Economies of Scale in Parallel-Server Systems

Josu Doncel, Samuli Aalto, Urtzi Ayesta

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

3 Citations (Scopus)
163 Downloads (Pure)


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 languageEnglish
Title of host publicationIEEE Conference on Computer Communications
Subtitle of host publicationProceedings : IEEE INFOCOM
Number of pages9
ISBN (Electronic)978-1-5090-5336-0
Publication statusPublished - 2017
MoE publication typeA4 Article in a conference publication
EventIEEE Conference on Computer Communications - Atlanta, United States
Duration: 1 May 20174 May 2017

Publication series

NameIEEE Conference on Computer Communications
ISSN (Print)0743-166X


ConferenceIEEE Conference on Computer Communications
Abbreviated titleINFOCOM
Country/TerritoryUnited States
Internet address


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