mirror of https://github.com/hpcaitech/ColossalAI
712 lines
35 KiB
Python
712 lines
35 KiB
Python
#!/usr/bin/env python
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# -*- encoding: utf-8 -*-
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import inspect
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from typing import Callable, List, Tuple, Union
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import colossalai.communication as comm
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import torch.cuda
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from colossalai.amp.naive_amp import NaiveAMPModel
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from colossalai.context.parallel_mode import ParallelMode
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from colossalai.core import global_context as gpc
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from colossalai.logging import get_dist_logger
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from colossalai.utils import switch_virtual_pipeline_parallel_rank
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from colossalai.utils.cuda import get_current_device
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from colossalai.zero.sharded_model import ShardedModelV2
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from ._base_schedule import BaseSchedule
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def pack_return_tensors(return_tensors):
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output, label = tuple(zip(*return_tensors))
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if isinstance(output[0], torch.Tensor):
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output = torch.cat(output, dim=0)
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elif isinstance(output[0], (list, tuple)):
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output = tuple(torch.cat(tensors, dim=0) for tensors in zip(*output))
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else:
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raise TypeError(f'Output of model must be tensor or list/tuple of tensors')
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if isinstance(label[0], torch.Tensor):
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label = torch.cat(label, dim=0)
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else:
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merged_label = {k: [] for k in label[0].keys()}
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for d in label:
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for k, v in d.items():
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merged_label[k].append(v)
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label = {k: torch.cat(v, dim=0) for k, v in merged_label.items()}
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return output, label
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class PipelineSchedule(BaseSchedule):
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"""A helper schedule class for pipeline parallelism running environment.
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It uses non-interleaved 1F1B strategy. Other properties are similar as
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:class:`NonPipelineSchedule`.
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:param num_microbatches: The number of microbatches
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:type num_microbatches: int
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:param batch_data_process_func: The preprocessing function which receives a batch of data, and it will be executed in `load_batch`
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:type batch_data_process_func: Callable, optional
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:param tensor_shape: Specified shape in pipeline communication
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:type tensor_shape: torch.Size, optional
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:param scatter_gather_tensors: If set to `True`, communication will be reduced over pipeline when using 1D tensor parallelization
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:type scatter_gather_tensors: bool, optional
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"""
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def __init__(self,
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num_microbatches,
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batch_data_process_func: Callable = None,
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tensor_shape: Union[torch.Size, List[int], Tuple[int]] = None,
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scatter_gather_tensors: bool = False):
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super().__init__(batch_data_process_func=batch_data_process_func)
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self.num_microbatches = num_microbatches
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self.dtype = torch.float
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self.tensor_shape = tensor_shape
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self.scatter_gather_tensors = False
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if gpc.is_initialized(ParallelMode.PARALLEL_1D) and gpc.get_world_size(ParallelMode.PARALLEL_1D) > 1:
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self.scatter_gather_tensors = scatter_gather_tensors
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self._logger = get_dist_logger()
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def load_batch(self, data_iter):
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# Pipeline schedule just puts data in memory
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self.batch_data, self.batch_label = super().load_batch(data_iter, to_gpu=False)
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self.microbatch_offset = 0
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if isinstance(self.batch_data, torch.Tensor):
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batch_size = self.batch_data.size(0)
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else:
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batch_size = next(iter(self.batch_data.values())).size(0)
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assert batch_size % self.num_microbatches == 0, \
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"Batch size should divided by the number of microbatches"
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self.microbatch_size = batch_size // self.num_microbatches
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def _get_data_slice(self, data, offset):
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if isinstance(data, torch.Tensor):
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return data[offset:offset + self.microbatch_size]
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elif isinstance(data, dict):
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return {k: v[offset:offset + self.microbatch_size] for k, v in data.items()}
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def load_micro_batch(self):
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data = self._get_data_slice(self.batch_data, self.microbatch_offset)
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label = self._get_data_slice(self.batch_label, self.microbatch_offset)
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self.microbatch_offset += self.microbatch_size
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return self._move_to_device(data), self._move_to_device(label)
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def pre_processing(self, engine):
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# TODO: remove this after testing new zero with pipeline parallelism
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model = engine.model
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if isinstance(model, (NaiveAMPModel, ShardedModelV2)):
