mirror of https://github.com/hpcaitech/ColossalAI
97 lines
3.7 KiB
Python
97 lines
3.7 KiB
Python
import torch
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import torch.distributed as dist
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from colossalai.core import global_context as gpc
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try:
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import fused_mix_prec_layer_norm_cuda
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except:
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fused_mix_prec_layer_norm_cuda = None
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class FusedLayerNormAffineFunction1D(torch.autograd.Function):
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r"""Layernorm
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Args:
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input: input matrix.
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weight: weight matrix.
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bias: bias matrix.
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normalized_shape: input shape from an expected input of size.
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:math:`[* \times \text{normalized_shape}[0] \times \text{normalized_shape}[1] \times \ldots \times \text{normalized_shape}[-1]]`
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If a single integer is used, it is treated as a singleton list, and this module will
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normalize over the last dimension which is expected to be of that specific size.
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eps: a value added to the denominator for numerical stability
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"""
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@staticmethod
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def forward(ctx, input, weight, bias, normalized_shape, eps):
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ctx.normalized_shape = normalized_shape
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ctx.eps = eps
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input_ = input.contiguous()
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weight_ = weight.contiguous()
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bias_ = bias.contiguous()
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output, mean, invvar = fused_mix_prec_layer_norm_cuda.forward_affine(input_, ctx.normalized_shape, weight_,
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bias_, ctx.eps)
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ctx.save_for_backward(input_, weight_, bias_, mean, invvar)
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return output
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@staticmethod
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def backward(ctx, grad_output):
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input_, weight_, bias_, mean, invvar = ctx.saved_tensors
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grad_input = grad_weight = grad_bias = None
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grad_input, grad_weight, grad_bias \
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= fused_mix_prec_layer_norm_cuda.backward_affine(
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grad_output.contiguous(), mean, invvar,
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input_, ctx.normalized_shape,
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weight_, bias_, ctx.eps)
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return grad_input, grad_weight, grad_bias, None, None
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class LinearWithAsyncCommunication(torch.autograd.Function):
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"""
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Linear layer execution with asynchronous communication in backprop.
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"""
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@staticmethod
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def forward(ctx, input_, weight, bias, parallel_mode, async_grad_allreduce):
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ctx.save_for_backward(input_, weight)
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ctx.use_bias = bias is not None
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ctx.parallel_mode = parallel_mode
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ctx.async_grad_allreduce = async_grad_allreduce
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output = torch.matmul(input_, weight.t())
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if bias is not None:
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output = output + bias
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return output
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@staticmethod
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def backward(ctx, grad_output):
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input, weight = ctx.saved_tensors
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use_bias = ctx.use_bias
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total_input = input
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grad_input = grad_output.matmul(weight)
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# Convert the tensor shapes to 2D for execution compatibility
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grad_output = grad_output.view(grad_output.shape[0] * grad_output.shape[1], grad_output.shape[2])
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total_input = total_input.view(total_input.shape[0] * total_input.shape[1], total_input.shape[2])
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if ctx.async_grad_allreduce:
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# Asynchronous all-reduce
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handle = dist.all_reduce(grad_input, group=gpc.get_group(ctx.parallel_mode), async_op=True)
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# Delay the start of weight gradient computation shortly (3us) to have
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# all-reduce scheduled first and have GPU resources allocated
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_ = torch.empty(1, device=grad_output.device) + 1
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grad_weight = grad_output.t().matmul(total_input)
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grad_bias = grad_output.sum(dim=0) if use_bias else None
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if ctx.async_grad_allreduce:
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handle.wait()
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return grad_input, grad_weight, grad_bias, None, None, None
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def linear_with_async_comm(input_, weight, bias, parallel_mode, async_grad_allreduce):
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return LinearWithAsyncCommunication.apply(input_, weight, bias, parallel_mode, async_grad_allreduce)
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