Galactos: Computing the 3-pt Anisotropic Correlation for
2 Billion Galaxies
SessionMultiphysics
Authors
Event Type
Paper
Applications
Scientific Computing
TimeTuesday, November 14th4pm -
4:30pm
Location301-302-303
DescriptionThe nature of dark energy and the complete theory of
gravity are two central questions currently facing
cosmology. A vital tool for addressing them is the
3-point correlation function (3PCF), which probes
deviations from a spatially random distribution of
galaxies. However, the 3PCF’s formidable computational
expense has prevented its application to astronomical
surveys comprising millions to billions of galaxies. We
present Galactos, a high-performance implementation of a
novel, O(N2) algorithm that uses a load-balanced k-d
tree and spherical harmonic expansions to compute the
anisotropic 3PCF. Our implementation is optimized for
the Intel Xeon Phi architecture, exploiting SIMD
parallelism, instruction and thread concurrency, and
significant L1 and L2 cache reuse, reaching 39% of peak
performance on a single node. Galactos scales to the
full Cori system, achieving 9.8 PFLOPS (peak) across
9636 nodes, making the 3PCF easily computable for all
galaxies in the observable universe.
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