avr-gprof Man page

Resume Wikipedia de OProfile

OProfile est un outil de profilage de code pour Linux, dont la première version a été écrite par John Levon en 2001 en tant que projet pour son Master en sciences.
Oprofile se compose d’un module noyau, ainsi que d’un daemon et de plusieurs utilitaires en espace utilisateur (un module noyau n’est plus requis depuis la version 0.9.8).
Oprofile permet de profiler le système entier ou bien un sous ensemble tel que les routines d’interruption, les pilotes de périphériques ou les process en espace utilisateur. Le surcoût de l’instrumentation reste faible.
Les modes d’instrumentation portable de Oprofile utilisent les timers système pour générer des évènements de mesure à intervalles réguliers. Certains modes, spécifiques à certains processeurs mais moins intrusifs, consistent à utiliser les hardware performance counters (en) intégrés. Le support pour les versions 2.2/2.4 de Linux ne comprend que les processeurs 32bits x86 et IA64. Pour les versions 2.6 du noyau Linux de nombreuses architectures sont supportées: x86 et x86_64, DEC Alpha, MIPS, ARM, Sparc64, PPC64, AVR. Les diagrammes de flux (en) ne sont disponibles que pour x86 et ARM.
En 2012, les ingénieurs d’IBM ont reconnu Oprofile comme étant l’un des outils de monitoring les plus utilisés sous Linux (avec perf tool).

Resume Wikipedia de OProfile

OProfile est un outil de profilage de code pour Linux, dont la première version a été écrite par John Levon en 2001 en tant que projet pour son Master en sciences.
Oprofile se compose d’un module noyau, ainsi que d’un daemon et de plusieurs utilitaires en espace utilisateur (un module noyau n’est plus requis depuis la version 0.9.8).
Oprofile permet de profiler le système entier ou bien un sous ensemble tel que les routines d’interruption, les pilotes de périphériques ou les process en espace utilisateur. Le surcoût de l’instrumentation reste faible.
Les modes d’instrumentation portable de Oprofile utilisent les timers système pour générer des évènements de mesure à intervalles réguliers. Certains modes, spécifiques à certains processeurs mais moins intrusifs, consistent à utiliser les hardware performance counters (en) intégrés. Le support pour les versions 2.2/2.4 de Linux ne comprend que les processeurs 32bits x86 et IA64. Pour les versions 2.6 du noyau Linux de nombreuses architectures sont supportées: x86 et x86_64, DEC Alpha, MIPS, ARM, Sparc64, PPC64, AVR. Les diagrammes de flux (en) ne sont disponibles que pour x86 et ARM.
En 2012, les ingénieurs d’IBM ont reconnu Oprofile comme étant l’un des outils de monitoring les plus utilisés sous Linux (avec perf tool).

GPROF(1) GNU GPROF(1)

NAME

gprof – display call graph profile data

SYNOPSIS

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 … ]

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.

SEE ALSO

monitor(3), profil(2), cc, 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.

COPRYRIGHT

Copyright (c) 1988-2014 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”.

binutils-2.25 2014-12-23 GPROF(1)

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