Parallelization of Atomic Image Reconstruction from X-ray Fluorescence Holograms with XcalableMP

X-ray fluorescence holography is a three-dimensional middle range local structure analysis method, which can provide three-dimensional atomic images around specific elements within a radius of a few nanometers. Three-dimensional atomic images are reconstructed by applying discrete Fourier transform (DFT) to hologram data. Presently, it takes long time to process this DFT. In this study, the DFT program is parallelized by using a parallel programming language XcalableMP. The DFT process, whose input is 21 holograms data of 179 × 360 points and output is a three-dimensional atomic image of 1923 points, is executed on PC cluster which consists of 8 nodes of Intel Xeon X5660 processors and 96 cores in total and we confirmed that the parallelized DFT execution is 94 times faster than the sequential execution.