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<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
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<chapter id="feature-pcp">
  <title>PCP</title>

  <para>If available, Cockpit uses the
    <ulink url="https://pcp.io/">Performance Co-Pilot</ulink> framework to
    gather metrics data about the system. This data is used to display graphs.
    Cockpit can use the PCP logging feature to display archived data about the
    system from a different point in time. If PCP is not available, then Cockpit
    gathers the metrics data itself, but archival features are not available.</para>

  <para>Whether or not metrics are archived depends on whether the
    <code>pmlogger.service</code> and <code>pmcd.service</code> systemd units
    are running or not.  The "Store Performance Data" button in Cockpit
    will enable and start these services.</para>

  <para>To see similar metrics data from the command line, you can use tools like
    <ulink url="https://pcp.io/books/PCP_UAG/html/LE38515-PARENT.html#LE91266-PARENT"><code>pmstat</code></ulink>
    or <ulink url="https://pcp.io/books/PCP_UAG/html/LE60452-PARENT.html"><code>pminfo</code></ulink>:</para>

<programlisting>
$ <command>pmstat</command>
@ Sat Sep 26 15:30:10 2015
 loadavg                      memory      swap        io    system         cpu
   1 min   swpd   free   buff  cache   pi   po   bi   bo   in   cs  us  sy  id
    4.19      0 20710m 605148  6450m    0    0    0 2548 5688  14K  19   3  76
...
</programlisting>

</chapter>
