Real-time disk scheduling for multimedia applications with deadline-modification-scan scheme
Journal
Real-Time Systems
Journal Volume
19
Journal Issue
2
Pages
149-168
Date Issued
2000
Author(s)
Abstract
Real-time disk scheduling (RTDS) is important for time-critical multimedia applications. In conventional approaches of real-time disk scheduling, such as SCAN-EDF, the seek-optimizing SCAN scheme is applied to reduce the disk service time of the real-time EDF schedule. Since only tasks with the same deadline are seek-optimized, the obtained improvement of SCAN-EDF is limited. In this paper, based on the maximum-scannable-group (MSG) concept, a deadline-modification-scan (DMS or DM-SCAN) algorithm is proposed. Our algorithm uses MSG to automatically decide the suitable task groups for seek-optimizing. Based on the MSG concept, we repeatedly apply DMS to further increase disk throughput to support more tasks. We have implemented the proposed algorithm on UnixWare 2.01. The appropriate problem behaviors and parameter values to yield good solutions are investigated. Experiments show that DMS is better than conventional approaches in both the obtained disk throughput and the supported tasks. Moreover, our proposed approach can schedule task sets that are not schedulable by EDF and SCAN-EDF.
Type
journal article