Compiler and Runtime Support for Scaling Adaptive Mesh Refinement Computations in Titanium
Toward Automatic Parallel Adaptive Mesh Refinement
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Transcript of Toward Automatic Parallel Adaptive Mesh Refinement
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Cactus Workshop - NCSA Sep 27 - Oct 1 1999
Scott H. Hawley*, Matthew W. Choptuik*
*University of Texas at Austin
*University of British Columbia
Toward Automatic Parallel Adaptive Mesh Refinement
Credits: Manish Parashar, James C. Browne, Paul Walker, Shyamal Mitra, Robert Marsa, Mijan Huq, Dae-Il Choi
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When we model physical phenomena using finite-difference approximations of partial differential equations…
For fixed local accuracy, required resolution may vary widely in space and time
Resolution requirements may not be known a priori Adaptive Mesh Refinement (AMR)
Even with the utility AMR provides, a code must be parallelizable to take advantage of modern computing machinery
MotivationMotivation
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Motivation, cont’dMotivation, cont’d
AMR and parallel processing are desirable, but both present challenges which may be prohibitive for many researchers
Investigate environments in which AMR and parallelism
are provided automatically
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ParadigmParadigm
Almost all details of AMR and parallelism hidden from user Provide unigrid routines Specify
– maximum # of levels
– truncation error tolerance for regridding
– clustering efficiency Entire AMR driver generated automatically
User selects “AMR: On” (someday soon)
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GrACE provides structures for AMR and parallelization
Goal: Make GrACE features easily accessible to end user
Provide: Generic Driver (“Your code here”) Output support Supplemental Documentation (“How to…”) Link to RNPL
Build Around GrACEBuild Around GrACE
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Rapid Numerical Prototyping Language (RNPL)Rapid Numerical Prototyping Language (RNPL)
Minimal development time Specify:
– Initial Data– Boundary Conditions– Finite Difference Equations
Examples: Pedagogy: Scalar wave in IEF coordinates Boson star simulations Generate framework for fluid codes
Easily used to write Cactus Thorns
Marsa & Choptuik
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Coincident GoalsCoincident Goals
Both this effort and Cactus seek automatic, parallel AMR in the very near future
Cactus needs to deliver AMR Generic GrACE driver could be run as a Cactus Thorn
– Maybe “The” Cactus AMR Thorn
Problems my group want to solve My dissertation: Accretion disk theory within IMSO (Scott needs to land a job…) Others: Gamma-ray burst models, Multi-D critical phenomena, and much
more! David Neilsen, Jason Ventrella, Ethan Honda, Scott Noble Cactus better connected with a wide variety of computing support than we
can provide on our own
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NeedsNeeds
Visualization of AMR data Interactive tool for daily use
– Not necessarily “flashy” or “high-performance” Inexpensive Curvilinear coordinate systems Animation Grid-grid operations (+,-,*,/,etc) Easy for user to add new functionality (filters, parameters)
Efficient Collaboration Daily e-mail is not interactive enough to achieve short turn-around
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