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		| Paper: | Gaia AVU–GSR parallel solver towards exascale infrastructure |  
		| Volume: | 535, Astronomical Data Analysis Software and Systems XXXI |  
		| Page: | 403 |  
		| Authors: | Cesare, V.; Becciani, U.; Vecchiato, A.; Lattanzi, M. G.; Pitari, F.; Raciti, M.; Tudisco, G.; Aldinucci, M.; Bucciarelli, B. |  
		| Abstract: | The Gaia Astrometric Verification Unit–Global Sphere Reconstruction Parallel Solver aims to find the astrometric parameters for ∼108 stars in the Milky Way, the attitude and the instrumental settings of the Gaia satellite, and the parameter γ of the Parametrized Post-Newtonian formalism. To perform this task, the code solves a system of linear equations, where the coefficient matrix is large and sparse. To deal with this big data problem, the application is parallelized with MPI+OpenMP and, to improve its performance, we ported the application on the GPU, replacing the OpenMP part with OpenACC. The OpenACC code obtains a gain in performance of ∼1.5 with respect to the OpenMP code and it is ready to run on pre-exascale systems. In the next months, we plan to port the application with CUDA, aiming to obtain higher gains. |  
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