PROFIL(2)	    UNIX Programmer's 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 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: 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 memory fault.

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

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


Printed 11/26/99	   May 6, 1987				1


 
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