gprof - display call graph profile data
gprof [options] [a.out [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, 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 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. 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
descendents.
Finally, an index of the function names is provided.
The options are as follows:
-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.
-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.
-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
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 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.
PROFDIR Directory to place profiling information in a file
named
pid.progname. If it is set to a null value, no
profiling information
is output. Otherwise, profiling information
is placed in
the file gmon.out.
a.out namelist and text space
gmon.out dynamic call graph and profile
gmon.sum summarized dynamic call graph and profile
cc(1), profil(2), moncontrol(3)
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 gmon.out file.
OpenBSD 3.6 June 6, 1993
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