profil(2)                                               profil(2)



     NAME
          profil - execution time profile

     SYNOPSIS
          profil (buff, bufsiz, offset, scale)
          char *buff;
          int bufsiz, offset, scale;

     DESCRIPTION
          buff points to an area of core whose length (in bytes) is
          given by bufsiz.  After this call, the user's program
          counter (pc) is examined each clock tick; offset is
          subtracted from it, and the result multiplied by scale.  If
          the resulting number corresponds to a word inside buff, that
          word is incremented.

          The scale is interpreted as an unsigned (16 bit), fixed-
          point fraction with binary point at the left: FFFF (hex)
          gives a 1-1 mapping of pc's to words in buff; FFFF (hex)
          maps each pair of instruction words together.  2(hex) maps
          all instructions onto the beginning of buff (producing a
          non-interrupting core clock).

          Profiling is turned off by giving a scale of 0 or 1.  It is
          rendered ineffective by giving a bufsiz of 0.  Profiling is
          turned off when an exec is executed, but remains on in child
          and parent both after a fork.  Profiling will be turned off
          if an update in buff would cause a memory fault.

     RETURN VALUE
          Not defined.

     SEE ALSO
          prof(1), monitor(3C).





















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