ref: 3e94fbcf9c6caa7cde6051bec82cae3b1c8d3e11 dir: /sys/src/cmd/1l/cputime.c/
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] / 100.; }