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mpi_wtime(3openmpi) [osx man page]

MPI_Wtime(3OpenMPI)													       MPI_Wtime(3OpenMPI)

MPI_Wtime - Returns an elapsed time on the calling processor. SYNTAX
C Syntax #include <mpi.h> double MPI_Wtime() Fortran Syntax INCLUDE 'mpif.h' DOUBLE PRECISION MPI_WTIME() C++ Syntax #include <mpi.h> double Wtime() RETURN VALUE
Time in seconds since an arbitrary time in the past. DESCRIPTION
MPI_Wtime returns a floating-point number of seconds, representing elapsed wall-clock time since some time in the past. The "time in the past" is guaranteed not to change during the life of the process. The user is responsible for converting large numbers of seconds to other units if they are preferred. This function is portable (it returns seconds, not "ticks"), it allows high resolution, and carries no unnecessary baggage. One would use it like this: { double starttime, endtime; starttime = MPI_Wtime(); .... stuff to be timed ... endtime = MPI_Wtime(); printf("That took %f seconds ",endtime-starttime); } The times returned are local to the node that called them. There is no requirement that different nodes return the "same" time. NOTES
The boolean variable MPI_WTIME_IS_GLOBAL, a predefined attribute key that indicates whether clocks are synchronized, does not have a valid value in Open MPI, as the clocks are not guaranteed to be synchronized. This is intended to be a high-resolution, elapsed (or wall) clock. See MPI_Wtick to determine the resolution of MPI_Wtime. This function does not return an error value. Consequently, the result of calling it before MPI_Init or after MPI_Finalize is undefined. SEE ALSO
MPI_Wtick Open MPI 1.2 September 2006 MPI_Wtime(3OpenMPI)

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MPI_Is_thread_main(3OpenMPI)											      MPI_Is_thread_main(3OpenMPI)

MPI_Is_thread_main - Determines if thread called MPI_Init SYNTAX
C Syntax #include <mpi.h> int MPI_Is_thread_main(int *flag) Fortran Syntax INCLUDE 'mpif.h' MPI_IS_THREAD_MAIN(FLAG, IERROR) LOGICAL FLAG INTEGER IERROR C++ Syntax #include <mpi.h> bool MPI::Is_thread_main() OUTPUT PARAMETERS
flag True if calling thread is main thread (boolean). IERROR Fortran only: Error status (integer). DESCRIPTION
MPI_Is_thread_main is called by a thread to find out whether the caller is the main thread (that is, the thread that called MPI_Init or MPI_Init_thread). 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 the MPI man page for a full list of MPI error codes. SEE ALSO
MPI_Init MPI_Init_thread Open MPI 1.2 September 2006 MPI_Is_thread_main(3OpenMPI)
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