All Outputs (73)

SYCL compute kernels for ExaHyPE (2024)
Conference Proceeding
Loi, C. M., Bockhorst, H., & Weinzierl, T. (2024). SYCL compute kernels for ExaHyPE. In Proceedings of the 2024 SIAM Conference on Parallel Processing for Scientific Computing (PP) (90-103). https://doi.org/10.1137/1.9781611977967.8

We discuss three SYCL realisations of a simple Finite Volume scheme over multiple Cartesian patches. The realisation flavours differ in the way how they map the compute steps onto loops and tasks: We compare an implementation that is exclusively usin... Read More about SYCL compute kernels for ExaHyPE.

A multiscale optimisation algorithm for shape and material reconstruction from a single X-ray image (2024)
Conference Proceeding
Westmacott, H., Ivrissimtzis, I., & Weinzierl, T. (2024). A multiscale optimisation algorithm for shape and material reconstruction from a single X-ray image. In ICIGP '24: Proceedings of the 2024 7th International Conference on Image and Graphics Processing (252-259). https://doi.org/10.1145/3647649.3647690

We produce thickness and bone to soft tissue ratio estimations from a single, 2D medical X-ray image. For this, we simulate the scattering of the rays through a model of the object and embed this simulation into an optimiser which iteratively adjusts... Read More about A multiscale optimisation algorithm for shape and material reconstruction from a single X-ray image.

Efficient GPU Offloading with OpenMP for a Hyperbolic Finite Volume Solver on Dynamically Adaptive Meshes (2023)
Conference Proceeding
Wille, M., Weinzierl, T., Brito Gadeschi, G., & Bader, M. (2023). Efficient GPU Offloading with OpenMP for a Hyperbolic Finite Volume Solver on Dynamically Adaptive Meshes. In A. Bhatele, J. Hammond, M. Baboulin, & C. Kruse (Eds.), High Performance Computing. ISC High Performance 2023 (65-85). https://doi.org/10.1007/978-3-031-32041-5_4

We identify and show how to overcome an OpenMP bottleneck in the administration of GPU memory. It arises for a wave equation solver on dynamically adaptive block-structured Cartesian meshes, which keeps all CPU threads busy and allows all of them to... Read More about Efficient GPU Offloading with OpenMP for a Hyperbolic Finite Volume Solver on Dynamically Adaptive Meshes.

Upscaling ExaHyPE – on each and every core (2023)
Report
Li, B., Schulz, H., Tuft, A., Weinzierl, T., & Zhang, H. (2023). Upscaling ExaHyPE – on each and every core. ARCHER2

We study a MPI+multithreaded PDE solver for hyperbolic partial differential equations. Each thread per rank handles a subdomain of the computational domain identified by a segment of a space-filling curve. The threads spawn additional tasks which sho... Read More about Upscaling ExaHyPE – on each and every core.

A multiresolution Discrete Element Method for triangulated objects with implicit time stepping (2022)
Journal Article
Noble, P., & Weinzierl, T. (2022). A multiresolution Discrete Element Method for triangulated objects with implicit time stepping. SIAM Journal on Scientific Computing, 44(4), A2121-A2149. https://doi.org/10.1137/21m1421842

Simulations of many rigid bodies colliding with each other sometimes yield particularly interesting results if the colliding objects differ significantly in size and are nonspherical. The most expensive part within such a simulation code is the colli... Read More about A multiresolution Discrete Element Method for triangulated objects with implicit time stepping.

Spherical accretion of collisional gas in modified gravity I: self-similar solutions and a new cosmological hydrodynamical code (2022)
Journal Article
Zhang, H., Weinzierl, T., Schulz, H., & Li, B. (2022). Spherical accretion of collisional gas in modified gravity I: self-similar solutions and a new cosmological hydrodynamical code. Monthly Notices of the Royal Astronomical Society, 515(2), 2464-2482. https://doi.org/10.1093/mnras/stac1991

The spherical collapse scenario has great importance in cosmology since it captures several crucial aspects of structure formation. The presence of self-similar solutions in the Einstein-de Sitter (EdS) model greatly simplifies its analysis, making i... Read More about Spherical accretion of collisional gas in modified gravity I: self-similar solutions and a new cosmological hydrodynamical code.

