Merge pull request #221 from utezduyar/man-cgtop-explain-max-cpu

[thirdparty/systemd.git] / man / systemd-bootchart.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
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<!--
  This file is part of systemd.

  Copyright 2012 Intel Corporation

  Authors:
    Auke Kok <auke-jan.h.kok@intel.com>
    William Giokas <1007380@gmail.com>

  systemd is free software; you can redistribute it and/or modify it
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<refentry id="systemd-bootchart" conditional='ENABLE_BOOTCHART'
    xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>systemd-bootchart</title>
    <productname>systemd</productname>

    <authorgroup>
      <author>
        <contrib>Developer</contrib>
        <firstname>Auke</firstname>
        <surname>Kok</surname>
        <email>auke-jan.h.kok@intel.com</email>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd-bootchart</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd-bootchart</refname>
    <refpurpose>Boot performance graphing tool</refpurpose>
  </refnamediv>

  <refsect1>
    <title>Description</title>
    <para>
      <command>systemd-bootchart</command> is a tool, usually run at
      system startup, that collects the CPU load, disk load, memory
      usage, as well as per-process information from a running system.
      Collected results are output as an SVG graph. Normally,
      systemd-bootchart is invoked by the kernel by passing
      <option>init=<filename>&rootlibexecdir;/systemd-bootchart</filename></option>
      on the kernel command line. systemd-bootchart will then fork the
      real init off to resume normal system startup, while monitoring
      and logging startup information in the background.
    </para>
    <para>
      After collecting a certain amount of data (usually 15-30
      seconds, default 20 s) the logging stops and a graph is
      generated from the logged information. This graph contains vital
      clues as to which resources are being used, in which order, and
      where possible problems exist in the startup sequence of the
      system. It is essentially a more detailed version of the
      <command>systemd-analyze plot</command> function.
    </para>
    <para>
      Of course, bootchart can also be used at any moment in time to
      collect and graph some data for an amount of time. It is
      recommended to use the <option>--rel</option> switch in this
      case.
    </para>
    <para>
      Bootchart does not require root privileges, and will happily run
      as a normal user.
    </para>
    <para>
      Bootchart graphs are by default written time-stamped in
      <filename>/run/log</filename> and saved to the journal with
      <varname>MESSAGE_ID=9f26aa562cf440c2b16c773d0479b518</varname>.
      Journal field <varname>BOOTCHART=</varname> contains the
      bootchart in SVG format.
    </para>

  </refsect1>

  <refsect1>
    <title>Invocation</title>

    <para><command>systemd-bootchart</command> can be invoked in several different ways:</para>

    <variablelist>

      <varlistentry>
        <term><emphasis>Kernel invocation</emphasis></term>
        <listitem><para>The kernel can invoke
        <command>systemd-bootchart</command> instead of the init
        process. In turn, <command>systemd-bootchart</command> will
        invoke <command>&rootlibexecdir;/systemd</command>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis>Started as a standalone program</emphasis></term>
        <listitem><para>One can execute
        <command>systemd-bootchart</command> as normal application
        from the command line. In this mode it is highly recommended
        to pass the <option>-r</option> flag in order to not graph the
        time elapsed since boot and before systemd-bootchart was
        started, as it may result in extremely large graphs. The time
        elapsed since boot might also include any time that the system
        was suspended.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>These options can also be set in the
    <filename>&pkgsysconfdir;/bootchart.conf</filename> file. See
    <citerefentry project='man-pages'><refentrytitle>bootchart.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
    </para>

