Cumulus Load Imbalances

Fig. 4. Cumulus convection load balance: (a) 60 proc, (b) 120 proc. In (a) each column of the graph is the wall time used by one of the 60 processors, where each processor contains 4 latitude rings of data. The longer columns near the left side of (a) are the result of combining two mirror image latitudes rings near the equator with two mirror image latitudes near the poles. The shorter columns near the right side contain two northern hemisphere mid-latitude rings with the mirror image set from the southern hemisphere. In (b), with 120 latitudes, only two latitude rings fit on a processor. Near the left side of (b) each long column represents two tropical latitudes and each short column two polar latitudes. Only in the mid-latitudes is there reasonable load balance. }