ColossalAI/colossalai/gemini/chunk/search_utils.py

136 lines
4.4 KiB
Python

import math
from typing import Dict, List, Tuple
import numpy as np
import torch.nn as nn
from colossalai.gemini.memory_tracer import OrderedParamGenerator
from colossalai.tensor import ColoParameter
def in_ddp(param: nn.Parameter) -> bool:
return not getattr(param, '_ddp_to_ignore', False)
def _filter_exlarge_params(model: nn.Module, size_dict: Dict[int, List[int]]) -> None:
"""
Filter those parameters whose size is too large (more than 3x standard deviations) from others.
"""
params_size = [p.numel() for p in model.parameters() if in_ddp(p)]
params_size_arr = np.array(params_size)
std = np.std(params_size_arr)
mean = np.mean(params_size_arr)
upper_limit = mean + 3 * std
for key in size_dict:
org_list = size_dict[key]
size_dict[key] = list(filter(lambda x: x <= upper_limit, org_list))
def _get_unused_byte(size_list: List[int], chunk_size: int) -> int:
"""Get unused byte for a certain chunk size.
"""
acc = 0
left = 0
for s in size_list:
if s > left:
acc += left
left = chunk_size
left -= s
return left + acc
def classify_params_by_dp_degree(param_order: OrderedParamGenerator) -> Dict[int, List[ColoParameter]]:
"""classify_params_by_dp_degree
Classify the parameters by their dp degree
Args:
param_order (OrderedParamGenerator): the order of param be visied
Returns:
Dict[int, List[ColoParameter]]: a dict contains the classification results.
The keys are dp_degrees and the values are parameters.
"""
params_dict: Dict[int, List[ColoParameter]] = dict()
for param in param_order.generate():
assert isinstance(param, ColoParameter), "please init model in the ColoInitContext"
if not in_ddp(param):
continue
param_key = param.process_group.dp_world_size()
if param_key not in params_dict:
params_dict[param_key] = []
params_dict[param_key].append(param)
return params_dict
def search_chunk_configuration(
model: nn.Module,
search_range_mb: float,
search_interval_byte: int, # hidden size is the best value for the interval
min_chunk_size_mb: float = 32,
filter_exlarge_params: bool = True) -> Tuple[Dict, int]:
"""search_chunk_configuration
Args:
model (nn.Module): torch module
search_range_mb (float): searching range in mega byte.
search_interval_byte (int): searching interval in byte.
filter_exlarge_params (bool, optional): filter extreme large parameters. Defaults to True.
Returns:
Tuple[Dict, int]: chunk config and its memory chunk waste in byte.
"""
param_order = OrderedParamGenerator()
for p in model.parameters():
param_order.append(p)
search_range_byte = round(search_range_mb * 1024**2)
min_chunk_size_byte = round(min_chunk_size_mb * 1024**2)
assert search_range_byte >= 0
params_dict = classify_params_by_dp_degree(param_order)
config_dict: Dict[int, Dict] = dict()
size_dict: Dict[int, List[int]] = dict()
for dp_degree in params_dict:
params_list = params_dict[dp_degree]
size_list = [p.numel() for p in params_list]
# let small parameters keep gathered in CUDA all the time
total_size = sum(size_list)
if total_size < min_chunk_size_byte:
config_dict[dp_degree] = dict(chunk_size=total_size, keep_gathered=True)
else:
size_dict[dp_degree] = size_list
if filter_exlarge_params:
_filter_exlarge_params(model, size_dict)
max_size = min_chunk_size_byte
for key in size_dict:
max_size = max(max_size, max(size_dict[key]))
start_size = int(math.ceil(max_size / search_interval_byte) * search_interval_byte)
min_chunk_waste = float('+inf')
best_chunk_size = start_size
for chunk_size in range(start_size, start_size + search_range_byte + 1, search_interval_byte):
temp_waste = 0
for key in size_dict:
temp_waste += _get_unused_byte(size_dict[key], chunk_size)
if temp_waste < min_chunk_waste:
min_chunk_waste = temp_waste
best_chunk_size = chunk_size
for dp_degree in params_dict:
if dp_degree in config_dict:
continue
config_dict[dp_degree] = dict(chunk_size=best_chunk_size, keep_gathered=False)
return config_dict, min_chunk_waste