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gprof - display call graph profile data
gprof
[ -abcsz ] [ -e|-E name ] [ -f|-F name ] [ -k fromname 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)
, pc(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, similar to that provided
by prof(1)
. 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.
monitor(3)
, profil(2)
,
cc(1)
, prof(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.
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