#define _GNU_SOURCE

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/uio.h>
#include <unistd.h>
#include <stdlib.h>

#define	NUM_PAGES	(256)

int main(int argc, char **argv)
{
	int ret, fd;
	long pagesize;
	struct iovec	iov;

	if (argc < 2) {
		fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
		return 1;
	}

	pagesize = sysconf(_SC_PAGESIZE);
	if (pagesize < 0) {
		perror("sysconf");
		return 1;
	}

	fd = open(argv[1], O_CREAT|O_WRONLY|O_DIRECT, 0666);
	if (fd < 0) {
		perror("open");
		return 1;
	}

	ret = posix_memalign(&iov.iov_base, pagesize, pagesize * NUM_PAGES);
	if (ret) {
		perror("posix_memalign");
		return 1;
	}
	iov.iov_len = pagesize * NUM_PAGES;

	ret = writev(fd, &iov, 1);
	if (ret < 0) {
		perror("writev");
		return 1;
	}

	return 0;
}