Dynamic task fusion for a block-structured finite volume solver over a dynamically adaptive mesh with local time stepping (2022)
Book Chapter
Li, B., Schulz, H., Weinzierl, T., & Zhang, H. (2022). Dynamic task fusion for a block-structured finite volume solver over a dynamically adaptive mesh with local time stepping. In High Performance Computing 37th International Conference, ISC High Performance 2022, Hamburg, Germany, May 29 – June 2, 2022, Proceedings (153-173). Springer Verlag. https://doi.org/10.1007/978-3-031-07312-0_8

Load balancing of generic wave equation solvers over dynamically adaptive meshes with local time stepping is dicult, as the load changes with every time step. Task-based programming promises to mitigate the load balancing problem. We study a Finite V... Read More about Dynamic task fusion for a block-structured finite volume solver over a dynamically adaptive mesh with local time stepping.

Principles of Parallel Scientific Computing (2022)
Book
Weinzierl, T. (in press). Principles of Parallel Scientific Computing. https://doi.org/10.1007/978-3-030-76194-3

Doubt and Redundancy Kill Soft Errors---Towards Detection and Correction of Silent Data Corruption in Task-based Numerical Software (2021)
Conference Proceeding
Samfass, P., Weinzierl, T., Reinarz, A., & Bader, M. (2021). Doubt and Redundancy Kill Soft Errors---Towards Detection and Correction of Silent Data Corruption in Task-based Numerical Software. . https://doi.org/10.1109/ftxs54580.2021.00005

Resilient algorithms in high-performance computing are subject to rigorous non-functional constraints. Resiliency must not increase the runtime, memory footprint or I/O demands too significantly. We propose a task-based soft error detection scheme th... Read More about Doubt and Redundancy Kill Soft Errors---Towards Detection and Correction of Silent Data Corruption in Task-based Numerical Software.

Task inefficiency patterns for a wave equation solver (2021)
Conference Proceeding
Schulz, H., Brito Gadeschi, G., Rudyy, O., & Weinzierl, T. (in press). Task inefficiency patterns for a wave equation solver.

Stabilized Asynchronous Fast Adaptive Composite Multigrid using Additive Damping (2020)
Journal Article
Murray, C. D., & Weinzierl, T. (2021). Stabilized Asynchronous Fast Adaptive Composite Multigrid using Additive Damping. Numerical Linear Algebra with Applications, 28(3), Article e2328. https://doi.org/10.1002/nla.2328

Multigrid solvers face multiple challenges on parallel computers. Two fundamental ones read as follows: Multiplicative solvers issue coarse grid solves which exhibit low concurrency and many multigrid implementations suffer from an expensive coarse g... Read More about Stabilized Asynchronous Fast Adaptive Composite Multigrid using Additive Damping.

Delayed approximate matrix assembly in multigrid with dynamic precisions (2020)
Journal Article
Murray, C. D., & Weinzierl, T. (2021). Delayed approximate matrix assembly in multigrid with dynamic precisions. Concurrency and Computation: Practice and Experience, 33(11), Article e5941. https://doi.org/10.1002/cpe.5941

The accurate assembly of the system matrix is an important step in any code that solves partial differential equations on a mesh. We either explicitly set up a matrix, or we work in a matrix‐free environment where we have to be able to quickly return... Read More about Delayed approximate matrix assembly in multigrid with dynamic precisions.

Lightweight Task Offloading Exploiting MPI Wait Times for Parallel Adaptive Mesh Refinement (2020)
Journal Article
Samfass, P., Weinzierl, T., Charrier, D. E., & Bader, M. (2020). Lightweight Task Offloading Exploiting MPI Wait Times for Parallel Adaptive Mesh Refinement. Concurrency and Computation: Practice and Experience, 32(24), Article e5916. https://doi.org/10.1002/cpe.5916

Balancing the workload of sophisticated simulations is inherently difficult, since we have to balance both computational workload and memory footprint over meshes that can change any time or yield unpredictable cost per mesh entity, while modern supe... Read More about Lightweight Task Offloading Exploiting MPI Wait Times for Parallel Adaptive Mesh Refinement.

teaMPI---replication-based resiliency without the (performance) pain (2020)
Conference Proceeding
Samfass, P., Weinzierl, T., Hazelwood, B., & Bader, M. (2020). teaMPI---replication-based resiliency without the (performance) pain. In P. Sadayappan, B. L. Chamberlain, G. Juckeland, & H. Ltaief (Eds.), High Performance Computing: 35th International Conference, ISC High Performance 2020, Frankfurt/Main, Germany, June 22–25, 2020 ; proceedings (455-473). https://doi.org/10.1007/978-3-030-50743-5_23

In an era where we can not afford to checkpoint frequently, replication is a generic way forward to construct numerical simulations that can continue to run even if hardware parts fail. Yet, replication often is not employed on larger scales, as naïv... Read More about teaMPI---replication-based resiliency without the (performance) pain.

