A Rate--Distortion View on Model Updates

Johannes Ballé
Jakub Konečný
ICLR 2023 TinyPapers (2023)

Abstract

Compressing model updates is critical for reducing communication costs in federated learning. We examine the problem using rate--distortion theory to present a compression method that is near-optimal in many use cases. We empirically show that common transforms applied to model updates in standard compression algorithms, normalization in QSGD and random rotation in DRIVE, yield sub-optimal compressed representations in practice.