AxE: An Approximate-Exact Multi-Processor System-on-Chip Platform

Abstract

Due to the ever-increasing complexity of computing tasks, emerging computing paradigms that increase efficiency, such as approximate computing, are gaining momentum. However, so far, the majority of proposed solutions for hardware-based approximation have been application-specific and/or limited to smaller units of the computing system and require engineering effort for integration into the rest of the system. In this paper, we present Approximate and Exact Multi-Processor system-on-chip (AxE) platform. AxE is the first general-purpose approximate Multi-Processor System-on-Chip (MPSoC). AxE is a heterogeneous RISC-V platform with exact and approximate cores that allows exploring hardware approximation for any application and using software instructions. Using the full capacity of an entire MPSoC, especially a heterogeneous one such as AxE, is an increasingly challenging problem. Therefore, we also propose a task mapping method for running exact and approximable applications on AxE. That is a mixed task mapping, in which applications are viewed as a set of tasks that can be run independently on different processors with different capabilities (exact or approximate). We evaluated our proposed method on AxE and reached a 32% average execution speed-up and 21% energy consumption saving with an average of 99.3% accuracy on three mixed workloads. We also ran a sample image processing application, namely gray-scale filter, on AxE and will present its results.