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systemd-stable/man/systemd-bootchart.xml
Karel Zak c358d728e7 bootchart: don't parse /proc/uptime, use CLOCK_BOOTTIME
* systemd-bootchart always parses /proc/uptime, although the
  information is unnecessary when --rel specified

* use /proc/uptime is overkill, since Linux 2.6.39 we have
  clock_gettime(CLOCK_BOOTTIME, ...). The backend on kernel side is
  get_monotonic_boottime() in both cases.

* main() uses "if (graph_start <= 0.0)" to detect that /proc is
  available.

  This is fragile solution as graph_start is always smaller than zero
  on all systems after suspend/resume (e.g. laptops), because in this
  case the system uptime includes suspend time and uptime is always
  greater number than monotonic time. For example right now difference
  between uptime and monotonic time is 37 hours on my laptop.

  Note that main() calls log_uptime() (to parse /proc/uptime) for each
  sample when it believes that /proc is not available. So on my laptop
  systemd-boochars spends all live with /proc/uptime parsing +
  nanosleep(), try

    strace  /usr/lib/systemd/systemd-bootchart

  to see the never ending loop.

  This patch uses access("/proc/vmstat", F_OK) to detect procfs.
2014-08-03 01:12:53 -04:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
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
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<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>/usr/lib/systemd/systemd-bootchart</filename></option>
on the kernel commandline. 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>/sbin/init</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
commandline. 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>/etc/systemd/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>/sbin/init</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>