Intel® Fortran Compiler XE 13.1 User and Reference Guides
Portability Function: Returns the elapsed time in seconds since the start of the current process.
result = DCLOCK( )
The result type is REAL(8). This routine provides accurate timing to the nearest millisecond (Windows* OS) or to the nearest microsecond (Linux* OS and OS X*), taking into account the frequency of the processor where the current process is running.
Note that the first call to DCLOCK performs calibration.
DOUBLE PRECISION START_TIME, STOP_TIME
START_CLOCK = DCLOCK()
STOP_CLOCK = DCLOCK()
PRINT *, 'foo took:', STOP_CLOCK - START_CLOCK, 'seconds.'