Analysis of Markov reward models using zero-suppressed multi-terminal BDDs

  • Authors:
  • K. Lampka;M. Siegle

  • Affiliations:
  • University of the Federal Armed Forces Munich;University of the Federal Armed Forces Munich

  • Venue:
  • valuetools '06 Proceedings of the 1st international conference on Performance evaluation methodolgies and tools
  • Year:
  • 2006

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Abstract

High-level stochastic description methods such as stochastic Petri nets, stochastic UML statecharts etc., together with specifications of performance variables (PVs), enable a compact description of systems and quantitative measures of interest. The underlying Markov reward models (MRMs) often exhibit a significant blow-up in size, commonly known as the state space explosion problem. In this paper we employ our recently developed type of symbolic data structure, zero-suppressed multi-terminal binary decision diagram (ZDD). In addition to earlier work [12] the following innovations are introduced: (a) new algorithms for efficiently generating ZDD-based representation of user-defined PVs, (b) a new ZDD-based variant of the approach of [17] for computing state probabilities, and (c) a new ZDD-based algorithm for computing moments of the PVs. These contributions yield a ZDD-based framework which allows the computation of complex performance and reliability measures of high-level system specifications, whose underlying MRMs consist of more than 108 states. The proposed algorithms for generating user-defined PVs and computing their moments are independent of the employed symbolic data type. Thus they are highly suited to fit into other symbolic frameworks as realized in popular performance evaluation tools. The efficiency of the presented approach, which we incorporated into the Möbius modeling framework [16], is demonstrated by analyzing several benchmark models from the literature and comparing the obtained run-time data to other techniques.