### Abstract

Consider a real-time system in which every task has a value that it obtains only if it completes by its deadline. The problem is to design an on-line scheduling algorithm (i.e., the scheduler has no knowledge of a task until it is released) that maximizes the guaranteed value obtained by the system. When such a system is underloaded (i.e., there exists a schedule for which all tasks meet their deadlines), Dertouzos [Proceedings IFIF Congress, 1974, pp. 807-813] showed that the earliest deadline first algorithm will achieve 100% of the possible value. Locke [Ph.D. thesis, Computer Science Dept., Carnegie-Mellon Univ., Pittsburgh, PA] showed that earliest deadline first performs very badly, however, when the system is overloaded, and he proposed heuristics to deal with overload. This paper presents an optimal on-line scheduling algorithm for overloaded uniprocessor systems. It is optimal in the sense that it gives the best competitive ratio possible relative to an off-line scheduler.

Original language | English (US) |
---|---|

Pages (from-to) | 318-339 |

Number of pages | 22 |

Journal | SIAM Journal on Computing |

Volume | 24 |

Issue number | 2 |

State | Published - Apr 1995 |

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### ASJC Scopus subject areas

- Computational Theory and Mathematics
- Applied Mathematics
- Theoretical Computer Science

### Cite this

*SIAM Journal on Computing*,

*24*(2), 318-339.

**Dover : an optimal on-line scheduling algorithm for overloaded uniprocessor real-time systems.** / Koren, Gilad; Shasha, Dennis.

Research output: Contribution to journal › Article

*SIAM Journal on Computing*, vol. 24, no. 2, pp. 318-339.

}

TY - JOUR

T1 - Dover

T2 - an optimal on-line scheduling algorithm for overloaded uniprocessor real-time systems

AU - Koren, Gilad

AU - Shasha, Dennis

PY - 1995/4

Y1 - 1995/4

N2 - Consider a real-time system in which every task has a value that it obtains only if it completes by its deadline. The problem is to design an on-line scheduling algorithm (i.e., the scheduler has no knowledge of a task until it is released) that maximizes the guaranteed value obtained by the system. When such a system is underloaded (i.e., there exists a schedule for which all tasks meet their deadlines), Dertouzos [Proceedings IFIF Congress, 1974, pp. 807-813] showed that the earliest deadline first algorithm will achieve 100% of the possible value. Locke [Ph.D. thesis, Computer Science Dept., Carnegie-Mellon Univ., Pittsburgh, PA] showed that earliest deadline first performs very badly, however, when the system is overloaded, and he proposed heuristics to deal with overload. This paper presents an optimal on-line scheduling algorithm for overloaded uniprocessor systems. It is optimal in the sense that it gives the best competitive ratio possible relative to an off-line scheduler.

AB - Consider a real-time system in which every task has a value that it obtains only if it completes by its deadline. The problem is to design an on-line scheduling algorithm (i.e., the scheduler has no knowledge of a task until it is released) that maximizes the guaranteed value obtained by the system. When such a system is underloaded (i.e., there exists a schedule for which all tasks meet their deadlines), Dertouzos [Proceedings IFIF Congress, 1974, pp. 807-813] showed that the earliest deadline first algorithm will achieve 100% of the possible value. Locke [Ph.D. thesis, Computer Science Dept., Carnegie-Mellon Univ., Pittsburgh, PA] showed that earliest deadline first performs very badly, however, when the system is overloaded, and he proposed heuristics to deal with overload. This paper presents an optimal on-line scheduling algorithm for overloaded uniprocessor systems. It is optimal in the sense that it gives the best competitive ratio possible relative to an off-line scheduler.

UR - http://www.scopus.com/inward/record.url?scp=0029289867&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029289867&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0029289867

VL - 24

SP - 318

EP - 339

JO - SIAM Journal on Computing

JF - SIAM Journal on Computing

SN - 0097-5397

IS - 2

ER -