U-link scheduling: bounding execution time of real-time tasks with multi-case execution time on SMT processors

The goal of this paper is to achieve hard real-time processing with admitting as many tasks as possible on simultaneous multithreaded (SMT) processors. For this goal we propose U-link scheduling scheme that determines the co-scheduled set that is the fixed combinations of co-scheduled tasks to bound the task execution time. Also we present practical algorithms, RR-DUP for building co-scheduled sets and UL-EDF for task scheduling. The performance evaluation shows that UL-EDF with RR-DUP outperforms the conventional scheduling algorithms, EDF-FF and EDF-US, in the point of execution time stability, task rejection ratio and deadline miss ratio.