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self.dtype = torch.half
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model = model.model
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sig = inspect.signature(model.forward)
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for p in sig.parameters.values():
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assert p.kind != inspect.Parameter.VAR_POSITIONAL, '*args is not supported'
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@staticmethod
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def _call_engine(model, input_tensor, batch_data):
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if isinstance(model, NaiveAMPModel):
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sig = inspect.signature(model.model.forward)
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elif isinstance(model, ShardedModelV2):
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sig = inspect.signature(model.module.forward)
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else:
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sig = inspect.signature(model.forward)
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if isinstance(batch_data, torch.Tensor):
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if input_tensor is None:
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return model(batch_data)
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elif len(sig.parameters) > 1:
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return model(input_tensor, batch_data)
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else:
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return model(input_tensor)
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else:
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filter_batch = True
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for p in sig.parameters.values():
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if p.kind == inspect.Parameter.VAR_KEYWORD:
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filter_batch = False
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if filter_batch:
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batch_data = {k: v for k, v in batch_data.items() if k in sig.parameters}
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if input_tensor is None:
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return model(**batch_data)
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else:
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return model(input_tensor, **batch_data)
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def forward_step(self, engine, input_tensor, return_tensors, return_output_label=True, accum_loss=None):
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"""Forward step for passed-in model. If it is the first stage, the input tensor
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is obtained from data_iterator, otherwise the passed-in input_tensor is used.
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Returns output tensor. This is a helper function and can be ignored by users.
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:param engine: Your engine object
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:type engine: colossalai.engine.Engine
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:param input_tensor: Input tensor for this pipeline stage
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:type input_tensor: :class:`torch.Tensor`
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:param return_tensors: A list of tensors to return
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:type return_tensors: List[:class:`torch.Tensor`]
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:param return_output_label: Whether returns output labels
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:type return_output_label: bool, optional
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:param accum_loss: Where accumulated loss stores
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:type accum_loss: optional
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:return: output or the loss value of the current pipeline stage
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:rtype: :class:`torch.Tensor`
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"""
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data, label = self.load_micro_batch()
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output_tensor = self._call_engine(engine.model, input_tensor, data)
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if gpc.is_last_rank(ParallelMode.PIPELINE):
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if return_output_label:
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return_tensors.append((output_tensor, label))
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if accum_loss is not None:
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loss_reduced = self._call_engine_criterion(engine, output_tensor, label) / self.num_microbatches
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accum_loss.add_(loss_reduced.detach())
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return loss_reduced
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else:
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# forward only, it's useless since backward is not needed
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return output_tensor
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else:
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assert isinstance(
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output_tensor,
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torch.Tensor), 'Output of model using pipeline parallelism must be a tensor (except the last stage).'
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self._logger.debug(
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f'Global rank {gpc.get_global_rank()}, pipeline rank {gpc.get_local_rank(ParallelMode.PIPELINE)} forward output tensor {output_tensor.shape}, dtype {output_tensor.dtype}'
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)
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return output_tensor
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def backward_step(self, engine, input_tensor, output_tensor, output_tensor_grad):
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"""Backward step through the passed-in output tensor. If it is the last stage, the
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output_tensor_grad is None, otherwise it is the gradients with respect to stage's output tensor.
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Returns the gradients with respect to the input tensor (None if first stage).
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This is a helper function and can be ignored by users.
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:param engine: your engine object
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:type engine: colossalai.engine.Engine
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:param input_tensor: input tensor for this pipeline stage
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:type input_tensor: :class:`torch.Tensor`
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:param output_tensor: output tensor for this pipeline stage
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:type output_tensor: :class:`torch.Tensor`
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:param output_tensor_grad: gradient of output tensor for this pipeline stage
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:type output_tensor_grad: :class:`torch.Tensor`
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:return: gradient of input tensor
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:rtype: :class:`torch.Tensor`
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"""
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# Retain the grad on the input_tensor.
