xmul
sleep_ms = xmul(hz, p->p_racct->r_resources[resource]);
sleep_ms = xmul(sleep_ms, rctl_throttle_pct) / 100;
sleep_ratio = xmul(sleep_ratio, sleep_ratio);
sleep_ratio = xmul(sleep_ratio, rctl_throttle_pct2) / 100;
sleep_ms = xadd(sleep_ms, xmul(sleep_ms, sleep_ratio));