commit 60ceb42f3917adc74d7d780eaa0becf366dec5fc
Author: Pete Travis <immanetize(a)fedoraproject.org>
Date: Sat Oct 19 19:32:01 2013 -0600
systemd has scope and slice units
en-US/System_Daemons.xml | 57 +++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 56 insertions(+), 1 deletions(-)
---
diff --git a/en-US/System_Daemons.xml b/en-US/System_Daemons.xml
index a7ffeb6..843bc51 100644
--- a/en-US/System_Daemons.xml
+++ b/en-US/System_Daemons.xml
@@ -53,10 +53,65 @@
</segmentedlist>
</para>
</section>
- <section>
+ <section id="system_daemons-systemd">
<title>systemd</title>
<indexterm><primary>systemd</primary></indexterm>
<para />
+ <section id="system_daemons-systemd-">
+ <title>New unit types: Scope</title>
+ <para>
+ Systemd now has two new unit types, <systemitem>scope</systemitem> and
<systemitem>slice</systemitem>.
+ </para>
+ <para>
+ <systemitem>scope</systemitem> units are automatically created by systemd
out of existing processes. By grouping a process and its children together, a scope unit
can be used to organize processes, apply resource units, or kill a group of processes.
User sessions are one example of processes contained in a scope unit.
+ </para>
+ <para>
+ <systemitem>slice</systemitem> units are used to group units that manage
processes into a hierarchy that allows control of resources allocated to the slice. The
default slices are machine.slice, for virtual machines and containers; system.slice, for
system services; and user.slice, for user sessions. These default slices are automatically
populated.
+ </para>
+ <para>
+ <systemitem>Instance units</systemitem>, such as
<systemitem>getty@.service</systemitem>, are spawned on demand using the
template defined in their configuration file. Each type of template is given a subslice of
the <literal>system slice</literal>, and instances are contained within that
slice.
+ </para>
+ <para>
+ Scope and service units assigned to a slice are descendants of that slice's node
in the control group tree. A slice's name describes its position relative to the root
slice. The output below demonstrates how <emphasis>user-1000.slice</emphasis>
is a child of <emphasis>user.slice</emphasis>, which is in turn a child of
<emphasis><literal>.</literal></emphasis>, the root slice. Each
session is further confined in a scope unit within the user's slice.
+ <screen>
+ <command>systemctl status user.slice</command>
+<![CDATA[
+ Loaded: loaded (/usr/lib/systemd/system/user.slice; static)
+ Active: active since Sun 2013-09-08 01:23:40 MDT; 18h ago
+ Docs: man:systemd.special(7)
+ CGroup: /user.slice
+ ├─user-1000.slice
+ │ ├─session-21.scope
+ │ │ ├─9226 sshd: pete [priv]
+ │ │ ├─9229 sshd: pete@pts/4
+ │ │ ├─9230 -bash
+ │ │ ├─9262 sudo su -
+ │ │ ├─9270 su -
+ │ │ ├─9271 -bash
+ │ │ └─9509 screen -R
+ │ ├─session-18.scope
+ │ │ ├─ 7939 sshd: pete [priv]
+ │ │ ├─ 7942 sshd: pete@pts/0
+ │ │ ├─ 7943 -bash
+ │ │ ├─ 7982 sudo su -
+ │ │ ├─ 7988 su -
+ │ │ ├─ 7989 -bash
+ │ │ ├─ 8206 SCREEN
+ │ │ ├─ 8207 /bin/bash
+ │ │ ├─ 8237 /bin/bash
+ │ │ ├─ 8486 less NEWS
+ │ │ ├─ 8489 /bin/bash
+ │ │ └─10637 systemctl status user.slice
+ ## truncated ##
+]]>
+ </screen>
+ </para>
+ <para>
+ Services can be added to a slice with the
<function>Slice=<replaceable>slicename</replaceable></function>
directive in their unit configuration file. Arguments allowing resource limitation within
a slice or service unit are described in <command>man
systemd.directives</command>. See also <command>man
systemd.slice</command> and <command>man systemd.cgroup</command>.
+ </para>
+ </section>
+
+
</section>
<section>
<title>journald</title>
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