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linux/tools/perf/Documentation/perf-config.txt
Tony Jones eadcaa3dfd perf callchain: Update docs regarding kernel/user space unwinding 
The method of unwinding for kernel space is defined by the kernel
config, not by the value of --call-graph.   Improve the documentation to
reflect this.

Signed-off-by: Tony Jones <tonyj@suse.de>
Link: http://lore.kernel.org/lkml/20200325164053.10177-1-tonyj@suse.de
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2020-03-25 16:13:21 -03:00

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perf-config(1)
==============
NAME
----
perf-config - Get and set variables in a configuration file.
SYNOPSIS
--------
[verse]
'perf config' [<file-option>] [section.name[=value] ...]
or
'perf config' [<file-option>] -l | --list
DESCRIPTION
-----------
You can manage variables in a configuration file with this command.
OPTIONS
-------
-l::
--list::
Show current config variables, name and value, for all sections.
--user::
For writing and reading options: write to user
'$HOME/.perfconfig' file or read it.
--system::
For writing and reading options: write to system-wide
'$(sysconfdir)/perfconfig' or read it.
CONFIGURATION FILE
------------------
The perf configuration file contains many variables to change various
aspects of each of its tools, including output, disk usage, etc.
The '$HOME/.perfconfig' file is used to store a per-user configuration.
The file '$(sysconfdir)/perfconfig' can be used to
store a system-wide default configuration.
One an disable reading config files by setting the PERF_CONFIG environment
variable to /dev/null, or provide an alternate config file by setting that
variable.
When reading or writing, the values are read from the system and user
configuration files by default, and options '--system' and '--user'
can be used to tell the command to read from or write to only that location.
Syntax
~~~~~~
The file consist of sections. A section starts with its name
surrounded by square brackets and continues till the next section
begins. Each variable must be in a section, and have the form
'name = value', for example:
[section]
name1 = value1
name2 = value2
Section names are case sensitive and can contain any characters except
newline (double quote `"` and backslash have to be escaped as `\"` and `\\`,
respectively). Section headers can't span multiple lines.
Example
~~~~~~~
Given a $HOME/.perfconfig like this:
#
# This is the config file, and
# a '#' and ';' character indicates a comment
#
[colors]
# Color variables
top = red, default
medium = green, default
normal = lightgray, default
selected = white, lightgray
jump_arrows = blue, default
addr = magenta, default
root = white, blue
[tui]
# Defaults if linked with libslang
report = on
annotate = on
top = on
[buildid]
# Default, disable using /dev/null
dir = ~/.debug
[annotate]
# Defaults
hide_src_code = false
use_offset = true
jump_arrows = true
show_nr_jumps = false
[help]
# Format can be man, info, web or html
format = man
autocorrect = 0
[ui]
show-headers = true
[call-graph]
# fp (framepointer), dwarf
record-mode = fp
print-type = graph
order = caller
sort-key = function
[report]
# Defaults
sort_order = comm,dso,symbol
percent-limit = 0
queue-size = 0
children = true
group = true
[llvm]
dump-obj = true
clang-opt = -g
You can hide source code of annotate feature setting the config to false with
% perf config annotate.hide_src_code=true
If you want to add or modify several config items, you can do like
% perf config ui.show-headers=false kmem.default=slab
To modify the sort order of report functionality in user config file(i.e. `~/.perfconfig`), do
% perf config --user report sort-order=srcline
To change colors of selected line to other foreground and background colors
in system config file (i.e. `$(sysconf)/perfconfig`), do
% perf config --system colors.selected=yellow,green
To query the record mode of call graph, do
% perf config call-graph.record-mode
If you want to know multiple config key/value pairs, you can do like
% perf config report.queue-size call-graph.order report.children
To query the config value of sort order of call graph in user config file (i.e. `~/.perfconfig`), do
% perf config --user call-graph.sort-order
To query the config value of buildid directory in system config file (i.e. `$(sysconf)/perfconfig`), do
% perf config --system buildid.dir
Variables
~~~~~~~~~
colors.*::
The variables for customizing the colors used in the output for the
'report', 'top' and 'annotate' in the TUI. They should specify the
foreground and background colors, separated by a comma, for example:
medium = green, lightgray
If you want to use the color configured for you terminal, just leave it
as 'default', for example:
medium = default, lightgray
Available colors:
red, yellow, green, cyan, gray, black, blue,
white, default, magenta, lightgray
colors.top::
'top' means a overhead percentage which is more than 5%.
