Numerical relativity in a distributed environment.

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We have found that the hardware and software infrastructure exists to simulate general relativity problems in a distributed computational environment, at some cost in performance. We examine two different issues for running the Cactus code in such a distributed environment The first issue is running a Cactus simulation on multiple parallel computer systems. Our objective is to perform larger simulations than are currently possible on a single parallel computer. We distribute Cactus simulations across multiple supercomputers using the mechanisms provided by the Globus toolkit. In particular, we use Globus mechanisms for authentication, access to remote computer systems, file transfer, and ... continued below

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13 p.

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Benger, W.; Foster, I.; Novotny, J.; Seidel, E.; Shalf, J.; Smith, W. et al. February 8, 1999.

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Description

We have found that the hardware and software infrastructure exists to simulate general relativity problems in a distributed computational environment, at some cost in performance. We examine two different issues for running the Cactus code in such a distributed environment The first issue is running a Cactus simulation on multiple parallel computer systems. Our objective is to perform larger simulations than are currently possible on a single parallel computer. We distribute Cactus simulations across multiple supercomputers using the mechanisms provided by the Globus toolkit. In particular, we use Globus mechanisms for authentication, access to remote computer systems, file transfer, and communication. The Cactus code uses MPI for communication and makes use of an MPI implementation layered atop Globus communication mechanisms. These communication mechanisms allow a MPI application to be executed on distributed resources. We find that without performing any code optimizations, our simulations ran 48% to 100% slower when using an Origin at the National Center for Supercomputing Applications (NCSA) and an Onyx2 at Argonne National Laboratory (ANL). We also ran simulations between Cray T3Es in Germany and a T3E at the San Diego Supercomputing Center (SDSC). Running between the T3Es in Germany resulted in an increase in execution time of 79% to 133%, and running between a German T3E and a T3E at the San Diego Supercomputing Center resulted in an execution time increase of 114% to 186%. We are very encouraged that we are able to run simulations on parallel computers that are geographically distributed, and we have identified several areas to investigate to improve the performance of Cactus simulations in this environment. The second issue we examine here is remote visualization and steering of the Cactus code. Cactus is a modular framework and we have implemented a module for this task. This module performs isosurfacing operations on the same parallel computers that are running the simulation and reduces bandwidth requirements between the simulation and visualization components by a factor of 2.5 to 114, depending on the complexity of the data being visualized. This performance improvement and the available high-performance wide area networks allow us to distribute the simulation and visualization components in different parts of the US and Europe and interactively visualize and steer cactus simulations.

Physical Description

13 p.

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OSTI as DE00012403

Medium: P; Size: 13 pages

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  • Parallel Processing for Scientific Computing 1999 Meeting, San Antonio, TX (US), 03/22/1999--03/24/1999

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  • Report No.: ANL/MCS/CP-98383
  • Grant Number: W-31109-ENG-38
  • Office of Scientific & Technical Information Report Number: 12403
  • Archival Resource Key: ark:/67531/metadc618320

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • February 8, 1999

Added to The UNT Digital Library

  • June 16, 2015, 7:43 a.m.

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  • April 7, 2017, 1:08 p.m.

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Benger, W.; Foster, I.; Novotny, J.; Seidel, E.; Shalf, J.; Smith, W. et al. Numerical relativity in a distributed environment., article, February 8, 1999; Illinois. (digital.library.unt.edu/ark:/67531/metadc618320/: accessed December 16, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.