BMCook

Model Compression for Big Models

Overview • Documentation • Installation • Usage • Quick Start • 简体中文

What's New

• 2023/5/27 Support structured pruning of Decoder-only models, and the compression of CPM-Live models。
• 2022/5/17 Support PLMs in model-center.
• 2022/3/29 (BMCook 0.1.0) Now we publicly release the first version of BMCook.

Overview

BMCook is a model compression toolkit for large-scale pre-trained language models (PLMs), which integrates multiple model compression methods. You can combine them in any way to achieve the desired speedup. Specifically, we implement the following four model compression methods, knowledge distillation, model pruning, model quantization, and model MoEfication. It has following features:

• Various Supported Methods. Compared to existing compression toolkits, BMCook supports all mainstream acceleration methods for pre-trained language models.
• User Friendly. Based on BMCook, we can implement different compression methods with just a few lines of codes.
• Combination in Any Way. Due to the decoupled implications, the compression methods can be combined in any way towards extreme acceleration.

Documentation

Our documentation provides more information about the package.

Installation

To use BMCook, first install BMTrain.

From PyPI (Recommend)

$ pip install bmtrain

From Source

$ git clone https://github.com/OpenBMB/BMTrain.git
$ cd BMTrain
$ python3 setup.py install

Please refer to the installation guide of BMTrain for more details.

Then, install BMCook.

From PyPI (Recommend)

$ pip install bmcook

From source

$ git clone git@github.com:OpenBMB/BMCook.git
cd BMCook
python3 setup.py install

Usage

1. Design your BMCook config.

You should give a json file to state your compress strategy.

{ "distillation": {
    "ce_scale": 0,
    "ce_temp": 1,
      
    "mse_hidn_scale": 0,
    "mse_hidn_module": ['[placehold]'],
    "mse_hidn_proj": false,
      
    "mse_att_scale": 0,
    "mse_att_module": ['[placehold]'],
  },

  "pruning": {
    "is_pruning": false,
    "pruning_mask_path": None,
    "pruned_module": ['[placehold]'],
    "mask_method": "m4n2_1d/m4n2_2d/sprune",
    "sprune": {
        "criterion": "l0",
        "training_mask": ['[placehold]'],
        "fixed_mask_path": "",
        "mask_mode": "train_mask",
        "target_sparsity": 0.5
    }
  },

  "quantization": {
    "is_quant": false,
    "quantized_module": [],
  },

  "MoEfication": {
    "is_moefy": false,
    "first_FFN_module": ['[placehold]'],
  }
}

To notice:

• is_moefy, is_quant, ispruning are switch parameters. If false, other parameters will be blocked. mask_method takes similar works. When mask_method is "m4n2_1d" or "m4n2_2d", it will execute unstructure pruning, but when is "sprune", the sprune field will be activated. For distillation, when the ce_scale or mse_hidn_scale is greater than 0, the corresponding distilling mode will be switched on.

• It's not recommended to use MoE and Distilling simultaneously.

2. Basic usage in your code.

BMCook provides unified interface CookTrainer. BMCook will introduce distillation pruning and MoEfication, which may add some terms to model outputs. You can use it to manage your model, and these modifications.

from bmcook import CookTrainer
from bmcook.utils.config import ConfigParser

#prepare your model, dataloader and optimizer...
...

# setting up your BMCook strategy
CookTrainer.set_compression(cookconfig, model, optimizer, model_distill)

# train
for data in dataloader:
    targets = ...
    ...
    outputs = CookTrainer.forward(model, loss_func, targets, *your_model_inputs, **your_model_kwinputs)

    [loss, model_outputs, lag_loss, sparsity, distill_loss] = outputs

the loss equals to the sum of model_loss, lag_loss and distill_loss. So if you wanna know the model performance, please minus them. Noticed that if sprune is not setted, the lag_loss and loss_func will be None, so do distilling.

model_loss = loss - lag_loss - distill_loss # sprune and distilling both setted.
model_loss = loss - distill_loss # only distilling used. 

