|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
<HTML>
|
|
Packit Service |
c5cf8c |
<HEAD>
|
|
Packit Service |
c5cf8c |
<META NAME="GENERATOR" CONTENT="DOCTEXT">
|
|
Packit Service |
c5cf8c |
<TITLE>MPI_Intercomm_merge</TITLE>
|
|
Packit Service |
c5cf8c |
</HEAD>
|
|
Packit Service |
c5cf8c |
<BODY BGCOLOR="FFFFFF">
|
|
Packit Service |
c5cf8c |
MPI_Intercomm_merge
|
|
Packit Service |
c5cf8c |
Creates an intracommuncator from an intercommunicator
|
|
Packit Service |
c5cf8c |
Synopsis
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
int MPI_Intercomm_merge(MPI_Comm intercomm, int high, MPI_Comm * newintracomm)
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Input Parameters
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
intercomm Intercommunicator (handle)
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
high Used to order the groups within comm (logical)
|
|
Packit Service |
c5cf8c |
when creating the new communicator. This is a boolean value; the group
|
|
Packit Service |
c5cf8c |
that sets high true has its processes ordered after the group that sets
|
|
Packit Service |
c5cf8c |
this value to false. If all processes in the intercommunicator provide
|
|
Packit Service |
c5cf8c |
the same value, the choice of which group is ordered first is arbitrary.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Output Parameters
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
newintracomm Created intracommunicator (handle)
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Notes
|
|
Packit Service |
c5cf8c |
While all processes may provide the same value for the <tt>high</tt> parameter,
|
|
Packit Service |
c5cf8c |
this requires the MPI implementation to determine which group of
|
|
Packit Service |
c5cf8c |
processes should be ranked first.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Thread and Interrupt Safety
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
This routine is thread-safe. This means that this routine may be
|
|
Packit Service |
c5cf8c |
safely used by multiple threads without the need for any user-provided
|
|
Packit Service |
c5cf8c |
thread locks. However, the routine is not interrupt safe. Typically,
|
|
Packit Service |
c5cf8c |
this is due to the use of memory allocation routines such as <tt>malloc
|
|
Packit Service |
c5cf8c |
</tt>or other non-MPICH runtime routines that are themselves not interrupt-safe.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Notes for Fortran
|
|
Packit Service |
c5cf8c |
All MPI routines in Fortran (except for <tt>MPI_WTIME</tt> and <tt>MPI_WTICK</tt>) have
|
|
Packit Service |
c5cf8c |
an additional argument <tt>ierr</tt> at the end of the argument list. <tt>ierr
|
|
Packit Service |
c5cf8c |
</tt>is an integer and has the same meaning as the return value of the routine
|
|
Packit Service |
c5cf8c |
in C. In Fortran, MPI routines are subroutines, and are invoked with the
|
|
Packit Service |
c5cf8c |
<tt>call</tt> statement.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
All MPI objects (e.g., <tt>MPI_Datatype</tt>, <tt>MPI_Comm</tt>) are of type <tt>INTEGER
|
|
Packit Service |
c5cf8c |
</tt>in Fortran.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Algorithm
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Allocate contexts
|
|
Packit Service |
c5cf8c |
Local and remote group leaders swap high values
|
|
Packit Service |
c5cf8c |
Determine the high value.
|
|
Packit Service |
c5cf8c |
Merge the two groups and make the intra-communicator
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
Errors
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
All MPI routines (except <tt>MPI_Wtime</tt> and <tt>MPI_Wtick</tt>) return an error value;
|
|
Packit Service |
c5cf8c |
C routines as the value of the function and Fortran routines in the last
|
|
Packit Service |
c5cf8c |
argument. Before the value is returned, the current MPI error handler is
|
|
Packit Service |
c5cf8c |
called. By default, this error handler aborts the MPI job. The error handler
|
|
Packit Service |
c5cf8c |
may be changed with <tt>MPI_Comm_set_errhandler</tt> (for communicators),
|
|
Packit Service |
c5cf8c |
<tt>MPI_File_set_errhandler</tt> (for files), and <tt>MPI_Win_set_errhandler</tt> (for
|
|
Packit Service |
c5cf8c |
RMA windows). The MPI-1 routine <tt>MPI_Errhandler_set</tt> may be used but
|
|
Packit Service |
c5cf8c |
its use is deprecated. The predefined error handler
|
|
Packit Service |
c5cf8c |
<tt>MPI_ERRORS_RETURN</tt> may be used to cause error values to be returned.
|
|
Packit Service |
c5cf8c |
Note that MPI does not guarentee that an MPI program can continue past
|
|
Packit Service |
c5cf8c |
an error; however, MPI implementations will attempt to continue whenever
|
|
Packit Service |
c5cf8c |
possible.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
MPI_SUCCESS No error; MPI routine completed successfully.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
MPI_ERR_COMM Invalid communicator. A common error is to use a null
|
|
Packit Service |
c5cf8c |
communicator in a call (not even allowed in <tt>MPI_Comm_rank</tt>).
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
MPI_ERR_INTERN This error is returned when some part of the MPICH
|
|
Packit Service |
c5cf8c |
implementation is unable to acquire memory.
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
See Also
|
|
Packit Service |
c5cf8c |
MPI_Intercomm_create, MPI_Comm_free
|
|
Packit Service |
c5cf8c |
|
|
Packit Service |
c5cf8c |
</BODY></HTML>
|