Showing 1–4 of 4 results for author: Esclapez, L

Accelerating the Dutch Atmospheric Large-Eddy Simulation (DALES) model with OpenACC

Authors: Lucas Esclapez, Laurent Soucasse, Caspar Jungbacker, Fredrik Jansson, Stephan R. de Roode, Pedro Costa, Gijs van den Oord, Alessio Sclocco

Abstract: This paper presents the GPU porting through OpenACC directives of the Dutch Atmospheric Large-Eddy Simulation (DALES) application, a high-resolution atmospheric model. The code is written in Fortran~90 and features parallel (distributed) execution through spatial domain decomposition. We assess the performance of the GPU offloading, comparing the time-to-solution on regular and accelerated HPC nod… ▽ More This paper presents the GPU porting through OpenACC directives of the Dutch Atmospheric Large-Eddy Simulation (DALES) application, a high-resolution atmospheric model. The code is written in Fortran~90 and features parallel (distributed) execution through spatial domain decomposition. We assess the performance of the GPU offloading, comparing the time-to-solution on regular and accelerated HPC nodes. %comparing the computational time between distributed and accelerated nodes. A weak scaling analysis is conducted and portability across NVIDIA A100 and H100 hardware %and AMD hardware is discussed. Finally, we show how targeted kernels can benefit from further optimization with Kernel Tuner, a GPU kernels auto-tuning package. △ Less

Submitted 21 February, 2025; originally announced February 2025.

Symbolic construction of the chemical Jacobian of quasi-steady state (QSS) chemistries for Exascale computing platforms

Authors: Malik Hassanaly, Nicholas T. Wimer, Anne Felden, Lucas Esclapez, Julia Ream, Marc T. Henry de Frahan, Jon Rood, Marc Day

Abstract: The Quasi-Steady State Approximation (QSSA) can be an effective tool for reducing the size and stiffness of chemical mechanisms for implementation in computational reacting flow solvers. However, for many applications, stiffness remains, and the resulting model requires implicit methods for efficient time integration. In this paper, we outline an approach to formulating the QSSA reduction that is… ▽ More The Quasi-Steady State Approximation (QSSA) can be an effective tool for reducing the size and stiffness of chemical mechanisms for implementation in computational reacting flow solvers. However, for many applications, stiffness remains, and the resulting model requires implicit methods for efficient time integration. In this paper, we outline an approach to formulating the QSSA reduction that is coupled with a strategy to generate C++ source code to evaluate the net species production rate, and the chemical Jacobian. The code-generation component employs a symbolic approach enabling a simple and effective strategy to analytically compute the chemical Jacobian. For computational tractability, the symbolic approach needs to be paired with common subexpression elimination which can negatively affect memory usage. Several solutions are outlined and successfully tested on a 3D multipulse ignition problem, thus allowing portable application across a chemical model sizes and GPU capabilities. The implementation of the proposed method is available at https://github.com/AMReX-Combustion/PelePhysics under an open-source license. △ Less

Submitted 8 September, 2024; v1 submitted 30 April, 2024; originally announced May 2024.

SUNDIALS Time Integrators for Exascale Applications with Many Independent ODE Systems

Authors: Cody J. Balos, Marc Day, Lucas Esclapez, Anne M. Felden, David J. Gardner, Malik Hassanaly, Daniel R. Reynolds, Jon Rood, Jean M. Sexton, Nicholas T. Wimer, Carol S. Woodward

Abstract: Many complex systems can be accurately modeled as a set of coupled time-dependent partial differential equations (PDEs). However, solving such equations can be prohibitively expensive, easily taxing the world's largest supercomputers. One pragmatic strategy for attacking such problems is to split the PDEs into components that can more easily be solved in isolation. This operator splitting approach… ▽ More Many complex systems can be accurately modeled as a set of coupled time-dependent partial differential equations (PDEs). However, solving such equations can be prohibitively expensive, easily taxing the world's largest supercomputers. One pragmatic strategy for attacking such problems is to split the PDEs into components that can more easily be solved in isolation. This operator splitting approach is used ubiquitously across scientific domains, and in many cases leads to a set of ordinary differential equations (ODEs) that need to be solved as part of a larger "outer-loop" time-stepping approach. The SUNDIALS library provides a plethora of robust time integration algorithms for solving ODEs, and the U.S. Department of Energy Exascale Computing Project (ECP) has supported its extension to applications on exascale-capable computing hardware. In this paper, we highlight some SUNDIALS capabilities and its deployment in combustion and cosmology application codes (Pele and Nyx, respectively) where operator splitting gives rise to numerous, small ODE systems that must be solved concurrently. △ Less

Submitted 2 May, 2024; originally announced May 2024.

Experiences Readying Applications for Exascale

Authors: Paul T. Bauman, Reuben D. Budiardja, Dmytro Bykov, Noel Chalmers, Jacqueline Chen, Nicholas Curtis, Marc Day, Markus Eisenbach, Lucas Esclapez, Alessandro Fanfarillo, William Freitag, Nicholas Frontiere, Antigoni Georgiadou, Joseph Glenski, Kalyana Gottiparthi, Marc T. Henry de Frahan, Gustav R. Jansen, Wayne Joubert, Justin G. Lietz, Jakub Kurzak, Nicholas Malaya, Bronson Messer, Damon McDougall, Paul Mullowney, Stephen Nichols , et al. (7 additional authors not shown)

Abstract: The advent of exascale computing invites an assessment of existing best practices for developing application readiness on the world's largest supercomputers. This work details observations from the last four years in preparing scientific applications to run on the Oak Ridge Leadership Computing Facility's (OLCF) Frontier system. This paper addresses a range of topics in software including programm… ▽ More The advent of exascale computing invites an assessment of existing best practices for developing application readiness on the world's largest supercomputers. This work details observations from the last four years in preparing scientific applications to run on the Oak Ridge Leadership Computing Facility's (OLCF) Frontier system. This paper addresses a range of topics in software including programmability, tuning, and portability considerations that are key to moving applications from existing systems to future installations. A set of representative workloads provides case studies for general system and software testing. We evaluate the use of early access systems for development across several generations of hardware. Finally, we discuss how best practices were identified and disseminated to the community through a wide range of activities including user-guides and trainings. We conclude with recommendations for ensuring application readiness on future leadership computing systems. △ Less

Submitted 2 October, 2023; originally announced October 2023.

Comments: Accepted at SC23