/[MITgcm]/manual/s_phys_pkgs/text/exch2.tex
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revision 1.19 by afe, Mon May 10 21:39:11 2004 UTC revision 1.23 by afe, Fri Jun 10 19:34:09 2005 UTC
# Line 215  regenerating the topology, \code{\varlin Line 215  regenerating the topology, \code{\varlin
215  The number of tiles MITgcm allocates and how they are distributed  The number of tiles MITgcm allocates and how they are distributed
216  between processors depends on \varlink{nPx}{nPx} and  between processors depends on \varlink{nPx}{nPx} and
217  \varlink{nSx}{nSx}.  \varlink{nSx}{nSx} is the number of tiles per  \varlink{nSx}{nSx}.  \varlink{nSx}{nSx} is the number of tiles per
218  processor and \varlink{nPx}{nPx} is the number of processors.  The total  processor and \varlink{nPx}{nPx} is the number of processors.  The
219  number of tiles in the topology minus those listed in  total number of tiles in the topology minus those listed in
220  \file{blanklist.txt} must equal \code{nSx*nPx}.  Note that in order to  \file{blanklist.txt} must equal \code{nSx*nPx}.  Note that in order to
221  obtain maximum usage from a given number of processors in some cases,  obtain maximum usage from a given number of processors in some cases,
222  this restriction might entail sharing a processor with a tile that would  this restriction might entail sharing a processor with a tile that
223  otherwise be excluded. \\  would otherwise be excluded because it is topographically outside of
224    the domain and therefore in \file{blanklist.txt}.  For example,
225    suppose you have five processors and a domain decomposition of
226    thirty-six tiles that allows you to exclude seven tiles.  To evenly
227    distribute the remaining twenty-nine tiles among five processors, you
228    would have to run one ``dummy'' tile to make an even six tiles per
229    processor.  Such dummy tiles are \emph{not} listed in
230    \file{blanklist.txt}.\\
231    
232    
233  The following is an example of \file{SIZE.h} for the twelve-tile  The following is an example of \file{SIZE.h} for the twelve-tile
234  configuration illustrated in figure \ref{fig:12tile} running on  configuration illustrated in figure \ref{fig:12tile} running on
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