/[MITgcm]/manual/s_phys_pkgs/text/exch2.tex
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revision 1.10 by afe, Mon Mar 15 20:11:56 2004 UTC revision 1.11 by afe, Mon Mar 15 22:39:28 2004 UTC
# Line 31  The exchange parameters are declared in Line 31  The exchange parameters are declared in
31  \filelink{pkg/exch2/W2\_EXCH2\_TOPOLOGY.h}{pkg-exch2-W2_EXCH2_TOPOLOGY.h}  \filelink{pkg/exch2/W2\_EXCH2\_TOPOLOGY.h}{pkg-exch2-W2_EXCH2_TOPOLOGY.h}
32  and assigned in  and assigned in
33  \filelink{pkg/exch2/w2\_e2setup.F}{pkg-exch2-w2_e2setup.F}. The  \filelink{pkg/exch2/w2\_e2setup.F}{pkg-exch2-w2_e2setup.F}. The
34  validity of the cube topology depends on the \texttt{SIZE.h} file as  validity of the cube topology depends on the \file{SIZE.h} file as
35  detailed below.  Both files are generated by Matlab scripts in  detailed below.  Both files are generated by Matlab scripts in
36  \texttt{utils/exch2/matlab-topology-generator}; see Section  \file{utils/exch2/matlab-topology-generator}; see Section
37  \ref{sec:topogen} for details on creating alternate topologies.  The  \ref{sec:topogen} \sectiontitle{Generating Topology Files for exch2}
38  default files provided in the release configure a cubed sphere  for details on creating alternate topologies.  The default files
39  topology of six tiles, one per subdomain, each with 32$\times$32 grid  provided in the release configure a cubed sphere topology of six
40  points, all running on a single processor.  Pregenerated examples of  tiles, one per subdomain, each with 32$\times$32 grid points, all
41  these files with alternate topologies are provided under  running on a single processor.  Pregenerated examples of these files
42  \texttt{utils/exch2/code-mods} along with the appropriate  with alternate topologies are provided under
43  \texttt{SIZE.h} file for single-processor execution.  \file{utils/exch2/code-mods} along with the appropriate \file{SIZE.h}
44    file for single-processor execution.
45    
46  \subsection{Invoking exch2}  \subsection{Invoking exch2}
47    
48  To use exch2 with the cubed sphere, the following conditions must be  To use exch2 with the cubed sphere, the following conditions must be
49  met: \\  met: \\
50    
51  $\bullet$ The exch2 package is included when \texttt{genmake2} is run.  The  $\bullet$ The exch2 package is included when \file{genmake2} is run.
52    easiest way to do this is to add the line \texttt{exch2} to the    The easiest way to do this is to add the line \code{exch2} to the
53    \texttt{profile.conf} file -- see Section \ref{sect:buildingCode}    \file{profile.conf} file -- see Section
54    for general details. \\    \ref{sect:buildingCode}\sectiontitle{Building the code} for general
55      details. \\
56  $\bullet$ An example of \texttt{W2\_EXCH2\_TOPOLOGY.h} and  
57    \texttt{w2\_e2setup.F} must reside in a directory containing code  $\bullet$ An example of \file{W2\_EXCH2\_TOPOLOGY.h} and
58    linked when \texttt{genmake2} runs.  The safest place to put these    \file{w2\_e2setup.F} must reside in a directory containing code
59    is the directory indicated in the \texttt{-mods=DIR} command line    linked when \file{genmake2} runs.  The safest place to put these
60    modifier (typically \texttt{../code}), or the build directory.  The    is the directory indicated in the \code{-mods=DIR} command line
61    default versions of these files reside in \texttt{pkg/exch2} and are    modifier (typically \file{../code}), or the build directory.  The
62      default versions of these files reside in \file{pkg/exch2} and are
63    linked automatically if no other versions exist elsewhere in the    linked automatically if no other versions exist elsewhere in the
64    link path, but they should be left untouched to avoid breaking    link path, but they should be left untouched to avoid breaking
65    configurations other than the one you intend to modify.\\    configurations other than the one you intend to modify.\\
66    
67  $\bullet$ Files containing grid parameters, named  $\bullet$ Files containing grid parameters, named
68    \texttt{tile}???\texttt{.mitgrid} where ??? is \texttt{001} through    \file{tile???.mitgrid} where \file{???} is \file{001} through
69    \texttt{006} (one per subdomain), must be in the working directory    \file{006} (one per subdomain), must be in the working directory
70    when the MITgcm executable is run.  These files are provided in the    when the MITgcm executable is run.  These files are provided in the
71    example experiments for cubed sphere configurations with    example experiments for cubed sphere configurations with
72    32$\times$32 cube sides and are non-trivial to generate -- please    32$\times$32 cube sides and are non-trivial to generate -- please
73    contact MITgcm support if you want to generate files for other    contact MITgcm support if you want to generate files for other
74    configurations. \\    configurations. \\
75    
76  $\bullet$ As always when compiling MITgcm, the file \texttt{SIZE.h}  $\bullet$ As always when compiling MITgcm, the file \file{SIZE.h}
77    must be placed where \texttt{genmake2} will find it.  In particular    must be placed where \file{genmake2} will find it.  In particular
78    for the exch2, the domain decompositin specified in \texttt{SIZE.h}    for the exch2, the domain decomposition specified in \file{SIZE.h}
79    must correspond with the particular configuration's topology    must correspond with the particular configuration's topology
80    specified in \texttt{W2\_EXCH2\_TOPOLOGY.h} and    specified in \file{W2\_EXCH2\_TOPOLOGY.h} and
