Tight Lower bound on power consumption for scheduling real-time periodic tasks in core-level DVFS systems

Abstract

Dynamic voltage and frequency scaling (DVFS) is a widely used solution to reduce power consumption. Modern multi-core architectures support core-level DVFS, where each core has its own power supply and can change its frequency independently from other cores. This paper aims at optimizing power consumption of multi-core processors while ensuring deadline constraints of real-time periodic tasks. From theoretical aspects, we prove a tight lower bound of power consumption for executing real-time tasks, which indicates to what extent scheduling algorithms can approach. From practical aspects, we propose a Power Scaling Algorithm (PSA) to assign real-time periodic tasks to a power efficient platform. PSA not only determines the optimal frequencies for each core, but also provides the appropriate number of active cores, which can skip the local optimum and achieve the global minimum. This lower power bound is validated by several extensive experiments.