Part I Computer Science

BIT Numerical Mathematics

, Volume 32, Issue 4, pp 546-558

First online:

Amortized analysis of some disk scheduling algorithms: SSTF, SCAN, andN-StepSCAN

  • Tung-Shou ChenAffiliated withDepartment of Computer Science and Information Engineering, National Chiao Tung UniversityDepartment of Computer and Information Science, National Chiao Tung UniversityDepartment of Computer Science, National Tsing Hua University
  • , Wei-Pang YangAffiliated withDepartment of Computer Science and Information Engineering, National Chiao Tung UniversityDepartment of Computer and Information Science, National Chiao Tung UniversityDepartment of Computer Science, National Tsing Hua University
  • , R. C. T. LeeAffiliated withDepartment of Computer Science and Information Engineering, National Chiao Tung UniversityDepartment of Computer and Information Science, National Chiao Tung UniversityDepartment of Computer Science, National Tsing Hua University

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

The amortized analysis is a useful tool for analyzing the time-complexity of performing a sequence of operations. The disk scheduling problem involves a sequence of requests in general. In this paper, the performances of representative disk scheduling algorithms,SSTF, SCAN, andN-StepSCAN, are analyzed in the amortized sense. A lower bound of the amortized complexity for the disk scheduling problem is also derived. According to our analysis,SCAN is not only better thanSSTF andN-StepSCAN, but also an optimal algorithm. Various authors have studied the disk scheduling problem based on some probability models and concluded that the most acceptable performance is obtained fromSCAN. Our result therefore supports their conclusion.

CR categories

F.2.2 D.4.2

Keywords

amortized analysis disk scheduling on-line problem