### Abstract

The mean flow time of a schedule provides a measure of the average time that a task spends within a computer system, and also the average number of unfinished tasks in the system. The mean flow time of a schedule is defined to be the sum of the finishing times of all tasks in the system. On a system of identical processors O(nlog n) algorithms exist for determining minimal mean flow time schedules for n independent tasks. In general, there will be a large class C of schedules, of widely differing lengths, that all minimize mean flow time. The problem of finding the shortest schedule in C is NP-complete. We give heuristics that find schedules in C that are no more than 25% longer than the shortest schedule in C. The advantage of a short schedule is that processor utilization is high.

Original language | English (US) |
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Pages (from-to) | 1-14 |

Number of pages | 14 |

Journal | Acta Informatica |

Volume | 6 |

Issue number | 1 |

DOIs | |

State | Published - Mar 1976 |

Externally published | Yes |

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### ASJC Scopus subject areas

- Information Systems

### Cite this

*Acta Informatica*,

*6*(1), 1-14. https://doi.org/10.1007/BF00263740

**Algorithms minimizing mean flow time : schedule-length properties.** / Coffman, E. G.; Sethi, Ravi.

Research output: Contribution to journal › Article

*Acta Informatica*, vol. 6, no. 1, pp. 1-14. https://doi.org/10.1007/BF00263740

}

TY - JOUR

T1 - Algorithms minimizing mean flow time

T2 - schedule-length properties

AU - Coffman, E. G.

AU - Sethi, Ravi

PY - 1976/3

Y1 - 1976/3

N2 - The mean flow time of a schedule provides a measure of the average time that a task spends within a computer system, and also the average number of unfinished tasks in the system. The mean flow time of a schedule is defined to be the sum of the finishing times of all tasks in the system. On a system of identical processors O(nlog n) algorithms exist for determining minimal mean flow time schedules for n independent tasks. In general, there will be a large class C of schedules, of widely differing lengths, that all minimize mean flow time. The problem of finding the shortest schedule in C is NP-complete. We give heuristics that find schedules in C that are no more than 25% longer than the shortest schedule in C. The advantage of a short schedule is that processor utilization is high.

AB - The mean flow time of a schedule provides a measure of the average time that a task spends within a computer system, and also the average number of unfinished tasks in the system. The mean flow time of a schedule is defined to be the sum of the finishing times of all tasks in the system. On a system of identical processors O(nlog n) algorithms exist for determining minimal mean flow time schedules for n independent tasks. In general, there will be a large class C of schedules, of widely differing lengths, that all minimize mean flow time. The problem of finding the shortest schedule in C is NP-complete. We give heuristics that find schedules in C that are no more than 25% longer than the shortest schedule in C. The advantage of a short schedule is that processor utilization is high.

UR - http://www.scopus.com/inward/record.url?scp=0016873384&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0016873384&partnerID=8YFLogxK

U2 - 10.1007/BF00263740

DO - 10.1007/BF00263740

M3 - Article

AN - SCOPUS:0016873384

VL - 6

SP - 1

EP - 14

JO - Acta Informatica

JF - Acta Informatica

SN - 0001-5903

IS - 1

ER -