On Effective Slack Reclamation in Task Scheduling for Energy Reduction

Abstract

Power consumed by modern computer systems, particularly servers in data centers has al- most reached an unacceptable level. However, their energy consumption is often not justifiable when their utilization is considered; that is, they tend to consume more energy than needed for their comput- ing related jobs. Task scheduling in distributed computing systems (DCSs) can play a crucial role in increasing utilization; this will lead to the reduction in energy consumption. In this paper, we address the problem of scheduling precedence-constrained parallel applications in DCSs, and present two en- ergy-conscious scheduling algorithms. Our scheduling algorithms adopt dynamic voltage and fre- quency scaling (DVFS) to minimize energy consumption. DVFS, as an efficient power management technology, has been increasingly integrated into many recent commodity processors. DVFS enables these processors to operate with different voltage supply levels at the expense of sacrificing clock fre- quencies. In the context of scheduling, this multiple voltage facility implies that there is a trade-off be- tween the quality of schedules and energy consumption. Our algorithms effectively balance these two performance goals using a novel objective function and its variant, which take into account both goals; this claim is verified by the results obtained from our extensive comparative evaluation study.