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ColossalAI/colossalai/nn/loss/loss_2d.py

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from colossalai.nn.layer.parallel_2d import reduce_by_batch_2d
from colossalai.nn.layer.parallel_2d._utils import assert_summa_initialization
from colossalai.registry import LOSSES
from torch.nn.functional import cross_entropy
from torch.nn.modules.loss import _Loss
@LOSSES.register_module
class CrossEntropyLoss2D(_Loss):
"""
Cross entropy loss for 2D parallelism
:param reduction: whether to average the loss, defaults to True
:type reduction: bool, optional
"""
def __init__(self, reduction=True, *args, **kwargs):
super().__init__()
assert_summa_initialization()
self.reduction_mean = reduction
self.loss_args = args
self.loss_kwargs = kwargs
def forward(self, logits, targets):
loss = cross_entropy(logits, targets, reduction='none', *self.loss_args, **self.loss_kwargs)
if self.reduction_mean:
loss = loss.mean()
loss = reduce_by_batch_2d.apply(loss, True)
return loss