ref: 55cb6d14396ec428fa8d02ce59f9e92b4ee80bc1
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;
}