GPROF(1) OpenBSD Reference Manual GPROF(1)NAMEgprof - display call graph profile data
SYNOPSISgprof [-abcsz] [-C count] [-E name] [-e name] [-F name] [-f name]
[-k from-name to-name] [a.out [gmon.out ...]]
DESCRIPTIONgprof 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. 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 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.
-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.
-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.)
-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.
-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.
-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.
-k from-name to-name
Will delete any arcs from routine from-name to routine to-name.
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.
ENVIRONMENT
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.
FILES
a.out namelist and text space
gmon.out dynamic call graph and profile
gmon.sum summarized dynamic call graph and profile
SEE ALSOcc(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.
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
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 4.9 May 25, 2010 OpenBSD 4.9