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if input_tensor is not None:
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input_tensor.retain_grad()
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# Backward pass.
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if output_tensor_grad is None:
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engine.backward(output_tensor)
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else:
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engine.backward_by_grad(output_tensor, output_tensor_grad)
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# Collect the grad of the input_tensor.
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input_tensor_grad = None
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if input_tensor is not None:
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input_tensor_grad = input_tensor.grad
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return input_tensor_grad
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def forward_backward_step(self, engine, data_iter, forward_only=False, return_loss=True, return_output_label=True):
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"""Runs non-interleaved 1F1B schedule, with communication between pipeline stages.
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Returns a tuple with losses if the last stage, an empty tuple otherwise.
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:param engine: Your engine object
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:type engine: colossalai.engine.Engine
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:param data_iter: Dataloader as the form of an iterator, obtained by calling iter(dataloader)
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:type data_iter: Iterable
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:param forward_only: Whether run forward step only. Default is false. If true, no backward will be run.
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:type forward_only: bool
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:param return_loss: Whether returns the loss value. Default is true.
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:type return_loss: bool
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:param return_output_label: If False, the output and label won't be returned
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:type return_output_label: bool
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:return: (output, label, loss)
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:rtype: Tuple[:class:`torch.Tensor`]
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"""
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assert forward_only or return_loss, \
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'The argument \'return_loss\' has to be True when \'forward_only\' is False, but got False.'
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self.load_batch(data_iter)
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num_warmup_microbatches = \
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(gpc.get_world_size(ParallelMode.PIPELINE)
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- gpc.get_local_rank(ParallelMode.PIPELINE) - 1)
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num_warmup_microbatches = min(num_warmup_microbatches, self.num_microbatches)
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num_microbatches_remaining = self.num_microbatches - num_warmup_microbatches
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# Input, output tensors only need to be saved when doing backward passes
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input_tensors = None
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output_tensors = None
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if not forward_only:
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input_tensors = []
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output_tensors = []
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return_tensors = []
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if return_loss and gpc.is_pipeline_last_stage(ignore_virtual=True):
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accum_loss = torch.zeros(1, device=get_current_device())
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else:
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accum_loss = None
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# Used for tensor meta information communication
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ft_shape = self.tensor_shape
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bt_shape = None
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fs_checker = self.tensor_shape is None
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# Run warmup forward passes.
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for i in range(num_warmup_microbatches):
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if not gpc.is_first_rank(ParallelMode.PIPELINE):
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ft_shape = comm.recv_tensor_meta(ft_shape)
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input_tensor = comm.recv_forward(ft_shape,
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dtype=self.dtype,
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scatter_gather_tensors=self.scatter_gather_tensors)
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output_tensor = self.forward_step(engine,
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input_tensor,
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return_tensors,
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return_output_label=return_output_label,
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accum_loss=accum_loss)
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if not gpc.is_last_rank(ParallelMode.PIPELINE):
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bt_shape = output_tensor.shape
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fs_checker = comm.send_tensor_meta(output_tensor, fs_checker)
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comm.send_forward(output_tensor, scatter_gather_tensors=self.scatter_gather_tensors)
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if not forward_only:
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input_tensors.append(input_tensor)
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output_tensors.append(output_tensor)
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# Before running 1F1B, need to receive first forward tensor.
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# If all microbatches are run in warmup / cooldown phase, then no need to
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# receive this tensor here.
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if num_microbatches_remaining > 0:
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if not gpc.is_first_rank(ParallelMode.PIPELINE):
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ft_shape = comm.recv_tensor_meta(ft_shape)
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input_tensor = comm.recv_forward(ft_shape,
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dtype=self.dtype,
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scatter_gather_tensors=self.scatter_gather_tensors)
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# Run 1F1B in steady state.
