NAME

monitor − prepare execution profile

SYNOPSIS

#include <mon.h>

void monitor (lowpc, highpc, buffer, bufsize, nfunc)
int (∗lowpc)( ), (∗highpc)( );
WORD ∗buffer;
int bufsize, nfunc;

DESCRIPTION

An executable program created by cc −p automatically includes calls for monitor with default parameters; monitor need not be called explicitly except to gain fine control over profiling. 

monitor is an interface to profil(2). lowpc and highpc are the addresses of two functions; buffer is the address of a (user supplied) array of bufsize WORDs (defined in the <mon.h> header file).  monitor arranges to record a histogram of periodically sampled values of the program counter, and of counts of calls of certain functions, in the buffer.  The lowest address sampled is that of lowpc and the highest is just below highpc. lowpc may not equal 0 for this use of monitor. At most nfunc call counts can be kept; only calls of functions compiled with the profiling option −p of cc(1) are recorded.

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. 

To profile the entire program, use

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

etext lies just above all the program text; see end(3C).

To stop execution monitoring and write the results, use

monitor ((int (∗)())0, 0, 0, 0, 0);

Use prof(1) to examine the results.

The name of the file written by monitor is controlled by the environment variable PROFDIR.  If PROFDIR does not exist, “mon.out” is created in the current directory.  If PROFDIR exists but has no value, monitor does not do any profiling and creates no output file.  Otherwise, the value of PROFDIR is used as the name of the directory in which to create the output file.  If PROFDIR is dirname, then the file written is “dirname/pid.mon.out” where pid is the program’s process id.  (When monitor is called automatically by compiling via cc −p, the file created is “dirname/pid.progname” where progname is the name of the program.) 

FILES

mon.out

SEE ALSO

cc(1), prof(1), profil(2), end(3C)

BUGS

The “dirname/pid.mon.out” form does not work; the “dirname/pid.progname” form (automatically called via cc −p) does work. 

September 02, 1992