"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", "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.
Several forms of output are available from the analysis.
The flat profile shows how much time your program spent in each function,
and how many times that function was called. If you simply want to know
which functions burn most of the cycles, it is stated concisely here.
The call graph shows, for each function, which functions called it, which
other functions it called, and how many times. There is also an estimate
of how much time was spent in the subroutines of each function. This can
suggest places where you might try to eliminate function calls that use a
lot of time.
The annotated source listing is a copy of the program's
source code, labeled with the number of times each line of the
program was executed.
OPTIONS
These options specify which of several output formats
"gprof" should produce.
Many of these options take an optional symspec to specify
functions to be included or excluded. These options can be
specified multiple times, with different symspecs, to include
or exclude sets of symbols.
Specifying any of these options overrides the default (-p -q),
which prints a flat profile and call graph analysis
for all functions.
-A[symspec]
--annotated-source[=
symspec]
The
-A option causes "gprof" to print annotated source code.
If symspec is specified, print output only for matching symbols.
-b
--brief
If the -b option is given, "gprof" doesn't print the
verbose blurbs that try to explain the meaning of all of the fields in
the tables. This is useful if you intend to print out the output, or
are tired of seeing the blurbs.
-C[symspec]
--exec-counts[=
symspec]
The
-C option causes "gprof" to
print a tally of functions and the number of times each was called.
If symspec is specified, print tally only for matching symbols.
If the profile data file contains basic-block count records, specifying
the -l option, along with -C, will cause basic-block
execution counts to be tallied and displayed.
-i
--file-info
The -i option causes "gprof" to display summary information
about the profile data file(s) and then exit. The number of histogram,
call graph, and basic-block count records is displayed.
-I dirs
--directory-path=
dirs
The
-I option specifies a list of search directories in
which to find source files. Environment variable GPROF_PATH
can also be used to convey this information.
Used mostly for annotated source output.
-J[symspec]
--no-annotated-source[=
symspec]
The
-J option causes "gprof" not to
print annotated source code.
If symspec is specified, "gprof" prints annotated source,
but excludes matching symbols.
-L
--print-path
Normally, source filenames are printed with the path
component suppressed. The -L option causes "gprof"
to print the full pathname of
source filenames, which is determined
from symbolic debugging information in the image file
and is relative to the directory in which the compiler
was invoked.
-p[symspec]
--flat-profile[=
symspec]
The
-p option causes "gprof" to print a flat profile.
If symspec is specified, print flat profile only for matching symbols.
-P[symspec]
--no-flat-profile[=
symspec]
The
-P option causes "gprof" to suppress printing a flat profile.
If symspec is specified, "gprof" prints a flat profile,
but excludes matching symbols.
-q[symspec]
--graph[=
symspec]
The
-q option causes "gprof" to print the call graph analysis.
If symspec is specified, print call graph only for matching symbols
and their children.
-Q[symspec]
--no-graph[=
symspec]
The
-Q option causes "gprof" to suppress printing the
call graph.
If symspec is specified, "gprof" prints a call graph,
but excludes matching symbols.
-t
--table-length=num
The
-t option causes the num most active source lines in
each source file to be listed when source annotation is enabled. The
default is 10.
-y
--separate-files
This option affects annotated source output only.
Normally, "gprof" prints annotated source files
to standard-output. If this option is specified,
annotated source for a file named path/filename
is generated in the file filename-ann. If the underlying
file system would truncate filename-ann so that it
overwrites the original filename, "gprof" generates
annotated source in the file filename.ann instead (if the
original file name has an extension, that extension is replaced
with .ann).
-Z[symspec]
--no-exec-counts[=
symspec]
The
-Z option causes "gprof" not to
print a tally of functions and the number of times each was called.
If symspec is specified, print tally, but exclude matching symbols.
-r
--function-ordering
The --function-ordering option causes "gprof" to print a
suggested function ordering for the program based on profiling data.
This option suggests an ordering which may improve paging, tlb and
cache behavior for the program on systems which support arbitrary
ordering of functions in an executable.
The exact details of how to force the linker to place functions
in a particular order is system dependent and out of the scope of this
manual.
-R map_file
--file-ordering
map_file
The
--file-ordering option causes "gprof" to print a
suggested .o link line ordering for the program based on profiling data.
This option suggests an ordering which may improve paging, tlb and
cache behavior for the program on systems which do not support arbitrary
ordering of functions in an executable.
Use of the -a argument is highly recommended with this option.
The map_file argument is a pathname to a file which provides
function name to object file mappings. The format of the file is similar to
the output of the program "nm".
c-parse.o:00000000 T yyparse
c-parse.o:00000004 C yyerrflag
c-lang.o:00000000 T maybe_objc_method_name
c-lang.o:00000000 T print_lang_statistics
c-lang.o:00000000 T recognize_objc_keyword
c-decl.o:00000000 T print_lang_identifier
c-decl.o:00000000 T print_lang_type
...
To create a map_file with GNU "nm", type a command like
"nm --extern-only --defined-only -v --print-file-name program-name".
-T
--traditional
The -T option causes "gprof" to print its output in
``traditional'' BSD style.
-w width
--width=
width
Sets width of output lines to
width.
Currently only used when printing the function index at the bottom
of the call graph.
-x
--all-lines
This option affects annotated source output only.
