An Architecture-Centric Approach to the Development of a Distributed Model-Checker for Timed Automata Fernando Schapachnik Departamento de Computaci6n, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
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Victor Braberman t Departamento de Computaci6n, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
[email protected]
ABSTRACT
[2] R. Alur and D. Dill. A theory of timed automata. Theoretical Computer Science, 126:183-235, 1994. [3] G. Behrmann, T. Hune, and F. W. Vaandrager. Distributing timed model checking - how the search order matters. In Computer Aided Verification, volume 1855 of LNCS, pages 216-231. Springer-Verlag, 2000. [4] P. Cousot. Methodes Iteratives de Construction et
Research in Model-Checking is focused on increasing the size of the problems tools can deal with. The ultimate wave has been the use of Distributed-Computing, where a cluster of computers work together to solve the problem [8, 3, 9]. In our work we present a distributed model-checker that evolves from the tool Kronos [5] and can handle backwards computation of TCTL-reachability formulae [1] over timedautomata [2]. Our proposal, including the arguments of its correctness, is based on software architectures, using a notation adapted from [6]. We find such an approach a natural and general way to address the development of complex tools that need to incorporate new features and optimizations as they evolve. We introduce some interesting features such as a priori graph partitioning (using METIS [7], a standard library for graph partitioning), a sophisticated machinery to reach optimum performance (communication piggybacking and delayed messaging) and dead-time utilization, where every processor uses time intervals of inactivity to perform auxiliary, time-consuming tasks that will later speed up the rest of the computation. The correctness proof strategy combines an architecture evolution with the theoretical results about fix point calculation developed by Patrick Cousot in 1978 [4].
1.
Alfredo Olivero* Departamento de Tecnologia Inform&tica, Facultad de Ingenieria y Ciencias Exactas, Universidad Argentina de la Empresa, Buenos Aires, Argentina. aolivero@ uade.edu.ar
[5]
[6]
[7]
[8]
REFERENCES [9]
[1] R. Alur, C. Courcoubetis, and D. Dill. Model-checking for real-time systems. Information and Computation, 104(1):2-34, 1993. *Author tDirector :~Director
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D'Aproximation de Points Fixes D'Operate,urs Monotones sur un Treillis, Analyse Semantique des Programmes. Ph d. thesis, Universit@ Scientifique et M@dicale de Grenoble, Institut National Polytechnique de Grenoble, 1978. C. Daws, A. Olivero, S. Tripakis, and S. Yovine. The Tool KRONOS. In Proc. of Hybrid Systems III, volume 1066 of LNCS, pages 208-219. Springer-Verlag, 1996. C. Hofmeister, R. Nord, and S. Dilip. Applied Software Architecture. Addison-Wesley Publishing Company, Reading, Massachusetts, 1999. G. Karypis and V. Kumar. Parallel multilevel k-way partitioning scheme for irregular graphs. Technical report, University of Minnesota, Department of Computer Science / US A r m y HPC Research Center. Minneapolis, USA., March 1998. F. Lerda and R. Sisto. Distributed-memory model checking with SPIN. In Proc. of the 5th International SPIN Workshop, volume 1680 of LNCS. Springer-Verlag, 1999. U. Stern and D. L. Dill. Parallelizing the M u r ~ verifier. In Computer Aided Verification, volume 1254 of LNCS, pages 256-278. Springer-Verlag, 1997.
