perf-config man page

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

Synopsis

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.

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

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.

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 options work only for TUI. 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;

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

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

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++;
│             }

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)

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

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.*

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

call-graph.record-mode

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.

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.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.

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.

See Also

perf(1)

Info

10/03/2016 perf perf Manual