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for i in range(num_microbatches_remaining):
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last_iteration = (i == (num_microbatches_remaining - 1))
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output_tensor = self.forward_step(engine,
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input_tensor,
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return_tensors,
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return_output_label=return_output_label,
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accum_loss=accum_loss)
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if forward_only:
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comm.send_forward(output_tensor, scatter_gather_tensors=self.scatter_gather_tensors)
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if not last_iteration:
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input_tensor = comm.recv_forward(ft_shape,
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dtype=self.dtype,
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scatter_gather_tensors=self.scatter_gather_tensors)
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else:
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output_tensor_grad = comm.send_forward_recv_backward(output_tensor,
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bt_shape,
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dtype=self.dtype,
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scatter_gather_tensors=self.scatter_gather_tensors)
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# Add input_tensor and output_tensor to end of list.
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input_tensors.append(input_tensor)
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output_tensors.append(output_tensor)
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# Pop input_tensor and output_tensor from the start of the list for
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# the backward pass.
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input_tensor = input_tensors.pop(0)
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output_tensor = output_tensors.pop(0)
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input_tensor_grad = self.backward_step(engine, input_tensor, output_tensor, output_tensor_grad)
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if last_iteration:
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input_tensor = None
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comm.send_backward(input_tensor_grad, scatter_gather_tensors=self.scatter_gather_tensors)
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else:
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input_tensor = comm.send_backward_recv_forward(input_tensor_grad,
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ft_shape,
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dtype=self.dtype,
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scatter_gather_tensors=self.scatter_gather_tensors)
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# Run cooldown backward passes.
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if not forward_only:
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for i in range(num_warmup_microbatches):
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input_tensor = input_tensors.pop(0)
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output_tensor = output_tensors.pop(0)
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output_tensor_grad = comm.recv_backward(bt_shape,
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dtype=self.dtype,
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scatter_gather_tensors=self.scatter_gather_tensors)
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input_tensor_grad = self.backward_step(engine, input_tensor, output_tensor, output_tensor_grad)
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comm.send_backward(input_tensor_grad, scatter_gather_tensors=self.scatter_gather_tensors)
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if len(return_tensors) > 0:
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output, label = pack_return_tensors(return_tensors)
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return output, label, accum_loss
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else:
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return None, None, accum_loss
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class InterleavedPipelineSchedule(PipelineSchedule):
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def __init__(self,
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num_microbatches,
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num_model_chunks,
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batch_data_process_func: Callable = None,
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tensor_shape: Union[torch.Size, List[int], Tuple[int]] = None,
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scatter_gather_tensors: bool = False):
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"""A helper schedule class for pipeline parallelism running environment.
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It uses interleaved 1F1B strategy. Other properties are similar as
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:class:`NonPipelineSchedule`.
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:param num_microbatches: The number of microbatches
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:type num_microbatches: int
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:param num_model_chunks: The number of model chunks
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:type num_model_chunks: int
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:param batch_data_process_func: The preprocessing function which receives a batch of data, and it will be executed in `load_batch`
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:type batch_data_process_func: Callable, optional
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:param tensor_shape: Specified shape in pipeline communication
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:type tensor_shape: torch.Size, optional
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:param scatter_gather_tensors: If set to `True`, communication will be reduced over pipeline when using 1D tensor parallelization
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:type scatter_gather_tensors: bool, optional
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"""
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assert num_microbatches % gpc.get_world_size(ParallelMode.PIPELINE) == 0, \
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'num_microbatches must be an integer multiple of pipeline parallel world size'
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super().__init__(num_microbatches,
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batch_data_process_func=batch_data_process_func,
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tensor_shape=tensor_shape,
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scatter_gather_tensors=scatter_gather_tensors)
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gpc.set_virtual_pipeline_parallel_size(num_model_chunks)
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gpc.set_virtual_pipeline_parallel_rank(0)
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self.num_model_chunks = num_model_chunks
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def pre_processing(self, engine):
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if isinstance(engine.model, ShardedModelV2):
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self.dtype = torch.half
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elif isinstance(engine.model[0], NaiveAMPModel):
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self.dtype = torch.half
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for model in engine.model:
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if isinstance(model, NaiveAMPModel):
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model = model.model
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sig = inspect.signature(model.forward)
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for p in sig.parameters.values():
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assert p.kind != inspect.Parameter.VAR_POSITIONAL, '*args is not supported'
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def load_batch(self, data_iter):
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super().load_batch(data_iter)
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# overwrite microbatch_offset, since model chunks load the same microbatch, and should tract the offset
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self.microbatch_offset = [0 for _ in range(self.num_model_chunks)]
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def load_micro_batch(self, model_chunk_id):
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data = self._get_data_slice(self.batch_data, self.microbatch_offset[model_chunk_id])
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label = self._get_data_slice(self.batch_label, self.microbatch_offset[model_chunk_id])
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self.microbatch_offset[model_chunk_id] += self.microbatch_size
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return self._move_to_device(data), self._move_to_device(label)
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def forward_step(self,
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engine,
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model_chunk_id,
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input_tensor,
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return_tensors,
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return_output_label=True,
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accum_loss=None):
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"""Forward step for passed-in model. If it is the first stage, the input tensor
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is obtained from data_iterator, otherwise the passed-in input_tensor is used.