Enclave Tasking for DG Methods on Dynamically Adaptive Meshes (2020)
Journal Article
Charrier, D. E., Hazelwood, B., & Weinzierl, T. (2020). Enclave Tasking for DG Methods on Dynamically Adaptive Meshes. SIAM Journal on Scientific Computing, 42(3), C69-C96. https://doi.org/10.1137/19m1276194

High-order discontinuous Galerkin (DG) methods promise to be an excellent discretization paradigm for hyperbolic differential equation solvers running on supercomputers, since they combine high arithmetic intensity with localized data access, since t... Read More about Enclave Tasking for DG Methods on Dynamically Adaptive Meshes.

ExaHyPE: An engine for parallel dynamically adaptive simulations of wave problems (2020)
Journal Article
Reinarz, A., Charrier, D. E., Bader, M., Bovard, L., Dumbser, M., Duru, K., …Weinzierl, T. (2020). ExaHyPE: An engine for parallel dynamically adaptive simulations of wave problems. Computer Physics Communications, 254, Article 107251. https://doi.org/10.1016/j.cpc.2020.107251

ExaHyPE (“An Exascale Hyperbolic PDE Engine”) is a software engine for solving systems of first-order hyperbolic partial differential equations (PDEs). Hyperbolic PDEs are typically derived from the conservation laws of physics and are useful in a wi... Read More about ExaHyPE: An engine for parallel dynamically adaptive simulations of wave problems.

Lazy Stencil Integration in multigrid algorithms (2019)
Conference Proceeding
Murray, C., & Weinzierl, T. (in press). Lazy Stencil Integration in multigrid algorithms.

The Peano software---parallel, automaton-based, dynamically adaptive grid traversals (2019)
Journal Article
Weinzierl, T. (2019). The Peano software---parallel, automaton-based, dynamically adaptive grid traversals. ACM Transactions on Mathematical Software, 45(2), Article 14. https://doi.org/10.1145/3319797

We discuss the design decisions, design alternatives, and rationale behind the third generation of Peano, a framework for dynamically adaptive Cartesian meshes derived from spacetrees. Peano ties the mesh traversal to the mesh storage and supports on... Read More about The Peano software---parallel, automaton-based, dynamically adaptive grid traversals.

Studies on the energy and deep memory behaviour of a cache-oblivious, task-based hyperbolic PDE solver (2019)
Journal Article
Charrier, D., Hazelwood, B., Tutlyaeva, E., Bader, M., Dumbser, M., Kudryavtsev, A., …Weinzierl, T. (2019). Studies on the energy and deep memory behaviour of a cache-oblivious, task-based hyperbolic PDE solver. International Journal of High Performance Computing Applications, 33(5), 973-986. https://doi.org/10.1177/1094342019842645

We study the performance behaviour of a seismic simulation using the ExaHyPE engine with a specific focus on memory characteristics and energy needs. ExaHyPE combines dynamically adaptive mesh refinement (AMR) with ADER-DG. It is parallelized using t... Read More about Studies on the energy and deep memory behaviour of a cache-oblivious, task-based hyperbolic PDE solver.

A simple diffuse interface approach on adaptive Cartesian grids for the linear elastic wave equations with complex topography (2019)
Journal Article
Tavelli, M., Dumbser, M., Charrier, D. E., Rannabauer, L., Weinzierl, T., & Bader, M. (2019). A simple diffuse interface approach on adaptive Cartesian grids for the linear elastic wave equations with complex topography. Journal of Computational Physics, 386, 158-189. https://doi.org/10.1016/j.jcp.2019.02.004

In most classical approaches of computational geophysics for seismic wave propagation problems, complex surface topography is either accounted for by boundary-fitted unstructured meshes, or, where possible, by mapping the complex computational domain... Read More about A simple diffuse interface approach on adaptive Cartesian grids for the linear elastic wave equations with complex topography.