kyoverview.tex

来自「刚才是说明 现在是安装程序在 LINUX环境下进行编程的MPICH安装文件」· TEX 代码 · 共 24 行

  Keyvals are MPI objects that, unlike most MPI objects, are defined to be
  integers rather than a handle (e.g., \texttt{MPI_Comm}).  However, they really
  \emph{are} MPI opaque objects and are handled by the MPICH implementation in
  the same way as all other MPI opaque objects.  The only difference is that
  there is no \texttt{typedef int MPI_Keyval;} in \texttt{mpi.h}.  In particular, keyvals
  are encoded (for direct and indirect references) in the same way that 
  other MPI opaque objects are

  Each keyval has a copy and a delete function associated with it.
  Unfortunately, these have a slightly different calling sequence for
  each language, particularly when the size of a pointer is 
  different from the size of a Fortran integer.  The unions 
  \texttt{MPID_Copy_function} and \texttt{MPID_Delete_function} capture the differences
  in a single union type.

\subsection{Notes}
  One potential user error is to access an attribute in one language (say
  Fortran) that was created in another (say C).  We could add a check and
  generate an error message in this case; note that this would have to 
  be an option, because (particularly when accessing the attribute from C), 
  it may be what the user intended, and in any case, it is a valid operation.