MONITOR(3C) (C Programming Language Utilities) MONITOR(3C)
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, it is sufficient to use
extern etext;
...
monitor ((int (*)())2, &etext, buf, bufsize, nfunc);
Page 1 May 1989
MONITOR(3C) (C Programming Language Utilities) MONITOR(3C)
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);
Prof(1) can then be used 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.
Page 2 May 1989