NAME
gprof - display call graph profile data

SYNOPSIS
gprof [ options ] [ a.out [ gmon.out ... ] ]

DESCRIPTION
GNU gprof produces an execution profile of C, Pascal*, or
Fortran77* programs. 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 default) which is created by
programs that are compiled with the -pg option of cc, pc*, and
f77*. The -pg option also links in versions of the library
routines that are compiled for profiling. The symbol table in the
named object file (a.out default) is read and correlated 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.

Gprof calculates the amount of time spent in each routine. 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. The first listing shows the functions sorted
according to the time they represent 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 function. A similar display above the function shows how this
function’s time and the time of its descendents is propagated to
its (direct) call graph parents.

Cycles are also shown, with an entry for the cycle as a whole and a
listing of the members of the cycle and their contributions to the
time and call counts of the cycle.

Second, a flat profile is given, similar to that provided by
prof(1)*. This listing gives the total execution times, the call
counts, the number of milliseconds per call in the routine itself,
and the number of milliseconds per call in the routine itself
including its descendents.

Finally, an index of the function names is provided.

The following options are available:

-a suppresses the printing of statically declared functions. If
this option is given, all relevant information about the
static function (e.g., 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 printing of a description of each field in the
profile.

-e name
suppresses the printing of the graph profile entry for routine
name and all its descendants (unless they have other ancestors
that aren’t suppressed). More than one -e option may be
given. Only one name may be given with each -e option.

-E name
suppresses the printing 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 -E
mcleanup is the default.)

-f name
prints the graph profile entry of only the specified 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
prints the graph profile entry of only the routine name and
its descendants (as -f, above) and also uses only the times of
the printed 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
overrides the -E option.

-s a profile file gmon.sum is produced that represents the sum of
the profile information in all the specified profile files.
This summary profile file may be given to later executions of
gprof (probably also with a -s) to accumulate profile data
across several runs of an a.out file.

-z displays routines that have zero usage (as shown by call
counts and accumulated time). This is useful 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.

SEE ALSO
monitor(3), profil(2), cc(1), prof(1)*
"gprof - The GNU Profiler" (included in the MachTen Programmer’s
Guide)
"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 the
function’s parents is directly proportional to the number of times
that arc is traversed.

Parents that 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 profiled, will appear to be spontaneous (although for
more obscure reasons). Any profiled children of signal catchers
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.

__________
* Not currently supported under MachTen