Intel Xeon Phi Provides Cambridge 30x Speedup in Production COSMOS WALLS Code

Professor Paul Shellard, the COSMOS Director at Cambridge University reports a 30x speedup of the heavily utilized production WALLS code and he notes “Our expectation is that all our cosmological field theory codes, like WALLS, will have similarly large speed-ups when optimized and ported to Xeon Phi.”  Currently the project is transferring a larger portion of the CMB analysis to Intel Xeon Phi coprocessors over the next twelve months.

Professor E.P.S. Shellard

COSMOS has proved essential to the CMB, particularly the Planck satellite maps of the entire sky. Professor Shellard states, “The magnitude of data is manageable, but the computational effort required to extract scientific information from it is formidable”. For example, when researchers look at the statistics described by the three-point correlation function, they need to add up all the contributions from all the possible triangles we can draw within the 10 million pixels in a single Planck map. Naively, this is 10²¹ sets of complex operations! These calculations need to be simulated and repeated many times to test and eliminate systematic experimental effects, so brute force methods are not possible. Just to calculate the three-point correlator data required 3 million core-hours. On a single core that would take over 300 years. We needed to be able to solve it within 300 days.

Using COSMOS, researchers have been able to rapidly develop and implement methods to calculate the complete three-point correlator for the first time, up to a given resolution. This is a statistic that looks at “triangles in the sky”, testing whether there is a connection between sets of three different points in the Universe. Porting the computational “hot spots” in our Planck pipeline to the Intel Xeon Phi coprocessors has greatly shortened turnaround times, which will ensure we substantially improve resolution in the future. We could not begin to analyse the Planck maps, let alone previous generations of experiments, without COSMOS.

 Another major project being undertaken on COSMOS is the study of spectroscopic signatures of particular molecules in exoplanet atmospheres (the EXOMOL project). These signatures can help in the identification of exoplanets and whether or not there is extra-terrestrial life there.