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<article class="markdown-body">
<header>
<h1 class="title">Kernel Settings Role</h1>
</header>
<hr>
<nav id="TOC">
<h1 class="toc-title">Contents</h1>
<ul>
<li><a href="#requirements" id="toc-requirements">Requirements</a>
<ul>
<li><a href="#collection-requirements"
id="toc-collection-requirements">Collection requirements</a></li>
</ul></li>
<li><a href="#role-variables" id="toc-role-variables">Role Variables</a>
<ul>
<li><a href="#kernel_settings_sysctl"
id="toc-kernel_settings_sysctl">kernel_settings_sysctl</a></li>
<li><a href="#kernel_settings_sysfs"
id="toc-kernel_settings_sysfs">kernel_settings_sysfs</a></li>
<li><a href="#kernel_settings_systemd_cpu_affinity"
id="toc-kernel_settings_systemd_cpu_affinity">kernel_settings_systemd_cpu_affinity</a></li>
<li><a href="#kernel_settings_transparent_hugepages"
id="toc-kernel_settings_transparent_hugepages">kernel_settings_transparent_hugepages</a></li>
<li><a href="#kernel_settings_transparent_hugepages_defrag"
id="toc-kernel_settings_transparent_hugepages_defrag">kernel_settings_transparent_hugepages_defrag</a></li>
<li><a href="#kernel_settings_purge"
id="toc-kernel_settings_purge">kernel_settings_purge</a></li>
<li><a href="#kernel_settings_reboot_ok"
id="toc-kernel_settings_reboot_ok">kernel_settings_reboot_ok</a></li>
<li><a href="#kernel_settings_transactional_update_reboot_ok"
id="toc-kernel_settings_transactional_update_reboot_ok">kernel_settings_transactional_update_reboot_ok</a></li>
<li><a href="#variables-exported-by-the-role"
id="toc-variables-exported-by-the-role">Variables Exported by the
Role</a></li>
<li><a href="#examples-of-settings-usage"
id="toc-examples-of-settings-usage">Examples of Settings Usage</a></li>
</ul></li>
<li><a href="#example-playbook" id="toc-example-playbook">Example
Playbook</a></li>
<li><a href="#warnings" id="toc-warnings">Warnings</a></li>
<li><a href="#rpm-ostree" id="toc-rpm-ostree">rpm-ostree</a></li>
<li><a href="#license" id="toc-license">License</a></li>
<li><a href="#author-information" id="toc-author-information">Author
Information</a></li>
</ul>
</nav>
<hr>
<p>This role is used to modify kernel settings. For example, on Linux,
settings in <code>/proc/sys</code> (using <code>sysctl</code>),
<code>/sys/fs</code>, and some other settings. It uses
<code>tuned</code> for its default provider on Enterprise Linux and
derivatives (RHEL and CentOS) and Fedora.</p>
<ul>
<li><code>tuned</code> homepage - <a
href="https://github.com/redhat-performance/tuned">https://github.com/redhat-performance/tuned</a></li>
</ul>
<h1 id="requirements">Requirements</h1>
<p>See below</p>
<h2 id="collection-requirements">Collection requirements</h2>
<p>If you want to manage <code>rpm-ostree</code> systems with this role,
you will need to install additional collections. Please run the
following command line to install the collection.</p>
<div class="sourceCode" id="cb1"><pre
class="sourceCode bash"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="ex">ansible-galaxy</span> collection install <span class="at">-vv</span> <span class="at">-r</span> meta/collection-requirements.yml</span></code></pre></div>
<h1 id="role-variables">Role Variables</h1>
<p>The values for some of the various <code>kernel_settings_GROUP</code>
parameters are a <code>list</code> of <code>dict</code> objects. Each
<code>dict</code> has the following keys:</p>
<ul>
<li><code>name</code> - Usually Required - The name the setting, or the
name of a file under <code>/sys</code> for the <code>sysfs</code> group.
<code>name</code> is omitted when using <code>replaced</code>.</li>
<li><code>value</code> - Usually Required - The value for the setting.
