BIT Numerical Mathematics

, Volume 32, Issue 4, pp 546–558 | Cite as

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

  • Tung-Shou Chen
  • Wei-Pang Yang
  • R. C. T. Lee
Part I Computer Science


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 


amortized analysis disk scheduling on-line problem 


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Copyright information

© BIT Foundations 1992

Authors and Affiliations

  • Tung-Shou Chen
    • 1
    • 2
    • 3
  • Wei-Pang Yang
    • 1
    • 2
    • 3
  • R. C. T. Lee
    • 1
    • 2
    • 3
  1. 1.Department of Computer Science and Information EngineeringNational Chiao Tung UniversityHsinchuTaiwan, ROC
  2. 2.Department of Computer and Information ScienceNational Chiao Tung UniversityHsinchuTaiwan, ROC
  3. 3.Department of Computer ScienceNational Tsing Hua UniversityHsinchuTaiwan, ROC

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