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# Copyright 2021 AlQuraishi Laboratory | |
# | |
# Licensed under the Apache License, Version 2.0 (the "License"); | |
# you may not use this file except in compliance with the License. | |
# You may obtain a copy of the License at | |
# | |
# http://www.apache.org/licenses/LICENSE-2.0 | |
# | |
# Unless required by applicable law or agreed to in writing, software | |
# distributed under the License is distributed on an "AS IS" BASIS, | |
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
# See the License for the specific language governing permissions and | |
# limitations under the License. | |
import importlib | |
from typing import Any, Tuple, List, Callable, Optional | |
import torch | |
import torch.utils.checkpoint | |
BLOCK_ARG = Any | |
BLOCK_ARGS = List[BLOCK_ARG] | |
def checkpoint_blocks( | |
blocks: List[Callable], | |
args: BLOCK_ARGS, | |
blocks_per_ckpt: Optional[int], | |
) -> BLOCK_ARGS: | |
""" | |
Chunk a list of blocks and run each chunk with activation | |
checkpointing. We define a "block" as a callable whose only inputs are | |
the outputs of the previous block. | |
Implements Subsection 1.11.8 | |
Args: | |
blocks: | |
List of blocks | |
args: | |
Tuple of arguments for the first block. | |
blocks_per_ckpt: | |
Size of each chunk. A higher value corresponds to fewer | |
checkpoints, and trades memory for speed. If None, no checkpointing | |
is performed. | |
Returns: | |
The output of the final block | |
""" | |
def wrap(a): | |
return (a,) if type(a) is not tuple else a | |
def exec(b, a): | |
for block in b: | |
a = wrap(block(*a)) | |
return a | |
def chunker(s, e): | |
def exec_sliced(*a): | |
return exec(blocks[s:e], a) | |
return exec_sliced | |
# Avoids mishaps when the blocks take just one argument | |
args = wrap(args) | |
if blocks_per_ckpt is None or not torch.is_grad_enabled(): | |
return exec(blocks, args) | |
elif blocks_per_ckpt < 1 or blocks_per_ckpt > len(blocks): | |
raise ValueError("blocks_per_ckpt must be between 1 and len(blocks)") | |
for s in range(0, len(blocks), blocks_per_ckpt): | |
e = s + blocks_per_ckpt | |
args = torch.utils.checkpoint.checkpoint(chunker(s, e), *args, use_reentrant=True) | |
args = wrap(args) | |
return args | |