pCache: An Observable L1 Data Cache Model for FPGA Prototyping of Embedded Systems

This paper presents a configurable and observable model of L1 data cache memory and a novel method for integrating the model into an FPGA prototype. Embedded system software designers use in-circuit emulation on FPGA platforms to validate the functionality and performance of embedded software. Data cache, particularly L1, has a major impact of system performance, yet remains unobservable during software debugging and analysis. Our solution is to model the data cache as an on-chip hardware peripheral that can be integrated into the processor system and can display the state of the data cache at any given time. The model is synthesized on Xilinx Virtex 5 FPGA and validated using several benchmarks. The experimental results show that the model can accurately track cache hits and misses and can estimate the run time of an embedded software application with an average error of only 5.4%, and a worst case error of only 13.7%.