Parallel Multi-Objective Bayesian Optimization Framework for CGRA Microarchitecture.

Recently, due to the flexibility and reconfigurability of Coarse-Grained Reconfigurable Architecture (CGRA), CGRA microarchitecture has become an inevitable trend to accelerate the convolution calculation in diverse deep neural networks. However, since the vast microarchitecture design space and the complicated VLSI verification flow, it is a huge challenge to explore a perfect microarchitecture to compromise between multiple performance metrics. In this paper, we formulate the CGRA microarchitecture design as a design space exploration problem, and propose a parallel multi-objective Bayesian optimization framework (PAMBOF) to automatically explore the CGRA microarchitecture design space. Meanwhile, high-precision performance and area models are built to enable fast design space exploration. To approximate the black-box objective function in the design space, the PAMBOF framework first builds multiple Gaussian processes (GP) with deep regularization kernel learning functions (DRKL-GP). Then a parallel Bayesian optimization algorithm is developed to sample a batch of candidate design points, which are simulated in parallel by the performance and area models. Experimental results demonstrate that compared to the prior arts, the proposed PAMBOF framework can search for a CGRA microarchitecture design with the better area and performance in a shorter runtime.