Summary: Energy-Efficient Algorithms for Flow Time Minimization
Topic classification: Algorithms and data structures
We study scheduling problems in battery-operated computing devices, aiming at schedules with low
total energy consumption. While most of the previous work has focused on finding feasible schedules
in deadline-based settings, in this paper we are interested in schedules that guarantee a good Quality-of-
Service. More specifically, our goal is to schedule a sequence of jobs on a variable speed processor so
as to minimize the total cost consisting of the power consumption and the total flow time of all the jobs.
We first show that when the amount of work, for any job, may take an arbitrary value, then no online
algorithm can achieve a constant competitive ratio. Therefore, most of the paper is concerned with unit-
size jobs. We devise a deterministic constant competitive online algorithm and show that the offline
problem can be solved in polynomial time.
Embedded systems and portable devices play an ever-increasing role in every day life. Prominent examples
are mobile phones, palmtops and laptop computers that are used by a significant fraction of the popula-
tion today. Many of these devices are battery-operated so that effective power management strategies are
essential to guarantee a good performance and availability of the systems. The microprocessors built into
these devices can typically perform tasks at different speeds the higher the speed, the higher the power