Speaker: Dr. Gerardo Rubino
Title: "The effectiveness performance metric"
Date: Monday, 9 October 2017
Time: 4:00pm - 5:00pm
Venue: Lecture Theater F (near lift nos. 25/26), HKUST
In this talk we present a new performance metric called "effectiveness"
that quantifies with a single number how well a stable queuing system in
equilibrium behaves. The metric implements a trade-off between three basic
aspects of a system: the quantity of work it does, captured by its
throughput, the cost in time to provide service measured by its mean
delay, and the cost in providing that service, as captured by the sum of
the service rates of the servers it uses. The effectiveness metric is
built based on previous seminal work done by Kleinrock some years ago
where he proposed a metric called "power". Power has some nice intuitive
properties, in particular the fact that for basic queues such as the M/M/1
or, more generally, the M/GI/1, it is maximal when the mean number of
customers in the queue is equal to 1. Kleinrock calls this the "keep the
pipe empty" property. Effectiveness coincides with power on single server
queues, but differs on multiple server models and on networks of queues.
In the talk, the main characteristics of the effectiveness will be
discussed, and, in particular, we will show that the "keep the pipe empty"
property also holds for it when the system is a Jackson product form
network. We will also provide arguments to support the definition itself,
showing that the metric allows to compare different systems and that it
provides reasonable results. The connection with Kleinrock's work will
also be discussed in detail.
Gerardo Rubino is a senior researcher at INRIA (the French National
Institute for Research in Computer Science and Control) where he leads the
DIONYSOS group, working on the analysis and design of networking
technologies. He is also a Board Member of the Media & Networks Cluster,
Brittany, France. Among his past responsibilities, he has been Scientific
Delegate for the Rennes unit of INRIA for 5 years, Research Director in
Networking at the Telecom Bretagne engineering school for 5 years,
Associate Editor of the Operations Research international journal "Naval
Research Logistics" for 9 years, former member of the Steering Board of
the European Network of Excellence EuroFGI and its coordinator for
industry collaborations during 4 years, and INRIA's representative at the
SISCom Brittany Research Cluster during its life-time. He has also been
the head of the International Partnership Office at INRIA Rennes. He is a
member of IFIP WG 7.3 and has recently served in the Steering Committee of
QEST (www.qest.org). He is interested in the quantitative analysis of
complex systems using probabilistic models, in networking and in other
engineering areas. He presently works on performance and dependability
analysis, and on perceptual quality assessment of audio and video
applications and services built on top of the Internet. In particular, he
is the author of the PSQA technology for automatic perceptual quality
real-time evaluation (Pseudo-Subjective Quality Assessment). He also works
on rare event analysis, he is a member of the Steering Committee of RESIM,
the only workshop dedicated to the topic, and co-author of the book
entitled "Rare Event Simulation Using Monte Carlo Methods" (Wiley, 2009).
He is the author of more than 200 publications in applied mathematics and
computer science. He recently (2014) co-authored the book "Markov Chains
and Dependability Theory", published by Cambridge University Press.