Implementation and Performance of a Grand Challenge 3d Quasi-Geostrophic Multi-Grid code on the Cray T3D and IBM SP2

We have taken our existing auto-tasked vector Cray C-90 3d Quasi-Geostrophic Multi-Grid (QGMG) code and implemented it in a portable way on most of todays MPPs. Here we report on its performance for the Cray T3D and IBM SP2. On all 16 processors of the C-90 the code achieved 6 GGops; currently on 256 processors of the T3D we obtain almost 4 GGops and on 256 processors of the SP2 we obtain 5 GGops. We nd almost perfect scaling of performance with processor number for the T3D all the way up to 256 processors, and good scaling for the SP2 up to 128 processors. In this paper we describe how we parallelized the QGMG code and report performance measurements of it.