MONITOR(3)                           BSD                            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 explicitly except to gain fine control over
     profil buffer allocation.  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);

     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
     functions 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), brk(2)