/[MITgcm]/manual/s_software/text/sarch.tex
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revision 1.6 by adcroft, Tue Nov 13 20:13:55 2001 UTC revision 1.10 by edhill, Thu Aug 7 18:27:52 2003 UTC
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1  % $Header$  % $Header$
2    
3  In this chapter we describe the software architecture and  This chapter focuses on describing the {\bf WRAPPER} environment within which
4  implementation strategy for the MITgcm code. The first part of this  both the core numerics and the pluggable packages operate. The description
5  chapter discusses the MITgcm architecture at an abstract level. In the second  presented here is intended to be a detailed exposition and contains significant
6  part of the chapter we described practical details of the MITgcm implementation  background material, as well as advanced details on working with the WRAPPER.
7  and of current tools and operating system features that are employed.  The tutorial sections of this manual (see sections
8    \ref{sect:tutorials}  and \ref{sect:tutorialIII})
9    contain more succinct, step-by-step instructions on running basic numerical
10    experiments, of varous types, both sequentially and in parallel. For many
11    projects simply starting from an example code and adapting it to suit a
12    particular situation
13    will be all that is required.
14    The first part of this chapter discusses the MITgcm architecture at an
15    abstract level. In the second part of the chapter we described practical
16    details of the MITgcm implementation and of current tools and operating system
17    features that are employed.
18    
19  \section{Overall architectural goals}  \section{Overall architectural goals}
20    
# Line 87  and operating systems. This allows numer Line 97  and operating systems. This allows numer
97  \resizebox{!}{4.5in}{\includegraphics{part4/fit_in_wrapper.eps}}  \resizebox{!}{4.5in}{\includegraphics{part4/fit_in_wrapper.eps}}
98  \end{center}  \end{center}
99  \caption{  \caption{
100  Numerical code is written too fit within a software support  Numerical code is written to fit within a software support
101  infrastructure called WRAPPER. The WRAPPER is portable and  infrastructure called WRAPPER. The WRAPPER is portable and
102  can be specialized for a wide range of specific target hardware and  can be specialized for a wide range of specific target hardware and
103  programming environments, without impacting numerical code that fits  programming environments, without impacting numerical code that fits
# Line 110  uniprocessor and multi-processor Sun sys Line 120  uniprocessor and multi-processor Sun sys
120  (UMA) and non-uniform memory access (NUMA) designs. Significant work has also  (UMA) and non-uniform memory access (NUMA) designs. Significant work has also
121  been undertaken on x86 cluster systems, Alpha processor based clustered SMP  been undertaken on x86 cluster systems, Alpha processor based clustered SMP
122  systems, and on cache-coherent NUMA (CC-NUMA) systems from Silicon Graphics.  systems, and on cache-coherent NUMA (CC-NUMA) systems from Silicon Graphics.
123  The MITgcm code, operating within the WRAPPER, is also used routinely used on  The MITgcm code, operating within the WRAPPER, is also routinely used on
124  large scale MPP systems (for example T3E systems and IBM SP systems). In all  large scale MPP systems (for example T3E systems and IBM SP systems). In all
125  cases numerical code, operating within the WRAPPER, performs and scales very  cases numerical code, operating within the WRAPPER, performs and scales very
126  competitively with equivalent numerical code that has been modified to contain  competitively with equivalent numerical code that has been modified to contain
# Line 771  The global domain size is again ninety g Line 781  The global domain size is again ninety g
781  forty grid points in y. The two sub-domains in each process will be computed  forty grid points in y. The two sub-domains in each process will be computed
782  sequentially if they are given to a single thread within a single process.  sequentially if they are given to a single thread within a single process.
783  Alternatively if the code is invoked with multiple threads per process  Alternatively if the code is invoked with multiple threads per process
784  the two domains in y may be computed on concurrently.  the two domains in y may be computed concurrently.
785  \item  \item
786  \begin{verbatim}  \begin{verbatim}
787        PARAMETER (        PARAMETER (
# Line 807  by the application code. The startup cal Line 817  by the application code. The startup cal
817  WRAPPER is shown in figure \ref{fig:wrapper_startup}.  WRAPPER is shown in figure \ref{fig:wrapper_startup}.
818    
819  \begin{figure}  \begin{figure}
820    {\footnotesize
821  \begin{verbatim}  \begin{verbatim}
822    
823         MAIN           MAIN  
# Line 835  WRAPPER is shown in figure \ref{fig:wrap Line 846  WRAPPER is shown in figure \ref{fig:wrap
846    
847    
848  \end{verbatim}  \end{verbatim}
849    }
850  \caption{Main stages of the WRAPPER startup procedure.  \caption{Main stages of the WRAPPER startup procedure.
851  This process proceeds transfer of control to application code, which  This process proceeds transfer of control to application code, which
852  occurs through the procedure {\em THE\_MODEL\_MAIN()}.  occurs through the procedure {\em THE\_MODEL\_MAIN()}.
# Line 1414  sequence shown in section \ref{sect:call Line 1426  sequence shown in section \ref{sect:call
1426    
1427  WRAPPER layer.  WRAPPER layer.
1428    
1429    {\footnotesize
1430  \begin{verbatim}  \begin{verbatim}
1431    
1432         MAIN           MAIN  
# Line 1441  WRAPPER layer. Line 1454  WRAPPER layer.
1454         |--THE_MODEL_MAIN   :: Numerical code top-level driver routine         |--THE_MODEL_MAIN   :: Numerical code top-level driver routine
1455    
1456  \end{verbatim}  \end{verbatim}
1457    }
1458    
1459  Core equations plus packages.  Core equations plus packages.
1460    
1461    {\footnotesize
1462  \begin{verbatim}  \begin{verbatim}
1463  C  C
1464  C  C
# Line 1782  C    |-COMM_STATS     :: Summarise inter Line 1797  C    |-COMM_STATS     :: Summarise inter
1797  C                     :: events.  C                     :: events.
1798  C  C
1799  \end{verbatim}  \end{verbatim}
1800    }
1801    
1802  \subsection{Measuring and Characterizing Performance}  \subsection{Measuring and Characterizing Performance}
1803    
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