-
- <para>systemd-bootchart is a tool used to analyze a boot sequence.
- It collects system information pertaining to the CPU and disk load, as
- well as per-process information, and then creates a chart with this
- information. Usually it is invoked by setting the init to
- <filename>systemd-bootchart</filename> on the kernel command line. It
- be run after boot to analyze running processes, though it is recommended
- to use the <option>--rel</option> switch when doing this.</para>
-
- <para>After collecting a certain amount of data (default: 20 seconds) it
- will write the SVG chart to <filename>/run/log</filename>. This chart
- can be used to find problems in the start up sequence and where these
- problems exist. It is essentially a more detailed version of the
- systemd-analyze plot function.</para>
+ <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>