The BlueGene/Q Supercomputer P A Boyle∗ University of Edinburgh E-mail:
[email protected] I introduce the BlueGene/Q supercomputer design, with an emphasis on features that enhance QCD performance, discuss the architectures performance for optimised QCD codes and compare these characteristics to other leading architectures. The 30 International Symposium on Lattice Field Theory - Lattice 2012, June 24-29, 2012 Cairns, Australia ∗Speaker. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/ The BlueGene/Q Supercomputer P A Boyle 1. QCD computer design challenge The floating point operation count in the Monte Carlo evaluation of the QCD path integral is dominated by the solution of discretised Euclidean Dirac equation. The solution of this equation is a classic sparse matrix inversion problem, for which one uses one of a number of iterative Krylov methods. The naive dimension of the (sparse) matrix is of O([109]2), and hundreds of thousands of inversions must be performed in a serially dependent chain to importance sample the QCD path integral. The precision with which we can solve QCD numerically is computationally limited, and the development of faster computers is of great interest to the field. Many processors are in principal faster than one, providing we can arrange for them to co- ordinate work effectively. QCD is easily parallelised with a geometrical decomposition spreading L4 space time points across multiple N4 processing nodes, each containing