And values of this variable specify percentage colors.
Basic key values are foreground-color 'red' and
background-color 'default'.
colors.medium::
'medium' means a overhead percentage which has more than 0.5%.
Default values are 'green' and 'default'.
colors.normal::
'normal' means the rest of overhead percentages
except 'top', 'medium', 'selected'.
Default values are 'lightgray' and 'default'.
colors.selected::
This selects the colors for the current entry in a list of entries
from sub-commands (top, report, annotate).
Default values are 'black' and 'lightgray'.
colors.jump_arrows::
Colors for jump arrows on assembly code listings
such as 'jns', 'jmp', 'jane', etc.
Default values are 'blue', 'default'.
colors.addr::
This selects colors for addresses from 'annotate'.
Default values are 'magenta', 'default'.
colors.root::
Colors for headers in the output of a sub-commands (top, report).
Default values are 'white', 'blue'.
core.*::
core.proc-map-timeout::
Sets a timeout (in milliseconds) for parsing /proc/<pid>/maps files.
Can be overridden by the --proc-map-timeout option on supported
subcommands. The default timeout is 500ms.
tui.*, gtk.*::
Subcommands that can be configured here are 'top', 'report' and 'annotate'.
These values are booleans, for example:
[tui]
top = true
will make the TUI be the default for the 'top' subcommand. Those will be
available if the required libs were detected at tool build time.
buildid.*::
buildid.dir::
Each executable and shared library in modern distributions comes with a
content based identifier that, if available, will be inserted in a
'perf.data' file header to, at analysis time find what is needed to do
symbol resolution, code annotation, etc.
The recording tools also stores a hard link or copy in a per-user
directory, $HOME/.debug/, of binaries, shared libraries, /proc/kallsyms
and /proc/kcore files to be used at analysis time.
The buildid.dir variable can be used to either change this directory
cache location, or to disable it altogether. If you want to disable it,
set buildid.dir to /dev/null. The default is $HOME/.debug
annotate.*::
These are in control of addresses, jump function, source code
in lines of assembly code from a specific program.
annotate.hide_src_code::
If a program which is analyzed has source code,
this option lets 'annotate' print a list of assembly code with the source code.
For example, let's see a part of a program. There're four lines.
If this option is 'true', they can be printed
without source code from a program as below.
│ push %rbp
│ mov %rsp,%rbp
│ sub $0x10,%rsp
│ mov (%rdi),%rdx
But if this option is 'false', source code of the part
can be also printed as below. Default is 'false'.
│ struct rb_node *rb_next(const struct rb_node *node)
│ {
│ push %rbp
│ mov %rsp,%rbp
│ sub $0x10,%rsp
│ struct rb_node *parent;
│
│ if (RB_EMPTY_NODE(node))
│ mov (%rdi),%rdx
│ return n;
This option works with tui, stdio2 browsers.
annotate.use_offset::
Basing on a first address of a loaded function, offset can be used.
Instead of using original addresses of assembly code,
addresses subtracted from a base address can be printed.
Let's illustrate an example.
If a base address is 0XFFFFFFFF81624d50 as below,
ffffffff81624d50 <load0>
an address on assembly code has a specific absolute address as below
ffffffff816250b8:│ mov 0x8(%r14),%rdi
but if use_offset is 'true', an address subtracted from a base address is printed.
Default is true. This option is only applied to TUI.
368:│ mov 0x8(%r14),%rdi
This option works with tui, stdio2 browsers.
annotate.jump_arrows::
There can be jump instruction among assembly code.
