Big Ratio of Data Memory Over Data File Size for AMR

The following summaries our understanding to the big ratio of Data memory over Data file size for AMR inspired by the results from Jonathan's memory checking tools — a typical number for the ratio could be 30~80.

Using AMR, extra ghost data are needed to do the interpolation. These ghost data size could be big when the refined patches are small.

Take a 3D problem with two-step updates for example,

where 2 comes from the copy we save for later restart and 16 comes from the ghost data.
So when , we have

.


Or the Data Memory is 54 times the size of the data file.


The smaller the AMR finer patches, the bigger the ratio is. So in Figure 1 we will have much smaller ratio than in Figure 2 though the total patches sizes are same. How these AMR patches distribute depends on the specific problem and calculation.

Figure 1
http://www.pas.rochester.edu/~bliu/MemRatio/2Dlattice2L.png


Figure 2
http://www.pas.rochester.edu/~bliu/MemRatio/2Dlattice2L_2.png

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