High performance lattice regression on FPGAs via a high level hardware description language

Lattice regression-based models are highly-constrainable and interpretable machine learning models used in applications such as query classification and path length prediction for maps. To improve their performance and better serve these models to millions of consumers, we accelerate them using field programmable gate arrays. We adopt a library-based approach using a high level hardware description language (HLHDL) to support the broad family of lattice models. HLHDLs improve productivity by providing both control abstraction such as looping, reductions, and memory hierarchies, as well as automatically handling low-level tasks such as retiming. However, these abstractions can lead to performance bottlenecks if not carefully used. We characterize these bottlenecks and implement a lattice regression library using a streaming tensor abstraction which avoids them. On a pair of models trained for network anomaly detection, we achieve a ${166\,-\,256\times}$ speedup over CPUs even with large batch sizes.