1 | .\"Copyright 2006-2008 Sun Microsystems, Inc. |
---|
2 | .\"Copyright (c) 1996 Thinking Machines |
---|
3 | .TH MPI_Buffer_attach 3 "Dec 08, 2009" "1.4" "Open MPI" |
---|
4 | .SH NAME |
---|
5 | \fBMPI_Buffer_attach\fP \- Attaches a user-defined buffer for sending. |
---|
6 | |
---|
7 | .SH SYNTAX |
---|
8 | .ft R |
---|
9 | .SH C Syntax |
---|
10 | .nf |
---|
11 | #include <mpi.h> |
---|
12 | int MPI_Buffer_attach(void \fI*buf\fP, int\fI size\fP) |
---|
13 | |
---|
14 | .SH Fortran Syntax |
---|
15 | .nf |
---|
16 | INCLUDE 'mpif.h' |
---|
17 | MPI_BUFFER_ATTACH(\fIBUF\fP,\fI SIZE\fP, \fIIERROR\fP) |
---|
18 | <type> \fIBUF\fP(\fI*\fP) |
---|
19 | INTEGER \fISIZE\fP,\fI IERROR \fP |
---|
20 | |
---|
21 | .SH C++ Syntax |
---|
22 | .nf |
---|
23 | #include <mpi.h> |
---|
24 | void Attach_buffer(void* \fIbuffer\fP, int \fIsize\fP) |
---|
25 | |
---|
26 | .SH INPUT PARAMETERS |
---|
27 | .ft R |
---|
28 | .TP 1i |
---|
29 | buf |
---|
30 | Initial buffer address (choice). |
---|
31 | .TP 1i |
---|
32 | size |
---|
33 | Buffer size, in bytes (integer). |
---|
34 | |
---|
35 | .SH OUTPUT PARAMETER |
---|
36 | .ft R |
---|
37 | .TP 1i |
---|
38 | IERROR |
---|
39 | Fortran only: Error status (integer). |
---|
40 | |
---|
41 | .SH DESCRIPTION |
---|
42 | .ft R |
---|
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. |
---|
44 | |
---|
45 | .SH NOTES |
---|
46 | .ft R |
---|
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 |
---|
48 | .sp |
---|
49 | .nf |
---|
50 | MPI_Buffer_attach( buf, size ); |
---|
51 | MPI_Bsend( \&..., count=20, datatype=type1, \&... ); |
---|
52 | \&... |
---|
53 | MPI_Bsend( \&..., count=40, datatype=type2, \&... ); |
---|
54 | .fi |
---|
55 | .sp |
---|
56 | the value of size in the MPI_Buffer_attach call should be greater than the value computed by |
---|
57 | .sp |
---|
58 | .nf |
---|
59 | MPI_Pack_size( 20, type1, comm, &s1 ); |
---|
60 | MPI_Pack_size( 40, type2, comm, &s2 ); |
---|
61 | size = s1 + s2 + 2 * MPI_BSEND_OVERHEAD; |
---|
62 | .fi |
---|
63 | .sp |
---|
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. |
---|
65 | |
---|
66 | .SH ERRORS |
---|
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. |
---|
68 | .sp |
---|
69 | Before the error value is returned, the current MPI error handler is |
---|
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. |
---|
71 | |
---|
72 | .SH SEE ALSO |
---|
73 | .ft R |
---|
74 | .sp |
---|
75 | MPI_Buffer_detach |
---|
76 | |
---|