[AAAI 2024 (Oral)]   OWQ: Outlier-Aware Weight Quantization for Efficient Fine-Tuning and Inference of Large Language Models

Currently our original code is available at xvyaward/owq.

This is the code for the paper [OWQ: Outlier-Aware Weight Quantization for Efficient Fine-Tuning and Inference of Large Language Models](https://arxiv.org/abs/2306.02272). OWQ preserves few weak columns as FP16, while quantizing other weights to 3/4-bits. OWQ achieves substantial quality improvements with only negligible storage and computation overhead, effectively preserving the benefits of low-precision acceleration.

Updates (2024-01-29)

• Integrated all models (OPT, LLaMA, BLOOM, Falcon) into main.py file. You can easily add custom or open-accessible huggingface models to model_config.json if you want.
• Support 4bit matrix - FP16 vector product CUDA kernel.
• Support BFloat16.

Features

• Implementation of the OWQ algorithm: owq/recon.py, main.py
• 3/4-bit weight quantization of LLMs (OPT, LLaMA-1,2 families and etc ...): main.py
• Evaluating the perplexity of quantized models: main.py
• Evaluating the zero-shot accuracy of quantized models: zeroshot.py
• Supports 3/4-bit packed weight save / load (~1/5, ~1/4 file size of FP16 checkpoint, respectively.)
• Efficient 3/4-bit matrix - FP16 vector product CUDA kernel for OWQ: owq/kernel

Table of contents

• Install
• Usage
• Zero-shot
• 3/4-bit CUDA kernels

Install

We highly recommend to use docker image that supports CUDA. If you use anaconda instead, you need to setup CUDA for kernel use.

0. A) Using Docker

docker run -it --gpus all --ipc=host -v {local_storage}:{docker_container_storage} pytorch/pytorch:2.0.0-cuda11.7-cudnn8-devel

# install git
apt update && apt install git -y

0. B) Using anaconda instead of docker

conda create -n owq python=3.10 -y
conda activate owq

1. Clone the OWQ repository

git clone https://github.com/xvyaward/owq
cd owq

2. Install all the dependencies

pip install -r requirements.txt

3. Install CUDA kernel (3/4bit_W x FP16_A)

cd owq/kernel
python setup_cuda.py install

• torch: tested on v2.0.0+cu117
• transformers: tested on v4.36.2 (or 4.29.2)
• datasets: tested on v2.16.1 (or 2.12.0)

Experiments were conducted on a single NVIDIA A100 GPU with 80GB memory. We also confirmed that reconstruction using OWQ works on RTX 3090 GPU (24GB memory) for <= 30B models.

We have tested 3/4-bit CUDA kernel on the NVIDIA A100, A6000 and RTX3090 GPU.

Usage

Running OWQ & measuring the perplexity (PPL)

Here we use llama-7b model (huggyllama/llama-7b) as an example. You can replace the model argument llama-7b among llama-13b, llama-30b, and llama-65b or other model families (e.g. meta-llama/Llama-2-7b-hf, facebook/opt-6.7b, lmsys/vicuna-33b-v1.3, etc ...).

• OWQ using 3.01-bit (3-bit quantization + few FP16 weight columns)

python main.py huggyllama/llama-7b c4 --wbits 3 --target_bit 3.01

• OWQ using 4.01-bit (4-bit quantization + few FP16 weight columns)

python main.py huggyllama/llama-7b c4 --wbits 4 --target_bit 4.01

Below are the example for the other options (FP16, RTN, GPTQ).

# Measuring the ppl of the full precision (FP16) model
python main.py huggyllama/llama-7b c4 --wbits 16

# 4-bit Round-to-Nearest (RTN) quantization
python main.py huggyllama/llama-7b c4 --wbits 4 --nearest

# GPTQ with 3-bit quantization
python main.py huggyllama/llama-7b c4 --wbits 3 --tuning minmax

Zero-shot

Here we give an example of measuring zero-shot accuracy on hellaswag tasks using llama-7b model. You need to generate quantized model checkpoint before measuring the zero-shot accuracy.

# making checkpoint file of OWQ reconstruction
python main.py huggyllama/llama-7b c4 --wbits 3 --target_bit 3.01 --no-eval --save llama-7b_3_01.pth --packing

# measuring zero-shot accuracy (using single-gpu)
CUDA_VISIBLE_DEVICES=0 python zeroshot.py --model hf-causal-owq --model_args pretrained=huggyllama/llama-7b,load=llama-7b_3_01.pth --batch_size 4 --tasks hellaswag --no_cache
# multi-gpu
CUDA_VISIBLE_DEVICES=0,1 python zeroshot.py --model hf-causal-owq --model_args pretrained=huggyllama/llama-7b,load=llama-7b_3_01.pth,use_accelerate=True --batch_size 4 --tasks hellaswag --no_cache

Easy OPT OWQ + Measuring PPL, Zeroshot sample

bash scripts/opt_end_to_end_evaluation.sh 0 opt-1.3b

Demo

Please refer to the README in the demo directory.

3/4-bit CUDA Kernels

Benchmark kernel performance

# Benchmark performance for the matrix-vector multiplication
cd owq/kernel/
python test_kernel.py

Benchmark language generation with 3/4-bit packed model (opt, llama, etc...)

# Example of OPT-66b language generation (single token)

# Save compressed model
python main.py facebook/opt-66b c4 --wbits 3 --target_bit 3.01 --no-eval --save opt-66b_3_01.pth --packing

# Benchmark generating a 128 token sequence with the saved model
CUDA_VISIBLE_DEVICE=0 python main.py facebook/opt-66b c4 --load opt-66b_3_01.pth --benchmark 128 --faster

# Benchmark FP16 baseline, note that the model will be split across all listed GPUs
CUDA_VISIBLE_DEVICES=0,1,2 python main.py facebook/opt-66b c4 --benchmark 128

Please note that our 3/4-bit kernels are currently only optimized for A100 or A6000 GPUs and may thus yield suboptimal performance on smaller models or on other GPUs.

Reference

GPTQ: Accurate Post-training Compression for Generative Pretrained Transformers

This code is based on GPTQ.

Our zero-shot experiment codes are based on EleutherAI/lm-evaluation-harness.

Thanks to Meta AI for releasing powerful LLM OPT and LLaMA.

Cite

If you find our code or OWQ useful for your research, please consider citing:

@article{lee2023owq,
  title={OWQ: Lessons learned from activation outliers for weight quantization in large language models},
  author={Lee, Changhun and Jin, Jungyu and Kim, Taesu and Kim, Hyungjun and Park, Eunhyeok},
  journal={arXiv preprint arXiv:2306.02272},
  year={2023}
}