GPROF(1) BSD GPROF(1)
NAME
gprof - display call graph profile data
SYNOPSIS
gprof [ options ] [ objfile [ gproffile ... ] ]
DESCRIPTION
gprof produces an execution profile of C 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 gproffile
(gmon.out default), which is created by programs which are compiled with
the -pg option of cc and f77. That option also links in versions of the
library routines which are compiled for profiling. The symbol table in
the named object file objfile (a.out 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 and a
listing of the members of the cycle and their contributions to the time
and call counts of the cycle.
OPTIONS
-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 objfile 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 which examines the text space of the object file.
Static-only parents or children are indicated with call counts
of 0.
-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.
-s Produce 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 objfile file.
-z Display 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
SEE ALSO
monitor(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 gproffile file.