<code>value</code> is omitted when using <code>state</code> or
<code>previous</code>. Values must not be <a
href="https://yaml.org/type/bool.html">YAML bool type</a>. One situation
where this might be a problem is using <code>value: on</code> or other
YAML <code>bool</code> typed value. You must quote these values, or
otherwise pass them as a value of <code>str</code> type e.g.
<code>value: "on"</code>.</li>
<li><code>state</code> - Optional - the value <code>absent</code> means
to remove a setting with name <code>name</code> from a group -
<code>name</code> must be provided</li>
<li><code>previous</code> - Optional - the only value is
<code>replaced</code> - this is used to specify that the previous values
in a group should be replaced with the given values.</li>
</ul>
<h2 id="kernel_settings_sysctl">kernel_settings_sysctl</h2>
<p>A <code>list</code> of settings to be applied using
<code>sysctl</code>. The settings are given in the format described
above. Note that the settings are <em>additive</em> - by default, each
setting is added to the existing settings, or replaces the setting of
the same name if it already exists. If you want to remove a specific
setting, use <code>state: absent</code> instead of giving a
<code>value</code>. If you want to remove all of the existing
<code>sysctl</code> settings and replace them with the given settings,
specify <code>previous: replaced</code> as one of the values in the
list. If you want to remove all of the <code>sysctl</code> settings, use
the <code>dict</code> value <code>{"state": "empty"}</code>, instead of
a <code>list</code>, as the only value for the parameter. See below for
examples.</p>
<h2 id="kernel_settings_sysfs">kernel_settings_sysfs</h2>
<p>A <code>list</code> of settings to be applied to <code>/sys</code>.
The settings are given in the format described above. Note that the
settings are <em>additive</em> - by default, each setting is added to
the existing settings, or replaces the setting of the same name if it
already exists. If you want to remove a specific setting, use
<code>state: absent</code> instead of giving a <code>value</code>. If
you want to remove all of the existing <code>sysfs</code> settings and
replace them with the given settings, specify
<code>previous: replaced</code> as one of the values in the list. If you
want to remove all of the <code>sysfs</code> settings, use the
<code>dict</code> value <code>{"state": "empty"}</code>, instead of a
<code>list</code>, as the only value for the parameter. See below for
examples.</p>
<h2
id="kernel_settings_systemd_cpu_affinity">kernel_settings_systemd_cpu_affinity</h2>
<p>To set the value, specify a <code>string</code> in the format
specified by <a
href="https://www.freedesktop.org/software/systemd/man/systemd-system.conf.html#CPUAffinity=">https://www.freedesktop.org/software/systemd/man/systemd-system.conf.html#CPUAffinity=</a>
If you want to remove the setting, use the <code>dict</code> value
<code>{"state": "absent"}</code>, instead of a <code>string</code>, as
the value for the parameter.</p>
<h2
id="kernel_settings_transparent_hugepages">kernel_settings_transparent_hugepages</h2>
<p>To set the value, specify one of the following <code>string</code>
values: <code>always</code> <code>madvise</code> <code>never</code>.
