mpid_group.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`\_}Group}{tex}{10/7/2002}
\manname{MPID{\tt \char`\_}Group}
--- Description of the Group data structure 
\subhead{Synopsis}
\startvb\begin{verbatim}
typedef struct {
    int          handle;
    volatile int ref_count;
    int          size;           /* Size of a group */
    int          rank;           /* Rank of this process in this group */
    int          *lrank_to_lpid; /* Array mapping a local rank in this
                                    group to local process number */
  /* other, device-specific information */
} MPID_Group;

\end{verbatim}
\endvb
The processes in the group of {\tt MPI{\tt \char`\_}COMM{\tt \char`\_}WORLD} have lpid values 0 to {\tt size}-1,
where {\tt size} is the size of {\tt MPI{\tt \char`\_}COMM{\tt \char`\_}WORLD}.  Processes created by
{\tt MPI{\tt \char`\_}Comm{\tt \char`\_}spawn} or {\tt MPI{\tt \char`\_}Comm{\tt \char`\_}spawn{\tt \char`\_}multiple} or added by {\tt MPI{\tt \char`\_}Comm{\tt \char`\_}attach
}or
{\tt MPI{\tt \char`\_}Comm{\tt \char`\_}connect
}are numbered greater than {\tt size - 1} (on the calling process). See the
discussion of LocalPID values.
\par
Note that when dynamic process creation is used, the pids are {\em not} unique
across the universe of connected MPI processes.  This is ok, as long as
pids are interpreted {\em only} on the process that owns them.
\par
Only for MPI-1 are the lpid's equal to the {\em global} pids.  The local pids
can be thought of as a reference not to the remote process itself, but
how the remote process can be reached from this process.  We may want to
have a structure {\tt MPID{\tt \char`\_}Lpid{\tt \char`\_}t} that contains information on the remote
process, such as (for TCP) the hostname, ip address (it may be different if
multiple interfaces are supported; we may even want plural ip addresses for
stripping communication), and port (or ports).  For shared memory connected
processes, it might have the address of a remote queue.  The lpid number
is an index into a table of {\tt MPID{\tt \char`\_}Lpid{\tt \char`\_}t'}s that contain this (device- and
method-specific) information.
\par
\subhead{Module}
Group-DS
\par
\endmanpage