PL/SQL Packages DBMS_ODCI

Calculate the CPU cost of a user function based on the elapsed time of the function.
This CPU cost is used by extensible optimizer routines.

Function:

ESTIMATE_CPU_UNITS Function 
              Returns the approximate number of CPU instructions (in thousands)
              corresponding to a specified time interval (in seconds).  

For full documentation of the packaged procedures above see the Oracle Manual:
"Oracle9i Supplied PL/SQL Packages and Types Reference"

or the book Oracle Built in Packages by Steven Feuerstein et al