This is the memory subsystem transparent hugepages value. If you want to
remove the setting, use the <code>dict</code> value
<code>{"state": "absent"}</code>, instead of a <code>string</code>, as
the value for the parameter.</p>
<h2
id="kernel_settings_transparent_hugepages_defrag">kernel_settings_transparent_hugepages_defrag</h2>
<p>To set the value, specify one of the following <code>string</code>
values: <code>always</code> <code>defer</code>
<code>defer+madvise</code> <code>madvise</code> <code>never</code>. This
is the memory subsystem transparent hugepages fragmentation handling
value. The actual supported values may be different depending on your
OS. If you want to remove the setting, use the <code>dict</code> value
<code>{"state": "absent"}</code>, instead of a <code>string</code>, as
the value for the parameter.</p>
<h2 id="kernel_settings_purge">kernel_settings_purge</h2>
<p>default <code>false</code> - If <code>true</code>, then the existing
configuration will be completely wiped out and replaced with your given
<code>kernel_settings_GROUP</code> settings.</p>
<h2 id="kernel_settings_reboot_ok">kernel_settings_reboot_ok</h2>
<p>default <code>false</code> - If <code>true</code>, then if the role
detects that something was changed that requires a reboot to take
effect, the role will reboot the managed host. If <code>false</code>, it
is up to you to determine when to reboot the managed host. The role will
return the variable <code>kernel_settings_reboot_required</code> (see
below) with a value of <code>true</code> to indicate that some change
has occurred which needs a reboot to take effect.</p>
<h2
id="kernel_settings_transactional_update_reboot_ok">kernel_settings_transactional_update_reboot_ok</h2>
<p>This variable is used to handle reboots required by transactional
updates. If a transactional update requires a reboot, the role will
proceed with the reboot if
<code>kernel_settings_transactional_update_reboot_ok</code> is set to
<code>true</code>. If set to <code>false</code>, the role will notify
the user that a reboot is required, allowing for custom handling of the
reboot requirement. If this variable is not set, the role will fail to
ensure the reboot requirement is not overlooked.</p>
<h2 id="variables-exported-by-the-role">Variables Exported by the
Role</h2>
<p>The role will export the following variables:</p>
<p><code>kernel_settings_reboot_required</code> - default
<code>false</code> - if <code>true</code>, this means a change has
occurred which will require rebooting the managed host in order to take
effect. If you want the role to reboot the managed host, set
<code>kernel_settings_reboot_ok: true</code>, otherwise, you will need
to handle rebooting the machine.</p>
<h2 id="examples-of-settings-usage">Examples of Settings Usage</h2>
<div class="sourceCode" id="cb2"><pre
class="sourceCode yaml"><code class="sourceCode yaml"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_sysctl</span><span class="kw">:</span></span>
<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> fs.epoll.max_user_watches</span></span>
<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">785592</span></span>
<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> fs.file-max</span></span>
<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">379724</span></span>
<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_sysfs</span><span class="kw">:</span></span>
<span id="cb2-7"><a href="#cb2-7" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> /sys/kernel/debug/x86/pti_enabled</span></span>
<span id="cb2-8"><a href="#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">0</span></span>
<span id="cb2-9"><a href="#cb2-9" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> /sys/kernel/debug/x86/retp_enabled</span></span>
<span id="cb2-10"><a href="#cb2-10" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">0</span></span>
<span id="cb2-11"><a href="#cb2-11" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> /sys/kernel/debug/x86/ibrs_enabled</span></span>
<span id="cb2-12"><a href="#cb2-12" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">0</span></span>
<span id="cb2-13"><a href="#cb2-13" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_systemd_cpu_affinity</span><span class="kw">:</span><span class="at"> </span><span class="st">"1,3,5,7"</span></span>
<span id="cb2-14"><a href="#cb2-14" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_transparent_hugepages</span><span class="kw">:</span><span class="at"> madvise</span></span>
<span id="cb2-15"><a href="#cb2-15" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_transparent_hugepages_defrag</span><span class="kw">:</span><span class="at"> defer</span></span></code></pre></div>
<p><em>NOTE</em> that the <code>list</code> valued settings are
<strong>additive</strong>. That is, they are applied <strong>in addition
to</strong> any current settings. For example, if you already had</p>
<div class="sourceCode" id="cb3"><pre
class="sourceCode yaml"><code class="sourceCode yaml"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_sysctl</span><span class="kw">:</span></span>
<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> kernel.threads-max</span></span>
<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">29968</span></span>
<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> vm.max_map_count</span></span>
