CoSA: Scheduling by Constrained Optimization for Spatial Accelerators

TL;DR

CoSA introduces a constrained optimization approach to automatically generate efficient scheduling strategies for DNN accelerators, significantly improving performance and reducing search time compared to existing methods.

Contribution

It formulates DNN scheduling as a mixed-integer programming problem, enabling deterministic and efficient schedule generation for spatial accelerators.

Findings

Up to 2.5x performance improvement over state-of-the-art methods.

90x reduction in scheduling time.

Effective utilization of hardware regularities in scheduling.

Abstract

Recent advances in Deep Neural Networks (DNNs) have led to active development of specialized DNN accelerators, many of which feature a large number of processing elements laid out spatially, together with a multi-level memory hierarchy and flexible interconnect. While DNN accelerators can take advantage of data reuse and achieve high peak throughput, they also expose a large number of runtime parameters to the programmers who need to explicitly manage how computation is scheduled both spatially and temporally. In fact, different scheduling choices can lead to wide variations in performance and efficiency, motivating the need for a fast and efficient search strategy to navigate the vast scheduling space. To address this challenge, we present CoSA, a constrained-optimization-based approach for scheduling DNN accelerators. As opposed to existing approaches that either rely on designers' heuristics or iterative methods to navigate the search space, CoSA expresses scheduling decisions as a constrained-optimization problem that can be deterministically solved using mathematical optimization techniques. Specifically, CoSA leverages the regularities in DNN operators and hardware to formulate the DNN scheduling space into a mixed-integer programming (MIP) problem with algorithmic and architectural constraints, which can be solved to automatically generate a highly efficient schedule in one shot. We demonstrate that CoSA-generated schedules significantly outperform state-of-the-art approaches by a geometric mean of up to 2.5x across a wide range of DNN networks while improving the time-to-solution by 90x.