Returns an elapsed time on the calling processor
double MPI_Wtime( void )
Time in seconds since an arbitrary time in the past.
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 .
This is a function, declared as DOUBLE PRECISION MPI_WTIME() in Fortran.
also: MPI_Wtick, MPI_Comm_get_attr, MPI_Attr_get
/tmp/gyCYfBi4J6/mpich-3.1/src/mpi/timer/wtime.c