<span id="cb3-5"><a href="#cb3-5" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">65530</span></span></code></pre></div>
<p>then after applying the above, you would have</p>
<div class="sourceCode" id="cb4"><pre
class="sourceCode yaml"><code class="sourceCode yaml"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_sysctl</span><span class="kw">:</span></span>
<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> kernel.threads-max</span></span>
<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">29968</span></span>
<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> vm.max_map_count</span></span>
<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">65530</span></span>
<span id="cb4-6"><a href="#cb4-6" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> fs.epoll.max_user_watches</span></span>
<span id="cb4-7"><a href="#cb4-7" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">785592</span></span>
<span id="cb4-8"><a href="#cb4-8" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> fs.file-max</span></span>
<span id="cb4-9"><a href="#cb4-9" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">379724</span></span></code></pre></div>
<p>This allows multiple higher level roles or playbooks to use this role
to provide the kernel settings specific to that component. For example,
if you are installing a web server and a database server on the same
machine, and they both require setting kernel parameters, the
<code>kernel_settings</code> role allows you to set them both.</p>
<p>If you specify multiple settings with the same name in a section, the
last one will be used.</p>
<p>If you want to replace <em>all</em> of the settings in a section with
your supplied values, use <code>previous: replaced</code> as a single,
preferably first element in the list of settings. This indicates that
the <code>previous</code> settings in the system should be
<code>replaced</code> with the given settings. For example:</p>
<div class="sourceCode" id="cb5"><pre
class="sourceCode yaml"><code class="sourceCode yaml"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_sysctl</span><span class="kw">:</span></span>
<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">previous</span><span class="kw">:</span><span class="at"> replaced</span></span>
<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> kernel.threads-max</span></span>
<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">30000</span></span>
<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> vm.max_map_count</span></span>
<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">50000</span></span></code></pre></div>
<p>This will have the effect of removing all of the existing settings
for <code>kernel_settings_sysctl</code>, and adding the specified
settings. If you want to remove a single setting, specify
<code>state: absent</code> in the individual setting, instead of a
<code>value</code>:</p>
<div class="sourceCode" id="cb6"><pre
class="sourceCode yaml"><code class="sourceCode yaml"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_sysctl</span><span class="kw">:</span></span>
<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> kernel.threads-max</span></span>
<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">30000</span></span>
<span id="cb6-4"><a href="#cb6-4" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> vm.max_map_count</span></span>
<span id="cb6-5"><a href="#cb6-5" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">state</span><span class="kw">:</span><span class="at"> absent</span></span></code></pre></div>
<p>This will remove the <code>vm.max_map_count</code> setting from the
<code>kernel_settings_sysctl</code> settings. If you want to remove all
of the settings from a group, specify <code>state: empty</code> as a
<code>dict</code> instead of a <code>list</code>:</p>
<div class="sourceCode" id="cb7"><pre
class="sourceCode yaml"><code class="sourceCode yaml"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_sysctl</span><span class="kw">:</span></span>
<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">state</span><span class="kw">:</span><span class="at"> empty</span></span></code></pre></div>
<p>This will have the effect of removing all of the
<code>kernel_settings_sysctl</code> settings.</p>
<p>Use <code>{"state":"absent"}</code> to remove a scalar valued
parameter. For example, to remove all of
<code>kernel_settings_systemd_cpu_affinity</code>,
<code>kernel_settings_transparent_hugepages</code>, and
<code>kernel_settings_transparent_hugepages_defrag</code> settings, use
this:</p>
<div class="sourceCode" id="cb8"><pre
class="sourceCode yaml"><code class="sourceCode yaml"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_systemd_cpu_affinity</span><span class="kw">:</span></span>
<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">state</span><span class="kw">:</span><span class="at"> absent</span></span>
<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_transparent_hugepages</span><span class="kw">:</span></span>
<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">state</span><span class="kw">:</span><span class="at"> absent</span></span>
<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a><span class="fu">kernel_settings_transparent_hugepages_defrag</span><span class="kw">:</span></span>
<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">state</span><span class="kw">:</span><span class="at"> absent</span></span></code></pre></div>
