gprof -- display call graph profile data
gprof [-abcKlLsuz] [-C count] [-e name] [-E name] [-f name] [-F name]
[-k fromname toname] [a.out [a.out.gmon ...]]
The gprof utility 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 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. By convention
these libraries have their name suffixed with _p, i.e. the profiled
version of libc.a is libc_p.a and if you specify libraries directly
to the compiler or linker you can use -lc_p instead of -lc. Read the
given object file (the default is a.out) and establishes the relation
between its symbol table and the call graph profile. The default graph
profile file name is the name of the executable with the suffix .gmon
appended. If more than one profile file is specified, the gprof output
shows the sum of the profile information in the given profile files.
The gprof utility 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 msec or usec the call spent in the routine itself, and the time in
msec or usec 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 Suppress 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 Suppress 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. This option
is not supported on some architectures.
-C count
Find a minimal set of arcs that can be broken to eliminate all
cycles with count or more members. Caution: the algorithm used
to break cycles is exponential, so using this option may cause
gprof to run for a very long time.
-e name
Suppress 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
Suppress 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
Print 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
Print 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.
-K Gather information about symbols from the currently-running kernel
using the sysctl(3) and kldsym(2) interfaces. This forces
the a.out argument to be ignored, and allows for symbols in
kld(4) modules to be used.
-l Suppress the printing of the call-graph profile.
-L Suppress the printing of the flat profile.
-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.
-u Suppress the printing of functions whose names are not visible to
C programs. For the ELF object format, this means names that
contain the `.' character. For the a.out object format, it means
names that do not begin with a `_' character. All relevant
information about such functions belongs to the (non-suppressed)
function with the next lowest address. This is useful for eliminating
"functions" that are just labels inside other functions.
-z Display 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.
a.out.gmon Dynamic call graph and profile.
gmon.sum Summarized dynamic call graph and profile.
cc(1), profil(2), clocks(7)
S. Graham, P. Kessler, and M. McKusick, "An Execution Profiler for
Modular Programs", Software - Practice and Experience, 13, pp. 671-685,
1983.
S. Graham, P. Kessler, and M. McKusick, "gprof: A Call Graph Execution
Profiler", Proceedings of the SIGPLAN '82 Symposium on Compiler
Construction, SIGPLAN Notices, 6, 17, pp. 120-126, June 1982.
The gprof profiler appeared in 4.2BSD.
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(3) or return normally for the profiling
information to be saved in the graph profile file.
FreeBSD 5.2.1 June 6, 1993 FreeBSD 5.2.1 [ Back ] |
