'Update the AMP'

def update(self, process_list):

    logger.debug('{}:    Update    stats    using    service    {}'.format(self.NAME, self.get('service_cmd')))
    try:
        res = self.get('command')
    except OSError as e:
        logger.debug('{}:    Error    while    executing    service    ({})'.format(self.NAME, e))
    else:
        if (res is not None):
            try:
                msg = u(check_output(res.split(), stderr=STDOUT))
                self.set_result(to_ascii(msg.rstrip()))
            except CalledProcessError as e:
                self.set_result(e.output)
        else:
            self.set_result('CPU:    {:.1f}%    |    MEM:    {:.1f}%'.format(sum([p['cpu_percent'] for p in process_list]), sum([p['memory_percent'] for p in process_list])))
    return self.result()
