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

int main (int argc, char *argv[])
{
	char *args[] = { "/bin/sh", "-c", "exit", "0", NULL };
	struct timeval start, end;
	long long reps;
	int i;
	int use_vfork = 1;

	if (argc >= 2)
		use_vfork = 0;
	printf("using %s\n", use_vfork ? "vfork" : "fork");
	gettimeofday(&start, NULL);
#define NR 1000
	for (i=0; i<NR; i++) {
		int pid;
		if (use_vfork)
			pid = vfork();
		else
			pid = fork();
		if (!pid) {
			int ret = execve("/bin/sh", args, NULL);
			if (ret)
				_exit(1);
		} else if (pid < 0) {
			perror("vfork");
			exit(1);
		} else {
			int status;
			if (waitpid(pid, &status, 0) < 0)
				perror("waitpid");
		}
	}
	gettimeofday(&end, NULL);

	end.tv_sec -= start.tv_sec;
	end.tv_usec -= start.tv_usec;

	if (end.tv_usec < 0) {
		end.tv_usec += 1000000;
		end.tv_sec -= 1;
	}

	reps = end.tv_sec * 1000000LL + end.tv_usec;
	reps = 1000000LL * NR * 100 / reps;

	printf("elapsed: %5lu.%06lu or %Lu.%02u/s\n",
		end.tv_sec, end.tv_usec, reps / 100, (unsigned)(reps % 100));
	return 0;
}