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GPROF(1)		  BSD General Commands Manual		      GPROF(1)

NAME
     gprof — display call graph profile data

SYNOPSIS
     gprof [-abKlLsuz] [-C count] [-e name] [-E name] [-f name] [-F name]
	   [-k fromname toname] [a.out [a.out.gmon ...]]

DESCRIPTION
     The gprof utility produces an execution profile of C, Pascal, or For‐
     tran77 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 ver‐
     sions of the library routines that are compiled for profiling.  By con‐
     vention these libraries have their name suffixed with _p, i.e., the pro‐
     filed 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 descen‐
     dants.  Below each function entry is shown its (direct) call graph chil‐
     dren, 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 list‐
     ing 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
     that the call spent in the routine itself, and the time that the call
     spent in the routine itself including its descendants.  The units for the
     per-call times are normally milliseconds, but they are nanoseconds if the
     profiling clock frequency is 10 million or larger, and if a function
     appears to be never called then its total self time is printed as a per‐
     centage in the self time per call column.	The very high profiling clock
     frequencies needed to get sufficient accuracy in the per-call times for
     short-lived programs are only implemented for “high resolution” (non-sta‐
     tistical) kernel profiling.

     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 func‐
	     tion (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 pro‐
	     file.

     -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
	     are not 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 ker‐
	     nel 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 sev‐
	     eral 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 elimi‐
	     nating "functions" that are just labels inside other functions.

     -z	     Display routines that have zero usage (as shown by call counts
	     and accumulated time).

FILES
     a.out	 The namelist and text space.
     a.out.gmon	 Dynamic call graph and profile.
     gmon.sum	 Summarized dynamic call graph and profile.

SEE ALSO
     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.

HISTORY
     The gprof profiler appeared in 4.2BSD.

BUGS
     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 num‐
     ber of times that arc is traversed.

     Parents that are not themselves profiled will have the time of their pro‐
     filed children propagated to them, but they will appear to be sponta‐
     neously 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 profil‐
     ing information to be saved in the graph profile file.

BSD			       December 25, 2008			   BSD
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