wtime, a FORTRAN77 code which returns a reading of the wall clock time.
For parallel programming, the important thing to measure is the elapsed wallclock time. This can be found by subtracting an initial reading of the wallclock time from a final one.
The OpenMP system provides a function used as follows:
seconds = omp_get_wtime ( )
operations to time;
seconds = omp_get_wtime ( ) - seconds;
while the MPI system provides a similar function used as:
seconds = MPI_Wtime ( );
operations;
seconds = MPI_Wtime ( ) - seconds;
and in MATLAB, wallclock time can be taken with "tic" and "toc":
tic;
operation;
seconds = toc;
WTIME provides a way to get a similar reading:
seconds = wtime ( );
operations;
seconds = wtime ( ) - seconds;
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
wtime is available in a C version and a C++ version and a FORTRAN77 version and a Fortran90 version and a MATLAB version and a Python version.
TIMER, a FORTRAN77 program which shows how to compute the elapsed CPU time inside a program.
TIMESTAMP, a FORTRAN77 library which displays the current wall clock time.