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

#define	DEFAULT_ALLOC_SIZE	(1024*1024)


int main(int argc, char *argv[])
{
	pid_t pid;
	char *p;
	int len;
	int num;

	if(argc != 2) {
		len = DEFAULT_ALLOC_SIZE;
	} else {
		len = strtol(argv[1], NULL, 10);
		if(len <= 0) {
			len = DEFAULT_ALLOC_SIZE;
		}
	}

	for(num=0; ; num++) {
		printf("\n*** Press return key to fork.(childlen=%d,len=%d)\n",
			num, len);
		getchar();
		pid = fork();
		if(pid == -1) {
			perror("fork");
			return 1;
		} else if(pid) {
			/* child process */
			int i;
			p = malloc(len);
			printf("*** pid=%d allocate=%p len=%d\n", pid, p, len);
			while(1) {
				for(i=0; i<len; i++) {
					p[i] = i%0xff; /* dummy access */
				}
				sleep((rand()%100)+5);
			}
			/* child process does not exit */
		}
		sleep(1);
		printf("\n*** free\n");
		system("free");
		printf("\n*** vmstat\n");
		system("vmstat");
	}
}