A Light-Weight Scheduler for Single-ISA Asymmetric Multi-core Processor Using Online Profiling

Single-ISA asymmetric multi-core processors are thought as next generation emerging multi-core architecture which has better performance per watt over symmetric multi-core processors. However, they also pose unique challenges to operating system, which traditionally assume homogeneous hardware. These challenges include how to analyze program behavior dynamically in kernel with low overhead, how to modify traditional scheduling algorithm using new load-balance policy that CPU-intensive tasks have fast cores bias, whereas memory-intensive have slow core bias, how to make Linux kernel asymmetric-aware and reevaluate the load of each core of different type. We propose a light-weight operating system scheduler and successfully solve above problems with negligible overhead and no assumption. We modified Linux kernel 2.6.18 with cpufreq and perfctr driver and finally used Power Now technology to emulate performance asymmetry. Experimental results show that our scheduler outperforms default scheduler and still maintains good fairness, high efficiency and repeatable.