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138 lines
4.0 KiB
138 lines
4.0 KiB
import collections
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import warnings
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from typing import Optional, Sequence, Union
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import torch.cuda
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__all__ = ["all_reduce", "reduce", "broadcast", "all_gather", "reduce_scatter"]
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SUM = 0 # ncclRedOp_t
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def is_available(tensors):
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if not hasattr(torch._C, "_nccl_all_reduce"):
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warnings.warn("PyTorch is not compiled with NCCL support")
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return False
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devices = set()
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for tensor in tensors:
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if tensor.is_sparse:
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return False
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if not tensor.is_contiguous():
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return False
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if not tensor.is_cuda:
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return False
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device = tensor.get_device()
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if device in devices:
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return False
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devices.add(device)
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return True
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def version():
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ver = torch._C._nccl_version()
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major = ver >> 32
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minor = (ver >> 16) & 65535
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patch = ver & 65535
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suffix = torch._C._nccl_version_suffix().decode("utf-8")
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if suffix == "":
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return (major, minor, patch)
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else:
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return (major, minor, patch, suffix)
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def unique_id():
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return torch._C._nccl_unique_id()
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def init_rank(num_ranks, uid, rank):
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return torch._C._nccl_init_rank(num_ranks, uid, rank)
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def _check_sequence_type(inputs: Union[torch.Tensor, Sequence[torch.Tensor]]) -> None:
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if not isinstance(inputs, collections.abc.Container) or isinstance(
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inputs, torch.Tensor
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):
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raise TypeError("Inputs should be a collection of tensors")
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def all_reduce(inputs, outputs=None, op=SUM, streams=None, comms=None):
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_check_sequence_type(inputs)
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if outputs is None:
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outputs = inputs
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_check_sequence_type(outputs)
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torch._C._nccl_all_reduce(inputs, outputs, op, streams, comms)
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# `output` used to be `outputs`, taking in a list of tensors. So we have two
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# arguments for BC reasons.
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def reduce(
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inputs: Sequence[torch.Tensor],
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output: Optional[Union[torch.Tensor, Sequence[torch.Tensor]]] = None,
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root: int = 0,
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op: int = SUM,
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streams: Optional[Sequence[torch.cuda.Stream]] = None,
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comms=None,
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*,
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outputs: Optional[Sequence[torch.Tensor]] = None,
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) -> None:
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_check_sequence_type(inputs)
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_output: torch.Tensor
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if outputs is not None:
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if output is not None:
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raise ValueError(
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"'output' and 'outputs' can not be both specified. 'outputs' is deprecated in "
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"favor of 'output', taking in a single output tensor. The signature of reduce is: "
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"reduce(inputs, output=None, root=0, op=SUM, streams=None, comms=None)."
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)
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else:
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warnings.warn(
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"nccl.reduce with an output tensor list is deprecated. "
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"Please specify a single output tensor with argument 'output' instead instead."
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)
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_output = outputs[root]
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elif not isinstance(output, torch.Tensor) and isinstance(
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output, collections.abc.Sequence
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):
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# User called old API with positional arguments of list of output tensors.
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warnings.warn(
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"nccl.reduce with an output tensor list is deprecated. "
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"Please specify a single output tensor."
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)
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_output = output[root]
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else:
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_output = inputs[root] if output is None else output
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torch._C._nccl_reduce(inputs, _output, root, op, streams, comms)
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def broadcast(
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inputs: Sequence[torch.Tensor], root: int = 0, streams=None, comms=None
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) -> None:
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_check_sequence_type(inputs)
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torch._C._nccl_broadcast(inputs, root, streams, comms)
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def all_gather(
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inputs: Sequence[torch.Tensor],
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outputs: Sequence[torch.Tensor],
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streams=None,
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comms=None,
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) -> None:
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_check_sequence_type(inputs)
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_check_sequence_type(outputs)
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torch._C._nccl_all_gather(inputs, outputs, streams, comms)
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def reduce_scatter(
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inputs: Sequence[torch.Tensor],
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outputs: Sequence[torch.Tensor],
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op: int = SUM,
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streams=None,
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comms=None,
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) -> None:
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_check_sequence_type(inputs)
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_check_sequence_type(outputs)
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torch._C._nccl_reduce_scatter(inputs, outputs, op, streams, comms)
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