GPROF(1)GPROF(1)NAMEgprof - display call graph profile data
SYNOPSISgprof [ options ] [ a.out [ gmon.out ... ] ]
DESCRIPTIONgprof 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 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.
First, a flat profile is given, similar to that provided by prof(1).
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 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 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 SUPPORTgprof 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 suppressed). 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 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
displays the graph profile entry of only the routine 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 overrides
the -E option.
-s a profile file gmon.sum is produced which represents 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 contain only
those functions which were called or sampled (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.
-z displays routines which have zero usage (as indicated 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 algorithm.
callf.order ordering based on call frequency.
callo.order ordering based on call order.
time.order ordering based on time.
SEE ALSOmonitor(3), profil(2), cc(1), prof(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
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.
NeXT Computer, Inc. May 25, 1995 GPROF(1)
