mpid_attribute.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`\_}Attribute}{tex}{10/7/2002}
\manname{MPID{\tt \char`\_}Attribute}
--- Structure of an MPID attribute 
\subhead{Synopsis}
\startvb\begin{verbatim}
typedef struct {
    void *      value;              /* Stored value */
    MPID_Keyval *keyval;            /* Keyval structure for this attribute */
    /* other, device-specific information */
} MPID_Attribute;

\end{verbatim}
\endvb

\subhead{Notes}
Attributes don't have {\tt ref{\tt \char`\_}count}s because they don't have reference
count semantics.  That is, there are no shallow copies or duplicates
of an attibute.  An attribute is copied when the communicator that
it is attached to is duplicated.  Subsequent operations, such as
{\tt MPI{\tt \char`\_}Comm{\tt \char`\_}attr{\tt \char`\_}free}, can change the attribute list for one of the
communicators but not the other, making it impractical to keep the
same list.  (We could defer making the copy until the list is changed,
but even then, there would be no reference count on the individual
attributes.)
\par
A pointer to the keyval, rather than the (integer) keyval itself is
used since there is no need within the attribute structure to make
it any harder to find the keyval structure.
\par
The attribute value is a {\tt void *}.  If {\tt sizeof(MPI{\tt \char`\_}Fint)} $>$ {\tt sizeof(void*)},
then this must be changed (no such system has been encountered yet).
For the Fortran 77 routines in the case where {\tt sizeof(MPI{\tt \char`\_}Fint)} $<$
{\tt sizeof(void*)}, the high end of the {\tt void *} value is used.  That is,
we cast it to {\tt MPI{\tt \char`\_}Fint *} and use that value.
\par
\subhead{Module}
Attribute-DS
\par
\endmanpage