Depending on a boolean value of jump_arrows,
arrows can be printed or not which represent
where do the instruction jump into as below.
│ ┌──jmp 1333
│ │ xchg %ax,%ax
│1330:│ mov %r15,%r10
│1333:└─→cmp %r15,%r14
If jump_arrow is 'false', the arrows isn't printed as below.
Default is 'false'.
│ ↓ jmp 1333
│ xchg %ax,%ax
│1330: mov %r15,%r10
│1333: cmp %r15,%r14
This option works with tui browser.
annotate.show_linenr::
When showing source code if this option is 'true',
line numbers are printed as below.
│1628 if (type & PERF_SAMPLE_IDENTIFIER) {
│ ↓ jne 508
│1628 data->id = *array;
│1629 array++;
│1630 }
However if this option is 'false', they aren't printed as below.
Default is 'false'.
│ if (type & PERF_SAMPLE_IDENTIFIER) {
│ ↓ jne 508
│ data->id = *array;
│ array++;
│ }
This option works with tui, stdio2 browsers.
annotate.show_nr_jumps::
Let's see a part of assembly code.
│1382: movb $0x1,-0x270(%rbp)
If use this, the number of branches jumping to that address can be printed as below.
Default is 'false'.
│1 1382: movb $0x1,-0x270(%rbp)
This option works with tui, stdio2 browsers.
annotate.show_total_period::
To compare two records on an instruction base, with this option
provided, display total number of samples that belong to a line
in assembly code. If this option is 'true', total periods are printed
instead of percent values as below.
302 │ mov %eax,%eax
But if this option is 'false', percent values for overhead are printed i.e.
Default is 'false'.
99.93 │ mov %eax,%eax
This option works with tui, stdio2, stdio browsers.
annotate.show_nr_samples::
By default perf annotate shows percentage of samples. This option
can be used to print absolute number of samples. Ex, when set as
false:
Percent│
74.03 │ mov %fs:0x28,%rax
When set as true:
Samples│
6 │ mov %fs:0x28,%rax
This option works with tui, stdio2, stdio browsers.
annotate.offset_level::
Default is '1', meaning just jump targets will have offsets show right beside
the instruction. When set to '2' 'call' instructions will also have its offsets
shown, 3 or higher will show offsets for all instructions.
This option works with tui, stdio2 browsers.
hist.*::
hist.percentage::
This option control the way to calculate overhead of filtered entries -
that means the value of this option is effective only if there's a
filter (by comm, dso or symbol name). Suppose a following example:
Overhead Symbols
........ .......
33.33% foo
33.33% bar
33.33% baz
This is an original overhead and we'll filter out the first 'foo'
entry. The value of 'relative' would increase the overhead of 'bar'
and 'baz' to 50.00% for each, while 'absolute' would show their
current overhead (33.33%).
ui.*::
ui.show-headers::
This option controls display of column headers (like 'Overhead' and 'Symbol')
in 'report' and 'top'. If this option is false, they are hidden.
This option is only applied to TUI.
call-graph.*::
The following controls the handling of call-graphs (obtained via the
-g/--call-graph options).
call-graph.record-mode::
The mode for user space can be 'fp' (frame pointer), 'dwarf'
and 'lbr'. The value 'dwarf' is effective only if libunwind
(or a recent version of libdw) is present on the system;
the value 'lbr' only works for certain cpus. The method for
kernel space is controlled not by this option but by the
kernel config (CONFIG_UNWINDER_*).
call-graph.dump-size::
The size of stack to dump in order to do post-unwinding. Default is 8192 (byte).
When using dwarf into record-mode, the default size will be used if omitted.
call-graph.print-type::
The print-types can be graph (graph absolute), fractal (graph relative),
flat and folded. This option controls a way to show overhead for each callchain
entry. Suppose a following example.
Overhead Symbols
........ .......
40.00% foo
|
---foo
|
|--50.00%--bar
| main
|
--50.00%--baz
main
This output is a 'fractal' format. The 'foo' came from 'bar' and 'baz' exactly
half and half so 'fractal' shows 50.00% for each
(meaning that it assumes 100% total overhead of 'foo').
