    def logging_outputs_can_be_summed(self) -> bool:
        """
        Whether the logging outputs returned by `forward` can be summed
        across workers prior to calling `reduce_metrics`. Setting this
        to True will improves distributed training speed.
        """
        # XXX: Gather based reduction not implemented for xla yet.
        # So we fall to sum based reduction for xla.
        return self.xla
Whether the logging outputs returned by `forward` can be summed
across workers prior to calling `reduce_metrics`. Setting this
to True will improves distributed training speed.
fairseq/criterions/wav2vec_criterion.py