Citation
Daniel Lazaro Cuadrado. "Automated Distribution Simulation in Ptolemy II". PhD thesis, Aalborg University, April, 2008.

Abstract
Despite the well known advantages of distributed processing for intensive computations like simulation, frameworks often fail to exploit them. A distributed simulation is harder to develop than a sequential one, because it is necessary to interface and map activities to processors and handle the ensuing communication and synchronization problems. Very often the designer has to explicitly specify information about distribution for the framework to exploit parallelism. This dissertation presents Automated Distributed Simulation (ADS), which allows designers to forget about distribution concerns while benefiting from the advantages. This study shows abstractions that help automate the distribution of a simulation by taking maximum advantage of inherent parallelism. ADS relies on an actor formalism to provide encapsulation of component behavior and reusability. Models of computation govern component interactions by defining execution and communication mechanisms and the notion of time; thus providing semantics. Different models of computation useful for embedded systems are surveyed to discuss possibilities for distribution. Synchronous Dataflow allows for static scheduling, therefore eliminating runtime overheads and having a higher potential for efficient parallelization. Moreover it is a popular formalism suited for a large number of embedded applications, thus is chosen for the initial implementation of ADS. We present a novel execution mechanism that produces optimal periodic admissible parallel schedules allowing the dispatching mechanism to apply pipelining techniques. The implementation is described with major emphasis on distribution issues as interfacing and mapping of activities, communication and synchronization. We have chosen Ptolemy II as the implementation framework since it provides the abstractions required to achieve ADS as open source. The Ptolemy project studies heterogeneous modeling, simulation and design of concurrent real-time, embedded systems; Ptolemy II is the current software incarnation. Experiments to explore the gain for varying values of relevant parameters such as block size, number of blocks, number of iterations and topology have been designed and run. Analytical expressions for the expected results are derived and compared with the empirical results to arrive at relative overheads. The experiments show significant gains over the original implementation. The topology of a dataflow model plays an important role. However, serialization can be mitigated by using pipelined execution. Time saved in parallelization plus linear speedup in makespans provided by ADS can help tackle hitherto infeasible simulations.

The implementation result of this work is publicly available as a new feature of the latest public release of Ptolemy II. Since it is open source, it constitutes a major mean of dissemination of the ideas presented here, as well as documentation for this work.

Electronic downloads

• LazaroCuadrado08AutomatedDistributedSimulationInPtolemyII1.pdf · download/application/pdf · 997 kbytes

• HTML

  Daniel Lazaro Cuadrado. <a
  href="http://chess.eecs.berkeley.edu/pubs/412.html"
  ><i>Automated Distribution Simulation in Ptolemy
  II</i></a>, PhD thesis,  Aalborg University,
  April, 2008.

• Plain text

  Daniel Lazaro Cuadrado. "Automated Distribution
  Simulation in Ptolemy II". PhD thesis,  Aalborg
  University, April, 2008.

• BibTeX

  @phdthesis{LazaroCuadrado08_AutomatedDistributionSimulationInPtolemyII,
      author = {Daniel Lazaro Cuadrado},
      title = {Automated Distribution Simulation in Ptolemy II},
      school = {Aalborg University},
      month = {April},
      year = {2008},
      abstract = {Despite the well known advantages of distributed
                processing for intensive computations like
                simulation, frameworks often fail to exploit them.
                A distributed simulation is harder to develop than
                a sequential one, because it is necessary to
                interface and map activities to processors and
                handle the ensuing communication and
                synchronization problems. Very often the designer
                has to explicitly specify information about
                distribution for the framework to exploit
                parallelism. This dissertation presents Automated
                Distributed Simulation (ADS), which allows
                designers to forget about distribution concerns
                while benefiting from the advantages. This study
                shows abstractions that help automate the
                distribution of a simulation by taking maximum
                advantage of inherent parallelism. ADS relies on
                an actor formalism to provide encapsulation of
                component behavior and reusability. Models of
                computation govern component interactions by
                defining execution and communication mechanisms
                and the notion of time; thus providing semantics.
                Different models of computation useful for
                embedded systems are surveyed to discuss
                possibilities for distribution. Synchronous
                Dataflow allows for static scheduling, therefore
                eliminating runtime overheads and having a higher
                potential for efficient parallelization. Moreover
                it is a popular formalism suited for a large
                number of embedded applications, thus is chosen
                for the initial implementation of ADS. We present
                a novel execution mechanism that produces optimal
                periodic admissible parallel schedules allowing
                the dispatching mechanism to apply pipelining
                techniques. The implementation is described with
                major emphasis on distribution issues as
                interfacing and mapping of activities,
                communication and synchronization. We have chosen
                Ptolemy II as the implementation framework since
                it provides the abstractions required to achieve
                ADS as open source. The Ptolemy project studies
                heterogeneous modeling, simulation and design of
                concurrent real-time, embedded systems; Ptolemy II
                is the current software incarnation. Experiments
                to explore the gain for varying values of relevant
                parameters such as block size, number of blocks,
                number of iterations and topology have been
                designed and run. Analytical expressions for the
                expected results are derived and compared with the
                empirical results to arrive at relative overheads.
                The experiments show significant gains over the
                original implementation. The topology of a
                dataflow model plays an important role. However,
                serialization can be mitigated by using pipelined
                execution. Time saved in parallelization plus
                linear speedup in makespans provided by ADS can
                help tackle hitherto infeasible simulations. <p>
                The implementation result of this work is publicly
                available as a new feature of the latest public
                release of Ptolemy II. Since it is open source, it
                constitutes a major mean of dissemination of the
                ideas presented here, as well as documentation for
                this work.},
      URL = {http://chess.eecs.berkeley.edu/pubs/412.html}
  }
  

Posted by Christopher Brooks on 13 Apr 2008.
Groups: ptolemy
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