Session 9a: Invited Presentation

Algorithms and Computation

Volume 1178 of the series Lecture Notes in Computer Science pp 356-365

Date:

Competitive analysis of on-line disk scheduling

  • Tzuoo-Hawn YehAffiliated withDepartment of Electrical Engineering, National Taiwan University
  • , Cheng-Ming KuoAffiliated withDepartment of Electrical Engineering, National Taiwan University
  • , Chin-Laung LeiAffiliated withDepartment of Electrical Engineering, National Taiwan University
  • , Hsu-Chun YenAffiliated withDepartment of Electrical Engineering, National Taiwan University

* Final gross prices may vary according to local VAT.

Get Access

Abstract

We give a detailed competitive analysis of a popular on-line disk scheduling algorithm, namely, LOOK. Our analysis yields a tight competitive ratio for the LOOK algorithm. By comparing and contrasting the competitive ratio of LOOK with the lower bounds of FCFS and SSTF (which are equally popular in disk scheduling), our results provide strong evidence to suggest that when the workload of disk access is heavy, LOOK outperforms SSTF and FCFS. As a by-product, our analysis also reveals (quantitatively) the role played by the degree of look-ahead in disk scheduling.