PRF(HW)                              UNIX System V



     Name
          prf - operating system profiler


     Description
          The  special  file  /dev/prf  provides  access  to  activity
          information in the operating system.  Writing the file loads
          the  measurement  facility  with  text   addresses   to   be
          monitored.   Reading  the file returns these addresses and a
          set of counters indicative of activity between adjacent text
          addresses.

          The recording mechanism is driven by the  system  clock  and
          samples the program counter at line frequency.  Samples that
          catch the operating system are matched  against  the  stored
          text  addresses  and  increment  corresponding  counters for
          later processing.

          The file /dev/prf is  a  pseudo-device  with  no  associated
          hardware.


     Files
          /dev/prf


     See Also
          profiler(ADM)


     (printed 2/15/90)                                    PRF(HW)