Georg Hager

On the Challenges of Energy-Efficiency Analysis in HPC Systems: Evaluating Synthetic Benchmarks and Gromacs

Rafael Ravedutti Lucio Machado, Jan Eitzinger, Georg Hager, Gerhard Wellein

This paper discusses the challenges encountered when analyzing the energy efficiency of synthetic benchmarks and the Gromacs package on the Fritz and Alex HPC clusters. Experiments were conducted using MPI parallelism on full sockets of Intel Ice Lake and Sapphire Rapids CPUs, …

Analytic roofline modeling and energy analysis of the LULESH proxy application on multi-core clusters

Ayesha Afzal, Georg Hager, Gerhard Wellein

We present a thorough performance and energy consumption analysis of the LULESH proxy application in its OpenMP and MPI variants on two different clusters based on Intel Ice Lake (ICL) and Sapphire Rapids (SPR) CPUs. We first study the strong scaling and …

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GROMACS Unplugged: How Power Capping and Frequency Shapes Performance on GPUs

Ayesha Afzal, Georg Hager, Gerhard Wellein

Molecular dynamics simulations are essential tools in computational biophysics, but their performance depend heavily on hardware choices and configuration. In this work, we presents a comprehensive performance analysis of four NVIDIA GPU accelerators -- A40, A100, L4, and L40 -- using six …

Exploring metrics for analyzing dynamic behavior in MPI programs via a coupled-oscillator model

Ayesha Afzal, Georg Hager, Gerhard Wellen

We propose a novel, lightweight, and physically inspired approach to modeling the dynamics of parallel distributed-memory programs. Inspired by the Kuramoto model, we represent MPI processes as coupled oscillators with topology-aware interactions, custom coupling potentials, and stochastic noise. The resulting system of …

Cache blocking of distributed-memory parallel matrix power kernels

Dane C. Lacey, Christie Louis Alappat, F. F. Lange, Georg Hager et autres

Sparse matrix-vector products (SpMVs) are a bottleneck in many scientific codes. Due to the heavy strain on the main memory interface from loading the sparse matrix and the possibly irregular memory access pattern, SpMV typically exhibits low arithmetic intensity. Repeating these products …

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Energy-aware operation of HPC systems in Germany

Estela Suarez, Hendryk Bockelmann, N. Eicker, Jan Eitzinger et autres

High Performance Computing (HPC) systems are among the most energy-intensive scientific facilities, with electric power consumption reaching and often exceeding 20 Megawatts per installation. Unlike other major scientific infrastructures such as particle accelerators or high-intensity light sources, which are few around the …

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Analytic Roofline Modeling and Energy Analysis of LULESH Proxy Application on Multi-Core Clusters

Ayesha Afzal, Georg Hager, Gerhard Wellein

We present a thorough performance and energy consumption analysis of the LULESH proxy application in its OpenMP and MPI variants on two different clusters based on Intel Ice Lake (ICL) and Sapphire Rapids (SPR) CPUs. We first study the strong scaling and …

Energy-aware operation of HPC systems in Germany

Estela Suarez, Hendryk Bockelmann, N. Eicker, Jan Eitzinger et autres

High-Performance Computing (HPC) systems are among the most energy-intensive scientific facilities, with electric power consumption reaching and often exceeding 20 megawatts per installation. Unlike other major scientific infrastructures such as particle accelerators or high-intensity light sources, which are few around the world, …

Microarchitectural comparison and in-core modeling of state-of-the-art CPUs: Grace, Sapphire Rapids, and Genoa

Jan Laukemann, Georg Hager, Gerhard Wellein

With Nvidia’s release of the Grace Superchip, all three big semiconductor companies in HPC (AMD, Intel, Nvidia) are currently competing in the race for the best CPU. In this work we analyze the performance of these state-of-the-art CPUs and create an accurate …

Algebraic temporal blocking for sparse iterative solvers on multi-core CPUs

Christie Louis Alappat, Jonas Thies, Georg Hager, Holger Fehske et autres

Sparse linear iterative solvers are essential for many large-scale simulations. Much of the runtime of these solvers is often spent in the implicit evaluation of matrix polynomials via a sequence of sparse matrix-vector products. A variety of approaches has been proposed to …

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Microarchitectural comparison and in-core modeling of state-of-the-art CPUs: Grace, Sapphire Rapids, and Genoa

Jan Laukemann, Georg Hager, Gerhard Wellein

With Nvidia's release of the Grace Superchip, all three big semiconductor companies in HPC (AMD, Intel, Nvidia) are currently competing in the race for the best CPU. In this work we analyze the performance of these state-of-the-art CPUs and create an accurate …

CloverLeaf on Intel Multi-Core CPUs: A Case Study in Write-Allocate Evasion

Jan Laukemann, Thomas Gruber, Georg Hager, Dossay Oryspayev et autres

In this paper we analyze the MPI-only version of the CloverLeaf code from the SPEChpc 2021 benchmark suite on recent Intel Xeon "Ice Lake" and "Sapphire Rapids" server CPUs. We observe peculiar breakdowns in performance when the number of processes is prime. …

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