Browse > Article

A Modified Least-Laxity First Scheduling Algorithm for Reducing Context Switches on Multiprocessor Systems  

오성흔 (㈜디지캡)
길아라 (숭실대학교 컴퓨터학부)
양승민 (숭실대학교 컴퓨터학부)
Publication Information
Journal of KIISE:Computer Systems and Theory / v.30, no.2, 2003 , pp. 68-77 More about this Journal
Abstract
The Least-Laxity First(or LLF) scheduling algorithm assigns the highest priority to a task with the least laxity, and has been proved to be optimal for a uni-processor and sub-optimal for a multi-processor. However, this algorithm Is Impractical to implement because laxity tie results in the frequent context switches among tasks. In this paper, a Modified Least-Laxity First on Multiprocessor(or MLLF/MP) scheduling algorithm is proposed to solve this problem, i.e., laxity tie results in the excessive scheduling overheads. The MLLF/MP is based on the LLF, but allows the laxity inversion. MLLF/MP continues executing the current running task as far as other tasks do not miss their deadlines. Consequently, it avoids the frequent context switches. We prove that the MLLF/MP is also sub-optimal in multiprocessor systems. By simulation results, we show that the MLLF/MP has less scheduling overheads than LLF.
Keywords
real-time system; real-time scheduling algorithm; real-time tasks; scheduling optimality; context switching overhead; laxity;
Citations & Related Records
연도 인용수 순위
  • Reference
1 An Overview of the Rialto Real-Time Architecture /
[ Michael B. Jones;Joseph S. Barrera Ⅲ;Alessandro Forin;Paul J. Leach;Daniela Rosu;Marcel-Catalin Rosu ] / Proceedings of the Seventh ACM SIGOPS European Workshop
2 M.L. Dertouzos and A.K. Mok, 'Multiprocessor On-Line Scheduling of Hard-Real-Time Tasks,' IEEE Transactions on Software Engineering, Vol. 15, No. 12, December 1989   DOI   ScienceOn
3 C.L. Liu and J.W. Layland, 'Scheduling Algorithms for Multiprogramming in a Hard-Real-Time Environment,' Journal of the Association for Computing Machinery, 20(1), 1973   DOI
4 Michael B. Jones, Joseph S. Barrera III, Alessandro Forin, Paul J. Leach, Daniela Rosu and Marcel-Catalin Rosu, 'An Overview of the Rialto Real-Time Architecture,' In Proceedings of the Seventh ACM SIGOPS European Workshop, Connemara, Ireland, pages 249-256, September, 1996
5 A. K. Mok, 'Fundamental Design Problems of Distributed Systems for the Hard-Real-Time Environment,' Ph.D. Thesis, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, May 1983
6 M.L. Dertouzos, 'Control Robotics: the Procedural Control of Physical Processes,' Information Processing 74, North-Holland Publishing Company, 1974
7 오성흔, 양승민, '실시간 시스템을 위한 최소 여유시간 우선 기반의 최소 선점을 갖는 스케줄링 알고리즘,' 한국정보과학회 논문지(A), 제26권, 제4호, pp.443-454, 1999년 4월
8 조성제, 이석균, 유해영, '산발적인 경성 실시간 태스크를 위한 온라인 스케줄링 알고리즘,' 한국정보과학회 논문지(A), 제25권, 제7호, pp. 708-718, 1998년 7월
9 S.K. Dhall and C.L. Liu, 'On a Real-Time Scheduling Problem,' Operations Research, Vol. 26, No. 1, pp. 127-140, February 1978   DOI   ScienceOn