# 2.11BSD#431 - /usr/man/cat3/monstartup.0

    MONITOR(3)	    UNIX Programmer's Manual	       MONITOR(3)

    NAME
         monitor, monstartup, moncontrol - prepare execution profile

    SYNOPSIS
         monitor(lowpc, highpc, buffer, bufsize, nfunc)
         int (*lowpc)(), (*highpc)();
         short buffer[];

         monstartup(lowpc, highpc)
         int (*lowpc)(), (*highpc)();

         moncontrol(mode)

    DESCRIPTION
         There are two different forms of monitoring available: An
         executable program created by:

    	  cc -p . . .

         automatically includes calls for the prof(1) monitor and
         includes an initial call to its start-up routine monstartup
         with default parameters; monitor need not be called expli-
         citly except to gain fine control over profil buffer alloca-
         tion.  An executable program created by:

    	  cc -pg . . .

         automatically includes calls for the gprof(1) monitor.

         Monstartup is a high level interface to profil(2).  Lowpc
         and highpc specify the address range that is to be sampled;
         the lowest address sampled is that of lowpc and the highest
         is just below highpc.  Monstartup allocates space using
         sbrk(2) and passes it to monitor (see below) to record a
         histogram of periodically sampled values of the program
         counter, and of counts of calls of certain functions, in the
         buffer.  Only calls of functions compiled with the profiling
         option -p of cc(1) are recorded.

         To profile the entire program, it is sufficient to use

    	  extern etext();
    	  . . .
    	  monstartup((int) 2, etext);

         Etext lies just above all the program text, see end(3).

         To stop execution monitoring and write the results on the
         file mon.out, use

    	  monitor(0);

    Printed 11/26/99	  May 15, 1985				1

    MONITOR(3)	    UNIX Programmer's Manual	       MONITOR(3)

         then prof(1) can be used to examine the results.

         Moncontrol is used to selectively control profiling within a
         program.  This works with either prof(1) or gprof(1) type
         profiling.  When the program starts, profiling begins.  To
         stop the collection of histogram ticks and call counts use
         moncontrol(0); to resume the collection of histogram ticks
         and call counts use moncontrol(1).  This allows the cost of
         particular operations to be measured.  Note that an output
         file will be produced upon program exit irregardless of the
         state of moncontrol.

         Monitor is a low level interface to profil(2).  Lowpc and
         highpc are the addresses of two functions; buffer is the
         address of a (user supplied) array of bufsize short
         integers.	At most nfunc call counts can be kept.	For the
         results to be significant, especially where there are small,
         heavily used routines, it is suggested that the buffer be no
         more than a few times smaller than the range of locations
         sampled.  Monitor divides the buffer into space to record
         the histogram of program counter samples over the range
         lowpc to highpc, and space to record call counts of func-
         tions compiled with the -p option to cc(1).

         To profile the entire program, it is sufficient to use

    	  extern etext();
    	  . . .
    	  monitor((int) 2, etext, buf, bufsize, nfunc);

    FILES
         mon.out

    SEE ALSO
         cc(1), prof(1), gprof(1), profil(2), sbrk(2)

    Printed 11/26/99	  May 15, 1985				2

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