mpid_memory_unregister.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`\_}Memory{\tt \char`\_}unregister}{tex}{10/7/2002}
\manname{MPID{\tt \char`\_}Memory{\tt \char`\_}unregister}
--- Remote previous registration 
\subhead{Synopsis}
\startvb\begin{verbatim}
int MPID_Memory_unregister( void *buf, int len, MPID_Comm *comm, int rank,
                          int rdwt )

\end{verbatim}
\endvb

\subhead{Input Parameters}
\startarg{buf }{Pointer to start of memory
}
\startarg{len }{Length of buffer, in bytes
}
\startarg{comm }{Communicator
}
\startarg{rank }{rank
}
\startarg{rdwt }{Indicate whether memory was registered to be read ({\tt MPID{\tt \char`\_}MEM{\tt \char`\_}READ}), 
written ({\tt MPID{\tt \char`\_}MEM{\tt \char`\_}WRITE}), 
or both ({\tt MPID{\tt \char`\_}MEM{\tt \char`\_}READ} {\tt \char`\|} {\tt MPID{\tt \char`\_}MEM{\tt \char`\_}WRITE}).
}
\par
\subhead{Return value}
{\tt MPI{\tt \char`\_}SUCCESS} if deregistration was successful, a valid MPI error code
otherwise.  This error is non-fatal; the error return is made to
allow for more detailed information on why the memory deregistration
failed.
\par
\subhead{Notes}
The arguments must be exactly the same as those used to register memory.
\par
It is valid to call this routine as many times as {\tt MPID{\tt \char`\_}Memory{\tt \char`\_}register
}returned success on the calling process.  If the same memory location is
registered multiple times, then only when {\tt MPID{\tt \char`\_}Memory{\tt \char`\_}unregister} is called
the {\em same} number of times should the memory be deregistered with the
operating system.
{\tt MPID{\tt \char`\_}Memory{\tt \char`\_}unregister} thus has the same reference-count
semantics as other MPI routines.  Note that this may require implementing
a reference count mechanism for registered memory.
\par
\subhead{Question}
How do routines that free requests (such as {\tt MPI{\tt \char`\_}Wait} and
{\tt MPI{\tt \char`\_}Request{\tt \char`\_}free}) know to call this routine?
Is there a registered memory pointer?  Do we need to keep track of
what type of memory (user-provide, registered, mpich-provided) is used
in different operations?
\par
\subhead{Module}
Communication
\endmanpage