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How many servers are best in a dual-priority system?

Wierman, Adam and Osogami, Takayuki and Harchol-Balter, Mor and Scheller-Wolf, Alan (2006) How many servers are best in a dual-priority system? Performance Evaluation, 63 (12). pp. 1253-1272. ISSN 0166-5316. doi:10.1016/j.peva.2005.12.004.

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We ask the question, “for minimizing mean response time (sojourn time), which is preferable: one fast server of speed 1, or slow servers each of speed?” Our setting is the system with two priority classes of customers, high priority and low priority, where PH is a phase-type distribution. We find that multiple slow servers are often preferable, and we demonstrate exactly how many servers are preferable as a function of the load and service time distribution. In addition, we find that the optimal number of servers with respect to the high priority jobs may be very different from that preferred by low priority jobs, and we characterize these preferences. We also study the optimal number of servers with respect to overall mean response time, averaged over high and low priority jobs. Lastly, we ascertain the effect of the service demand variability of high priority jobs on low priority jobs.

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Additional Information:© 2006 Elsevier Ltd. Received 4 August 2004, Revised 26 November 2005, Available online 20 March 2006. This work was supported by NSF Grant CCR-0311383 and grant sponsorship from IBM Corporation.
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Subject Keywords:Scheduling; Queueing; Multiserver; Priority; Preemptive; M/PH/k; Dimensionality reduction; Busy period
Issue or Number:12
Record Number:CaltechAUTHORS:20201020-075618304
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Official Citation:Adam Wierman, Takayuki Osogami, Mor Harchol-Balter, Alan Scheller-Wolf, How many servers are best in a dual-priority M/PH/k system?, Performance Evaluation, Volume 63, Issue 12, 2006, Pages 1253-1272, ISSN 0166-5316, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:106162
Deposited By: Tony Diaz
Deposited On:20 Oct 2020 19:11
Last Modified:16 Nov 2021 18:51

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