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/*
A ping-pong fcntl byte range lock test
Copyright (C) Andrew Tridgell 2002
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 3 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, see <http://www.gnu.org/licenses/>.
*/
/*
This measures the ping-pong byte range lock latency. It is
especially useful on a cluster of nodes sharing a common lock
manager as it will give some indication of the lock managers
performance under stress.
tridge@samba.org, February 2002
*/
#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <getopt.h>
#include <sys/mman.h>
static struct timeval tp1,tp2;
static int do_reads, do_writes, use_mmap;
static void start_timer(void)
{
gettimeofday(&tp1,NULL);
}
static double end_timer(void)
{
gettimeofday(&tp2,NULL);
return (tp2.tv_sec + (tp2.tv_usec*1.0e-6)) -
(tp1.tv_sec + (tp1.tv_usec*1.0e-6));
}
/* lock a byte range in a open file */
static int lock_range(int fd, int offset, int len)
{
struct flock lock;
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = offset;
lock.l_len = len;
lock.l_pid = 0;
return fcntl(fd,F_SETLKW,&lock);
}
/* unlock a byte range in a open file */
static int unlock_range(int fd, int offset, int len)
{
struct flock lock;
lock.l_type = F_UNLCK;
lock.l_whence = SEEK_SET;
lock.l_start = offset;
lock.l_len = len;
lock.l_pid = 0;
return fcntl(fd,F_SETLKW,&lock);
}
/* run the ping pong test on fd */
static void ping_pong(int fd, int num_locks)
{
unsigned count = 0;
int i=0, loops=0;
unsigned char *val;
unsigned char incr=0, last_incr=0;
unsigned char *p = NULL;
int ret;
ret = ftruncate(fd, num_locks+1);
if (ret == -1) {
printf("ftruncate failed: %s\n", strerror(errno));
return;
}
if (use_mmap) {
p = mmap(NULL, num_locks+1, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (p == MAP_FAILED) {
printf("mmap failed: %s\n", strerror(errno));
return;
}
}
val = (unsigned char *)calloc(num_locks+1, sizeof(unsigned char));
if (val == NULL) {
printf("calloc failed\n");
return;
}
start_timer();
lock_range(fd, 0, 1);
i = 0;
while (1) {
if (lock_range(fd, (i+1) % num_locks, 1) != 0) {
printf("lock at %d failed! - %s\n",
(i+1) % num_locks, strerror(errno));
}
if (do_reads) {
unsigned char c;
if (use_mmap) {
c = p[i];
} else if (pread(fd, &c, 1, i) != 1) {
printf("read failed at %d\n", i);
}
incr = c - val[i];
val[i] = c;
}
if (do_writes) {
char c = val[i] + 1;
if (use_mmap) {
p[i] = c;
} else if (pwrite(fd, &c, 1, i) != 1) {
printf("write failed at %d\n", i);
}
}
if (unlock_range(fd, i, 1) != 0) {
printf("unlock at %d failed! - %s\n",
i, strerror(errno));
}
i = (i+1) % num_locks;
count++;
if (loops > num_locks && incr != last_incr) {
last_incr = incr;
printf("data increment = %u\n", incr);
fflush(stdout);
}
if (end_timer() > 1.0) {
printf("%8u locks/sec\r",
(unsigned)(2*count/end_timer()));
fflush(stdout);
start_timer();
count=0;
}
loops++;
}
}
int main(int argc, char *argv[])
{
char *fname;
int fd, num_locks;
int c;
while ((c = getopt(argc, argv, "rwm")) != -1) {
switch (c){
case 'w':
do_writes = 1;
break;
case 'r':
do_reads = 1;
break;
case 'm':
use_mmap = 1;
break;
default:
fprintf(stderr, "Unknown option '%c'\n", c);
exit(1);
}
}
argv += optind;
argc -= optind;
if (argc < 2) {
printf("ping_pong [options] <file> <num_locks>\n");
printf(" -r do reads\n");
printf(" -w do writes\n");
printf(" -m use mmap\n");
exit(1);
}
fname = argv[0];
num_locks = atoi(argv[1]);
fd = open(fname, O_CREAT|O_RDWR, 0600);
if (fd == -1) exit(1);
ping_pong(fd, num_locks);
return 0;
}
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