Variations on Multi-Core Nested Depth-First Search

Alfons Laarman, Jan Cornelis van de Pol

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    Recently, two new parallel algorithms for on-the-fly model checking of LTL properties were presented at the same conference: Automated Technology for Verification and Analysis, 2011. Both approaches extend Swarmed NDFS, which runs several sequential NDFS instances in parallel. While parallel random search already speeds up detection of bugs, the workers must share some global information in order to speed up full verification of correct models. The two algorithms differ considerably in the global information shared between workers, and in the way they synchronize. Here, we provide a thorough experimental comparison between the two algorithms, by measuring the runtime of their implementations on a multi-core machine. Both algorithms were implemented in the same framework of the model checker LTSmin, using similar optimizations, and have been subjected to the full BEEM model database. Because both algorithms have complementary advantages, we constructed an algorithm that combines both ideas. This combination clearly has an improved speedup. We also compare the results with the alternative parallel algorithm for accepting cycle detection OWCTY-MAP. Finally, we study a simple statistical model for input models that do contain accepting cycles. The goal is to distinguish the speedup due to parallel random search from the speedup that can be attributed to clever work sharing schemes.
    Original languageEnglish
    Title of host publicationProceedings of the 10th International Workshop on Parallel and Distributed Methods in verifiCation, PDMC 2011
    EditorsJ. Barnat, K. Heljanko
    Place of PublicationUSA
    Number of pages16
    Publication statusPublished - 14 Jul 2011
    Event10th International Workshop on Parallel and Distributed Methods in verifiCation, PDMC 2011 - Snowbird, United States
    Duration: 14 Jul 201114 Jul 2011
    Conference number: 10

    Publication series

    NameElectronic Proceedings in Theoretical Computer Science
    ISSN (Print)2075-2180
    ISSN (Electronic)2075-2180


    Workshop10th International Workshop on Parallel and Distributed Methods in verifiCation, PDMC 2011
    Abbreviated titlePDMC
    Country/TerritoryUnited States
    Internet address


    • IR-78261
    • METIS-278846
    • Parallel
    • LTL model checking
    • EWI-20618
    • Multi-Core
    • depth first search
    • swarmed
    • Nested DFS


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