Fairness and Interactivity of Three CPU Schedulers in Linux

CPU scheduler is a very important subsystem which affects system throughput, interactivity and fairness. The development of Linux kernel is relatively fast-paced. By now, many CPU schedulers have been designed by researchers, hobbyists and kernel hackers. It is necessary to accurately compare and analyze different characteristics among these schedulers, so as to understand and design better CPU schedulers for various applications. However, researchers lack a straight-forward method to compare and analyze these CPU schedulers precisely. In this paper, we systematically analyze and measure fairness, interactivity and multi-processors performance of three schedulers: O(1), RSDL and CFS, by using micro, synthesis and real application benchmarks. They have been ported into one scheduler framework in Linux kernel-2.6.29. Experimental results show that there are notable differences in fairness and interactivity under micro benchmarks, while minor differences in synthesis and real applications. We also analyze the impact of implementations of schedulers on fairness and interactivity of applications, discuss challenges in estimating application resource requirements in different environments, and present some ideas for developing future CPU schedulers.