MONITOR(3) MONITOR(3)
NAME
monitor - prepare execution profile
SYNOPSIS
monitor(lowpc, highpc, buffer, bufsize, nfunc)
int (*lowpc)(), (*highpc)();
short buffer[];
DESCRIPTION
An executable program created by cc -p automatically
includes calls for monitor with default parameters; monitor
needn't 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 bytes. Monitor arranges to
record a histogram of periodically sampled values of the
program counter, and of counts of calls of certain func-
tions, in the buffer. The lowest address sampled is that of
lowpc and the highest is just below highpc. 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. The default values for bufsize and nfunc are
(highpc-lowpc)/8 and 300 respectively.
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(3). For
the highest resolution profiling on the VAX, use bufsize =
((int)highpc)-((int)lowpc)+12+8*nfunc.
To stop execution monitoring and write the results on the
file mon.out, use
monitor((int (*)())0);
then prof(1) can be used to examine the results.
FILES
prof(1), profil(2), cc(1)