DisCo: Remedying Self-supervised Learning on Lightweight Models with Distilled Contrastive Learning.

While Self-Supervised Learning (SSL) has received widespread attention from the community, recent researches argue that its performance often suffers a cliff fall when the model size decreases. Since current SSL methods mainly rely on contrastive learning to train the network, we propose a simple yet effective method termed Distilled Contrastive Learning (DisCo) to ease this issue. Specifically, we find that the final inherent embedding of the mainstream SSL methods contains the most important information, and propose to distill the final embedding to maximally transmit a teacher’s knowledge to a lightweight model by constraining the last embedding of the student to be consistent with that of the teacher. In addition, we find that there exists a phenomenon termed Distilling BottleNeck and propose to enlarge the embedding dimension to alleviate this problem. Since the MLP only exists during the SSL phase, our method does not introduce any extra parameters to lightweight models for the downstream task deployment. Experimental results demonstrate that our method surpasses the state-of-the-art on many lightweight models by a large margin. Particularly, when ResNet-101/ResNet-50 is used respectively as a teacher to teach EfficientNet-B0, the linear result of EfficientNet-B0 on ImageNet is improved by 22.1% and 19.7%, respectively, which is very close to ResNet-101/ResNet-50 with much fewer parameters. Code is available at https://github.com/Yuting-Gao/DisCo-pytorch.