mpid_user_function.tex

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

\startmanpage
\mantitle{MPID{\tt \char`\_}User{\tt \char`\_}function}{tex}{10/7/2002}
\manname{MPID{\tt \char`\_}User{\tt \char`\_}function}
--- Definition of a user function for MPI{\tt \char`\_}Op types. 
\subhead{Synopsis}
\startvb\begin{verbatim}
typedef union {
    void (*c_function) ( const void restrict *, void restrict *, 
                       const int *, const MPI_Datatype * ); 
    void (f77_function) ( const void restrict *, void restrict *,
                        const MPI_Fint *, const MPI_Fint * );
} MPID_User_function;

\end{verbatim}
\endvb

\subhead{Notes}
This includes a {\tt const} to make clear which is the {\tt in} argument and
which the {\tt inout} argument, and to indicate that the {\tt count} and {\tt datatype
}arguments are unchanged (they are addresses in an attempt to allow
interoperation with Fortran).  It includes {\tt restrict} to emphasize that
no overlapping operations are allowed.
\par
We need to include a Fortran version, since those arguments will
have type {\tt MPI{\tt \char`\_}Fint *} instead.  We also need to add a test to the
test suite for this case; in fact, we need tests for each of the handle
types to ensure that the transfered handle works correctly.
\par
This is part of the collective module because user-defined operations
are valid only for the collective computation routines and not for
RMA accumulate.
\par
Yes, the {\tt restrict} is in the correct location.  C compilers that
support {\tt restrict} should be able to generate code that is as good as a
Fortran compiler would for these functions.
\par
We should note on the manual pages for user-defined operations that
{\tt restrict} should be used when available, and that a cast may be
required when passing such a function to {\tt MPI{\tt \char`\_}Op{\tt \char`\_}create}.
\par
\subhead{Question}
Should each of these function types have an associated typedef?
\par
Should there be a C++ function here?
\par
\subhead{Module}
Collective-DS
\endmanpage