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BEGIN:VEVENT
DTSTAMP:20210916T132449Z
LOCATION:Lise Girardin
DTSTART;TZID=Europe/Stockholm:20210706T123000
DTEND;TZID=Europe/Stockholm:20210706T130000
UID:submissions.pasc-conference.org_PASC21_sess124_msa336@linklings.com
SUMMARY:Integrated Fusion Simulation at Exascale Using GTC
DESCRIPTION:Minisymposium\n\nIntegrated Fusion Simulation at Exascale Usin
 g GTC\n\nLin\n\nConfinement properties in burning plasmas with self-heatin
 g by energetic αlpha-particles is one of the most uncertain physics i
 ssues when extrapolating from existing fusion plasma experiments to the fu
 sion reactor ITER, the crucial next step in the quest for the fusion energ
 y. Predictive capability requires exascale simulation of nonlinear interac
 tions of multiple kinetic-MHD (magnetohydrodynamic) processes across dispa
 rate spatial-temporal scales. Thanks to cross-disciplinary and multi-insti
 tutional collaborations, Gyrokinetic Toroidal Code (GTC) has been develope
 d with extensive V&V for integrated simulation of fusion plasmas incorpora
 ting microturbulence driven by thermal plasmas, meso-scale Alfven eigenmod
 es excited by energetic particles, and macroscopic MHD instabilities. GTC 
 has been ported to and optimized for the pre-exascale GPU supercomputing p
 latform using multi-level parallelization. Heterogeneous programming with 
 directives (MPI+OpenMP+OpenACC) has been used to balance the continuously 
 implemented physical capabilities and rapidly evolving software/hardware s
 ystems. After extensive GPU optimization, the real physics tests on the Su
 mmit supercomputer at ORNL showed impressive scaling properties that reach
 es roughly 50% efficiency on 928 nodes of the Summit. The GPU + CPU speed 
 up from purely CPU is over 20 times. In the Summit acceptance test, GTC de
 monstrated good scaling up to the whole system of 4600 nodes (27600 NVIDIA
  V100 GPUs).\n\nDomain: CS and Math, Physics
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