CAT: Compression-Aware Training for bandwidth reduction
Authors: Chaim Baskin, Brian Chmiel, Evgenii Zheltonozhskii, Ron Banner, Alex M. Bronstein, Avi Mendelson
Keywords: compression, quantization, efficient inference, memory bandwidth, entropy, compression-aware training, Huffman, variable length coding
TL;DR: Adding an entropy-reducing regularization to the loss to improve activation compression in inference time reducing memory bandwidth.
Abstract: Convolutional neural networks (CNNs) have become the dominant neural network architecture for solving visual processing tasks. One of the major obstacles hindering the ubiquitous use of CNNs for inference is their relatively high memory bandwidth requirements, which can be a main energy consumer and throughput bottleneck in hardware accelerators. Accordingly, an efficient feature map compression method can result in substantial performance gains. Inspired by quantization-aware training approaches, we propose a compression-aware training (CAT) method that involves training the model in a way that allows better compression of feature maps during inference. Our method trains the model to achieve low-entropy feature maps, which enables efficient compression at inference time using classical transform coding methods. CAT significantly improves the state-of-the-art results reported for quantization. For example, on ResNet-34 we achieve 73.1% accuracy (0.2% degradation from the baseline)  with an average representation of only 1.79 bits per value. Reference implementation accompanies the paper.