We present an overview of the Graphics Processing Unit (GPU) based spatial processing system created for the Canadian Hydrogen Intensity Mapping Experiment (CHIME). The design employs AMD S9300x2 GPUs and readily-available commercial hardware in its processing nodes to provide a cost- and power-efficient processing substrate. These nodes are supported by a liquid-cooling system which allows continuous operation with modest power consumption and in all but the most adverse conditions. Capable of continuously correlating 2048 receiver-polarizations across 400\,MHz of bandwidth, the CHIME X-engine constitutes the most powerful radio correlator currently in existence. It receives 6.6\,Tb/s of channelized data from CHIME's FPGA-based F-engine, and the primary correlation task requires 8.39×1014 complex multiply-and-accumulate operations per second. The same system also provides formed-beam data products to commensal FRB and Pulsar experiments; it constitutes a general spatial-processing system of unprecedented scale and capability, with correspondingly great challenges in computation, data transport, heat dissipation, and interference shielding.
@article{arxiv.2005.09481,
title = {A GPU Spatial Processing System for CHIME},
author = {Nolan Denman and Andre Renard and Keith Vanderlinde and Philippe Berger and Kiyoshi Masui and Ian Tretyakov and the CHIME Collaboration},
journal= {arXiv preprint arXiv:2005.09481},
year = {2020}
}