The 'graph' uses absolute overhead value of 'foo' as total so each of
'bar' and 'baz' callchain will have 20.00% of overhead.
If 'flat' is used, single column and linear exposure of call chains.
'folded' mean call chains are displayed in a line, separated by semicolons.
call-graph.order::
This option controls print order of callchains. The default is
'callee' which means callee is printed at top and then followed by its
caller and so on. The 'caller' prints it in reverse order.
If this option is not set and report.children or top.children is
set to true (or the equivalent command line option is given),
the default value of this option is changed to 'caller' for the
execution of 'perf report' or 'perf top'. Other commands will
still default to 'callee'.
call-graph.sort-key::
The callchains are merged if they contain same information.
The sort-key option determines a way to compare the callchains.
A value of 'sort-key' can be 'function' or 'address'.
The default is 'function'.
call-graph.threshold::
When there're many callchains it'd print tons of lines. So perf omits
small callchains under a certain overhead (threshold) and this option
control the threshold. Default is 0.5 (%). The overhead is calculated
by value depends on call-graph.print-type.
call-graph.print-limit::
This is a maximum number of lines of callchain printed for a single
histogram entry. Default is 0 which means no limitation.
report.*::
report.sort_order::
Allows changing the default sort order from "comm,dso,symbol" to
some other default, for instance "sym,dso" may be more fitting for
kernel developers.
report.percent-limit::
This one is mostly the same as call-graph.threshold but works for
histogram entries. Entries having an overhead lower than this
percentage will not be printed. Default is '0'. If percent-limit
is '10', only entries which have more than 10% of overhead will be
printed.
report.queue-size::
This option sets up the maximum allocation size of the internal
event queue for ordering events. Default is 0, meaning no limit.
report.children::
'Children' means functions called from another function.
If this option is true, 'perf report' cumulates callchains of children
and show (accumulated) total overhead as well as 'Self' overhead.
Please refer to the 'perf report' manual. The default is 'true'.
report.group::
This option is to show event group information together.
Example output with this turned on, notice that there is one column
per event in the group, ref-cycles and cycles:
# group: {ref-cycles,cycles}
# ========
#
# Samples: 7K of event 'anon group { ref-cycles, cycles }'
# Event count (approx.): 6876107743
#
# Overhead Command Shared Object Symbol
# ................ ....... ................. ...................
#
99.84% 99.76% noploop noploop [.] main
0.07% 0.00% noploop ld-2.15.so [.] strcmp
0.03% 0.00% noploop [kernel.kallsyms] [k] timerqueue_del
top.*::
top.children::
Same as 'report.children'. So if it is enabled, the output of 'top'
command will have 'Children' overhead column as well as 'Self' overhead
column by default.
The default is 'true'.
top.call-graph::
This is identical to 'call-graph.record-mode', except it is
applicable only for 'top' subcommand. This option ONLY setup
the unwind method. To enable 'perf top' to actually use it,
the command line option -g must be specified.
man.*::
man.viewer::
This option can assign a tool to view manual pages when 'help'
subcommand was invoked. Supported tools are 'man', 'woman'
(with emacs client) and 'konqueror'. Default is 'man'.
New man viewer tool can be also added using 'man.<tool>.cmd'
or use different path using 'man.<tool>.path' config option.
pager.*::
pager.<subcommand>::
When the subcommand is run on stdio, determine whether it uses
pager or not based on this value. Default is 'unspecified'.
kmem.*::
kmem.default::
This option decides which allocator is to be analyzed if neither
'--slab' nor '--page' option is used. Default is 'slab'.
record.*::
record.build-id::
This option can be 'cache', 'no-cache' or 'skip'.
'cache' is to post-process data and save/update the binaries into
the build-id cache (in ~/.debug). This is the default.
But if this option is 'no-cache', it will not update the build-id cache.
