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Colossal-AI: Making large AI models cheaper, faster, and more accessible

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Why Colossal-AI

Prof. James Demmel (UC Berkeley): Colossal-AI makes training AI models efficient, easy, and scalable.

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Colossal-AI provides a collection of parallel components for you. We aim to support you to write your distributed deep learning models just like how you write your model on your laptop. We provide user-friendly tools to kickstart distributed training and inference in a few lines.

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Colossal-AI in the Real World


Open-Sora:Revealing Complete Model Parameters, Training Details, and Everything for Sora-like Video Generation Models [code] [blog] [HuggingFace model weights] [Demo]

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Model Backbone Tokens Consumed MMLU (5-shot) CMMLU (5-shot) AGIEval (5-shot) GAOKAO (0-shot) CEval (5-shot)
Baichuan-7B - 1.2T 42.32 (42.30) 44.53 (44.02) 38.72 36.74 42.80
Baichuan-13B-Base - 1.4T 50.51 (51.60) 55.73 (55.30) 47.20 51.41 53.60
Baichuan2-7B-Base - 2.6T 46.97 (54.16) 57.67 (57.07) 45.76 52.60 54.00
Baichuan2-13B-Base - 2.6T 54.84 (59.17) 62.62 (61.97) 52.08 58.25 58.10
ChatGLM-6B - 1.0T 39.67 (40.63) 41.17 (-) 40.10 36.53 38.90
ChatGLM2-6B - 1.4T 44.74 (45.46) 49.40 (-) 46.36 45.49 51.70
InternLM-7B - 1.6T 46.70 (51.00) 52.00 (-) 44.77 61.64 52.80
Qwen-7B - 2.2T 54.29 (56.70) 56.03 (58.80) 52.47 56.42 59.60
Llama-2-7B - 2.0T 44.47 (45.30) 32.97 (-) 32.60 25.46 -
Linly-AI/Chinese-LLaMA-2-7B-hf Llama-2-7B 1.0T 37.43 29.92 32.00 27.57 -
wenge-research/yayi-7b-llama2 Llama-2-7B - 38.56 31.52 30.99 25.95 -
ziqingyang/chinese-llama-2-7b Llama-2-7B - 33.86 34.69 34.52 25.18 34.2
TigerResearch/tigerbot-7b-base Llama-2-7B 0.3T 43.73 42.04 37.64 30.61 -
LinkSoul/Chinese-Llama-2-7b Llama-2-7B - 48.41 38.31 38.45 27.72 -
FlagAlpha/Atom-7B Llama-2-7B 0.1T 49.96 41.10 39.83 33.00 -
IDEA-CCNL/Ziya-LLaMA-13B-v1.1 Llama-13B 0.11T 50.25 40.99 40.04 30.54 -
Colossal-LLaMA-2-7b-base Llama-2-7B 0.0085T 53.06 49.89 51.48 58.82 50.2
Colossal-LLaMA-2-13b-base Llama-2-13B 0.025T 56.42 61.80 54.69 69.53 60.3


ColossalChat: An open-source solution for cloning ChatGPT with a complete RLHF pipeline. [code] [blog] [demo] [tutorial]

  • Up to 10 times faster for RLHF PPO Stage3 Training

  • Up to 7.73 times faster for single server training and 1.42 times faster for single-GPU inference

  • Up to 10.3x growth in model capacity on one GPU
  • A mini demo training process requires only 1.62GB of GPU memory (any consumer-grade GPU)

  • Increase the capacity of the fine-tuning model by up to 3.7 times on a single GPU
  • Keep at a sufficiently high running speed

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Acceleration of AIGC (AI-Generated Content) models such as Stable Diffusion v1 and Stable Diffusion v2.

  • Training: Reduce Stable Diffusion memory consumption by up to 5.6x and hardware cost by up to 46x (from A100 to RTX3060).

  • Inference: Reduce inference GPU memory consumption by 2.5x.

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Acceleration of AlphaFold Protein Structure

  • FastFold: Accelerating training and inference on GPU Clusters, faster data processing, inference sequence containing more than 10000 residues.

  • xTrimoMultimer: accelerating structure prediction of protein monomers and multimer by 11x.

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Parallel Training Demo


  • 70 billion parameter LLaMA3 model training accelerated by 18% [code]


  • 70 billion parameter LLaMA2 model training accelerated by 195% [code] [blog]


  • 65-billion-parameter large model pretraining accelerated by 38% [code] [blog]


  • Enhanced MoE parallelism, Open-source MoE model training can be 9 times more efficient [code] [blog]


  • Save 50% GPU resources and 10.7% acceleration


  • 11x lower GPU memory consumption, and superlinear scaling efficiency with Tensor Parallelism

  • 24x larger model size on the same hardware
  • over 3x acceleration


  • 2x faster training, or 50% longer sequence length



  • Open Pretrained Transformer (OPT), a 175-Billion parameter AI language model released by Meta, which stimulates AI programmers to perform various downstream tasks and application deployments because of public pre-trained model weights.
  • 45% speedup fine-tuning OPT at low cost in lines. [Example] [Online Serving]

Please visit our documentation and examples for more details.


