gprof - display call graph profile data
gprof [ -abcsz ] [ -e|-E name ] [ -f|-F name ] [ -k from-
name toname ] [ objfile [ gmon.out ] ]
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(1), c++(1), and f77(1). The -pg
option also links in versions of the library routines that
are compiled for profiling. Gprof reads the given object
file (the default is `a.out') and establishes the relation
between its symbol table and the call graph profile from
`gmon.out'. 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 descendants.
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 descendants
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. This listing gives the
total execution times, the call counts, the time in milliseconds
the call spent in the routine itself, and the
time in milliseconds the call spent in the routine itself
including its descendants.
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 `objfile' file.
-b suppresses the printing of a description of each
field in the profile.
-c the static call graph of the program is discovered
by a heuristic that examines the text space of the
object file. Static-only parents or children are
shown with call counts of 0.
-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.
-k fromname toname
will delete any arcs from routine fromname to routine
toname. This can be used to break undesired
cycles. More than one -k option may be given.
Only one pair of routine names may be given with
each -k 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 `objfile' file.
-v prints the version number for gprof, and then
exits.
-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.
a.out the namelist and text space.
gmon.out dynamic call graph and profile.
gmon.sum summarized dynamic call graph and profile.
moncontrol(3), monstartup(3), profil(2), cc(1), c++(1),
f77(1)
``An Execution Profiler for Modular Programs'', by S. Graham,
P. Kessler, M. McKusick; Software - Practice and
Experience, Vol. 13, pp. 671-685, 1983.
``gprof: A Call Graph Execution Profiler'', by S. Graham,
P. Kessler, M. McKusick; Proceedings of the SIGPLAN '82
Symposium on Compiler Construction, SIGPLAN Notices, Vol.
17, No 6, pp. 120-126, June 1982.
Gprof appeared in 4.2 BSD.
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.
January 29, 1993 GPROF(1)
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