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99 lines
4.3 KiB
99 lines
4.3 KiB
from colossalai.tensor.distspec import _DistSpec
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from colossalai.nn.layer.utils import divide
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from numpy import prod
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from contextlib import contextmanager
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import torch
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import torch.distributed as dist
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class TransformDistSpec(torch.autograd.Function):
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@staticmethod
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def forward(ctx, tensor, old_dist_spec, dist_spec, forward_trans_func, backward_trans_func):
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ctx.old_dist_spec = old_dist_spec
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ctx.dist_spec = dist_spec
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ctx.backward_trans_func = backward_trans_func
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return forward_trans_func(tensor, old_dist_spec, dist_spec)
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@staticmethod
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def backward(ctx, grad_outputs):
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return ctx.backward_trans_func(grad_outputs, ctx.dist_spec, ctx.old_dist_spec), None, None, None, None
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class DistSpecManager:
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_use_autograd_function: bool = True
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@staticmethod
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def _shard_as(tensor: torch.Tensor, old_dist_spec: _DistSpec, dist_spec: _DistSpec) -> torch.Tensor:
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chunk = tensor
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idx = dist_spec.process_group.rank()
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num_parts = prod(dist_spec.num_partitions)
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for i, dim in enumerate(dist_spec.dims):
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num_parts //= dist_spec.num_partitions[i]
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chunk_size = divide(tensor.size(dim), dist_spec.num_partitions[i])
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chunk = chunk.narrow(dim, idx // num_parts * chunk_size, chunk_size)
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idx %= num_parts
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return chunk.detach().contiguous()
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@staticmethod
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def _gather(tensor: torch.Tensor, old_dist_spec: _DistSpec) -> torch.Tensor:
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buffer = [torch.empty_like(tensor) for _ in range(old_dist_spec.process_group.size())]
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dist.all_gather(buffer, tensor, group=old_dist_spec.process_group)
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for i in range(len(old_dist_spec.dims) - 1, -1, -1):
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new_buffer = []
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dim = old_dist_spec.dims[i]
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num_parts = old_dist_spec.num_partitions[i]
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for start in range(0, len(buffer), num_parts):
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new_buffer.append(torch.cat(buffer[start:start + num_parts], dim))
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buffer = new_buffer
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assert len(buffer) == 1
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return buffer[0]
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@staticmethod
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def _r2r(tensor: torch.Tensor, old_dist_spec: _DistSpec, dist_spec: _DistSpec) -> torch.Tensor:
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if old_dist_spec.process_group is not None and old_dist_spec.process_group != dist_spec.process_group \
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and dist_spec.process_group is not None:
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raise NotImplementedError
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return tensor
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@staticmethod
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def _r2s(tensor: torch.Tensor, old_dist_spec: _DistSpec, dist_spec: _DistSpec) -> torch.Tensor:
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if old_dist_spec.process_group is not None and old_dist_spec.process_group != dist_spec.process_group:
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raise NotImplementedError
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return DistSpecManager._shard_as(tensor, old_dist_spec, dist_spec)
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@staticmethod
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def _s2r(tensor: torch.Tensor, old_dist_spec: _DistSpec, dist_spec: _DistSpec) -> torch.Tensor:
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if old_dist_spec.process_group != dist_spec.process_group \
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and dist_spec.process_group is not None:
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raise NotImplementedError
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return DistSpecManager._gather(tensor, old_dist_spec)
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@staticmethod
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def _s2s(tensor: torch.Tensor, old_dist_spec: _DistSpec, dist_spec: _DistSpec) -> torch.Tensor:
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if old_dist_spec.process_group != dist_spec.process_group:
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raise NotImplementedError
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if old_dist_spec == dist_spec:
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return tensor
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tensor = DistSpecManager._gather(tensor, old_dist_spec)
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return DistSpecManager._shard_as(tensor, old_dist_spec, dist_spec)
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@staticmethod
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def handle_trans_spec(tensor: torch.Tensor, old_dist_spec: _DistSpec, dist_spec: _DistSpec) -> torch.Tensor:
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forward_trans_handle = getattr(DistSpecManager, f'_{old_dist_spec.placement.value}2{dist_spec.placement.value}')
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if not DistSpecManager._use_autograd_function:
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return forward_trans_handle(tensor, old_dist_spec, dist_spec)
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backward_trans_handle = getattr(DistSpecManager,
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f'_{dist_spec.placement.value}2{old_dist_spec.placement.value}')
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return TransformDistSpec.apply(tensor, old_dist_spec, dist_spec, forward_trans_handle, backward_trans_handle)
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@staticmethod
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@contextmanager
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def no_grad():
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try:
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DistSpecManager._use_autograd_function = False
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yield
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finally:
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DistSpecManager._use_autograd_function = True
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