bsd man page for profil

PROFIL(2)							System Calls Manual							 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 (VAX and TAHOE: 100 ticks/second = 10 milliseconds per tick; 60 ticks/second ~= 16 milliseconds per tick); offset  is  sub-
       tracted 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 fraction with 16 bits of fraction: 0xffff gives a 1-1 mapping of pc's to words in
       buff; 0x7fff maps each pair of instruction words together.

       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
       execve  is executed, but remains on in child and parent both after a fork.  Profiling is turned off if an update in buff would cause a mem-
       ory fault.

RETURN VALUE
       A 0, indicating success, is always returned.

SEE ALSO
       gprof(1), prof(1), setitimer(2), monitor(3)

3rd Berkeley Distribution					    May 6, 1987 							 PROFIL(2)