GPROF(1) GPROF(1)
NAME
gprof - display call graph profile data
SYNOPSIS
gprof [ options ] [ a.out [ gmon.out ... ] ]
DESCRIPTION
gprof produces an execution profile of a C, Pascal, or
Fortran77 program. The effect of called routines is
incorporated in the profile of each caller. The profile
data is taken from the call graph profile file (gmon.out
by default), which is created by programs compiled with
the -pg option of cc, pc, and f77. The symbol table in
the named object file (a.out by default) is read and cor-
related with the call graph profile file. If more than
one profile file is specified, the gprof output shows the
sum of the profile information in the given profile files.
First, a flat profile is given. This listing gives the
total execution times and call counts for each of the
functions in the program, sorted by decreasing time.
Next, these times are propagated along the edges of the
call graph. Cycles are discovered, and calls into a cycle
are made to share the time of the cycle. A second listing
shows the functions sorted according to the time they rep-
resent including the time of their call graph descendents.
Below each function entry is shown its (direct) call graph
children, and how their times are propagated to this func-
tion. A similar display above the function shows how this
function's time and the time of its descendents is propa-
gated to its (direct) call graph parents.
Cycles are also shown, with an entry for the cycle as a
whole as well as a listing of the members of the cycle and
their contributions to the time and call counts of the
cycle.
FAT FILE SUPPORT
gprof accepts a ``fat'' file for the a.out file, using the
host architecture from the file. (It is an error if the
``fat'' file does not contain the host architecture.)
OPTIONS
The following options are available:
-a suppresses the displaying of statically declared
functions. If this option is given, all relevant
information about the static function (such as time
samples, calls to other functions, calls from other
functions) belongs to the function loaded just
before the static function in the a.out file.
-b suppresses the displaying of a description of each
field in the profile.
-c the static call graph of the program is discovered
by a heuristic which examines the text space of the
object file. Static-only parents or children are
indicated with call counts of 0. (The -c option is
currently not supported.)
-e name
suppresses the displaying of the graph profile
entry for routine name and all its descendants
(unless they have other ancestors that aren't sup-
pressed). More than one -e option may be given.
Only one name may be given with each -e option.
-E name
suppresses the displaying of the graph profile
entry for routine name (and its descendants) as -e,
above, and also excludes the time spent in name
(and its descendants) from the total and percentage
time computations. (For example, -E mcount and all
of the other monitor(3) routines are excluded by
default.)
-f name
displays the graph profile entry of only the speci-
fied routine name and its descendants. More than
one -f option may be given. Only one name may be
given with each -f option.
-F name
displays the graph profile entry of only the rou-
tine name and its descendants (as -f, above) and
also uses only the times of the displayed routines
in total time and percentage computations. More
than one -F option may be given. Only one name may
be given with each -F option. The -F option over-
rides the -E option.
-s a profile file gmon.sum is produced which repre-
sents the sum of the profile information in all the
specified profile files. This summary profile file
may be given to subsequent executions of gprof
(probably also with a -s) to accumulate profile
data across several runs of an a.out file.
-S produces four order files suitable as input to
ld(1): gmon.order is an ordering based on a closest
is best algorithm, callf.order is based on call
frequency, callo.order is based on call order and
time.order is based on time. The order files con-
tain only those functions which were called or sam-
pled (including spontaneous functions). For library
functions to appear correctly in the order file, a
whatsloaded file produced by ld(1) should exist in
the working directory. Filenames in the order file
will be missing for: files compiled without the -g
option, assembly files, and stripped executables.
This option does not work with executables that
have already been scattered. The gmon.order file
can take a long time to produce and can be sup-
pressed with the -x option.
-z displays routines which have zero usage (as indi-
cated by call counts and accumulated time). This
is useful in conjunction with the -c option for
discovering which routines were never called.
FILES
a.out the namelist and text space.
gmon.out dynamic call graph and profile.
gmon.sum summarized dynamic call graph and profile.
gmon.order ordering based on closest is best algo-
rithm.
callf.order ordering based on call frequency.
callo.order ordering based on call order.
time.order ordering based on time.
SEE ALSO
monitor(3), profil(2), cc(1)
``gprof: A Call Graph Execution Profiler'', by Graham,
S.L., Kessler, P.B., McKusick, M.K.; Proceedings of the
SIGPLAN '82 Symposium on Compiler Construction, SIGPLAN
Notices, Vol. 17, No. 6, pp. 120-126, June 1982.
BUGS
Beware of quantization errors. The granularity of the
sampling is shown, but remains statistical at best. We
assume that the time for each execution of a function can
be expressed by the total time for the function divided by
the number of times the function is called. Thus the time
propagated along the call graph arcs to parents of that
function is directly proportional to the number of times
that arc is traversed.
Parents which are not themselves profiled will have the
time of their profiled children propagated to them, but
they will appear to be spontaneously invoked in the call
graph listing, and will not have their time propagated
further. Similarly, signal catchers, even though pro-
filed, will appear to be spontaneous (although for more
obscure reasons). Any profiled children of signal catch-
ers should have their times propagated properly, unless
the signal catcher was invoked during the execution of the
profiling routine, in which case all is lost.
The profiled program must call exit(2) or return normally
for the profiling information to be saved in the gmon.out
file.
Apple Computer, Inc. August 30, 1999 GPROF(1)