### Abstract

We consider a parallel-server system with K homogeneous servers where incoming tasks, arriving at rate λ, are dispatched by n dispatchers. Servers are FCFS queues and dispatchers implement a size-based policy such that the servers are equally loaded. We compare the performance of a system with n> 1 dispatchers and of a system with a single dispatcher. Every dispatcher handles a fraction 1/n of the incoming traffic and balances the load to K/n servers. We show that the performance of a system with n dispatchers, K servers and arrival rate λ coincides with that of a system with one dispatcher, K/n servers and arrival rate λ/n. Therefore, the performance comparison can be interpreted as the economies of scale in a system with one dispatcher when we scale up the number of servers and the arrival rate proportionately. We consider two continuous service time distributions: uniform and Bounded Pareto that have increasing and decreasing failure rates, respectively; and a discrete distribution with two values, which is the distribution that maximizes the variance for a given mean. We show that the performance degradation is small for uniformly distributed job sizes, but that for Bounded Pareto and two points distributions it can be unbounded.

Original language | English |
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Title of host publication | IEEE Conference on Computer Communications |

Subtitle of host publication | Proceedings : IEEE INFOCOM |

Publisher | IEEE |

Pages | 1350-1358 |

Number of pages | 9 |

ISBN (Electronic) | 978-1-5090-5336-0 |

DOIs | |

Publication status | Published - 2017 |

MoE publication type | A4 Article in a conference publication |

Event | IEEE Conference on Computer Communications - Atlanta, United States Duration: 1 May 2017 → 4 May 2017 http://infocom2017.ieee-infocom.org/ |

### Publication series

Name | IEEE Conference on Computer Communications |
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ISSN (Print) | 0743-166X |

### Conference

Conference | IEEE Conference on Computer Communications |
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Abbreviated title | INFOCOM |

Country | United States |

City | Atlanta |

Period | 01/05/2017 → 04/05/2017 |

Internet address |

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## Cite this

Doncel, J., Aalto, S., & Ayesta, U. (2017). Economies of Scale in Parallel-Server Systems. In

*IEEE Conference on Computer Communications: Proceedings : IEEE INFOCOM*(pp. 1350-1358). (IEEE Conference on Computer Communications). IEEE. https://doi.org/10.1109/INFOCOM.2017.8057093