ref: 7fa5db9d6a8d3b7d1430cab7df9fda9b8ee1ec0b
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;
}