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DTSTART;TZID=Europe/Paris:20260617T130000
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DTSTAMP:20260530T194921
CREATED:20260528T133335Z
LAST-MODIFIED:20260528T134923Z
UID:2171-1781701200-1781708400@ceec-coe.eu
SUMMARY:Extreme-Scale High-Fidelity Computational Fluid Dynamics with Neko
DESCRIPTION:Neko is a portable framework for high-order spectral element-based simulations\, focusing primarily on incompressible and compressible fluid flows. Written using a modern object-oriented approach\, the framework supports a wide range of hardware backends\, including general-purpose processors\, accelerators\, and vector processors. Neko has demonstrated excellent performance and scalability across various hardware architectures and was nominated as a finalist for the ACM Gordon Bell prize in 2023. \nIn this interactive\, hands-on webinar\, we will provide a practical introduction to Neko and its capabilities. Participants will be guided step-by-step through installing\, creating\, and running simulations. Special focus will be placed on the major feature updates and user-interaction improvements in the upcoming Neko v1.1 release. Additionally\, we will deep-dive into the optimal configuration settings required to extract maximum performance from your hardware. By the end of the session\, attendees will have a solid foundation\, reference materials\, and the optimization insights needed to confidently work with Neko on their own. \nRegistration deadline 11 June\, 2026!\n\n	Notice: JavaScript is required for this content.
URL:https://ceec-coe.eu/event/extreme-scale-high-fidelity-computational-fluid-dynamics-with-neko-2/
CATEGORIES:Training,Webinar
ATTACH;FMTTYPE=image/png:https://ceec-coe.eu/wp-content/uploads/2026/05/NekoPosterDraft2-e1779968821767.png
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DTSTART;TZID=Europe/Paris:20260624T154500
DTEND;TZID=Europe/Paris:20260624T171500
DTSTAMP:20260530T194921
CREATED:20260518T085613Z
LAST-MODIFIED:20260518T085613Z
UID:2123-1782315900-1782321300@ceec-coe.eu
SUMMARY:Mixed-Precision and Energy-Efficiency in SEM Codes
DESCRIPTION:If you’re going to be at ISC26 in Hamburg this year\, take a break and visit our own Yanxiang Chen and his poster “Poster: Mixed-Precision and Energy-Efficiency in SEM Codes.” \nMixed-precision computing has emerged as a key strategy to improve performance and energy efficiency on current and future high-performance computing (HPC) systems. However\, integrating mixed-precision into large\, production-level scientific applications remains challenging due to concerns about numerical stability\, accuracy\, and the complexity of identifying which computations can safely tolerate reduced precision. In this work\, we propose a systematic and practical methodology for enabling mixed-precision in spectral element codes by combining insights from computer arithmetic tools\, performance modeling\, and targeted algorithmic analysis. \nOur approach leverages three complementary components: first\, computer arithmetic tools\, such as Verificarlo\, to instrument and analyze floating-point behavior throughout an application; second\, a roofline performance model to quantify the potential computational benefits of lower-precision arithmetic; and third\, precision-aware numerical techniques to mitigate or eliminate instabilities introduced when reducing precision in critical algorithmic kernels. Together\, these elements form a repeatable framework that guides developers in deciding where and how to apply mixed precision without compromising scientific correctness. \nTo demonstrate the effectiveness of our methodology\, we apply it to two representative spectral element codes widely used in computational fluid dynamics (CFD): Nekbone and Neko. Nekbone is a mini-application proxy for the spectral element CFD code Nek5000\, while Neko is a modern spectral element code used for solving incompressible Navier–Stokes equations. For each code\, we perform a detailed precision analysis\, identify precision-sensitive and precision-robust regions\, and design mixed-precision variants accordingly. \nIn the Nekbone case study\, our analysis reveals that mixed precision can significantly accelerate the Conjugate Gradient (CG) solver without adversely affecting convergence or solution quality. We address stagnation phenomena often observed in reduced-precision CG by integrating arithmetic verification with adaptive precision controls\, effectively preserving numerical stability. When executed on the MareNostrum 5 supercomputer\, the mixed-precision Nekbone achieves a 1.62x speedup in time-to-solution and a 2.43x reduction in energy-to-solution relative to the double-precision baseline\, demonstrating substantial gains in both performance and energy efficiency. \nFor the full Neko application\, we extend our precision strategy to a broader set of computational kernels\, leveraging the insights gained from Nekbone and applying them within the context of the momentum solver in the Navier-Stokes equation on the Poisson example. The mixed-precision Neko implementation attains up to ~1.3x improvement in both execution time and energy consumption compared to the double-precision version\, while maintaining the solution accuracy. \nThese results confirm that mixed-precision approaches\, when carefully designed and guided by arithmetic and performance analysis\, can yield significant improvements on HPC platforms for real-world scientific applications. Our methodology provides a general blueprint for HPC developers to adopt mixed precision in other spectral element and iterative methods\, ultimately contributing to more efficient utilization of future exascale systems.
URL:https://ceec-coe.eu/event/mixed-precision-and-energy-efficiency-in-sem-codes/
LOCATION:Congress Center Hamburg\, Congressplatz 1\, Hamburg\, 20355\, Germany
CATEGORIES:Conference,Poster,Poster Session
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