Mixed-Precision and Energy-Efficient Computations
2025-10-09 12:10 - 14:30 (Europe/Paris)
If you’re at the Workshop on Approximate Computing in Numerical Linear Algebra in Paris this week, don’t miss Yanxiang Chen’s lunch poster talk on mixed precision and energy efficient computations!
Abstract: High Performance Computing has traditionally focused on optimizing between memory usage, arithmetic intensity, parallelism, and communication costs. However, as simulations grow, energy consumption has surged, presenting significant sustainability challenges for large-scale computing infrastructures. Addressing these challenges requires innovative strategies that enhance energy efficiency without compromising computational accuracy or performance.
We present a systematic methodology for reducing the energy footprint of large-scale simulations via mixed-precision computing, without compromising accuracy or performance. Our approach combines performance profiling with numerical sensitivity analysis to identify precision-insensitive code regions, select promising candidates, and gradually convert them to lower precision. Applied to representative high-performance computing kernels, this strategy yields up to 40% speedup and 47% energy savings in an implicit Poisson solver, and roughly 30% gains in both execution time and energy consumption in explicit solvers, all while preserving double-precision level accuracy. These results demonstrate that our methodology provides a versatile and effective lever for enhancing the sustainability of HPC applications.

Mixed-Precision Strategies in Spectral Element Codes: Accuracy-Aware Approximation for Energy-Efficient Simulations
2025-10-09 15:50 - 16:10
If you’re at the Workshop on Approximate Computing in Numerical Linear Algebra in Paris this week, chec out Roman Iakymchuk’s talk on mixed-precision strategies in spectral element codes on Thursday!
Abstract: Approximate computing via mixed precision arithmetic offers a promising path to energy-efficient high-performance computing. However, identifying where and how to apply reduced precision without compromising solution accuracy remains a key challenge in scientific simulations. In this talk, we present a comprehensive methodology for enabling mixed-precision in spectral element codes using floating-point analysis tools, roofline modeling, and empirical verification. We apply our strategy to Nekbone and Neko—two fluid dynamics solvers—by combining reduced-precision iterative solvers with double-precision critical operations such as dot products and global communications. Our method is supported by Verificarlo’s Monte Carlo arithmetic and precision emulation, which help detect numerically stable kernels for approximation. The resulting mixed-precision versions deliver up to 2.38x faster time-to-solution and 2.8× lower energy-to-solution, while retaining double-precision-level accuracy. This work highlights a practical, accuracy-aware approach to integrating approximation into large-scale legacy applications, making them fit for future exascale platforms.

Task-decomposed Overlapped Preconditioner for Sustained Strong Scalability on Accelerated Exascale Systems
2026-01-28 11:30 - 12:00
Join Niclas Jannson in Osaka, Japan at SCA/HPCAsia2026 for his talk on “Task-decomposed Overlapped Preconditioner for Sustained Strong Scalability on Accelerated Exascale Systems.”

A Matrix-Free Algebraic hp-Multigrid Method for Computational Fluid Dynamics Applications
2026-01-28 12:00 - 12:30
After the talk on preconditioners in Osaka, Japan at SCA/HPCAsia2026 , stick with Niclas Jannson for his next talk on “A Matrix-Free Algebraic hp-Multigrid Method for Computational Fluid Dynamics Application., a best paper finalist. “

CEEC at the 1st Stuttgart Research Software Day
2026-03-02 16:45 - 18:30
What is research software and why does it matter? These questions are the point of the first ever Research Software Day at the University of Stuttgart. Come learn about the CEEC codes FLEXI/GALAXI during the poster session and stay to learn about what else is being developed on campus.

FAIR-FLEXI - A Trustworthy CFD Code for Simulation and Training
2026-03-03 16:10 - 16:30
Engineering and science disciplines, especially computational fluid dynamics (CFD) generate massive amounts of research data, but they can only become knowledge if they can be shared and explored through data analytics and AI. This, in turn, requires a FAIR (findable, accessible, interoperable, reusable) infrastructure. For complex research software, however, FAIR goes far beyond being open-source: reproducibility is hindered by hidden expertise such as user-defined parameters, compile options, hardware constraints, and third-party dependencies.
This talk outlines the design, implementation, and lessons learned from FAIR-FLEXI. We discuss how comprehensive provenance capture, portable environments, and interactive notebooks turn CFD workflows into trustworthy, reproducible research assets.

GALAEXI: An Architecture-Agnostic GPU-Acceleration Approach for Legacy Fortran Software
2026-03-03 18:25 - 18:50
Join Spencer Starr at the Society for Industrial and Applied Mathematics (SIAM)Processing for Scientific Computing (PP26)confrence in Berlin for his talk on “GALAEXI: An Architecture-Agnostic GPU-Acceleration Approach for Legacy Fortran Software”
GALAEXI is a high-order discontinuous Galerkin spectral element method (DGSEM) computational fluid dynamics (CFD) code used for the study of compressible, turbulent flows. It is the device-accelerated version of an existing Fortran-based, CPU-only CFD framework. In this talk, the chosen strategy for porting the Fortran-based compute kernels in GALAEXI to CUDA/HIP C++ is covered. Included are discussions on managing device memory, retaining support for CPU computations, strategies for writing and testing kernels and how to handle GPU-to-GPU MPI communication. Specific emphasis is placed on how the strategies covered can be abstracted in an architecture-agnostic way to allow the greatest degree of portability. The information presented will then be distilled into advice for those seeking to perform a similar porting effort.
