- Contents
- PEPSY-QNS
- Network types
- Node types
- Analysis methods
- Results

- XPEPSY
- What do you need?
- Getting more information
- OnLineHelp
- Publications
- Contact

- Network types that PEPSY-QNS can handle:
- open queueing networks
- closed networks
- mixed networks containing open and closed job-classes.

- Node types that can be used:
- BCMP-nodes (M/M/m-FCFS, M/G/1-Processor-Sharing, M/G/.-Infinite-Server, M/G/1-LCFS)
- ./G/m-FCFS
- nodes with preemptive or nonpreemtpive priority policies
- multiple server nodes with different service-stations (M/M/m-FCFS-ASYM, M/G/m-FCFS-ASYM)

- Methods that calculate the performance values using state-probabilities (numerical analysis),
- Methods that calculate the performance values using a normalisation constant (Convolution, RECAL - Recursion by Chain ALgorithm),
- Analysis by decomposition (Kuehn, Chylla, Whitt, Pujolle, Gelenbe, Summ.., Marie, MEM - Maximum Entropy Method),
- Product form approximation (EPM - Extended Product form Method, diffusion approximation, ...),
- ABA - Asymtotic Bounds Analysis, BJB - Balanced Job Bounds analysis,
- Methods based on the MVA - Mean Value Analysis (MVA, SCAT - Self Correcting Approximation Technique) and
- two different simulation methods.

- throughput (lambda)
- visit ratio (e)
- average service time (1/mue)
- utilization (rho)
- average response time (mvz)
- average number of jobs (maa)
- average waiting time (mwt)
- average queueing length (mwsl)

- for every job class separately and
- summary over all job classes.

- throughput (lambda)
- average response time (mvz)
- average number of jobs (maa)

This is the greeting window of XPEPSY

After the layout of the network is done, the parameters of the nodes have to be specified. This is done in the Node Data Dialog.

After you specified all parameters that are needed, save the queueing network model and change to the Analysis Mode to perform the analysis.

When switching to the Analysis Mode the Analysis Menu appears and the feasible methods are listed in it. The methods shown up are selected out of the internal database by comparing the networks characteristics with the possibilities of the algorithms. For any method that is not able to analyze the network the reason why can be queried.

Now it is very simple to perform the analysis. Select the method and simply click on the "Analyze"-button and the program will start the calculations. They will be shown up a few seconds later in a results window. You can continue by selecting further algorithms to compare their results to the ones you've got already or go back to the Graphical Editor to change your model for case study purposes.

For the installation of the graphical front-end XPEPSY you need the X-Window-System (at least revision 4) and the Motif widget-set (version 1.2 or higher).

Bolch, G., **Kirschnick, M.**: PEPSY-QNS - Performance Evaluation and
Prediction SYstem for Queueing NetworkS; Universität
Erlangen-Nürnberg; Institut für Mathematische
Maschinen und Datenverarbeitung IV; Tech. Report TR-I4-92-21; Oct. 1992; German:
(compr. Postscript, ~266kB).

Bolch, G., **Kirschnick, M.**: PEPSY-QNS - Ein Programmsystem zur
Leistungsanalyse von Warteschlangennetzwerken; In: Walke, B., Spaniol, O.
[Eds.]: Messung, Modellierung und Bewertung von Rechen- und
Kommunikationssystemen; Kurzberichte und Werkzeugvorstellungen zur
7.ITG/GI-Fachtagung Aachen, 21.-23. Sep. 1993; Aachener Beiträge zur Informatik
(Bd. 2), Verlag der Augustinus Buchhandlung, Aachen 1993, pp. 216-220.

**Kirschnick, M.**: The Performance Evaluation and
Prediction SYstem for Queueing NetworkS - PEPSY-QNS; University of
Erlangen-Nuremberg; Institut für Mathematische
Maschinen und Datenverarbeitung IV; Tech. Report TR-I4-94-18; Jun. 1994;
(compr. Postscript, 60kB).

Done by Matthias Roessler with changes by Stephan Kösters