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ColossalAI/colossalai/tensor/spec.py

81 lines
3.0 KiB

import torch.distributed as dist
from enum import Enum
from typing import List, Optional
from colossalai.tensor.distspec import _DistSpec, DistPlacementPattern
class ComputePattern(Enum):
TP1D = 0
TP2D = 1
TP2P5D = 2
TP3D = 3
class ParallelAction(object):
def __init__(self, compute_pattern: ComputePattern, gather_out: bool = True) -> None:
assert isinstance(compute_pattern, ComputePattern)
self.compute_pattern = compute_pattern
self.gather_out = gather_out
def __repr__(self):
return f'compute pattern: {self.compute_pattern}, gather out: {self.gather_out}'
class TensorSpec(object):
"""
It contains two aspects of information:
First, How are tensors distributed in Heterougenous memory space.
Second, if the tensor is a model parameter, the Spec contains the
parallel computation pattern of the Operator (Layer).
We have to consider the hybrid parallel mode.
"""
# a list of parallel actions.
# For example: On 8 GPUs, a hybrid parallel strategy is applied using
# using ZeRO with DP-degree = 4 and 1DRowTP with TP-degree = 2.
# parallel_action_list = [
# ParallelAction(10, ComputePattern.ZeRO, gpc.get_group(ParallelMode.DATA)),
# ParallelAction(1, ComputePattern.TP1D_Linear, gpc.get_group(ParallelMode.PARALLEL_1D))
# ]
# When the ColoTensor is initialized,
# we first splitting tensor according to ParallelAction of ZeRO,
# then splitting tensor according to ParallelAction of TP1D_Linear.
# During Linear computation
# Before Linear Op, we gather the tensors according to ZeRO.
# We perform Linear Op according to compute pattern of TP1D_Linear.
# After Linear Op, we split the tensors according to ZeRO.
def __init__(self, dist_spec: _DistSpec, parallel_action: Optional[ParallelAction] = None):
self.parallel_action = parallel_action
self.dist_spec = dist_spec
def get_process_group(self):
return self.dist_spec.process_group
def get_process_group_size(self):
return dist.get_world_size(self.dist_spec.process_group)
def get_placement(self):
return self.dist_spec.placement
def is_gathered(self):
return self.dist_spec.placement == DistPlacementPattern.REPLICATE \
or (len(self.dist_spec.num_partitions) == 1
and self.dist_spec.num_partitions[0] == 1) \
or (self.dist_spec.process_group.size() == 1)
def is_1D_col(self):
return self.dist_spec.placement == DistPlacementPattern.SHARD \
and len(self.dist_spec.dims) == 1 and self.dist_spec.dims[0] == -1
def is_1D_row(self):
return self.dist_spec.placement == DistPlacementPattern.SHARD \
and len(self.dist_spec.dims) == 1 and self.dist_spec.dims[0] == 0
def has_compute_pattern(self, compute_pattern: ComputePattern):
return self.parallel_action.compute_pattern == compute_pattern
def __repr__(self):
return f'parallel action: {self.parallel_action}, dist_spec: {self.dist_spec}'