gprof
display call graph profile data
TLDR
Compile binary with gprof information and run it to get gmon.out
Run gprof to obtain profile output
Suppress profile field's description
Display routines that have zero usage
SYNOPSIS
gprof [ -[abcDhilLrsTvwxyz] ] [ -[ACeEfFJnNOpPqQRStZ][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 ... ]
DESCRIPTION
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. 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.
Miscellaneous Options
- "-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.
Deprecated Options
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.
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.
COPYRIGHT
Copyright (c) 1988-2022 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.
SEE ALSO
monitor (3), profil (2), 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.