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標題: GSR: A global seek-optimizing real-time disk-scheduling algorithm
作者: Chang, H.P.
Chang, R.I.
Shih, W.K.
Chang, R.C.
關鍵字: real-time disk scheduling;disk scheduling;operating systems;continuous media;storage;systems
Project: Journal of Systems and Software
期刊/報告no:: Journal of Systems and Software, Volume 80, Issue 2, Page(s) 198-215.
Earliest-deadline-first (EDF) is good for scheduling real-time tasks in order to meet timing constraint. However, it is not good enough for scheduling real-time disk tasks to achieve high disk throughput. In contrast, although SCAN can maximize disk throughput, its schedule results may violate real-time requirements. Thus, during the past few years, various approaches were proposed to combine EDF and SCAN (e.g., SCAN-EDF and RG-SCAN) to resolve the real-time disk-scheduling problem. However, in previous schemes, real-time tasks can only be rescheduled by SCAN within a local group. Such restriction limited the obtained data throughput. In this paper, we proposed a new globally rescheduling scheme for real-time disk scheduling. First, we formulate the relations between the EDF schedule and the SCAN schedule of input tasks as EDF-to-SCAN mapping (ESM). Then, on the basis of ESM, we propose a new real-time disk-scheduling algorithm: globally seek-optimizing rescheduling (GSR) scheme. Different from previous approaches, a task in GSR may be rescheduled to anywhere in the input schedule to optimize data throughput. Owing to such a globally rescheduling characteristic, GSR obtains a higher disk throughput than previous approaches. Furthermore, we also extend the GSR to serve fairly non-real-time tasks. Experiments show that given 15 real-time tasks, our data throughput is 1.1 times that of RG-SCAN. In addition, in a mixed workload, compared with RG-SCAN, our GSR achieves over 7% improvement in data throughput and 33% improvement in average response time. (C) 2006 Elsevier Inc. All rights reserved.
ISSN: 0164-1212
DOI: 10.1016/j.jss.2006.03.045
Appears in Collections:資訊科學與工程學系所

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