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Benefits of SMT and of Parallel Transpose Algorithm for the Large-Scale GYSELA Application

Abstract : This article describes how we manage to increase performance and to extend features of a large parallel application through the use of simultaneous multithreading (SMT) and by designing a robust parallel transpose algorithm. The semi-Lagrangian code Gysela typically performs large physics simulations using a few thousands of cores, between 1k cores up to 16k on x86-based clusters. However, simulations with finer resolutions and with kinetic electrons increase those needs by a huge factor, providing a good example of applications requiring Exascale machines. To improve Gysela compute times, we take advantage of efficient SMT implementations available on recent INTEL architectures. We also analyze the cost of a transposition communication scheme that involves a large number of cores in our case. Adaptation of the code for balance load whenever using both SMT and good deployment strategy led to a significant reduction that can be up to 38% of the execution times.
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Contributor : Julien Bigot <>
Submitted on : Tuesday, July 10, 2018 - 2:35:59 PM
Last modification on : Friday, June 19, 2020 - 9:22:05 AM

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Guillaume Latu, Julien Bigot, Nicolas Bouzat, Judit Gimenez, Virginie Grandgirard. Benefits of SMT and of Parallel Transpose Algorithm for the Large-Scale GYSELA Application. PASC '16 - Proceedings of the Platform for Advanced Scientific Computing Conference, Jun 2016, Lausanne, France. ⟨10.1145/2929908.2929912⟩. ⟨hal-01834323⟩



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