of controller names. Pass an empty
string to ensure that systemd does not
touch any hierarchies but its
- own.</para></listitem>
+ own.</para>
+
+ <para>Note that the default value of
+ 'cpu' will make realtime scheduling
+ unavailable to system services. See
+ <ulink
+ url="http://www.freedesktop.org/wiki/Software/systemd/MyServiceCantGetRealtime">My
+ Service Can't Get Realtime!</ulink>
+ for more
+ information.</para></listitem>
</varlistentry>
<varlistentry>
'cpu,cpuacct'. Pass an empty string to
ensure that systemd mounts all
controllers in separate
- hierarchies.</para></listitem>
+ hierarchies.</para>
+
+ <para>Note that this option is only
+ applied once, at very early boot. If
+ you use an initial RAM disk (initrd)
+ that uses systemd it might hence be
+ necessary to rebuild the initrd if
+ this option is changed, and make sure
+ the new configuration file is included
+ in it. Otherwise the initrd might
+ mount the controller hierachies in a
+ different configuration than intended,
+ and the main system cannot remount
+ them anymore.</para></listitem>
</varlistentry>
<varlistentry>
<refsect1>
<title>See Also</title>
<para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>