103 строки
3.9 KiB
Groff
103 строки
3.9 KiB
Groff
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.\"Copyright 2006, Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.
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.\" Copyright (c) 1996 Thinking Machines Corporation
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.TH MPI_Intercomm_create 3OpenMPI "September 2006" "Open MPI 1.2" " "
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.SH NAME
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\fBMPI_Intercomm_create\fP \- Creates an intercommuncator from two intracommunicators.
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.SH SYNTAX
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.ft R
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.SH C Syntax
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.nf
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#include <mpi.h>
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int MPI_Intercomm_create(MPI_Comm \fIlocal_comm\fP, int\fI local_leader\fP,
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MPI_Comm\fI peer_comm\fP, int\fI remote_leader\fP, int\fI tag\fP, MPI_Comm\fI *newintercomm\fP)
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.SH Fortran Syntax
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.nf
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INCLUDE 'mpif.h'
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MPI_INTERCOMM_CREATE(\fILOCAL_COMM, LOCAL_LEADER, PEER_COMM,
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REMOTE_LEADER, TAG, NEWINTERCOMM, IERROR\fP)
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INTEGER \fILOCAL_COMM, LOCAL_LEADER, PEER_COMM, REMOTE_LEADER\fP
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INTEGER \fITAG, NEWINTERCOMM, IERROR\fP
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.SH C++ Syntax
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.nf
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#include <mpi.h>
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Intercomm Intracomm::Create_intercomm(int \fIlocal_leader\fP, const
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Comm& \fIpeer_comm\fP, int \fIremote_leader\fP, int \fItag\fP) const
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.SH INPUT PARAMTERS
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.ft R
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.TP 1i
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local_comm
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The communicator containing the process that initiates the inter-communication (handle).
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.TP 1i
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local_leader
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Rank of local group leader in local_comm (integer).
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.TP 1i
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peer_comm
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"Peer" communicator; significant only at the local_leader (handle).
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.TP 1i
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remote_leader
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Rank of remote group leader in peer_comm; significant only at the local_leader (integer).
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.TP 1i
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tag
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Message tag used to identify new intercommunicator (integer).
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.SH OUTPUT PARAMETERS
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.ft R
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.TP 1i
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newintercomm
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Created intercommunicator (handle).
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.ft R
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.TP 1i
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IERROR
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Fortran only: Error status (integer).
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.SH DESCRIPTION
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.ft R
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This call creates an intercommunicator. It is collective over the union of the local and remote groups. Processes should provide identical local_comm and local_leader arguments within each group. Wildcards are not permitted for remote_leader, local_leader, and tag.
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.sp
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This call uses point-to-point communication with communicator peer_comm,
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and with tag tag between the leaders. Thus, care must be taken that there be no pending communication on peer_comm that could interfere with this communication.
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If multiple MPI_Intercomm_creates are being made, they should use different tags (more precisely, they should ensure that the local and remote leaders are using different tags for each MPI_intercomm_create).
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.SH NOTES
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We recommend using a dedicated peer communicator, such as a duplicate of MPI_COMM_WORLD, to avoid trouble with peer communicators.
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.sp
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The MPI 1.1 Standard contains two mutually exclusive comments on the
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input intracommunicators. One says that their repective groups must be
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disjoint; the other that the leaders can be the same process. After
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some discussion by the MPI Forum, it has been decided that the groups must
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be disjoint. Note that the
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.B reason
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given for this in the standard is
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.B not
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the reason for this choice; rather, the
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.B other
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operations on
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intercommunicators (like
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.I MPI_Intercomm_merge
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) do not make sense if the
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groups are not disjoint.
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.SH ERRORS
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Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI:Exception object.
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.sp
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Before the error value is returned, the current MPI error handler is
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called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.
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.SH SEE ALSO
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MPI_Intercomm_merge
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.br
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MPI_Comm_free
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.br
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MPI_Comm_remote_group
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.br
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MPI_Comm_remote_size
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' @(#)MPI_Intercomm_create.3 1.17 00/02/02
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' @(#)MPI_Intercomm_create.3 1.23 06/03/09
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