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Returns output tensor. This is a helper function and can be ignored by users.
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"""
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data, label = self.load_micro_batch(model_chunk_id)
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output_tensor = self._call_engine(engine.model[model_chunk_id], input_tensor, data)
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if gpc.is_pipeline_last_stage():
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if return_output_label:
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return_tensors.append((output_tensor, label))
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if accum_loss is not None:
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loss_reduced = self._call_engine_criterion(engine, output_tensor, label) / self.num_microbatches
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accum_loss.add_(loss_reduced.detach())
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return loss_reduced
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else:
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# forward only, it's useless since backward is not needed
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return output_tensor
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else:
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assert isinstance(
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output_tensor,
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torch.Tensor), 'Output of model using pipeline parallelism must be a tensor (except the last stage).'
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self._logger.debug(
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f'Global rank {gpc.get_global_rank()}, pipeline rank {gpc.get_local_rank(ParallelMode.PIPELINE)} forward output tensor {output_tensor.shape}, dtype {output_tensor.dtype}'
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)
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return output_tensor
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def forward_backward_step(self, engine, data_iter, forward_only=False, return_loss=True, return_output_label=True):
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"""Run interleaved 1F1B schedule (model split into model chunks), with
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communication between pipeline stages as needed.
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Returns dictionary with losses if the last stage, empty dict otherwise.
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:param engine: Your engine object
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:type engine: colossalai.engine.Engine
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:param data_iter: Dataloader as the form of an iterator, obtained by calling iter(dataloader)
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:type data_iter: Iterable
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:param forward_only: Whether run forward step only. Default is false. If true, no backward will be run.
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:type forward_only: bool
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:param return_loss: Whether returns the loss value. Default is true.
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:type return_loss: bool
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:param return_output_label: If False, the output and label won't be returned
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:type return_output_label: bool
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"""
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assert forward_only or return_loss, \
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'The argument \'return_loss\' has to be True when \'forward_only\' is False, but got False.'
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self.load_batch(data_iter)
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model = engine.model
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input_tensors = [[] for _ in range(len(model))]
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output_tensors = [[] for _ in range(len(model))]
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return_tensors = []
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if not forward_only:
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output_tensor_grads = [[] for _ in range(len(model))]
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if return_loss and gpc.is_pipeline_last_stage(ignore_virtual=True):
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accum_loss = torch.zeros(1, device=get_current_device())
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else:
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accum_loss = None
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# Used for tensor meta information communication
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input_tensor_shapes = [self.tensor_shape for _ in range(len(model))]
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output_tensor_shapes = [None for _ in range(len(model))]
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send_tensor_shape_flags = [self.tensor_shape is None for _ in range(len(model))]
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pipeline_parallel_size = gpc.get_world_size(ParallelMode.PIPELINE)
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pipeline_parallel_rank = gpc.get_local_rank(ParallelMode.PIPELINE)
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# Compute number of warmup and remaining microbatches.
