ColossalAI/colossalai/utils/model/colo_init_context.py

124 lines
4.5 KiB
Python

from typing import Dict, Iterator, Optional, Tuple, Union
import torch
from torch import nn
from colossalai.nn.parallel.layers import ColoEmbedding, ColoLinear, register_colo_module
from colossalai.tensor import ColoParameter, ColoTensor, ProcessGroup, ShardSpec
from .utils import InsertPostInitMethodToModuleSubClasses
# find named_params includes replica
def _named_params_with_replica(
module: nn.Module,
prefix: str = '',
recurse: bool = True,
) -> Iterator[Tuple[str, Union[nn.Parameter, ColoTensor]]]:
modules = module.named_modules(prefix=prefix) if recurse else [(prefix, module)]
for mod_prefix, mod in modules:
for name, val in mod._parameters.items():
if val is None:
continue
name = mod_prefix + ('.' if mod_prefix else '') + name
yield name, val
def ColoModulize(module):
"""
Replacing the parameters() and named_parameters() with our customized ones
"""
module._colo_visited = True
class ColoInitContext(InsertPostInitMethodToModuleSubClasses):
def __init__(self,
device: torch.device = torch.device('cpu'),
dtype: torch.dtype = torch.float,
default_pg: Optional[ProcessGroup] = None,
default_dist_spec=None):
"""
Args:
device (torch.device): the device where parameters initialized are resident. Defaults to torch.device('cpu').
dtype (torch.dtype): the dtype of parameters initialized. Defults to torch.float.
default_pg (ProcessGroup): the default process group for all initialized parameters.
default_dist_spec: the default distributed specifications.
"""
super().__init__()
self._device = device
self._dtype = dtype
self._register_colo_modules()
self._default_pg = default_pg
self._default_dist_spec = default_dist_spec
def _register_colo_modules(self):
register_colo_module(torch.nn.Linear, ColoLinear())
register_colo_module(torch.nn.Embedding, ColoEmbedding())
def _pre_context_exec(self):
pass
def _post_init_method(self, module: torch.nn.Module, *args, **kwargs):
"""
The function to call at the end of the constructor of each module.
FIXME(fjr) The module may be passed to this function multiple times?
"""
if hasattr(module, '_colo_visited'):
return
name_list = []
for name, param in _named_params_with_replica(module):
if isinstance(param, ColoTensor):
continue
split = name.rfind('.')
if split >= 0: # param in submodule
module_name = name[:split]
param_name = name[split + 1:]
else:
module_name = '' # param in current module
param_name = name
name_list.append((module_name, param_name))
replaced_tensors = dict(
) # record mapping between (torch.Tensor, ColoTensor) to distinguish the same reference
for module_name, param_name in name_list:
submodule = module.get_submodule(module_name)
param = submodule.get_parameter(param_name)
if param in replaced_tensors:
colo_param = replaced_tensors[param]
else:
# detaching tensor is necessary for optimizers.
requires_grad = param.requires_grad
# param is the global tensor.
colo_param = ColoParameter(param.to(device=self._device, dtype=self._dtype),
requires_grad=requires_grad)
# if default_shard_plan exists, shard the param during initialization.
# This can reduce the model size after initialization.
# NOTE() embedding usually can not be correctly sharded. So I use except to handle
# the param that can not be sharded by the default plan
if self._default_pg is not None:
colo_param.set_process_group(self._default_pg)
if self._default_dist_spec is not None:
try:
colo_param.set_dist_spec(self._default_dist_spec)
except:
pass
replaced_tensors[param] = colo_param
delattr(submodule, param_name)
setattr(submodule, param_name, colo_param)
colo_param.shared_param_modules.append(submodule)
module.to(self._device)
ColoModulize(module)