  • 14x larger batch size, and 5x faster training for Tensor Parallelism = 64

Recommendation System Models

  • Cached Embedding, utilize software cache to train larger embedding tables with a smaller GPU memory budget.

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Single GPU Training Demo


  • 20x larger model size on the same hardware

  • 120x larger model size on the same hardware (RTX 3080)


  • 34x larger model size on the same hardware

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  • Large AI models inference speed doubled, compared to the offline inference performance of vLLM in some cases. [code] [blog]


  • 314 Billion Parameter Grok-1 Inference Accelerated by 3.8x, an easy-to-use Python + PyTorch + HuggingFace version for Inference.

[code] [blog] [HuggingFace Grok-1 PyTorch model weights] [ModelScope Grok-1 PyTorch model weights]


  • SwiftInfer: Inference performance improved by 46%, open source solution breaks the length limit of LLM for multi-round conversations

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If you encounter any problem with installation, you may want to raise an issue in this repository.

Install from PyPI

You can easily install Colossal-AI with the following command. By default, we do not build PyTorch extensions during installation.

pip install colossalai

Note: only Linux is supported for now.

However, if you want to build the PyTorch extensions during installation, you can set BUILD_EXT=1.

BUILD_EXT=1 pip install colossalai

Otherwise, CUDA kernels will be built during runtime when you actually need them.

We also keep releasing the nightly version to PyPI every week. This allows you to access the unreleased features and bug fixes in the main branch. Installation can be made via

pip install colossalai-nightly

Download From Source

The version of Colossal-AI will be in line with the main branch of the repository. Feel free to raise an issue if you encounter any problems. :)

git clone
cd ColossalAI

# install colossalai
pip install .

By default, we do not compile CUDA/C++ kernels. ColossalAI will build them during runtime. If you want to install and enable CUDA kernel fusion (compulsory installation when using fused optimizer):

BUILD_EXT=1 pip install .

For Users with CUDA 10.2, you can still build ColossalAI from source. However, you need to manually download the cub library and copy it to the corresponding directory.

# clone the repository
git clone
cd ColossalAI

# download the cub library
cp -r cub-1.8.0/cub/ colossalai/kernel/cuda_native/csrc/kernels/include/

# install
BUILD_EXT=1 pip install .

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Use Docker

Pull from DockerHub

You can directly pull the docker image from our DockerHub page. The image is automatically uploaded upon release.

Build On Your Own

Run the following command to build a docker image from Dockerfile provided.

Building Colossal-AI from scratch requires GPU support, you need to use Nvidia Docker Runtime as the default when doing docker build. More details can be found here. We recommend you install Colossal-AI from our project page directly.

cd ColossalAI
docker build -t colossalai ./docker

Run the following command to start the docker container in interactive mode.

docker run -ti --gpus all --rm --ipc=host colossalai bash

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Join the Colossal-AI community on Forum, Slack, and WeChat(微信) to share your suggestions, feedback, and questions with our engineering team.


Referring to the successful attempts of BLOOM and Stable Diffusion, any and all developers and partners with computing powers, datasets, models are welcome to join and build the Colossal-AI community, making efforts towards the era of big AI models!

You may contact us or participate in the following ways:

  1. Leaving a Star ⭐ to show your like and support. Thanks!
  2. Posting an issue, or submitting a PR on GitHub follow the guideline in Contributing
  3. Send your official proposal to email

Thanks so much to all of our amazing contributors!

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We leverage the power of GitHub Actions to automate our development, release and deployment workflows. Please check out this documentation on how the automated workflows are operated.

Cite Us

This project is inspired by some related projects (some by our team and some by other organizations). We would like to credit these amazing projects as listed in the Reference List.

To cite this project, you can use the following BibTeX citation.

author = {Li, Shenggui and Liu, Hongxin and Bian, Zhengda and Fang, Jiarui and Huang, Haichen and Liu, Yuliang and Wang, Boxiang and You, Yang},
title = {Colossal-AI: A Unified Deep Learning System For Large-Scale Parallel Training},
year = {2023},
isbn = {9798400708435},
publisher = {Association for Computing Machinery},
address = {New York, NY, USA},
url = {},
doi = {10.1145/3605573.3605613},
abstract = {The success of Transformer models has pushed the deep learning model scale to billions of parameters, but the memory limitation of a single GPU has led to an urgent need for training on multi-GPU clusters. However, the best practice for choosing the optimal parallel strategy is still lacking, as it requires domain expertise in both deep learning and parallel computing. The Colossal-AI system addressed the above challenge by introducing a unified interface to scale your sequential code of model training to distributed environments. It supports parallel training methods such as data, pipeline, tensor, and sequence parallelism and is integrated with heterogeneous training and zero redundancy optimizer. Compared to the baseline system, Colossal-AI can achieve up to 2.76 times training speedup on large-scale models.},
booktitle = {Proceedings of the 52nd International Conference on Parallel Processing},
pages = {766–775},
numpages = {10},
keywords = {datasets, gaze detection, text tagging, neural networks},
location = {Salt Lake City, UT, USA},
series = {ICPP '23}

Colossal-AI has been accepted as official tutorial by top conferences NeurIPS, SC, AAAI, PPoPP, CVPR, ISC, NVIDIA GTC ,etc.

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