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PERF_4.16-CONFIG(1) perf Manual PERF_4.16-CONFIG(1)


perf-config - Get and set variables in a configuration file.


perf config [<file-option>] [[=value] ...]
perf config [<file-option>] -l | --list


You can manage variables in a configuration file with this command.


-l, --list

Show current config variables, name and value, for all sections.


For writing and reading options: write to user $HOME/.perfconfig file or read it.


For writing and reading options: write to system-wide $(sysconfdir)/perfconfig or read it.


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.

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.


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:


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.


Given a $HOME/.perfconfig like this:

# # This is the config file, and # a # and ; character indicates a comment #


# Color variables
top = red, default
medium = green, default
normal = lightgray, default
selected = white, lightgray
jump_arrows = blue, default
addr = magenta, default
root = white, blue


# Defaults if linked with libslang
report = on
annotate = on
top = on


# Default, disable using /dev/null
dir = ~/.debug


# Defaults
hide_src_code = false
use_offset = true
jump_arrows = true
show_nr_jumps = false


# Format can be man, info, web or html
format = man
autocorrect = 0


show-headers = true


# fp (framepointer), dwarf
record-mode = fp
print-type = graph
order = caller
sort-key = function


# Defaults
sort-order = comm,dso,symbol
percent-limit = 0
queue-size = 0
children = true
group = true

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 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



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

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.


medium means a overhead percentage which has more than 0.5%. Default values are green and default.


normal means the rest of overhead percentages except top, medium, selected. Default values are lightgray and default.


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 for jump arrows on assembly code listings such as jns, jmp, jane, etc. Default values are blue, default.


This selects colors for addresses from annotate. Default values are magenta, default.


Colors for headers in the output of a sub-commands (top, report). Default values are white, blue.

tui., gtk.

Subcommands that can be configured here are top, report and annotate. These values are booleans, for example:


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 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


These options work only for TUI. These are in control of addresses, jump function, source code in lines of assembly code from a specific program.


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;


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


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


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++;
│             }


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)


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

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%).


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.


When sub-commands top and report work with -g/—-children there’re options in control of call-graph.


The record-mode can be fp (frame pointer), dwarf and lbr. The value of dwarf is effective only if perf detect needed library (libunwind or a recent version of libdw). lbr only work for cpus that support it.


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.


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
| 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.


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'.


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.


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.


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.


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.


This option sets up the maximum allocation size of the internal event queue for ordering events. Default is 0, meaning no limit.


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.

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 [.] 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.

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.


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.

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).


This options sets the method for computing the diff result. Possible values are delta, delta-abs, ratio and wdiff. Default is delta.



2018-04-08 perf