gprof(1)							     gprof(1)



NAME

  gprof - Displays call graph profile data

SYNOPSIS

  gprof [-absz] [-e routine | -f routine] ...  [-E routine | -F routine] ...
       [object_file] [profile_file ...]

DESCRIPTION

  The gprof command produces an execution profile of C programs.  The effect
  of called routines is incorporated into the profile of each caller.

  The profile data is taken from the specified call graph profile_file
  (gmon.out by default), created by programs compiled with the -pg flag with
  the cc driver command.  The -pg flag also links in versions of the library
  routines compiled for profiling when your program is linked by using the
  -non_shared flag with the cc command.

  The gprof profiling tool reads the symbol table in the specified
  object_file (a.out by default), correlating it with the call profile file.
  If more than one profile_file is specified, gprof output shows the sum of
  the profile information in the given profile files.

  To produce call graph data, follow these steps:

   1.  Compile your program with the -pg switch to the cc command.

   2.  Execute the program to produce a data file.

   3.  Run gprof on the data file.

  The gprof command produces three items:

   1.  First, a flat profile is given, similar to that provided by prof.
       This listing gives the total execution times and call counts for each
       of the functions in the program, sorted by decreasing time.

   2.  Next, these execution 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 are propagated to its
       (direct) call graph parents.

   3.  Lastly, 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.

  To obtain call graph data on libraries, link your program by using the
  -non_shared flag with cc command. To disable profiling of a library, use
  the -no_pg flag when linking. For example, to enable call graph profiling
  of your executable program and then disable call graph profiling for system
  supplied libraries, such as libc, link your program by using the following
  command:

	  % cc -non_shared -pg myprog -no_pg

  You can use environment variables to change the default profiling behavior.
  The variables are PROFDIR and PROFFLAGS. The general form for setting these
  variables is:

	  For C shell:	setenv varname "value"

	  For Bourne shell: varname = "value"; export varname

  In the preceding example, varname can be one of the following:

  PROFDIR
      This environment variable causes PC-sampling data files to be generated
      with unique names in the directory you specify.

      You specify a directory path as the value and your prof results are
      placed in the file path/pid.progname where path is the pathname, pid is
      the process of the executing program, and progname is the program name.

  PROFFLAGS
      This environment variable, which takes -threads as the value, causes a
      separate data file to be generated for each thread. The name of the
      data file takes the following form:
      pid.sid.progname.

      The form of the filename resolves to pid as the process ID of the pro-
      gram, sid as the sequence ID of the thread and progname as the name of
      the program being profiled.

  You can use the PROFDIR and PROFFLAGS environment variables together. For
  more information, see the Programmer's Guide.

FLAGS

  -a	    Suppresses the printing of statically declared functions.  If
	    this flag is given, all relevant information about the static
	    function (for example, 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.

  -e routine
	    Suppresses the printing of the graph profile entry for routine
	    and all its descendants (unless they have other ancestors that
	    are not suppressed).  More than one -e flag may be given.  Only
	    one routine may be given with each -e flag.

  -E routine
	    Suppresses the printing of the graph profile entry for routine
	    and its descendants (same as -e), and also excludes the time
	    spent in routine and its descendants from the total and percen-
	    tage time computations.  (For example, _gprof_mcount -E
	    _gprof_monstop is the default.)

  -f routine
	    Prints the graph profile entry of only the specified routine and
	    its descendants.  More than one -f flag may be given.  Only one
	    routine may be given with each -f flag.  The -f flag overrides
	    the -e flag.

  -F routine
	    Prints the graph profile entry of only routine and its
	    descendants (same as -f), and also uses only the times of the
	    printed routines in total time and percentage computations.	 More
	    than one -F flag may be given.  Only one routine may be given
	    with each -F flag.	The -F flag overrides the -E flag.

  -s	    Produces a profile file, gmon.sum, 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.

  -z	    Displays routines that have zero usage, as indicated by call
	    counts and accumulated time.

NOTES

   1.  Be aware of possible quantization errors when using gprof.  The granu-
       larity of the sampling is shown, but remains statistical at best.  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.

   2.  Parents that are not themselves profiled have the time of their pro-
       filed children propagated to them, but appear to be spontaneously
       invoked in the call graph listing; they do not have their time pro-
       pagated further.

   3.  Similarly, signal catchers, even though profiled, appear to be spon-
       taneous.	 Any profiled children of signal catchers should have their
       times propagated properly, unless the signal catcher was invoked dur-
       ing the execution of the profiling routine, in which case propagation
       cannot occur.

   4.  The profiled program must call exit or return normally for the profil-
       ing information to be saved in the gmon.out file.

ERRORS

  If the program makes more procedure calls than can be recorded, the error
  "Arc limit exceeded" will occur.  The program will continue to execute to
  completion, but some call-arc information will be lost.  A possible work-
  around for this problem is to reduce the portion of the program that is
  profiled using the monstartup() routine.  See monitor(3) for more informa-
  tion.

FILES

  a.out	    Default object file.

  gmon.out  Dynamic call graph and profile.

  gmon.sum  Summarized dynamic call graph and profile.

RELATED INFORMATION

  Programmer's Guide


  Commands:  prof(1).

  Functions:  profil(2), monitor(3).

  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.