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Modern real-time systems increasingly operate with multiple interactive applications. While these systems often require reliable quality of service (QoS) for the applications, even under heavy workloads, many existing CPU schedulers are not very capable of satisfying such requirements. In this paper, we design and implement an Advanced Interactive and Real-time Scheduler, called AIRS. AIRS is aimed at supporting systems that run multiple interactive real-time applications, particularly on multicore platforms. It provides a new CPU reservation mechanism to enhance the QoS of the overall system. The reservation algorithm is based on the prior Constant Bandwidth Server (CBS) algorithm, but is more flexible and efficient, when multiple applications reserve CPU bandwidth. It also provides a new multicore scheduler to improve the absolute CPU bandwidth available for the applications to perform well. The scheduling algorithm is subject to the prior Earliest Deadline First with Window-constraint Migration (EDF-WM) algorithm, but is extended to work with the new CPU reservation mechanism. Experimental evaluation shows that AIRS delivers higher quality to simultaneous playback of multiple movies than the existing real-time scheduler. It also demonstrates that AIRS offers hard timing guarantees for randomly-generated task sets with heavy workloads.
Date of Conference: 6-9 July 2010