EFFECT OF THREAD WEIGHT READJUSTMENT SCHEDULER ON FAIRNESS IN MULTITASKING OS

In this paper, we investigate the effectiveness of Thread Weight Readjustment Scheduler (TWRS) for multitasking operating systems from the view point of fairness. Fairness is one of the most important criteria in designing any operating system scheduler. TWRS is a proportional share CPU scheduler designed explicitly for scheduling multithreaded processes depending on weight readjustment. We show that weight readjustment enables existing scheduler to significantly reduce, but not eliminate, the unfair in its allocations. TWRS preallocates certain amount of CPU time to each thread of the running multi-threaded processes. The scheduler was implemented and evaluated under specific hardware and software environment. We implement our scheduler in the Linux kernel and demonstrate its efficacy through an experimental evaluation. According to our evaluation results, our scheduler is promising to optimize some scheduling criteria, fairness in this context. We conclude from our results that TWRS is practical and desirable for general-purpose operating systems.