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num_model_chunks = len(model)
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num_microbatches = self.num_microbatches * num_model_chunks
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all_warmup_microbatches = False
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if forward_only:
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num_warmup_microbatches = num_microbatches
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else:
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# Run all forward passes and then all backward passes if number of
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# microbatches is just the number of pipeline stages.
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# Otherwise, perform (num_model_chunks-1)*pipeline_parallel_size on
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# all workers, followed by more microbatches after depending on
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# stage ID (more forward passes for earlier stages, later stages can
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# immediately start with 1F1B).
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if self.num_microbatches == pipeline_parallel_size:
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num_warmup_microbatches = num_microbatches
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all_warmup_microbatches = True
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else:
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num_warmup_microbatches = \
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(pipeline_parallel_size - pipeline_parallel_rank - 1) * 2
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num_warmup_microbatches += (num_model_chunks - 1) * pipeline_parallel_size
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num_warmup_microbatches = min(num_warmup_microbatches, num_microbatches)
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num_microbatches_remaining = \
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num_microbatches - num_warmup_microbatches
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def get_model_chunk_id(microbatch_id, forward):
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"""Helper method to get the model chunk ID given the iteration number."""
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microbatch_id_in_group = microbatch_id % (pipeline_parallel_size * num_model_chunks)
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model_chunk_id = microbatch_id_in_group // pipeline_parallel_size
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if not forward:
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model_chunk_id = (num_model_chunks - model_chunk_id - 1)
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return model_chunk_id
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def forward_step_helper(microbatch_id):
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"""Helper method to run forward step with model split into chunks
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(run set_virtual_pipeline_model_parallel_rank() before calling
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forward_step())."""
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model_chunk_id = get_model_chunk_id(microbatch_id, forward=True)
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gpc.set_virtual_pipeline_parallel_rank(model_chunk_id)
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# forward step
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if gpc.is_pipeline_first_stage():
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if len(input_tensors[model_chunk_id]) == \
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len(output_tensors[model_chunk_id]):
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input_tensors[model_chunk_id].append(None)
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input_tensor = input_tensors[model_chunk_id][-1]
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output_tensor = self.forward_step(engine,
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model_chunk_id,
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input_tensor,
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return_tensors,
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return_output_label=return_output_label,
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accum_loss=accum_loss)
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output_tensors[model_chunk_id].append(output_tensor)
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|
|
# if forward-only, no need to save tensors for a backward pass
|
|
if forward_only:
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input_tensors[model_chunk_id].pop()
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output_tensors[model_chunk_id].pop()
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|
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return output_tensor
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|
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def backward_step_helper(microbatch_id):
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"""Helper method to run backward step with model split into chunks
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|
(run set_virtual_pipeline_model_parallel_rank() before calling
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|
backward_step())."""
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model_chunk_id = get_model_chunk_id(microbatch_id, forward=False)
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gpc.set_virtual_pipeline_parallel_rank(model_chunk_id)
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if gpc.is_pipeline_last_stage():
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if len(output_tensor_grads[model_chunk_id]) == 0:
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output_tensor_grads[model_chunk_id].append(None)
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|
input_tensor = input_tensors[model_chunk_id].pop(0)
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|
output_tensor = output_tensors[model_chunk_id].pop(0)
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|
output_tensor_grad = output_tensor_grads[model_chunk_id].pop(0)
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input_tensor_grad = self.backward_step(engine, input_tensor, output_tensor, output_tensor_grad)
