Voltage Island Aware Energy Efficient Scheduling of Real-Time Tasks on Multi-core Processors

There have been many energy-efficient real-time task scheduling research works on multi-core processors. Most assume that the voltage/frequency level for each core can be individually controlled by using Dynamic Voltage and Frequency Scaling (DVFS). However, providing individual voltage for each core can be very complicated and expensive. Most modern processors adopt voltage islands, in which a group of cores in an island always operate at the same voltage level. We propose a Voltage Island Largest Capacity First (VILCF) algorithm for energy efficient scheduling of periodic real-time tasks on multi-core processors. It achieves great energy efficiency by fully utilizing the remaining capacity of an island before turning on more islands or increasing the voltage level of the current islands. We provide detailed theoretical analysis of the approximation ratio of the proposed VILCF algorithm in terms of energy efficiency. Furthermore, our experiment results show that VILCF significantly outperforms the existing algorithms when there are more than one cores in each voltage island.