gprof - display call graph profile data
gprof [ -[abcDhilLrsTvwxyz] ] [ -[ACeEfFJnNOpPqQZ][name] ]
[ -I dirs ] [ -d[num] ] [ -k from/to ]
[ -m min-count ] [ -R map_file ] [ -t table-length ]
[ --[no-]annotated-source[=name] ]
[ --[no-]exec-counts[=name] ]
[ --[no-]flat-profile[=name] ] [ --[no-]graph[=name] ]
[ --[no-]time=name] [ --all-lines ] [ --brief ]
[ --debug[=level] ] [ --function-ordering ]
[ --file-ordering map_file ] [ --directory-path=dirs ]
[ --display-unused-functions ] [ --file-format=name ]
[ --file-info ] [ --help ] [ --line ] [ --inline-file-names ]
[ --min-count=n ] [ --no-static ] [ --print-path ]
[ --separate-files ] [ --static-call-graph ] [ --sum ]
[ --table-length=len ] [ --traditional ] [ --version ]
[ --width=n ] [ --ignore-non-functions ]
[ --demangle[=STYLE] ] [ --no-demangle ]
[--external-symbol-table=name]
[ image-file ] [ profile-file ... ]
"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.
If you use gcc 2.95.x or 3.0 to compile your binaries, you may
need to add the -fprofile-arcs to the compile command line in order
for the call graphs to be properly stored in gmon.out.
"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.
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.
- "-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. This feature only works with programs compiled by older
versions of the "gcc" compiler. Newer
versions of "gcc" are designed to work
with the "gcov" tool instead.
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.
- "--inline-file-names"
- This option causes "gprof" to print the
source file after each symbol in both the flat profile and the call graph.
The full path to the file is printed if used with the -L
option.
- "-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.
- "-Sfilename"
- "--external-symbol-table=filename"
- The -S option causes "gprof" to
read an external symbol table file, such as /proc/kallsyms, rather
than read the symbol table from the given object file (the default is
"a.out"). This is useful for profiling
kernel modules.
- "-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.
- "-d[num]"
- "--debug[=num]"
- The -d num 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.
These options have been replaced with newer versions that use
symspecs.
- "-e function_name"
- The -e function 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 -f function 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 -F function 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.
- "a.out"
- the namelist and text space.
- "gmon.out"
- dynamic call graph and profile.
- "gmon.sum"
- summarized dynamic call graph and profile.
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.
cc(1), prof(1), and the Info entry for
gprof.
"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.
Copyright (c) 1988-2018 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version 1.3
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".