Landau Gauge Fixing on GPUs

In this paper we present and explore the performance of Landau gauge fixing in GPUs using CUDA. We consider the steepest descent algorithm with Fourier acceleration, and compare the GPU performance with a parallel CPU implementation. Using $32^4$ lattice volumes, we find that the computational power of a single Tesla C2070 GPU is equivalent to approximately 256 CPU cores.Comment: 10 pages, 3 figures and 3 table

Landau Gauge Fixing on GPUs and String Tension

We explore the performance of CUDA in performing Landau gauge fixing in Lattice QCD, using the steepest descent method with Fourier acceleration. The code performance was tested in a Tesla C2070, Fermi architecture. We also present a study of the string tension at finite temperature in the confined phase. The string tension is extracted from the color averaged free energy and from the color singlet using Landau gauge fixing.Comment: 7 pages, 4 figures, 1 table. Contribution to the International Meeting "Excited QCD", Peniche, Portugal, 06 - 12 May 201

Gauge fixing using overrelaxation and simulated annealing on GPUs

We adopt CUDA-capable Graphic Processing Units (GPUs) for Coulomb, Landau and maximally Abelian gauge fixing in 3+1 dimensional SU(3) lattice gauge field theories. The local overrelaxation algorithm is perfectly suited for highly parallel architectures. Simulated annealing preconditioning strongly increases the probability to reach the global maximum of the gauge functional. We give performance results for single and double precision. To obtain our maximum performance of ~300 GFlops on NVIDIA's GTX 580 a very fine grained degree of parallelism is required due to the register limits of NVIDIA's Fermi GPUs: we use eight threads per lattice site, i.e., one thread per SU(3) matrix that is involved in the computation of a site update.Comment: 7 pages, 2 figures. Talk presented at the 30th International Symposium on Lattice Field Theory, June 24-29, 2012, Cairns, Australi

Landau gauge fixing on the lattice using GPU's

In this work, we consider the GPU implementation of the steepest descent method with Fourier acceleration for Laudau gauge fixing, using CUDA. The performance of the code in a Tesla C2070 GPU is compared with a parallel CPU implementation.Comment: 3 pages, 1 figure, Proceedings of the Xth Quark Confinement and the Hadron Spectrum, 8-12 October 2012, TUM Campus Garching, Munich, German

cuLGT: Lattice Gauge Fixing on GPUs

We adopt CUDA-capable Graphic Processing Units (GPUs) for Landau, Coulomb and maximally Abelian gauge fixing in 3+1 dimensional SU(3) and SU(2) lattice gauge field theories. A combination of simulated annealing and overrelaxation is used to aim for the global maximum of the gauge functional. We use a fine grained degree of parallelism to achieve the maximum performance: instead of the common 1 thread per site strategy we use 4 or 8 threads per lattice site. Here, we report on an improved version of our publicly available code (www.cuLGT.com and github.com/culgt) which again increases performance and is much easier to include in existing code. On the GeForce GTX 580 we achieve up to 470 GFlops (utilizing 80% of the theoretical peak bandwidth) for the Landau overrelaxation code.Comment: 6 pages, 2 figures, code available on cuLGT.com and github.com/culgt, talk presented at GPU Computing in High Energy Physics, September 10-12, 2014, Pisa, Ital

More effects of Dirac low-mode removal

In previous studies we have shown that hadrons, except for a pion, survive the removal of the lowest lying Dirac eigenmodes from the valence quark propagators. The low-modes are tied to the dynamical breaking of chiral symmetry and we found chiral symmetry to be restored by means of matching masses of chiral partners, like, e.g., the vector and axial vector currents. Here we investigate the influence of removing the lowest part of the Dirac spectrum on the locality of the Dirac operator. Moreover, we analyze the influence of low-mode truncation on the quark momenta and thereupon on the hadron spectrum and, finally, introduce a reweighting scheme to extend the truncation to the sea quark sector.Comment: 7pages, 4 figures. Proceedings of the 31st International Symposium on Lattice Field Theory, July 29 - August 3, 2013, Mainz, German