (p->mbtest == 0)
			n_mberror++;
		rcu_read_lock_nest();
		for (i = 0; i < 100; i++)
			garbage++;
		rcu_read_unlock_nest();
		pc = p->pipe_count;
		rcu_read_unlock();
		if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0))
			pc = RCU_STRESS_PIPE_LEN;
		__get_thread_var(rcu_stress_count)[pc]++;
		__get_thread_var(n_reads_pt)++;
		mark_rcu_quiescent_state();
		if ((++itercnt % 0x1000) == 0) {
			put_thread_offline();
			put_thread_online_delay();
			put_thread_online();
		}
	}
	put_thread_offline();
	rcu_unregister_thread();

	return (NULL);
}

void *rcu_update_stress_test(void *arg)
{
	int i;
	struct rcu_stress *p;

	while (goflag == GOFLAG_INIT)
		poll(NULL, 0, 1);
	rcu_register_thread();
	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;
		smp_mb();
		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++;
		synchronize_rcu();
		n_updates++;
	}
	rcu_unregister_thread();
	return NULL;
}

void *rcu_fake_update_stress_test(void *arg)
{
	while (goflag == GOFLAG_INIT)
		poll(NULL, 0, 1);
	rcu_register_thread();
	while (goflag == GOFLAG_RUN) {
		synchronize_rcu();
		poll(NULL, 0, 1);
	}
	rcu_unregister_thread();
	return NULL;
}

void stresstest(int nreaders)
{
	int i;
	int t;
	long long *p;
	long long sum;

	init_per_thread(n_reads_pt, 0LL);
	for_each_thread(t) {
		p = &per_thread(rcu_stress_count,t)[0];
		for (i = 0; i <= RCU_STRESS_PIPE_LEN; i++)
			p[i] = 0LL;
	}
	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);
	smp_mb();
	goflag = GOFLAG_RUN;
	smp_mb();
	sleep(10);
	smp_mb();
	goflag = GOFLAG_STOP;
	smp_mb();
	wait_all_threads();
	for_each_thread(t)
		n_reads += per_thread(n_reads_pt, t);
	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++) {
		sum = 0LL;
		for_each_thread(t) {
			sum += per_thread(rcu_stress_count, t)[i];
		}
		printf(" %lld", sum);
	}
	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 cpustride = 1;

	smp_init();
	rcu_init();

	if (argc > 1) {
		nreaders = strtoul(argv[1], NULL, 0);
		if (argc == 2)
			perftest(nreaders, cpustride);
		if (argc > 3)
			cpustride = strtoul(argv[3], NULL, 0);
		if (strcmp(argv[2], "perf") == 0)
			perftest(nreaders, cpustride);
		else if (strcmp(argv[2], "rperf") == 0)
			rperftest(nreaders, cpustride);
		else if (strcmp(argv[2], "uperf") == 0)
			uperftest(nreaders, cpustride);
		else if (strcmp(argv[2], "stress") == 0)
			stresstest(nreaders);
		usage(argc, argv);
	}
	perftest(nreaders, cpustride);
}