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/**
* gcc -o iotest io.c
*/
#include <assert.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <sys/time.h>
#include <assert.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
static int c = 0;
static int tsize = 1000 * 1048576;
static const char path[] = "/tmp/wt.dat";
static char buf[65536];
static uint64_t now(void) {
struct timeval tv;
if (gettimeofday(&tv, NULL))
abort();
return tv.tv_sec * 1000000ULL + tv.tv_usec;
}
static void writetest(int size, size_t bsize)
{
int i;
uint64_t start, end;
double elapsed;
double mbps;
assert(bsize <= sizeof buf);
int fd = open(path, O_CREAT|O_WRONLY, 0644);
if (fd < 0) {
perror("open failed");
exit(254);
}
start = now();
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);
}
}
#ifndef NSYNC
# ifdef __linux__
fdatasync(fd);
# else
fsync(fd);
# endif
#endif /* SYNC */
close(fd);
end = now();
elapsed = (end - start) / 1e6;
mbps = ((tsize/elapsed)) / 1048576;
fprintf(stderr, "\nWrote %d bytes in %03fs using %ld byte buffers: %03fmB/s\n", size, elapsed, bsize, mbps);
}
void readtest(int size, size_t bsize)
{
int i;
uint64_t start, end;
double elapsed;
double mbps;
assert(bsize <= sizeof buf);
int fd = open(path, O_RDONLY, 0644);
if (fd < 0) {
perror("open failed");
exit(254);
}
start = now();
for (i = 0; i < size; i += bsize) {
int rv = read(fd, buf, bsize);
if (rv < 0) {
perror("write failed");
exit(254);
}
}
close(fd);
end = now();
elapsed = (end - start) / 1e6;
mbps = ((tsize/elapsed)) / 1048576;
fprintf(stderr, "Read %d bytes in %03fs using %ld byte buffers: %03fmB/s\n", size, elapsed, bsize, mbps);
}
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;
}