MPI_Pcontrol(3OpenMPI)MPI_Pcontrol(3OpenMPI)NAME
MPI_Pcontrol - Controls profiling.
SYNTAX C Syntax
#include <mpi.h>
int MPI_Pcontrol(const int level, ... )
Fortran Syntax
INCLUDE 'mpif.h'
MPI_PCONTROL(LEVEL)
INTEGER LEVEL, ...
C++ Syntax
#include <mpi.h>
void Pcontrol(const int level, ...)
INPUT PARAMETER
level Profiling level.
DESCRIPTION
MPI libraries themselves make no use of this routine; they simply return immediately to the user code. However the presence of calls to
this routine allows a profiling package to be explicitly called by the user.
Since MPI has no control of the implementation of the profiling code, we are unable to specify precisely the semantics that will be pro-
vided by calls to MPI_Pcontrol. This vagueness extends to the number of arguments to the function, and their datatypes.
However to provide some level of portability of user codes to different profiling libraries, we request the following meanings for certain
values of level:
o level==0 Profiling is disabled.
o level==1 Profiling is enabled at a normal default level of detail.
o level==2 Profile buffers are flushed. (This may be a no-op in some profilers).
o All other values of level have profile library-defined effects and additional arguments.
We also request that the default state after MPI_Init has been called is for profiling to be enabled at the normal default level (i.e., as
if MPI_Pcontrol had just been called with the argument 1). This allows users to link with a profiling library and obtain profile output
without having to modify their source code at all.
The provision of MPI_Pcontrol as a no-op in the standard MPI library allows users to modify their source code to obtain more detailed pro-
filing information, but still be able to link exactly the same code against the standard MPI library.
NOTES
This routine provides a common interface for profiling control. The interpretation of level and any other arguments is left to the profil-
ing library.
This function does not return an error value. Consequently, the result of calling it before MPI_Init or after MPI_Finalize is undefined.
Open MPI 1.2 September 2006 MPI_Pcontrol(3OpenMPI)
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MPI_Init_thread(3OpenMPI)MPI_Init_thread(3OpenMPI)NAME
MPI_Init_thread - Initializes the MPI execution environment
SYNTAX C Syntax
#include <mpi.h>
int MPI_Init_thread(int *argc, char ***argv,
int required, int *provided)
Fortran Syntax
INCLUDE 'mpif.h'
MPI_INIT(REQUIRED, PROVIDED, IERROR)
INTEGER REQUIRED, PROVIDED, IERROR
C++ Syntax
#include <mpi.h>
int MPI::Init_thread(int& argc, char**& argv, int required)
int MPI::Init_thread(int required)
INPUT PARAMETERS
argc C/C++ only: Pointer to the number of arguments.
argv C/C++ only: Argument vector.
required Desired level of thread support (integer).
OUTPUT PARAMETERS
provided Available level of thread support (integer).
IERROR Fortran only: Error status (integer).
DESCRIPTION
This routine, or MPI_Init, must be called before any other MPI routine (apart from MPI_Initialized) is called. MPI can be initialized at
most once; subsequent calls to MPI_Init or MPI_Init_thread are erroneous.
MPI_Init_thread, as compared to MPI_Init, has a provision to request a certain level of thread support in required:
MPI_THREAD_SINGLE Only one thread will execute.
MPI_THREAD_FUNNELED If the process is multithreaded, only the thread that called MPI_Init_thread will make MPI calls.
MPI_THREAD_SERIALIZED If the process is multithreaded, only one thread will make MPI library calls at one time.
MPI_THREAD_MULTIPLE If the process is multithreaded, multiple threads may call MPI at once with no restrictions.
The level of thread support available to the program is set in
provided, except in C++, where it is the return value of the function. In Open MPI, the value is dependent on how the library was config-
ured and built. Note that there is no guarantee that provided will be greater than or equal to required.
All MPI programs must contain a call to MPI_Init or MPI_Init_thread. Open MPI accepts the C/C++ argc and argv arguments to main, but nei-
ther modifies, interprets, nor distributes them:
{
/* declare variables */
MPI_Init_thread(&argc, &argv, req, &prov);
/* parse arguments */
/* main program */
MPI_Finalize();
}
NOTES
The Fortran version does not have provisions for argc and argv and takes only IERROR.
It is the caller's responsibility to check the value of provided, as it may be less than what was requested in required.
The MPI Standard does not say what a program can do before an MPI_Init_thread or after an MPI_Finalize. In the Open MPI implementation, it
should do as little as possible. In particular, avoid anything that changes the external state of the program, such as opening files, read-
ing standard input, or writing to standard output.
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++ func-
tions 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.
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.
SEE ALSO
MPI_Init
MPI_Initialized
MPI_Finalize
Open MPI 1.2 September 2006 MPI_Init_thread(3OpenMPI)