    <variablelist>
      <xi:include href="standard-options.xml" xpointer="help" />

      <varlistentry>
        <term><option>-n</option></term>
        <term><option>--sample <replaceable>N</replaceable></option></term>
        <listitem><para>Specify the number of samples,
        <replaceable>N</replaceable>, to record. Samples will be
        recorded at intervals defined with <option>--freq</option>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-f</option></term>
        <term><option>--freq <replaceable>f</replaceable></option></term>
        <listitem><para>Specify the sample log frequency, a positive
        real <replaceable>f</replaceable>, in Hz. Most systems can
        cope with values up to 25-50 without creating too much
        overhead.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-r</option></term>
        <term><option>--rel</option></term>
        <listitem><para>Use relative times instead of absolute times.
        This is useful for using bootchart at post-boot time to
        profile an already booted system. Without this option the
        graph would become extremely large. If set, the horizontal
        axis starts at the first recorded sample instead of time
        0.0.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-F</option></term>
        <term><option>--no-filter</option></term>
        <listitem><para>Disable filtering of tasks that did not
        contribute significantly to the boot. Processes that are too
        short-lived (only seen in one sample) or that do not consume
        any significant CPU time (less than 0.001 s) will not be
        displayed in the output graph. </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-C</option></term>
        <term><option>--cmdline</option></term>
        <listitem><para>Display the full command line with arguments
        of processes, instead of only the process name.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-g</option></term>
        <term><option>--control-group</option></term>
        <listitem><para>Display process control group
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-o</option></term>
        <term><option>--output <replaceable>path</replaceable></option></term>
        <listitem><para>Specify the output directory for the graphs.
        By default, bootchart writes the graphs to
        <filename>/run/log</filename>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-i</option></term>
        <term><option>--init <replaceable>path</replaceable></option></term>
        <listitem><para>Use this init binary. Defaults to
        <command>&rootlibexecdir;/systemd</command>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-p</option></term>
        <term><option>--pss</option></term>
        <listitem><para>Enable logging and graphing of processes' PSS
        (Proportional Set Size) memory consumption. See
        <filename>filesystems/proc.txt</filename> in the kernel
        documentation for an explanation of this field.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-e</option></term>
        <term><option>--entropy</option></term>
        <listitem><para>Enable logging and graphing of the kernel
        random entropy pool size.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-x</option></term>
        <term><option>--scale-x <replaceable>N</replaceable></option></term>
        <listitem><para>Horizontal scaling factor for all variable
        graph components.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-y</option></term>
        <term><option>--scale-y <replaceable>N</replaceable></option></term>
        <listitem><para>Vertical scaling factor for all variable graph
        components.</para></listitem>
      </varlistentry>

    </variablelist>


  </refsect1>

  <refsect1>
    <title>Output</title>

    <para><command>systemd-bootchart</command> generates SVG graphs.
    In order to render those on a graphical display any SVG capable
    viewer can be used. It should be noted that the SVG render engines
    in most browsers (including Chrome and Firefox) are many times
    faster than dedicated graphical applications like Gimp and
    Inkscape. Just point your browser at
    <ulink url="file:///run/log/" />!
    </para>
  </refsect1>

  <refsect1>
    <title>History</title>

    <para>This version of bootchart was implemented from scratch, but
    is inspired by former bootchart incantations:</para>

    <variablelist>
      <varlistentry>
        <term><emphasis>Original bash</emphasis></term>
        <listitem><para>The original bash/shell code implemented
        bootchart. This version created a compressed tarball for
        processing with external applications. This version did not
        graph anything, only generated data.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis>Ubuntu C Implementation</emphasis></term>
        <listitem><para>This version replaced the shell version with a
        fast and efficient data logger, but also did not graph the
        data.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis>Java bootchart</emphasis></term>
        <listitem><para>This was the original graphing application for
        charting the data, written in java.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis>pybootchartgui.py</emphasis></term>
        <listitem><para>pybootchart created a graph from the data
        collected by either the bash or C version.</para></listitem>
      </varlistentry>
    </variablelist>

    <para>The version of bootchart you are using now combines both the
    data collection and the charting into a single application, making
    it more efficient and simpler. There are no longer any timing
    issues with the data collector and the grapher, as the graphing
    cannot be run until the data has been collected. Also, the data
    kept in memory is reduced to the absolute minimum needed.</para>

  </refsect1>

  <refsect1>
    <title>See Also</title>

    <para>
      <citerefentry project='man-pages'><refentrytitle>bootchart.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
    </para>
  </refsect1>

  <refsect1>
    <title>Bugs</title>

    <para>systemd-bootchart does not get the model information for the
    hard drive unless the root device is specified with
    <code>root=/dev/sdxY</code>. Using UUIDs or PARTUUIDs will boot
    fine, but the hard drive model will not be added to the
    chart.</para>
    <para>For bugs, please contact the author and current maintainer:</para>
    <simplelist>
      <member>Auke Kok <email>auke-jan.h.kok@intel.com</email></member>
    </simplelist>
  </refsect1>

</refentry>