Memory Layouts for GPU-Data Transfer Buffering in SPH

arXiv (Cornell University)

Abstract

The rise in GPU compute speed has outpaced improvements in host-to-device memory transfer speeds, despite the advent of shared-memory superchips. Consequently, memory transfer times now constitute an increasingly large fraction of total time-to-solution, compelling developers to compress GPU kernel input and output data into compact, minimal formats prior to GPU-offloading. This complements existing work on GPU- and compute-friendly data arrangements. We study a Smoothed Particle Hydrodynamics solver and propose memory layout strategies for host-side particle data that are particularly well-suited to GPU-offloading. Specifically, we advocate splitting classic array-of-struct data structures into a split array-of-struct arrangement, in which each logical struct decomposes into substructs determined by kernel read/write access patterns and attribute types. Splitting a monolithic particle struct into several bespoke, finer-grained structs can reduce the time required to pack data to and from buffers by ~20% - 40%, lowering total time spent on GPU-offloading by ~12% - 25%.

Authors 7

1. Mladen Ivković

   Durham University

   Affiliation as printed

   Department of Computer Science , Durham University , South Road , Durham DH1 3LE , UK

2. Abouzied Nasar

   University of Manchester

   Affiliation as printed

   School of Engineering , The University of Manchester , Nancy Rothwell Building , Manchester M13 9QS , UK

3. Tobias Weinzierl

   Durham University

   Affiliation as printed

   Department of Computer Science , Durham University , South Road , Durham DH1 3LE , UK

4. Matthieu Schaller Aachen Leiden Observatory Lorentz Institute for Theoretical Physics

   Leiden University

   Affiliation as printed

   Leiden observatory , Leiden University , PO Box 9513 , NL-2300 RA Leiden , the Netherlands

   Lorentz Institute for Theoretical Physics , Leiden University , PO Box 9506 , NL-2300 RA Leiden , the Netherlands

5. Benedict D. Rogers

   University of Manchester

   Affiliation as printed

   School of Engineering , The University of Manchester , Nancy Rothwell Building , Manchester M13 9QS , UK

6. Georgios Fourtakas

   University of Manchester

   Affiliation as printed

   School of Engineering , The University of Manchester , Nancy Rothwell Building , Manchester M13 9QS , UK

7. Scott T. Kay

   University of Manchester

   Affiliation as printed

   Jodrell Bank Centre for Astrophysics , Department of Physics and Astronomy , The University of Manchester , Manchester M13 9PL , UK