BMCook also provides discrete interfaces to initialize compression settings. If you want to design your Trainer for your own needs, you can use these discrete interfaces. Noticed that the output format should keep the same with CookTrainer when you define your own Trainer. For details about extension on CookTrainer, you can refer to CPMAntTrainer.

from bmcook import BMDistill

# Define your own Trainer. 
Trainer = ...

# Set up the distillation
Trainer.forward = BMDistill.set_forward(model, teacher, Trainer.forward, cook_config)

3. How to run your code

You can run your code as normal, but should state where your cookconfig is:

    torchrun --nnodes=1 --nproc_per_node=1 --rdzv_id=1 --rdzv_backend=c10d --rdzv_endpoint=localhost train.py \
     --save-dir ... \
     --model ... \
     --start-lr ... \
     --cook-config  ... \ # give your cook config path

Quick Start

The examples folder provides pruning example based on CPM-Live, GPT2-Base, T5-large, please check examples for more details.

Take GPT2 as example:

Quantization-aware training：

    torchrun --nnodes=1 --nproc_per_node=1 --rdzv_id=1 --rdzv_backend=c10d --rdzv_endpoint=localhost train.py \
     --save-dir results/gpt2-int8 \
     --model gpt2-base \
     --start-lr 1e-4 \
     --cook-config configs/gpt2-int8.json \

Quantization-aware training with knowledge distillation：

    torchrun --nnodes=1 --nproc_per_node=1 --rdzv_id=1 --rdzv_backend=c10d --rdzv_endpoint=localhost train.py \
     --save-dir results/gpt2-int8-kd \
     --model gpt2-base \
     --start-lr 1e-4 \
     --cook-config configs/gpt2-int8-kd.json \

Model pruning：

    torchrun --nnodes=1 --nproc_per_node=1 --rdzv_id=1 --rdzv_backend=c10d --rdzv_endpoint=localhost train.py \
     --save-dir results/gpt2-prune \
     --model gpt2-base \
     --start-lr 1e-4 \
     --cook-config configs/gpt2-prune.json \

In this case, we only prune the input embedding layer. You can include more modules by changing the pruned_module field in the config file.

MoEfication (save the hidden states and then use the MoEfication toolkit)：

    torchrun --nnodes=1 --nproc_per_node=1 --rdzv_id=1 --rdzv_backend=c10d --rdzv_endpoint=localhost train.py \
     --save-dir results/gpt2-moe \
     --model gpt2-base \
     --start-lr 1e-4 \
     --cook-config configs/gpt2-moe.json \

Combine quantization, pruning and knowledge distillation：

    torchrun --nnodes=1 --nproc_per_node=1 --rdzv_id=1 --rdzv_backend=c10d --rdzv_endpoint=localhost train.py \
     --save-dir results/gpt2-combine \
     --model gpt2-base \
     --start-lr 1e-4 \
     --cook-config configs/gpt2-combine.json \

Performances

Based on T5-3B, we evaluate different combinations of compression techniques. The corpus for compression is the Pile. The evaluation datasets includes SST-2, MNLI, and SQuAD. Specifically, we freeze the compressed models and adopt adapter-tuning.

	Average Performance	Relative Performance	Speedup
T5-3B	0.9258	-	1x
T5-Base	0.8796	95.0%	14x
T5-3B (P+D)	0.9150	98.8%	2x
T5-3B (P+D+Q)	0.9126	98.6%	8x
T5-3B (P+D+Q+M)	0.9017	97.4%	12x

D denotes knowledge distillation. P denotes pruning. Q denotes quantization. M denotes MoEfication.

Comparisons

	Model Quantization	Model Pruning	Knowledge Distillation	Model MoEfication
TextPruner	-	✅	-	-
TensorFlow Lite	✅	✅	-	-
PyTorch	✅	✅	-	-
TextBrewer	-	✅	✅	-
BMCook	✅	✅	✅	✅

Community

We welcome everyone to contribute codes following our contributing guidelines.

You can also find us on other platforms:

• QQ Group: 735930538
• WeChat Official Account: OpenBMB
• Website: https://www.openbmb.org
• Weibo: http://weibo.cn/OpenBMB
• Twitter: https://twitter.com/OpenBMB

License

The package is released under the Apache 2.0 License.

Contributors

We thank Zhengyan Zhang, Baitao Gong, Yingfa Chen, Guoyang Zeng, Jie Zhou, and Zhi Zheng for the contribution. More contributors are welcome!