By default, only the lines at the beginning of a basic-block
are annotated. If this option is specified, every line in
a basic-block is annotated by repeating the annotation for the
first line. This behavior is similar to "tcov"'s -a.
--demangle[=style]
--no-demangle
These options control whether C++ symbol names should be demangled when
printing output. The default is to demangle symbols. The
"--no-demangle"
option may be used to turn off demangling. Different
compilers have different mangling styles. The optional demangling style
argument can be used to choose an appropriate demangling style for your
compiler.
Analysis Options
-a
--no-static
The -a option causes "gprof" to suppress the printing of
statically declared (private) functions. (These are functions whose
names are not listed as global, and which are not visible outside the
file/function/block where they were defined.) Time spent in these
functions, calls to/from them, etc., will all be attributed to the
function that was loaded directly before it in the executable file.
This option affects both the flat profile and the call graph.
-c
--static-call-graph
The -c option causes the call graph of the program to be
augmented by a heuristic which examines the text space of the object
file and identifies function calls in the binary machine code.
Since normal call graph records are only generated when functions are
entered, this option identifies children that could have been called,
but never were. Calls to functions that were not compiled with
profiling enabled are also identified, but only if symbol table
entries are present for them.
Calls to dynamic library routines are typically not found
by this option.
Parents or children identified via this heuristic
are indicated in the call graph with call counts of 0.
-D
--ignore-non-functions
The -D option causes "gprof" to ignore symbols which
are not known to be functions. This option will give more accurate
profile data on systems where it is supported (Solaris and HPUX for
example).
-k from/to
The
-k option allows you to delete from the call graph any arcs from
symbols matching symspec from to those matching symspec to.
-l
--line
The -l option enables line-by-line profiling, which causes
histogram hits to be charged to individual source code lines,
instead of functions.
If the program was compiled with basic-block counting enabled,
this option will also identify how many times each line of
code was executed.
While line-by-line profiling can help isolate where in a large function
a program is spending its time, it also significantly increases
the running time of "gprof", and magnifies statistical
inaccuracies.
-m num
--min-count=
num
This option affects execution count output only.
Symbols that are executed less than
num times are suppressed.
-nsymspec
--time=
symspec
The
-n option causes "gprof", in its call graph analysis,
to only propagate times for symbols matching symspec.
-Nsymspec
--no-time=
symspec
The
-n option causes "gprof", in its call graph analysis,
not to propagate times for symbols matching symspec.
-z
--display-unused-functions
If you give the -z option, "gprof" will mention all
functions in the flat profile, even those that were never called, and
that had no time spent in them. This is useful in conjunction with the
-c option for discovering which routines were never called.
Miscellaneous Options
-d[num]
--debug[=
num]
The
-dnum option specifies debugging options.
If num is not specified, enable all debugging.
-h
--help
The -h option prints command line usage.
-Oname
--file-format=
name
Selects the format of the profile data files. Recognized formats are
auto (the default), bsd, 4.4bsd, magic, and
prof (not yet supported).
-s
--sum
The -s option causes "gprof" to summarize the information
in the profile data files it read in, and write out a profile data
file called gmon.sum, which contains all the information from
the profile data files that "gprof" read in. The file gmon.sum
may be one of the specified input files; the effect of this is to
merge the data in the other input files into gmon.sum.
Eventually you can run "gprof" again without -s to analyze the
cumulative data in the file gmon.sum.
-v
--version
The -v flag causes "gprof" to print the current version
number, and then exit.
Deprecated Options
These options have been replaced with newer versions that use symspecs.
-e function_name
The
-efunction option tells "gprof" to not print
information about the function function_name (and its
children...) in the call graph. The function will still be listed
as a child of any functions that call it, but its index number will be
shown as [not printed]. More than one -e option may be
given; only one function_name may be indicated with each -e
option.
-E function_name
The "-E
function" option works like the "-e" option, but
time spent in the function (and children who were not called from
anywhere else), will not be used to compute the percentages-of-time for
the call graph. More than one -E option may be given; only one
function_name may be indicated with each -E option.
-f function_name
The
-ffunction option causes "gprof" to limit the
call graph to the function function_name and its children (and
their children...). More than one -f option may be given;
only one function_name may be indicated with each -f
option.
-F function_name
The
-Ffunction option works like the "-f" option, but
only time spent in the function and its children (and their
children...) will be used to determine total-time and
percentages-of-time for the call graph. More than one -F option
may be given; only one function_name may be indicated with each
-F option. The -F option overrides the -E option.
FILES
a.out
the namelist and text space.
gmon.out
dynamic call graph and profile.
gmon.sum
summarized dynamic call graph and profile.
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"(2)
or return normally for the profiling information to be saved
in the gmon.out file.
``An Execution Profiler for Modular Programs'',
by S. Graham, P. Kessler, M. McKusick;
Software - Practice and Experience,
Vol. 13, pp. 671-685, 1983.
``gprof: A Call Graph Execution Profiler'',
by S. Graham, P. Kessler, M. McKusick;
Proceedings of the SIGPLAN '82 Symposium on Compiler Construction,
SIGPLAN Notices, Vol. 17, No 6, pp. 120-126, June 1982.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts. A copy of the license is included in the
section entitled ``GNU Free Documentation License''.