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|
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return input_tensor_grad
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|
|
# Run warmup forward passes.
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|
gpc.set_virtual_pipeline_parallel_rank(0)
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|
if not gpc.is_pipeline_first_stage():
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|
input_tensor_shapes[0] = comm.recv_tensor_meta(input_tensor_shapes[0])
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|
input_tensors[0].append(
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comm.recv_forward(input_tensor_shapes[0],
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dtype=self.dtype,
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|
scatter_gather_tensors=self.scatter_gather_tensors))
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|
|
|
for k in range(num_warmup_microbatches):
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|
model_chunk_id = get_model_chunk_id(k, forward=True)
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|
output_tensor = forward_step_helper(k)
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|
if not gpc.is_pipeline_last_stage():
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|
output_tensor_shapes[model_chunk_id] = output_tensor.shape
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|
send_tensor_shape_flags[model_chunk_id] = comm.send_tensor_meta(output_tensor,
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|
send_tensor_shape_flags[model_chunk_id])
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|
# Determine if tensor should be received from previous stage.
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|
next_forward_model_chunk_id = get_model_chunk_id(k + 1, forward=True)
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|
recv_prev = True
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|
if gpc.is_pipeline_first_stage(ignore_virtual=True):
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|
if next_forward_model_chunk_id == 0:
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|
recv_prev = False
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|
if k == (num_microbatches - 1):
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|
recv_prev = False
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|
|
|
# Don't send tensor downstream if on last stage.
|
|
if gpc.is_pipeline_last_stage():
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|
output_tensor = None
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|
|
|
with switch_virtual_pipeline_parallel_rank(next_forward_model_chunk_id):
|
|
if not gpc.is_pipeline_first_stage():
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|
input_tensor_shapes[next_forward_model_chunk_id] = comm.recv_tensor_meta(
|
|
input_tensor_shapes[next_forward_model_chunk_id])
|
|
# Send and receive tensors as appropriate (send tensors computed
|
|
# in this iteration; receive tensors for next iteration).
|
|
input_shape = input_tensor_shapes[next_forward_model_chunk_id] if recv_prev else None
|
|
if k == (num_warmup_microbatches - 1) and not forward_only and \
|
|
not all_warmup_microbatches:
|
|
input_tensor_grad = None
|
|
recv_next = True
|
|
if gpc.is_pipeline_last_stage(ignore_virtual=True):
|
|
recv_next = False
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|
output_shape = output_tensor_shapes[num_model_chunks - 1] if recv_next else None
|
|
input_tensor, output_tensor_grad = \
|
|
comm.send_forward_backward_recv_forward_backward(
|
|
output_tensor, input_tensor_grad,
|
|
input_shape,
|
|
output_shape,
|
|
recv_prev=recv_prev, recv_next=recv_next,
|
|
dtype=self.dtype,
|
|
scatter_gather_tensors=self.scatter_gather_tensors)
|
|
output_tensor_grads[num_model_chunks - 1].append(output_tensor_grad)
|
|
else:
|
|
input_tensor = \
|
|
comm.send_forward_recv_forward(
|
|
output_tensor,
|
|
input_shape,
|
|
recv_prev=recv_prev,
|
|
dtype=self.dtype,
|
|
scatter_gather_tensors=self.scatter_gather_tensors)
|
|
input_tensors[next_forward_model_chunk_id].append(input_tensor)
|
|
|
|
# Run 1F1B in steady state.
|
|
for k in range(num_microbatches_remaining):
|
|
# Forward pass.
|
|
forward_k = k + num_warmup_microbatches
|
|
output_tensor = forward_step_helper(forward_k)
|
|
|
|
# Backward pass.
|
|
backward_k = k
|
|
input_tensor_grad = backward_step_helper(backward_k)
|
|
|
|
# Send output_tensor and input_tensor_grad, receive input_tensor
|
|
# and output_tensor_grad.
|
|
|
|
# Determine if current stage has anything to send in either direction,
|
|
# otherwise set tensor to None.
|
|
forward_model_chunk_id = get_model_chunk_id(forward_k, forward=True)
|
|
gpc.set_virtual_pipeline_parallel_rank(forward_model_chunk_id)
|
|
if gpc.is_pipeline_last_stage():
|
|
output_tensor = None
|
|
|
|
backward_model_chunk_id = get_model_chunk_id(backward_k, forward=False)
|
|
gpc.set_virtual_pipeline_parallel_rank(backward_model_chunk_id)
|
|
if gpc.is_pipeline_first_stage():
