HAL : inria-00597576, version 2
 arXiv : 1106.0159
 Versions disponibles v1 (01-06-2011) v2 (05-06-2012)
 Parallel Spherical Harmonic Transforms on heterogeneous architectures (GPUs/multi-core CPUs)
 (15/05/2012)
 Spherical Harmonic Transforms (SHT) are at the heart of many scientific and practical applications ranging from climate modelling to cosmological observations. In many of these areas new, cutting-edge science goals have been recently proposed requiring simulations and analyses of experimental or observational data at very high resolutions and of unprecedented volumes. Both these aspects pose formidable challenge for the currently existing implementations of the transforms. This paper describes parallel algorithms for computing the SHTs with two variants of intra-node parallelism appropriate for novel supercomputer architectures, multi-core processors and Graphic Processing Units (GPU) and discusses their performance tests, alone and embedded within a top-level, MPI-based parallelization layer ported from the S$^2$HAT library, in terms of their accuracy, overall efficiency and scalability. We show that our inverse SHTs with GeForce 400 Series GPUs equipped with latest CUDA architecture ("Fermi") outperforms the state of the art implementation for a multi-core processor executed on a current Intel Core i7-2600K. Furthermore, we show that an MPI/CUDA version of the inverse transform run on a cluster of 128 NVIDIA Tesla S1070 is as much as 3 times faster than the hybrid MPI/OpenMP version executed on the same number of quad-core processors Intel Nahalem for problem sizes motivated by our target applications. For the direct transforms, the performance is however found to be at the best comparable. Here we discuss in detail optimizations of two major steps involved in the transforms calculation, demonstrating how the overall performance efficiency can be obtained, and elucidating the sources of the dichotomy between the direct and the inverse operations
 Équipe de recherche (sauf Inria) : APC - ADAMIS
 Domaine : Informatique/Calcul parallèle, distribué et partagéPhysique/Astrophysique/Cosmologie et astrophysique extra-galactiquePlanète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactiquePhysique/Physique/Physique Atmosphérique et OcéaniquePhysique/Physique/GéophysiquePlanète et Univers/Sciences de la Terre/GéophysiqueSciences de l'environnement/Milieux et Changements globaux
 Mots-clés : Spherical Harmonic Transforms – hybrid architectures – hybrid programming – OpenMP – CUDA – Multi-GPU – CMB
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 s2hat_jpaper_inria_format.pdf(7.5 MB)
 inria-00597576, version 2 http://hal.inria.fr/inria-00597576 oai:hal.inria.fr:inria-00597576 Contributeur : Mikolaj Szydlarski <> Soumis le : Mercredi 30 Mai 2012, 11:55:52 Dernière modification le : Vendredi 8 Juin 2012, 17:10:07