ref: 4696de84b4553d33d2bc1649a55d303c1788a41b
dir: /sys/src/libc/9sys/cputime.c/
#include <u.h>
#include <libc.h>
#define	HZ	1000
double
cputime(void)
{
	long t[4];
	long times(long*);
	int i;
	times(t);
	for(i=1; i<4; i++)
		t[0] += t[i];
	return t[0] / (double)HZ;
}