'skip' skips post-processing and does not update the cache.
record.call-graph::
This is identical to 'call-graph.record-mode', except it is
applicable only for 'record' subcommand. This option ONLY setup
the unwind method. To enable 'perf record' to actually use it,
the command line option -g must be specified.
record.aio::
Use 'n' control blocks in asynchronous (Posix AIO) trace writing
mode ('n' default: 1, max: 4).
diff.*::
diff.order::
This option sets the number of columns to sort the result.
The default is 0, which means sorting by baseline.
Setting it to 1 will sort the result by delta (or other
compute method selected).
diff.compute::
This options sets the method for computing the diff result.
Possible values are 'delta', 'delta-abs', 'ratio' and
'wdiff'. Default is 'delta'.
trace.*::
trace.add_events::
Allows adding a set of events to add to the ones specified
by the user, or use as a default one if none was specified.
The initial use case is to add augmented_raw_syscalls.o to
activate the 'perf trace' logic that looks for syscall
pointer contents after the normal tracepoint payload.
trace.args_alignment::
Number of columns to align the argument list, default is 70,
use 40 for the strace default, zero to no alignment.
trace.no_inherit::
Do not follow children threads.
trace.show_arg_names::
Should syscall argument names be printed? If not then trace.show_zeros
will be set.
trace.show_duration::
Show syscall duration.
trace.show_prefix::
If set to 'yes' will show common string prefixes in tables. The default
is to remove the common prefix in things like "MAP_SHARED", showing just "SHARED".
trace.show_timestamp::
Show syscall start timestamp.
trace.show_zeros::
Do not suppress syscall arguments that are equal to zero.
trace.tracepoint_beautifiers::
Use "libtraceevent" to use that library to augment the tracepoint arguments,
"libbeauty", the default, to use the same argument beautifiers used in the
strace-like sys_enter+sys_exit lines.
ftrace.*::
ftrace.tracer::
Can be used to select the default tracer. Possible values are
'function' and 'function_graph'.
llvm.*::
llvm.clang-path::
Path to clang. If omit, search it from $PATH.
llvm.clang-bpf-cmd-template::
Cmdline template. Below lines show its default value. Environment
variable is used to pass options.
"$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\
"-DLINUX_VERSION_CODE=$LINUX_VERSION_CODE " \
"$CLANG_OPTIONS $PERF_BPF_INC_OPTIONS $KERNEL_INC_OPTIONS " \
"-Wno-unused-value -Wno-pointer-sign " \
"-working-directory $WORKING_DIR " \
"-c \"$CLANG_SOURCE\" -target bpf $CLANG_EMIT_LLVM -O2 -o - $LLVM_OPTIONS_PIPE"
llvm.clang-opt::
Options passed to clang.
llvm.kbuild-dir::
kbuild directory. If not set, use /lib/modules/`uname -r`/build.
If set to "" deliberately, skip kernel header auto-detector.
llvm.kbuild-opts::
Options passed to 'make' when detecting kernel header options.
llvm.dump-obj::
Enable perf dump BPF object files compiled by LLVM.
llvm.opts::
Options passed to llc.
samples.*::
samples.context::
Define how many ns worth of time to show
around samples in perf report sample context browser.
scripts.*::
Any option defines a script that is added to the scripts menu
in the interactive perf browser and whose output is displayed.
The name of the option is the name, the value is a script command line.
The script gets the same options passed as a full perf script,
in particular -i perfdata file, --cpu, --tid
convert.*::
convert.queue-size::
Limit the size of ordered_events queue, so we could control
allocation size of perf data files without proper finished
round events.
intel-pt.*::
intel-pt.cache-divisor::
intel-pt.mispred-all::
If set, Intel PT decoder will set the mispred flag on all
branches.
auxtrace.*::
auxtrace.dumpdir::
s390 only. The directory to save the auxiliary trace buffer
can be changed using this option. Ex, auxtrace.dumpdir=/tmp.
If the directory does not exist or has the wrong file type,
the current directory is used.
SEE ALSO
--------
linkperf:perf[1]
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