Block Fusion on Dynamically Adaptive Spacetree Grids for Shallow Water Waves

Tobias Weinzierl, Michael Bader, Kristof Unterweger, Roland Wittmann

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


© 2014 World Scientific Publishing Company. Spacetrees are a popular formalism to describe dynamically adaptive Cartesian grids. Even though they directly yield a mesh, it is often computationally reasonable to embed regular Cartesian blocks into their leaves. This promotes stencils working on homogeneous data chunks. The choice of a proper block size is sensitive. While large block sizes foster loop parallelism and vectorisation, they restrict the adaptivity's granularity and hence increase the memory footprint and lower the numerical accuracy per byte. In the present paper, we therefore use a multiscale spacetree-block coupling admitting blocks on all spacetree nodes. We propose to find sets of blocks on the finest scale throughout the simulation and to replace them by fused big blocks. Such a replacement strategy can pick up hardware characteristics, i.e. which block size yields the highest throughput, while the dynamic adaptivity of the fine grid mesh is not constrained - applications can work with fine granular blocks. We study the fusion with a state-of-the-art shallow water solver at hands of an Intel Sandy Bridge and a Xeon Phi processor where we anticipate their reaction to selected block optimisation and vectorisation.
Original languageEnglish (US)
Pages (from-to)1441006
JournalParallel Processing Letters
Issue number03
StatePublished - Sep 29 2014
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): UK-c0020
Acknowledgements: Tobias Weinzierl appreciates the support of the School of Engineering and Computing Sciences and in particular Tomasz Koziara at Durham University for providing
This publication acknowledges KAUST support, but has no KAUST affiliated authors.


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