White Papers – Prototyping

The whitepapers document the work done in work package 11 “Prototyping” of the PRACE-2IP project.

Title: Current Bottlenecks in the Scalability of OpenFOAM on Massively Parallel Clusters

Author: Massimiliano Culpo,
CINECA, Via Magnanelli 6/3, Casalecchio di Reno (BO) I-40033, Italy

Abstract: The scaling behavior of different OpenFOAM versions is analyzed on two benchmark problems. Results show that the applications scale reasonably well up to a thousand tasks. An in-depth profiling identifies the calls to the MPI_Allreduce function in the linear algebra core libraries as the main communication bottleneck. A sub-optimal performance on-core is due to the sparse matrices storage format that does not employ any cache-blocking mechanism at present. Possible strategies to overcome these limitations are proposed and analyzed, and preliminary results on prototype implementations are presented.

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