def disable_cpu(self, rg):
        '''
        Disable cpus

        rg: range or list of threads to disable
        '''
        if type(rg) == int:
            rg= [rg]
        to_disable= set(rg) & set(self.__get_ranges("online"))
        for cpu in to_disable:
            fpath = path.join("cpu%i"%cpu,"online")
            self.__write_cpu_file(fpath, b"0")