Energy efficient scheduling of real-time tasks on multi-core processors with voltage islands

• A Voltage Island Largest Capacity First (VILCF) algorithm is proposed.
• VILCF fully utilizes the capacity of voltage islands to achieve energy efficiency.
• The energy consumption is optimal when the workloads of all cores are balanced.
• The approximation ratio is bounded by a value depending on the number of islands.

This paper studies energy efficient scheduling of periodic real-time tasks on multi-core processors with voltage islands, in which cores are partitioned into multiple blocks (termed voltage islands) and each block has its own power source to supply voltage. Cores in the same block always operate at the same voltage level, but can be adjusted by using Dynamic Voltage and Frequency Scaling (DVFS). 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 better energy efficiency by fully utilizing the remaining capacity of an island before turning on more islands or increasing the voltage level of the current active islands. We provide detailed theoretical analysis of the approximation ratio of the proposed VILCF algorithm in terms of energy efficiency. In addition, our experimental results show that VILCF significantly outperforms the existing algorithms when there are multiple cores in a voltage island.