[97] | 1 | .\"Copyright 2006-2008 Sun Microsystems, Inc. |
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| 2 | .\"Copyright (c) 1996 Thinking Machines |
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| 3 | .TH MPI_Buffer_attach 3 "Dec 08, 2009" "1.4" "Open MPI" |
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| 4 | .SH NAME |
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| 5 | \fBMPI_Buffer_attach\fP \- Attaches a user-defined buffer for sending. |
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| 6 | |
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| 7 | .SH SYNTAX |
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| 8 | .ft R |
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| 9 | .SH C Syntax |
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| 10 | .nf |
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| 11 | #include <mpi.h> |
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| 12 | int MPI_Buffer_attach(void \fI*buf\fP, int\fI size\fP) |
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| 13 | |
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| 14 | .SH Fortran Syntax |
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| 15 | .nf |
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| 16 | INCLUDE 'mpif.h' |
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| 17 | MPI_BUFFER_ATTACH(\fIBUF\fP,\fI SIZE\fP, \fIIERROR\fP) |
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| 18 | <type> \fIBUF\fP(\fI*\fP) |
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| 19 | INTEGER \fISIZE\fP,\fI IERROR \fP |
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| 20 | |
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| 21 | .SH C++ Syntax |
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| 22 | .nf |
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| 23 | #include <mpi.h> |
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| 24 | void Attach_buffer(void* \fIbuffer\fP, int \fIsize\fP) |
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| 25 | |
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| 26 | .SH INPUT PARAMETERS |
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| 27 | .ft R |
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| 28 | .TP 1i |
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| 29 | buf |
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| 30 | Initial buffer address (choice). |
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| 31 | .TP 1i |
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| 32 | size |
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| 33 | Buffer size, in bytes (integer). |
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| 34 | |
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| 35 | .SH OUTPUT PARAMETER |
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| 36 | .ft R |
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| 37 | .TP 1i |
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| 38 | IERROR |
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| 39 | Fortran only: Error status (integer). |
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| 40 | |
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| 41 | .SH DESCRIPTION |
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| 42 | .ft R |
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| 43 | Provides to MPI a buffer in the user's memory to be used for buffering outgoing messages. The buffer is used only by messages sent in buffered mode. Only one buffer can be attached to a process at a time. |
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| 44 | |
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| 45 | .SH NOTES |
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| 46 | .ft R |
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| 47 | The size given should be the sum of the sizes of all outstanding Bsends that you intend to have, plus MPI_BSEND_OVERHEAD bytes for each Bsend that you do. For the purposes of calculating size, you should use MPI_Pack_size. In other words, in the code |
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| 48 | .sp |
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| 49 | .nf |
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| 50 | MPI_Buffer_attach( buf, size ); |
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| 51 | MPI_Bsend( \&..., count=20, datatype=type1, \&... ); |
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| 52 | \&... |
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| 53 | MPI_Bsend( \&..., count=40, datatype=type2, \&... ); |
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| 54 | .fi |
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| 55 | .sp |
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| 56 | the value of size in the MPI_Buffer_attach call should be greater than the value computed by |
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| 57 | .sp |
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| 58 | .nf |
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| 59 | MPI_Pack_size( 20, type1, comm, &s1 ); |
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| 60 | MPI_Pack_size( 40, type2, comm, &s2 ); |
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| 61 | size = s1 + s2 + 2 * MPI_BSEND_OVERHEAD; |
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| 62 | .fi |
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| 63 | .sp |
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| 64 | MPI_BSEND_OVERHEAD gives the maximum amount of buffer space that may be used by the Bsend routines. This value is in mpi.h for C and mpif.h for Fortran. |
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| 65 | |
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| 66 | .SH ERRORS |
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| 67 | 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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| 68 | .sp |
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| 69 | Before the error value is returned, the current MPI error handler is |
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| 70 | 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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| 71 | |
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| 72 | .SH SEE ALSO |
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| 73 | .ft R |
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| 74 | .sp |
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| 75 | MPI_Buffer_detach |
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| 76 | |
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