A Reconfigurable Approximate Computing RISC-V Platform for Fault-Tolerant Applications

TL;DR

This paper introduces 'phoeniX', a reconfigurable RISC-V platform that integrates approximate computing to enhance energy efficiency in embedded systems while maintaining acceptable accuracy levels.

Contribution

It presents a novel reconfigurable platform enabling integration of approximate circuits without core modifications, optimizing energy efficiency and accuracy trade-offs.

Findings

Core consumes 4.23mW at 1.1V

Achieves 7.85pJ per operation at 620MHz

Supports diverse application accuracy-energy trade-offs

Abstract

The demand for energy-efficient and high performance embedded systems drives the evolution of new hardware architectures, including concepts like approximate computing. This paper presents a novel reconfigurable embedded platform named "phoeniX", using the standard RISC-V ISA, maximizing energy efficiency while maintaining acceptable application-level accuracy. The platform enables the integration of approximate circuits at the core level with diverse structures, accuracies, and timings without requiring modifications to the core, particularly in the control logic. The platform introduces novel control features, allowing configurable trade-offs between accuracy and energy consumption based on specific application requirements. To evaluate the effectiveness of the platform, experiments were conducted on a set of applications, such as image processing and Dhrystone benchmark. The core with its original execution engine, occupies 0.024mm2 of area, with average power consumption of 4.23mW at 1.1V operating voltage, average energy-efficiency of 7.85pJ per operation at 620MHz frequency in 45nm CMOS technology. The configurable platform with a highly optimized 3-stage pipelined RV32I(E)M architecture, possesses a DMIPS/MHz of 1.89, and a CPI of 1.13, showcasing remarkable capabilities for an embedded processor.