1
1
openmpi/ompi/mpi/man/man3/MPI_Status_set_elements.3in
Nathan Hjelm c4c69b4ddf MPI-3: add support for large counts using derived datatypes
Add support for MPI_Count type and MPI_COUNT datatype and add the required
MPI-3 functions MPI_Get_elements_x, MPI_Status_set_elements_x,
MPI_Type_get_extent_x, MPI_Type_get_true_extent_x, and MPI_Type_size_x.
This commit adds only the C bindings. Fortran bindins will be added in
another commit. For now the MPI_Count type is define to have the same size
as MPI_Offset. The type is required to be at least as large as MPI_Offset
and MPI_Aint. The type was initially intended to be a ssize_t (if it was
the same size as a long long) but there were issues compiling romio with
that definition (despite the inclusion of stddef.h).

I updated the datatype engine to use size_t instead of uint32_t to support
large datatypes. This will require some review to make sure that 1) the
changes are beneficial, 2) nothing was broken by the change (I doubt
anything was), and 3) there are no performance regressions due to this
change.

Increase the maximum number of predifined datatypes to support MPI_Count

Put common get_elements code to ompi/datatype/ompi_datatype_get_elements.c

Update MPI_Get_count to reflect changes in MPI-3 (return MPI_UNDEFINED when the count is too large for an int)

This commit was SVN r28932.
2013-07-23 15:35:14 +00:00

80 строки
3.8 KiB
Plaintext

.\" Copyright 2013 Los Alamos National Security, LLC. All rights reserved.
.\" Copyright 2010 Cisco Systems, Inc. All rights reserved.
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines
.TH MPI_Status_set_elements 3 "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
.SH NAME
\fBMPI_Status_set_elements\fP, \fBMPI_Status_set_elements_x\fP \- Modifies opaque part of \fIstatus\fP to allow MPI_Get_elements to return \fIcount\fP.
.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Status_set_elements(MPI_Status *\fIstatus\fP, MPI_Datatype \fIdatatype\fP, int \fIcount\fP)
int MPI_Status_set_elements_x(MPI_Status *\fIstatus\fP, MPI_Datatype \fIdatatype\fP, MPI_Count \fIcount\fP)
.fi
.SH Fortran Syntax
.nf
INCLUDE 'mpif.h'
MPI_STATUS_SET_ELEMENTS(\fISTATUS, DATATYPE, COUNT, IERROR\fP)
INTEGER \fISTATUS\fP(MPI_STATUS_SIZE), DATATYPE, COUNT, IERROR\fP
MPI_STATUS_SET_ELEMENTS_X(\fISTATUS, DATATYPE, COUNT, IERROR\fP)
INTEGER \fISTATUS\fP(MPI_STATUS_SIZE), DATATYPE\fP
INTEGER(KIND=MPI_COUNT_KIND) \fICOUNT\fP
INTEGER \fIIERROR\fP
.fi
.SH C++ Syntax
.nf
#include <mpi.h>
void MPI::Status::Set_elements(const MPI::Datatype& \fIdatatype\fP, int \fIcount\fP)
.fi
.SH INPUT/OUTPUT PARAMETER
.ft R
.TP 1i
status
Status to associate with \fIcount\fP (status).
.SH INPUT PARAMETERS
.ft R
.TP 1i
datatype
Data type associated with \fIcount\fP (handle).
.TP 1i
count
Number of elements to associate with \fIstatus\fP (integer).
.SH OUTPUT PARAMETER
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).
.SH DESCRIPTION
.ft R
MPI_Status_set_elements modifies the opaque part of \fIstatus\fP so that a call to MPI_Get_elements or MPI_Get_elements_x will return \fIcount\fP. MPI_Get_count will return a compatible value.
.sp
A subsequent call to MPI_Get_count(\fIstatus, datatype, count\fP), to MPI_Get_elements(\fIstatus, datatype, count\fP), or to MPI_Get_elements_x(\fIstatus, datatype, count\fP) must use a data-type argument that has the same type signature as the data-type argument that was used in the call to MPI_Status_set_elements.
.SH NOTES
.ft R
Users are advised not to reuse the status fields for values other than those for which they were intended. Doing so may lead to unexpected results when using the status object. For example, calling MPI_Get_elements may cause an error if the value is out of range, or it may be impossible to detect such an error. The \fIextra_state\fP argument provided with a generalized request can be used to return information that does not logically belong in \fIstatus\fP. Furthermore, modifying the values in a status set internally by MPI, such as MPI_Recv, may lead to unpredictable results and is strongly discouraged.
.SH ERRORS
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.
.sp
Before the error value is returned, the current MPI error handler is
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.
.SH FORTRAN 77 NOTES
.ft R
The MPI standard prescribes portable Fortran syntax for the \fICOUNT\fP argument of MPI_Status_set_elements_x only for Fortran 90. FORTRAN 77 users may use the non-portable syntax
.sp
.nf
INTEGER*MPI_COUNT_KIND \fICOUNT\fP
.sp
where MPI_COUNT_KIND is a constant defined in mpif.h and gives the length of the declared integer in bytes.