def _stringify_performance_states(state_dict):
    """ Stringifies performance states across multiple gpus

    Args:
        state_dict (dict(str)): a dictionary of gpu_id performance state values

    Returns:
        str: a stringified version of the dictionary with gpu_id::performance state|gpu_id2::performance_state2 format
    """
    return "|".join("::".join(map(lambda x: str(x), z)) for z in state_dict.items())