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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2009 Oracle. All rights reserved.
*
* $Id$
*/
#include "bench.h"
#ifdef _POSIX_THREADS
typedef struct {
pthread_t id;
DB_ENV *dbenv;
int iterations;
db_mutex_t mutex;
int contentions;
} threadinfo_t;
static void *latch_threadmain __P((void *));
#endif
static int time_latches __P((DB_ENV *, db_mutex_t, int));
#define LATCH_THREADS_MAX 100
/* Return the environment needed for __mutex_lock(), depending on release.
*/
#if DB_VERSION_MAJOR <4 || DB_VERSION_MAJOR == 4 && DB_VERSION_MINOR < 7
#define ENV_ARG(dbenv) (dbenv)
#else
#define ENV_ARG(dbenv) ((dbenv)->env)
#endif
/*
* In the mulithreaded latch test each thread locks and updates this variable.
* It detects contention when the value of this counter changes during the
* mutex lock call.
*/
static int CurrentCounter = 0;
static int latch_usage __P((void));
static int
latch_usage()
{
(void)fprintf(stderr, "usage: b_latch [-c number of %s",
"lock+unlock pairs] [-n number of threads]\n");
return (EXIT_FAILURE);
}
/*
* time_latches --
* Repeat acquire and release of an exclusive latch, counting the
* number of times that 'someone else' got it just as we tried to.
*/
static int time_latches(dbenv, mutex, iterations)
DB_ENV *dbenv;
db_mutex_t mutex;
int iterations;
{
int contended, i, previous;
contended = 0;
for (i = 0; i < iterations; ++i) {
previous = CurrentCounter;
DB_BENCH_ASSERT(__mutex_lock(ENV_ARG(dbenv), mutex) == 0);
if (previous != CurrentCounter)
contended++;
CurrentCounter++;
DB_BENCH_ASSERT(__mutex_unlock(ENV_ARG(dbenv), mutex) == 0);
}
return (contended);
}
#ifdef _POSIX_THREADS
/*
* latch_threadmain --
* Entry point for multithreaded latching test.
*
* Currently only supported for POSIX threads.
*/
static void *
latch_threadmain(arg)
void *arg;
{
threadinfo_t *info = arg;
info->contentions = time_latches(info->dbenv,
info->mutex, info->iterations);
return ((void *) 0);
}
#endif
/*
* b_latch --
* Measure the speed of latching and mutex operations.
*
*
*/
int
b_latch(argc, argv)
int argc;
char *argv[];
{
extern char *optarg;
extern int optind;
DB_ENV *dbenv;
int ch, count, nthreads;
#ifdef _POSIX_THREADS
threadinfo_t threads[LATCH_THREADS_MAX];
int i, ret;
void *status;
#endif
db_mutex_t mutex;
int contended;
contended = 0;
count = 1000000;
nthreads = 0; /* Default to running the test without extra threads */
while ((ch = getopt(argc, argv, "c:n:")) != EOF)
switch (ch) {
case 'c':
count = atoi(optarg);
break;
case 'n':
nthreads = atoi(optarg);
break;
case '?':
default:
return (latch_usage());
}
argc -= optind;
argv += optind;
if (argc != 0 || count < 1 || nthreads < 0 ||
nthreads > LATCH_THREADS_MAX)
return (latch_usage());
#ifndef _POSIX_THREADS
if (nthreads > 1) {
(void)fprintf(stderr,
"Sorry, support for -n %d: threads not yet available\n",
nthreads);
exit(EXIT_FAILURE);
}
#endif
/* Create the environment. */
DB_BENCH_ASSERT(db_env_create(&dbenv, 0) == 0);
dbenv->set_errfile(dbenv, stderr);
#if DB_VERSION_MAJOR == 3 && DB_VERSION_MINOR < 1
DB_BENCH_ASSERT(dbenv->open(dbenv, TESTDIR,
NULL, DB_CREATE | DB_INIT_LOCK | DB_INIT_LOG |
DB_INIT_MPOOL | DB_INIT_TXN | DB_PRIVATE, 0666) == 0);
#else
DB_BENCH_ASSERT(dbenv->open(dbenv, TESTDIR,
DB_CREATE | DB_INIT_LOCK | DB_INIT_LOG |
DB_INIT_MPOOL | DB_INIT_TXN | DB_PRIVATE, 0666) == 0);
#endif
DB_BENCH_ASSERT(dbenv->mutex_alloc(dbenv, DB_MUTEX_SELF_BLOCK,
&mutex) == 0);
#ifdef _POSIX_THREADS
for (i = 0; i < nthreads; i++) {
threads[i].dbenv = dbenv;
threads[i].mutex = mutex;
threads[i].iterations =
nthreads <= 1 ? count : count / nthreads;
}
#endif
/* Start and acquire and release a mutex count times. If there's
* posix support and a non-zero number of threads start them.
*/
TIMER_START;
#ifdef _POSIX_THREADS
if (nthreads > 0) {
for (i = 0; i < nthreads; i++)
DB_BENCH_ASSERT(pthread_create(&threads[i].id,
NULL, latch_threadmain, &threads[i]) == 0);
for (i = 0; i < nthreads; i++) {
ret = pthread_join(threads[i].id, &status);
DB_BENCH_ASSERT(ret == 0);
contended += threads[i].contentions;
}
} else
#endif
contended = time_latches(dbenv, mutex, count);
TIMER_STOP;
printf("# %d mutex lock-unlock pairs of %d thread%s\n", count,
nthreads, nthreads == 1 ? "" : "s");
TIMER_DISPLAY(count);
DB_BENCH_ASSERT(dbenv->mutex_free(dbenv, mutex) == 0);
DB_BENCH_ASSERT(dbenv->close(dbenv, 0) == 0);
COMPQUIET(contended, 0);
return (0);
}
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