Vector Post-Training Quantization (VPTQ) is a novel Post-Training Quantization method that leverages Vector Quantization to high accuracy on LLMs at an extremely low bit-width (<2-bit). VPTQ can compress 70B, even the 405B model, to 1-2 bits without retraining and maintain high accuracy.
pip install vptq
.recommend For saving your time to build the package, Please install VPTQ from the latest Release directly
pip install vptq
or from
https://github.com/microsoft/VPTQ/releases
[Not Aavailbe if Release package]
Preparation steps that might be needed: Set up CUDA_HOME and PATH.
Set cuda-12
to your own CUDA version and environment. Run nvcc --version
to find out your version, and which nvcc
to check your CUDA PATH.
# example
export CUDA_HOME=/usr/local/cuda-12
export PATH=/usr/local/cuda-12/bin/:$PATH # set dependent on your environment
Will Take several minutes to compile CUDA kernels, please be patient. Current compilation builds on SM 7.0, 7.5, 8.0, 8,6, 9.0 to reduce the compilation time. You can set TORCH_CUDA_ARCH_LIST
to your specific architecture.
pip install git+https://github.com/microsoft/VPTQ.git --no-build-isolation
You can configure the required CUDA architectures and the number of nvcc compile threads by setting
TORCH_CUDA_ARCH_LIST=8.0,9.0 NVCC_THREADS=16 pip install -e . --no-build-isolation
to reduce compilation time.
Example: Run Llama 3.1 70b on RTX4090 (24G @ ~2bits) in real time
VPTQ is an ongoing project. If the open-source community is interested in optimizing and expanding VPTQ, please feel free to submit an issue or DM.
β οΈ The repository only provides a method of model quantization algorithm.
β οΈ The open-source community VPTQ-community provides models based on the technical report and quantization algorithm.
β οΈ The repository cannot guarantee the performance of those models.
Quick Estimation of Model Bitwidth (Excluding Codebook Overhead):
Model Naming Convention: The model's name includes the vector length $v$, codebook (lookup table) size, and residual codebook size. For example, "Meta-Llama-3.1-70B-Instruct-v8-k65536-256-woft" is "Meta-Llama-3.1-70B-Instruct", where:
Equivalent Bitwidth Calculation:
Model Size Estimation: 70B * 3 bits / 8 bits per Byte = 26.25 GB
Note: This estimate does not include the size of the codebook (lookup table), other parameter overheads, and the padding overhead for storing indices. For the detailed calculation method, please refer to Tech Report Appendix C.2.
To generate text using the pre-trained model, you can use the following code snippet:
The model VPTQ-community/Meta-Llama-3.1-70B-Instruct-v8-k65536-0-woft (~2 bit) is provided by open source community. The repository cannot guarantee the performance of those models.
python -m vptq --model=VPTQ-community/Meta-Llama-3.1-70B-Instruct-v8-k65536-0-woft --prompt="Explain: Do Not Go Gentle into That Good Night"
Launching a chatbot: Note that you must use a chat model for this to work
python -m vptq --model=VPTQ-community/Meta-Llama-3.1-70B-Instruct-v8-k65536-0-woft --chat
Using the Python API:
import vptq
import transformers
tokenizer = transformers.AutoTokenizer.from_pretrained("VPTQ-community/Meta-Llama-3.1-70B-Instruct-v8-k65536-0-woft")
m = vptq.AutoModelForCausalLM.from_pretrained("VPTQ-community/Meta-Llama-3.1-70B-Instruct-v8-k65536-0-woft", device_map='auto')
inputs = tokenizer("Explain: Do Not Go Gentle into That Good Night", return_tensors="pt").to("cuda")
out = m.generate(**inputs, max_new_tokens=100, pad_token_id=2)
print(tokenizer.decode(out[0], skip_special_tokens=True))
An environment variable is available to control share link or not.
export SHARE_LINK=1
python -m vptq.app
Scaling model size significantly challenges the deployment and inference of Large Language Models (LLMs). Due to the redundancy in LLM weights, recent research has focused on pushing weight-only quantization to extremely low-bit (even down to 2 bits). It reduces memory requirements, optimizes storage costs, and decreases memory bandwidth needs during inference. However, due to numerical representation limitations, traditional scalar-based weight quantization struggles to achieve such extreme low-bit. Recent research on Vector Quantization (VQ) for LLMs has demonstrated the potential for extremely low-bit model quantization by compressing vectors into indices using lookup tables.
Read tech report at Tech Report and arXiv Paper
VPTQ achieves better accuracy and higher throughput with lower quantization overhead across models of different sizes. The following experimental results are for reference only; VPTQ can achieve better outcomes under reasonable parameters, especially in terms of model accuracy and inference speed.
Model | bitwidth | W2β | C4β | AvgQAβ | tok/sβ | mem(GB) | cost/hβ |
---|---|---|---|---|---|---|---|
LLaMA-2 7B | 2.02 | 6.13 | 8.07 | 58.2 | 39.9 | 2.28 | 2 |
2.26 | 5.95 | 7.87 | 59.4 | 35.7 | 2.48 | 3.1 | |
LLaMA-2 13B | 2.02 | 5.32 | 7.15 | 62.4 | 26.9 | 4.03 | 3.2 |
2.18 | 5.28 | 7.04 | 63.1 | 18.5 | 4.31 | 3.6 | |
LLaMA-2 70B | 2.07 | 3.93 | 5.72 | 68.6 | 9.7 | 19.54 | 19 |
2.11 | 3.92 | 5.71 | 68.7 | 9.7 | 20.01 | 19 |
EMNLP 2024 Main
@inproceedings{
vptq,
title={VPTQ: Extreme Low-bit Vector Post-Training Quantization for Large Language Models},
author={Yifei Liu and
Jicheng Wen and
Yang Wang and
Shengyu Ye and
Li Lyna Zhang and
Ting Cao and
Cheng Li and
Mao Yang},
booktitle={The 2024 Conference on Empirical Methods in Natural Language Processing},
year={2024},
}
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