function index

MPI_Wtime

Returns an elapsed time on the calling processor

double MPI_Wtime( void );

Return value

Time in seconds since an arbitrary time in the past.

Remarks

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.

The times returned are local to the node that called them. There is no requirement that different nodes return "the same time."

This is intended to be a high-resolution, elapsed (or wall) clock. See MPI_WTICK to determine the resolution of MPI_WTIME. If the attribute MPI_WTIME_IS_GLOBAL is defined and true, then the value is synchronized across all processes in MPI_COMM_WORLD.

Notes for Fortran

This is a function, declared as DOUBLE PRECISION MPI_WTIME() in Fortran.

See Also

also: MPI_Wtick, MPI_Comm_get_attr, MPI_Attr_get

Example Code

The following sample code illustrates MPI_Wtime.

#include "mpi.h"
#include <windows.h>
#include <stdio.h>

int main( int argc, char *argv[] )
{
    double t1, t2;

    MPI_Init( 0, 0 );
    t1 = MPI_Wtime();
    Sleep(1000);
    t2 = MPI_Wtime();
    printf("MPI_Wtime measured a 1 second sleep to be: %1.2f\n", t2-t1);fflush(stdout);
    MPI_Finalize( );
    return 0;
}