edu.ucar.opensky::technotes:530 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T03:04:54.197428 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7668cn5 Accelerating 'fields' by revamping the Cholesky Decomposition 2015-08-01T00:00:00Z publication https://n2t.org/ark:/85065/d7668cn5 https://doi.org/10.5065/D6QF8QXR Ramakrishnaiah, V. author Prasanna Kumar, Raghu Raj author Paige, J. author Hammerling, Dorit author UCAR/NCAR - Library publisher The Geophysical Statistics project group within the Institute for Mathematics Applied to Geosciences (IMAGe) has been making use of Matrix Algebra on GPU and Multicore Architectures (MAGMA) to accelerate the Cholesky decomposition. The acceleration is motivated by a) Its frequent use in key computations in the spatial statistics R 'fields' package, b) Major bottleneck in 'fields' package execution and c) Operations involving big matrices make it suitable for parallelization. The Cholesky Decomposition was accelerated last summer using the MAGMA library. However, the performance of the accelerated version on multiple GPUs was observed to be unconventional - a) Execution time on multiple GPUs was higher in comparison to single GPU execution and b) Deep copy and in-place algorithms had opposite impacts on performance when executed on one and multiple GPUs. Our CPU and GPU profiling, conducted this summer, explains the unconventional behavior observed in the multi-GPU executions. The profiling provided insight to further accelerate the Cholesky Decomposition hierarchically– a) accelerating the underlying C function, b) reducing the function call overhead in R and c) optimizing the R environment. We were able to optimize the code and the environment to get a speedup greater than 75x (single precision) and 65x (double precision) for large matrices. We also found a potential way to improve the MAGMA functions by replacing the communications with direct device-to-device calls. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Statistical applications theme U.S. National Aeronautics and Space Administration Global Change Master Directory GCMD 2021-09-17 revision 11.2 NASA Global Change Master Directory originator Valids List: Science and Services Keywords Copyright Author(s). This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. None eng geoscientificInformation