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/**
* gcc -o iotest io.c
*/
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <sys/time.h>
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
int tsize = 1000 * 1048576;
const char *path = "/tmp/wt.dat";
int c = 0;
char* bufit(size_t l)
{
char *p = malloc(l);
memset(p, '!', l);
return p;
}
void writetest(int size, size_t bsize)
{
int i;
char *buf = bufit(bsize);
struct timeval start, end;
double elapsed;
double mbps;
int fd = open(path, O_CREAT|O_WRONLY, 0644);
if (fd < 0) {
perror("open failed");
exit(254);
}
assert(0 == gettimeofday(&start, NULL));
for (i = 0; i < size; i += bsize) {
int rv = write(fd, buf, bsize);
if (c++ % 2000 == 0) fprintf(stderr, ".");
if (rv < 0) {
perror("write failed");
exit(254);
}
}
#ifdef __linux__
fdatasync(fd);
#else
fsync(fd);
#endif
close(fd);
assert(0 == gettimeofday(&end, NULL));
elapsed = (end.tv_sec - start.tv_sec) + ((double)(end.tv_usec - start.tv_usec))/100000.;
mbps = ((tsize/elapsed)) / 1048576;
fprintf(stderr, "\nWrote %d bytes in %03fs using %ld byte buffers: %03fmB/s\n", size, elapsed, bsize, mbps);
free(buf);
}
void readtest(int size, size_t bsize)
{
int i;
char *buf = bufit(bsize);
struct timeval start, end;
double elapsed;
double mbps;
int fd = open(path, O_RDONLY, 0644);
if (fd < 0) {
perror("open failed");
exit(254);
}
assert(0 == gettimeofday(&start, NULL));
for (i = 0; i < size; i += bsize) {
int rv = read(fd, buf, bsize);
if (rv < 0) {
perror("write failed");
exit(254);
}
}
close(fd);
assert(0 == gettimeofday(&end, NULL));
elapsed = (end.tv_sec - start.tv_sec) + ((double)(end.tv_usec - start.tv_usec))/100000.;
mbps = ((tsize/elapsed)) / 1048576;
fprintf(stderr, "Read %d bytes in %03fs using %ld byte buffers: %03fmB/s\n", size, elapsed, bsize, mbps);
free(buf);
}
void cleanup() {
unlink(path);
}
int main()
{
int i;
int bsizes[] = {1024, 4096, 8192, 16384, 32768, 65536, 0};
for (i = 0; bsizes[i] != 0; i++) {
writetest(tsize, bsizes[i]);
}
for (i = 0; bsizes[i] != 0; i++) {
readtest(tsize, bsizes[i]);
}
atexit(cleanup);
return 0;
}
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