When: Thursday, February 16, 1:30 p.m.

Where: 3305 Newell-Simon Hall

Bert Zwart, Eindhoven University of Technology

Faculty Candidate Talk

Abstract:
Processor Sharing (PS) queues were originally introduced to analyze the performance of time-sharing in computer networks. Nowadays, PS queues are one of the most popular congestion models for TCP traffic on the Internet. Under the PS discipline, each customer in the system receives the same service rate.

Motivated by obtaining a better understanding of the impact of reneging (e.g. aborting the download of a file) in communication networks, we consider a PS queue in overload where customers may leave after a certain amount of time, before their service is finished. Under the PS service discipline, such behavior is unwelcome, since it always implies that some work is done in vain. Therefore, when the queue is in overload, the actual throughput can be much lower than the total service rate.

We consider a fluid approximation of this queue, which is accurate when both the arrival and service rates are large. We apply this fluid approximation to analyze the impact of reneging on system performance in PS queues. By studying several examples, we show that the impact can be quite substantial and propose an admission control scheme to reduce its effect.

BIO:

Bert Zwart received his Ph.D at Eindhoven University of Technology in september 2001 under the supervision of Onno Boxma and Sem Borst. After that, he did a postdoc at INRIA Rocquencourt (France). In 2002, Bert returned to Eindhoven as an assistant professor. Bert is currently associate editor of Mathematics of Operations Research and serves as TPC member in several conferences.His current research focuses on various topics in applied probability and the performance analysis of computer and communication systems.

Host: Mor Harchol-Balter:
For Appointments contact Charlotte Yano (yano@cs.cmu.edu - 8-7656)

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