Lattice QCD Calculations on Commodity Clusters at DESY

TL;DR

This paper evaluates the performance of commodity PC clusters at DESY for lattice QCD calculations, demonstrating their suitability for high-performance particle physics research through benchmarks and system analysis.

Contribution

It presents practical performance benchmarks and system insights showing commodity clusters can effectively support large-scale lattice QCD computations.

Findings

Intel Pentium 4 Xeon CPUs with SSE/SSE2 show promising performance.

Parallel performance depends on hardware components like chipsets and communication interfaces.

Linux clusters with Myrinet interconnects are viable for high-performance lattice QCD.

Abstract

Lattice Gauge Theory is an integral part of particle physics that requires high performance computing in the multi-Tflops regime. These requirements are motivated by the rich research program and the physics milestones to be reached by the lattice community. Over the last years the enormous gains in processor performance, memory bandwidth, and external I/O bandwidth for parallel applications have made commodity clusters exploiting PCs or workstations also suitable for large Lattice Gauge Theory applications. For more than one year two clusters have been operated at the two DESY sites in Hamburg and Zeuthen, consisting of 32 resp. 16 dual-CPU PCs, equipped with Intel Pentium 4 Xeon processors. Interconnection of the nodes is done by way of Myrinet. Linux was chosen as the operating system. In the course of the projects benchmark programs for architectural studies were developed. The performance of the Wilson-Dirac Operator (also in an even-odd preconditioned version) as the inner loop of the Lattice QCD (LQCD) algorithms plays the most important role in classifying the hardware basis to be used. Using the SIMD Streaming Extensions (SSE/SSE2) on Intel's Pentium 4 Xeon CPUs give promising results for both the single CPU and the parallel version. The parallel performance, in addition to the CPU power and the memory throughput, is nevertheless strongly influenced by the behavior of hardware components like the PC chip-set and the communication interfaces. The paper covers the physics motivation for using PC clusters as well as a system description, operating experiences, and benchmark results for various hardware.