Gadget3 on GPUs with OpenACC

Ragagnin, Antonio; Dolag, Klaus; Wagner, Mathias; Gheller, Claudio; Roffler, Conradin; Goz, David; Hubber, David und Arth, Alexander (2020): Gadget3 on GPUs with OpenACC. In: Parallel Computing: Technology Trends, Bd. 36: S. 209-218

Abstract

We present preliminary results of a GPU porting of all main Gadget3 modules (gravity computation, SPH density computation, SPH hydrodynamic force, and thermal conduction) using OpenACC directives. Here we assign one GPU to each MPI rank and exploit both the host and accellerator capabilities by overlapping computations on the CPUs and GPUs: while GPUs asynchronously compute interactions between particles within their MPI ranks, CPUs perform treewalks and MPI communications of neighbouring particles. We profile various portions of the code to understand the origin of our speedup, where we find that a peak speedup is not achieved because of time-steps with few active particles. We run a hydrodynamic cosmological simulation from the Magneticum project, with 2 . 10(7) particles, where we find a final total speedup of approximate to 2. We also present the results of an encouraging scaling test of a preliminary gravity-only OpenACC porting, run in the context of the EuroHack17 event, where the prototype of the porting proved to keep a constant speedup up to 1024 GPUs.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 0927-5452
• Sprache: Englisch