Enlarged-maximum-scannable-groups for real-time disk scheduling in a multimedia system

In a multimedia system, disk I/O subsystem is the most important component due to its relatively limited throughput and large delay. Previously, by applying SCAN to reschedule tasks having the same deadline, SCAN-EDF tries to improve disk throughput while real time constraints can be satisfied. In DM-SCAN, groups of tasks that can be successfully rescheduled by SCAN under specified real time requirements are identified. They are called MSGs (maximum-scannable-groups). An enlarged-MSG (E-MSG) is proposed to further expand the MSG concept and thus to obtain more improvement in disk throughput. By removing some excess constraints on MSG, E-MSG merges several MSGs as a new scannable group. Experimental results show that the E-MSG scheme is better than both SCAN-EDF and MSG in the disk throughput obtained