This paper presents a concrete implementation and a comprehensive assessment of the Energy-based Fair Queuing (EFQ) scheduling algorithm based on the Linux operating system. EFQ is an extended application of the classical fair queuing algorithm in the energy domain. It is designed to provide proportional power sharing as well as effective time-constraint compliance in energy-centric Power Management (PM) schemes, a type of operating system-level PM scheme targeted at providing a battery lifetime guarantee for energy-limited mobile systems. In this work, the structure of the Linux Completely Fair Scheduler (CFS) has been effectively utilized to ease the EFQ implementation and to reduce the scheduling overhead. To assess the properties of the EFQ scheduler, a test-bench based on various types of load has been developed and tested. The EFQ algorithm is assessed from two aspects: energy management and real-time scheduling. Experimental results on energy management show that EFQ is more effective than the CFS scheduler in managing energy and it can achieve a proportional share of the system power regardless of the device on which the energy is spent. Experimental results on real-time scheduling demonstrate that EFQ can achieve strict time-constraint compliance and a robust response time when the energy estimation error and the number of active tasks increase.

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