XMPI_Buoy(3)

NAME
XMPI_Buoy - LAM/MPI-specific function to drop a buoy in the XMPI trace stream.

SYNOPSIS
#include <mpi.h>
int
XMPI_Buoy(const char* name)

INPUT PARAMETER
name
    - buoy name (string)

NOTES
The LAM implementation of MPI is integrated with the XMPI run/debug viewer. It can generate tracefiles and on-the-fly trace streams suitable for display in XMPI. A new functionality in XMPI is the ability to view "buoys" in the trace stream that can be helpful in marking particular sections of code. LAM/MPI allows the dropping of buoys with the XMPI_Buoy function. Calling XMPI_Buoy with a string will drop a bouy of that name (if tracing is enabled) in the trace stream. Dropping a buoy is a local action; the call will return immediately. The buoy is dropped in the trace stream of the local rank, and will appear on the corresponding rank timeline in XMPI. The name can be a maximum of 32 characters long; if it is longer, it will be truncated. If this function is invoked and tracing is not active, the buoy is ignored. There is no profiling version of this function. This is a LAM/MPI-specific function and is intended mainly for use with XMPI. If this function is used, it should be used in conjunction with the LAM_MPI C preprocessor macro
#if LAM_MPI
XMPI_Buoy("my function begins");
// ... message passing code
XMPI_Buoy("my function ends");
#endif

NOTES FOR FORTRAN
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have an additional argument ierr at the end of the argument list. ierr is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the call statement. All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS
If an error occurs in an MPI function, the current MPI error handler is called to handle it. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Errhandler_set ; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned (in C and Fortran; this error handler is less useful in with the C++ MPI bindings. The predefined error handler MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value needs to be recovered). Note that MPI does not guarantee that an MPI program can continue past an error. All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as the value of the function and Fortran routines in the last argument. The C++ bindings for MPI do not return error values; instead, error values are communicated by throwing exceptions of type MPI::Exception (but not by default). Exceptions are only thrown if the error value is not MPI::SUCCESS
 . Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI functions will return upon an error, there will be no way to recover what the actual error value was.
MPI_SUCCESS
    - No error; MPI routine completed successfully.
MPI_ERR_ARG
    - Invalid argument. Some argument is invalid and is not identified by a specific error class. This is typically a NULL pointer or other such error.
MPI_ERR_INTERN
    - An internal error has been detected. This is fatal. Please send a bug report to the LAM mailing list (see http://www.lam-mpi.org/contact.php ).

SEE ALSO
XMPI_Coloron, XMPI_Coloroff

LOCATION
xbuoy.c