calcru
calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL);
calcru(&tu, &rup->ru_utime, &rup->ru_stime, NULL);
calcru(&p->p_tu, &rup->ru_utime, &rup->ru_stime, NULL);
void calcru(struct tusage *, struct timeval *, struct timeval *,