MCUNet: Tiny Deep Learning on IoT Devices

website | paper | paper (v2) | demo video

News

We will soon release TinyEngine. If you are interested in getting updates, please sign up here to get notified!

• (2022/06) We refactor the MCUNet repo as a standalone repo (previous repo: https://github.com/mit-han-lab/tinyml)
• (2021/10) MCUNetV2 is accepted to NeurIPS 2021: https://arxiv.org/abs/2110.15352 !
• (2020/10) MCUNet is accepted to NeurIPS 2020 as spotlight: https://arxiv.org/abs/2007.10319 !
• Our projects are covered by: MIT News, MIT News (v2), WIRED, Morning Brew, Stacey on IoT, Analytics Insight, Techable, etc.

Overview

Microcontrollers are low-cost, low-power hardware. They are widely deployed and have wide applications.

But the tight memory budget (50,000x smaller than GPUs) makes deep learning deployment difficult.

MCUNet is a system-algorithm co-design framework for tiny deep learning on microcontrollers. It consists of TinyNAS and TinyEngine. They are co-designed to fit the tight memory budgets.

With system-algorithm co-design, we can significantly improve the deep learning performance on the same tiny memory budget.

Our TinyEngine inference engine could be a useful infrastructure for MCU-based AI applications. It significantly improves the inference speed and reduces the memory usage compared to existing libraries like TF-Lite Micro, CMSIS-NN, MicroTVM, etc. It improves the inference speed by 1.5-3x, and reduces the peak memory by 2.7-4.8x.

Model Zoo

Usage

You can build the pre-trained PyTorch fp32 model or the int8 quantized model in TF-Lite format.

from mcunet.model_zoo import net_id_list, build_model, download_tflite
print(net_id_list)  # the list of models in the model zoo

# pytorch fp32 model
model, image_size, description = build_model(net_id="mcunet-320kB", pretrained=True)  # you can replace net_id with any other option from net_id_list

# download tflite file to tflite_path
tflite_path = download_tflite(net_id="mcunet-320kB")

Evaluate

To evaluate the accuracy of PyTorch fp32 models, run:

python eval_torch.py --net_id mcunet-320kB --dataset {imagenet/vww} --data-dir PATH/TO/DATA/val

To evaluate the accuracy of TF-Lite int8 models, run:

python eval_tflite.py --net_id mcunet-320kB --dataset {imagenet/vww} --data-dir PATH/TO/DATA/val

Model List

• Note that all the latency, SRAM, and Flash usage are profiled with TinyEngine on STM32F746.
• Here we only provide the int8 quantized modes. int4 quantized models (as shown in the paper) can further push the accuracy-memory trade-off, but lacking a general format support.
• For accuracy (top1, top-5), we report the accuracy of fp32/int8 models respectively

The ImageNet model list:

net_id	MACs	#Params	SRAM	Flash	Top-1 (fp32/int8)	Top-5 (fp32/int8)
# baseline models
mbv2-320kB	23.5M	0.75M	308kB	862kB	49.7%/49.0%	74.6%/73.8%
proxyless-320kB	38.3M	0.75M	292kB	892kB	57.0%/56.2%	80.2%/79.7%
# mcunet models
mcunet-10fps	6.4M	0.75M	266kB	889kB	41.5%/40.4%	66.3%/65.2%
mcunet-5fps	12.8M	0.64M	307kB	992kB	51.5%/49.9%	75.5%/74.1%
mcunet-256kB	67.3M	0.73M	242kB	878kB	60.9%/60.3%	83.3%/82.6%
mcunet-320kB	81.8M	0.74M	293kB	897kB	62.2%/61.8%	84.5%/84.2%
mcunet-512kB	125.9M	1.73M	456kB	1876kB	68.4%/68.0%	88.4%/88.1%

The VWW model list:

Note that the VWW dataset might be hard to prepare. You can download our pre-built minival set from here, around 380MB.

net_id	MACs	#Params	SRAM	Flash	Top-1 (fp32/int8)
mcunet-10fps-vww	6.0M	0.37M	146kB	617kB	87.4%/87.3%
mcunet-5fps-vww	11.6M	0.43M	162kB	689kB	88.9%/88.9%
mcunet-320kB-vww	55.8M	0.64M	311kB	897kB	91.7%/91.8%

For TF-Lite int8 models we do not use quantization-aware training (QAT), so some results is slightly lower than paper numbers.

Requirement

• Python 3.6+

• PyTorch 1.4.0+

• Tensorflow 1.15 (if you want to test TF-Lite models; CPU support only)

Acknowledgement

We thank MIT Satori cluster for providing the computation resource. We thank MIT-IBM Watson AI Lab, SONY, Qualcomm, NSF CAREER Award #1943349 and NSF RAPID Award #2027266 for supporting this research.

Citation

If you find the project helpful, please consider citing our paper:

@article{lin2020mcunet,
  title={Mcunet: Tiny deep learning on iot devices},
  author={Lin, Ji and Chen, Wei-Ming and Lin, Yujun and Gan, Chuang and Han, Song},
  journal={Advances in Neural Information Processing Systems},
  volume={33},
  year={2020}
}

@inproceedings{
  lin2021mcunetv2,
  title={MCUNetV2: Memory-Efficient Patch-based Inference for Tiny Deep Learning},
  author={Lin, Ji and Chen, Wei-Ming and Cai, Han and Gan, Chuang and Han, Song},
  booktitle={Annual Conference on Neural Information Processing Systems (NeurIPS)},
  year={2021}
} 

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