A Pruning-Based Disk Scheduling Algorithm for Heterogeneous I/O Workloads

Autor: Taeseok Kim, Hyokyung Bahn, Youjip Won
Jazyk: angličtina
Rok vydání: 2014
Předmět:
Zdroj: The Scientific World Journal, Vol 2014 (2014)
Druh dokumentu: article
ISSN: 2356-6140
1537-744X
DOI: 10.1155/2014/940850
Popis: In heterogeneous I/O workload environments, disk scheduling algorithms should support different QoS (Quality-of-Service) for each I/O request. For example, the algorithm should meet the deadlines of real-time requests and at the same time provide reasonable response time for best-effort requests. This paper presents a novel disk scheduling algorithm called G-SCAN (Grouping-SCAN) for handling heterogeneous I/O workloads. To find a schedule that satisfies the deadline constraints and seek time minimization simultaneously, G-SCAN maintains a series of candidate schedules and expands the schedules whenever a new request arrives. Maintaining these candidate schedules requires excessive spatial and temporal overhead, but G-SCAN reduces the overhead to a manageable level via pruning the state space using two heuristics. One is grouping that clusters adjacent best-effort requests into a single scheduling unit and the other is the branch-and-bound strategy that cuts off inefficient or impractical schedules. Experiments with various synthetic and real-world I/O workloads show that G-SCAN outperforms existing disk scheduling algorithms significantly in terms of the average response time, throughput, and QoS-guarantees for heterogeneous I/O workloads. We also show that the overhead of G-SCAN is reasonable for on-line execution.
Databáze: Directory of Open Access Journals
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