An Evaluation of Decoupled Access Execute on ARMv8

Sammanfattning: Energy saving techniques on the hardware level are not always capable of adapting to the applications. Thus energy saving techniques at software level are needed to overcome the limitations of the hardware. Dynamic Voltage Frequency Scaling (DVFS)is one of the most widely used techniques to scale down the voltage and frequency atruntime as needed. However, in modern processors the current leakage becomessignificant in low voltage (breakdown of Dennard’s scaling), leaving frequency scalingas the only solution. But frequency changes can take many CPU cycles, making DVFSnon applicable at instruction level granularity. Decoupled Access/Execute (DAE) is asolution to the above problem. DAE is an energy efficiency model with minimalperformance loss and has been evaluated on x86 platforms, showing significantimprovements in energy consumption, on task-based parallel programs and complexsequential applications. In this project we evaluate the DAE model on ARMv8 platforms using the SPEC CPU2006 benchmark suit. The results show energy benefitsand performance improvements up to 40%. Furthermore we discuss the behaviour ofDAE on x86 and ARMv8 architectures.