Performance Evaluation of Distributed Systems Based on Process Algebras

Organisation:	Technical University of Eindhoven (THE NETHERLANDS)
Functionality:	Performance evaluation for discrete-event systems.
Tools used:	Chi toolset CADP (Construction and Analysis of Distributed Processes)
Period:	2009
Description:	This work proposes a performance evaluation framework based on process algebraic specifications and their analysis in an extended environment of the Chi toolset. First, a sound and ground-complete process algebra is provided that accommodates timed delays in a racing context. The underlying theory provides an explicit maximal progress operator and a non-trivial expansion law for the parallel composition. The algebra also provides the possibility of specifying a partial race of stochastic delays, e.g., that one delay has always a shorter, equal, or longer sample than the other delay. This is required when modeling timed systems whose correct behavior depends on the relative ordering of the timed delays, e.g., in a time dependent controller. Second, an approach for automated performance analysis is proposed. The systems under analysis are specified using Chi, a hybrid process algebra with data. Chi specifications are translated into discrete-time probabilistic reward graphs, which comprise deterministic delays and immediate probabilistic choices. These graphs are further transformed, using either unfolding, or geometrization methods, into discrete-time Markov reward chains. Finally, the transient and long-run analysis of these chains is carried out using the BCG_TRANSIENT and BCG_STEADY tools of CADP. The approach was successfully applied for the analysis of the concurrent alternating bit protocol. The analytical results are compared with the ones obtained from discrete-event simulation and Markovian analysis using the Chi toolset on the same specification.
Conclusions:	The performance evaluation framework proposed is based on a process theory that enables specification of distributed systems with discrete timed and stochastic delays. The process theory axiomatizes sequential processes comprising termination, immediate actions, and timed delays in a racing context. Performance evaluation of the process terms relies on the environment of the language Chi, which was augmented to cater for transient performance analysis by a connection to the CADP toolbox.
Publications:	[Markovski-deVink-09] Jasen Markovski and Erik de Vink. "Performance Evaluation of Distributed Systems Based on a Discrete Real- and Stochastic-Time Process Algebra". Fundamenta Informaticae 95(1):157-186, 2009. Available on-line at: http://www.win.tue.nl/~evink/research/Postscript/fi09.pdf or from the CADP Web site in PDF or PostScript
Contact:	Erik de Vink Department of Mathematics and Computer Science Technische Universiteit Eindhoven P.O. Box 513 5600 MB Eindhoven The Netherlands Tel: +31 40 2473146 Fax: +31 40 2476685 Email: [email protected]
Further remarks:	This tool, amongst others, is described on the CADP Web site: http://cadp.inria.fr/software

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