profil(2)                                               profil(2)



     NAME
          profil - execution time profile

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

     DESCRIPTION
          profil is used to report performance analysis of an applica-
          tion.  buff points to an area of core whose length (in
          bytes) is given by bufsiz.  After the call, the user's pro-
          gram counter (pc) is examined for 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, fixed-point frac-
          tion with 16 bits of fraction:  0x10000 gives a 1-1 mapping
          of pc's to words in buff; 0x8000 maps each pair of instruc-
          tion words together; 2 maps all instructions onto the begin-
          ning of buff (producing a noninterrupting 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).





















     April, 1990                                                     1