Improved Schedulability Analysis for Multiprocessor Systems with Resource Sharing

This report presents our recent efforts to close the gap between the state-of-the-art homogeneous (or identical) multiprocessor and uniprocessor schedulability analyses in the context of resource sharing. Although many multiprocessor resource sharing protocols have been proposed, their impact on the schedulability of real-time tasks is largely ignored in most existing literature. Recently, work has been done to integrate queue locks (FIFO-queue-based non-preemptive spin locks) with multiprocessor schedulability analysis but the techniques used introduce a substantial amount of pessimism, some of which, as explained in this report, can be easily eliminated. For global fixed task priority preemptive multiprocessor systems, this pessimism impacts low priority tasks, greatly reducing the number of tasksets that can be recognised as schedulable. We develop a new schedulability analysis lp-CDW to target this issue specifically. By combing lp-CDW with existing techniques, we significantly increase the number of tasksets that can be recognised as schedulable.