Multimedia Real-Time Disk Scheduling by Hybrid Local/Global Seek-Optimizing Approaches

Real-time disk scheduling is one of the most important problems in designing a multimedia system. It has been proved to be NP-Complete. In these years, various approaches are proposed to improve disk throughput under guaranteed real-time requirements. SCAN-EDF, which utilizes SCAN to reschedule tasks in a real-time EDF schedule, is one of the best-known real-time disk scheduling methods. Since tasks rescheduled in SCAN-EDF should have the sume deadline, its efficiency depends oti the number of tasks with the same deadlines. I f all tasks have different deadlines, the schedule result of SCAN-EDF would be the same us EDF. In this paper, we improve SCAN-EDF b y applying diflerent hybrid local-merging and global-inserting schemes. Different from SCAN-EDF, in our method, tasks rescheduled b j SCAN may have different deadlines. Our efficiency is not limited on the number of tasks that have the same deadlines. Experiments show that the proposed method is significantly better than SCAN-EDF. Comparing by disk throughput, the amount of our improvement obtained is 24% more than the best-known SCAN-EDF method.