SC Conference - Activity Details

Managing Locality in a Parallel Grand Challenge Application: A Case Study of the Gyrokinetic Toroidal Code

Gabriel Marin  (Rice University)
Guohua Jin  (Rice University)
John Mellor-Crummey  (Rice University)
Posters Session
Tuesday,  05:15PM - 07:00PM
Room Rotunda Lobby
Achieving high performance with grand challenge applications on today's large-scale parallel systems requires tailoring applications for the characteristics of the modern microprocessor architectures. As part of the US Department of Energy's Scientific Discovery through Advanced Computing (SciDAC-2) program, we studied and tuned the Gyrokinetic Toroidal Code (GTC), a particle-in-cell code for simulating turbulent transport of particles and energy in burning plasma, developed at Princeton Plasma Physics Laboratory. In this poster, we present a detailed performance study of the application which revealed several opportunities for improving performance by enhancing its data locality. We tuned GTC by performing three kinds of transformations: static data structure reorganization to improve spatial locality, loop nest restructuring for better temporal locality, and dynamic data reordering at run-time to enhance both spatial and temporal reuse. Experimental results show that these changes improve execution time by more than 20% on large parallel systems, including a Cray XT4.
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