Frequency Affinity: Analyzing and Maximizing Power Efficiency in Multi-core Systems

Performance optimization and energy efficiency are the major challenges in multi-core system design. Of the state-of-the-art approaches, cache affinity aware scheduling and techniques based on dynamic voltage frequency scaling (DVFS) are widely applied to improve performance and save energy consumptions respectively. In modern operating systems, schedulers exploit high cache affinity by allocating a process on a recently used processor whenever possible. When a process runs on a high-affinity processor it will find most of its states already in the cache and will thus achieve more efficiency. However, most state-of-the-art DVFS techniques do not concentrate on the cost analysis for DVFS mechanism. In this paper, we firstly propose frequency affinity which retains the voltage frequency as long as possible to avoid frequently switching, and then present a frequency affinity aware scheduling (FAS) to maximize power efficiency for multi-core systems. Experimental results demonstrate our frequency affinity aware scheduling algorithms are much more power efficient than single-ISA heterogeneous multi-core processors.