81    \texttt{w2\_e2setup.F}.  Domain decomposition issues particular to    \file{w2\_e2setup.F}.  Domain decomposition issues particular to
82    exch2 are addressed in Section \ref{sec:topogen}: ``Generating    exch2 are addressed in Section \ref{sec:topogen} \sectiontitle{Generating
83    Topology Files for exch2''; a more general background on the subject    Topology Files for exch2}; a more general background on the subject
84    relvant to MITgcm is presented in Section    relvant to MITgcm is presented in Section
85    \ref{sect:specifying_a_decomposition}: ``Specifying a    \ref{sect:specifying_a_decomposition}\sectiontitle{Specifying a
86    decomposition''.\\    decomposition}.\\
87    
88  As of the time of writing the following examples use exch2 and may be  As of the time of writing the following examples use exch2 and may be
89  used for guidance:  used for guidance:
# Line 101  verification/hs94.cs-32x32x5 Line 103  verification/hs94.cs-32x32x5
103  \label{sec:topogen}  \label{sec:topogen}
104    
105  Alternate cubed sphere topologies may be created using the Matlab  Alternate cubed sphere topologies may be created using the Matlab
106  scripts in \texttt{utils/exch2/matlab-topology-generator}. Running the  scripts in \file{utils/exch2/matlab-topology-generator}. Running the
107  m-file \texttt{driver} from the Matlab prompt (without passing any  m-file \file{driver.m} from the Matlab prompt (there are no parameters
108  function parameters) generates exch2 topology files  to pass) generates exch2 topology files \file{W2\_EXCH2\_TOPOLOGY.h}
109  \texttt{W2\_EXCH2\_TOPOLOGY.h} and \texttt{w2\_e2setup.F} in the  and \file{w2\_e2setup.F} in the working directory and displays a
110  working directory and displays via Matlab a figure of the topology.  figure of the topology via Matlab.  The other m-files in the directory
111  The other m-files in the directory are subroutines of \texttt{driver}  are subroutines of \file{driver.m} and should not be run except for
112  and should not be run except for development purposes. \\  development purposes. \\
113    
114  The parameters that determine the dimensions and topology of the  The parameters that determine the dimensions and topology of the
115  generated configuration are nr, nb, ng, tnx and tny, and all are  generated configuration are \code{nr}, \code{nb}, \code{ng},
116  assigned early in the script.  \code{tnx} and \code{tny}, and all are assigned early in the script.
117    
118  The first three determine the size of the subdomains (cube faces) and  The first three determine the size of the subdomains (cube faces) and
119  hence the size of the overall domain.  Each one determines the number  hence the size of the overall domain.  Each one determines the number
# Line 122  but they provide for future releases of Line 124  but they provide for future releases of
124  resolutions around the axes to allow (for example) greater resolution  resolutions around the axes to allow (for example) greater resolution
125  around the equator.\\  around the equator.\\
126    
127  The parameters tnx and tny determine the dimensions of the tiles into  The parameters \code{tnx} and \code{tny} determine the dimensions of
128  which the subdomains are decomposed, and must evenly divide the  the tiles into which the subdomains are decomposed, and must evenly
129  integer assigned to nr, nb and ng.  The result is a rectangular tiling  divide the integer assigned to \code{nr}, \code{nb} and \code{ng}.
130  of the subdomain.  Figure \ref{fig:24tile} shows one possible topology  The result is a rectangular tiling of the subdomain.  Figure
131  for a twenty-four tile cube, and figure \ref{fig:12tile} shows one for  \ref{fig:24tile} shows one possible topology for a twenty-four tile
132  twelve tiles. \\  cube, and figure \ref{fig:12tile} shows one for twelve tiles. \\
133    
134  \begin{figure}  \begin{figure}
135  \begin{center}  \begin{center}
# Line 136  twelve tiles. \\ Line 138  twelve tiles. \\
138   }   }
139  \end{center}  \end{center}
140  \caption{Plot of cubed sphere topology with a 32$\times$32 grid and  \caption{Plot of cubed sphere topology with a 32$\times$32 grid and
141  twenty-four tiles (tnx=16, tny=16)  twenty-four tiles (\code{tnx=16, tny=16})
142  } \label{fig:24tile}  } \label{fig:24tile}
143  \end{figure}  \end{figure}
144    
# Line 147  twenty-four tiles (tnx=16, tny=16) Line 149  twenty-four tiles (tnx=16, tny=16)
149   }   }
150  \end{center}  \end{center}
151  \caption{Plot of cubed sphere topology with a 32$\times$32 grid and  \caption{Plot of cubed sphere topology with a 32$\times$32 grid and
152  twelve tiles (tnx=16, tny=32)  twelve tiles (\code{tnx=16, tny=32})
153  } \label{fig:12tile}  } \label{fig:12tile}
154  \end{figure}  \end{figure}
155    
156  Tiles can be selected from the topology to be omitted from being  Tiles can be selected from the topology to be omitted from being
157  allocated memory and processors.  This kind of tuning is useful in  allocated memory and processors.  This kind otuning is useful in
158  ocean modeling for omitting tiles that fall entirely on land.  The  ocean modeling for omitting tiles that fall entirely on land.  The
159  tiles omitted are specified in the file \texttt{blanklist.txt} by  tiles omitted are specified in the file \file{blanklist.txt} by
160  their tile number in the topology, separated by a newline. \\  their tile number in the topology, separated by a newline. \\
161    
162    
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