NAME
monitor, monstartup, moncontrol - prepare execution profile

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

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

void moncontrol(mode)
int mode;

DESCRIPTION
An executable program created by:

cc -pg . . .

automatically includes calls for the gprof(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.

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 malloc(3) 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 -pg 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 gprof(1) can be used to examine the results.

Moncontrol is used to selectively control profiling within a
program. 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 regardless 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 -pg 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), gprof(1), profil(2), malloc(3)