|
|
input_tensor_grad = None
|
|
|
|
# Determine if peers are sending, and where in data structure to put
|
|
# received tensors.
|
|
recv_prev = True
|
|
if gpc.is_pipeline_first_stage(ignore_virtual=True):
|
|
# First stage is ahead of last stage by (pipeline_parallel_size - 1).
|
|
next_forward_model_chunk_id = get_model_chunk_id(forward_k - (pipeline_parallel_size - 1), forward=True)
|
|
if next_forward_model_chunk_id == (num_model_chunks - 1):
|
|
recv_prev = False
|
|
next_forward_model_chunk_id += 1
|
|
else:
|
|
next_forward_model_chunk_id = get_model_chunk_id(forward_k + 1, forward=True)
|
|
|
|
recv_next = True
|
|
if gpc.is_pipeline_last_stage(ignore_virtual=True):
|
|
# Last stage is ahead of first stage by (pipeline_parallel_size - 1).
|
|
next_backward_model_chunk_id = get_model_chunk_id(backward_k - (pipeline_parallel_size - 1),
|
|
forward=False)
|
|
if next_backward_model_chunk_id == 0:
|
|
recv_next = False
|
|
next_backward_model_chunk_id -= 1
|
|
else:
|
|
next_backward_model_chunk_id = get_model_chunk_id(backward_k + 1, forward=False)
|
|
|
|
# If last iteration, don't receive; we already received one extra
|
|
# before the start of the for loop.
|
|
if k == (num_microbatches_remaining - 1):
|
|
recv_prev = False
|
|
|
|
input_shape = input_tensor_shapes[next_forward_model_chunk_id] if recv_prev else None
|
|
output_shape = output_tensor_shapes[next_backward_model_chunk_id] if recv_next else None
|
|
# Communicate tensors.
|
|
input_tensor, output_tensor_grad = \
|
|
comm.send_forward_backward_recv_forward_backward(
|
|
output_tensor, input_tensor_grad,
|
|
input_shape,
|
|
output_shape,
|
|
recv_prev=recv_prev, recv_next=recv_next,
|
|
dtype=self.dtype,
|
|
scatter_gather_tensors=self.scatter_gather_tensors)
|
|
|
|
# Put input_tensor and output_tensor_grad in data structures in the
|
|
# right location.
|
|
if recv_prev:
|
|
input_tensors[next_forward_model_chunk_id].append(input_tensor)
|
|
if recv_next:
|
|
output_tensor_grads[next_backward_model_chunk_id].append(output_tensor_grad)
|
|
|
|
# Run cooldown backward passes (flush out pipeline).
|
|
if not forward_only:
|
|
if all_warmup_microbatches:
|
|
output_tensor_grads[num_model_chunks - 1].append(
|
|
comm.recv_backward(output_tensor_shapes[num_model_chunks - 1],
|
|
scatter_gather_tensors=self.scatter_gather_tensors))
|
|
for k in range(num_microbatches_remaining, num_microbatches):
|
|
input_tensor_grad = backward_step_helper(k)
|
|
next_backward_model_chunk_id = get_model_chunk_id(k + 1, forward=False)
|
|
recv_next = True
|
|
if gpc.is_pipeline_last_stage(ignore_virtual=True):
|
|
if next_backward_model_chunk_id == (num_model_chunks - 1):
|
|
recv_next = False
|
|
if k == (num_microbatches - 1):
|
|
recv_next = False
|
|
output_shape = output_tensor_shapes[next_backward_model_chunk_id] if recv_next else None
|
|
output_tensor_grads[next_backward_model_chunk_id].append(
|
|
comm.send_backward_recv_backward(input_tensor_grad,
|
|
output_shape,
|
|
recv_next=recv_next,
|
|
dtype=self.dtype,
|
|
scatter_gather_tensors=self.scatter_gather_tensors))
|
|
|
|
if len(return_tensors) > 0:
|
|
output, label = pack_return_tensors(return_tensors)
|
|
return output, label, accum_loss
|
|
else:
|
|
return None, None, accum_loss
|