<h1 id="example-playbook">Example Playbook</h1>
<div class="sourceCode" id="cb9"><pre
class="sourceCode yaml"><code class="sourceCode yaml"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> Manage kernel settings</span></span>
<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">hosts</span><span class="kw">:</span><span class="at"> all</span></span>
<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">vars</span><span class="kw">:</span></span>
<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">kernel_settings_sysctl</span><span class="kw">:</span></span>
<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> fs.epoll.max_user_watches</span></span>
<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">785592</span></span>
<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> fs.file-max</span></span>
<span id="cb9-8"><a href="#cb9-8" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">379724</span></span>
<span id="cb9-9"><a href="#cb9-9" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> kernel.threads-max</span></span>
<span id="cb9-10"><a href="#cb9-10" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">state</span><span class="kw">:</span><span class="at"> absent</span></span>
<span id="cb9-11"><a href="#cb9-11" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">kernel_settings_sysfs</span><span class="kw">:</span></span>
<span id="cb9-12"><a href="#cb9-12" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> /sys/kernel/debug/x86/pti_enabled</span></span>
<span id="cb9-13"><a href="#cb9-13" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">0</span></span>
<span id="cb9-14"><a href="#cb9-14" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> /sys/kernel/debug/x86/retp_enabled</span></span>
<span id="cb9-15"><a href="#cb9-15" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">0</span></span>
<span id="cb9-16"><a href="#cb9-16" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> </span><span class="fu">name</span><span class="kw">:</span><span class="at"> /sys/kernel/debug/x86/ibrs_enabled</span></span>
<span id="cb9-17"><a href="#cb9-17" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">value</span><span class="kw">:</span><span class="at"> </span><span class="dv">0</span></span>
<span id="cb9-18"><a href="#cb9-18" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">kernel_settings_systemd_cpu_affinity</span><span class="kw">:</span><span class="at"> </span><span class="st">"1,3,5,7"</span></span>
<span id="cb9-19"><a href="#cb9-19" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">kernel_settings_transparent_hugepages</span><span class="kw">:</span><span class="at"> madvise</span></span>
<span id="cb9-20"><a href="#cb9-20" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">kernel_settings_transparent_hugepages_defrag</span><span class="kw">:</span><span class="at"> defer</span></span>
<span id="cb9-21"><a href="#cb9-21" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="fu">roles</span><span class="kw">:</span></span>
<span id="cb9-22"><a href="#cb9-22" aria-hidden="true" tabindex="-1"></a><span class="at"> </span><span class="kw">-</span><span class="at"> linux-system-roles.kernel_settings</span></span></code></pre></div>
<h1 id="warnings">Warnings</h1>
<p>The <code>kernel_settings</code> role will cause other
<code>sysctl</code> settings to be applied when using the
<code>tuned</code> implementation, which is the default. This can happen
when you manually edit <code>/etc/sysctl.d/</code> files, or if the
<code>sysctl.d</code> files are installed by some system package. For
example, on Fedora, installing the <code>libreswan</code> package
provides <code>/etc/sysctl.d/50-libreswan.conf</code>. Using the
<code>kernel_settings</code> role will cause this file to be reloaded
and reapplied. If this behavior is not desired, you will need to edit
the <code>tuned</code> configuration on the managed hosts in
<code>/etc/tuned/tuned-main.conf</code> and set
<code>reapply_sysctl=0</code>.</p>
<p>The settings you apply with the <code>kernel_settings</code> role may
conflict with other settings. For example, if you manually run the
<code>sysctl</code> command, or manually edit
<code>/etc/sysctl.d/</code> files, or if the <code>sysctl.d</code> files
are installed by some system package, they may set the same values you
are setting with the <code>kernel_settings</code> role. For
<code>sysctl</code> settings, the precedence goes like this:</p>
<ul>
<li><code>sysctl</code> files have highest precedence -
<code>/etc/sysctl.conf</code> and <code>/etc/sysctl.d/*</code> will
override everything</li>
<li><code>kernel_settings</code> role settings have the next highest
precedence</li>
<li>settings set manually using the <code>sysctl</code> command have the
lowest precedence</li>
</ul>
<p>For all other settings such as <code>sysfs</code>, the settings from
<code>kernel_settings</code> role have the highest precedence.</p>
<h1 id="rpm-ostree">rpm-ostree</h1>
<p>See README-ostree.md</p>
<h1 id="license">License</h1>
<p>Some parts related to <code>tuned</code> are <code>GPLv2+</code>.
These are noted in the headers of the files. Everything else is
<code>MIT</code>, except where noted. See the file <code>LICENSE</code>
for more information.</p>
<h1 id="author-information">Author Information</h1>
<p>Rich Megginson (richm on github, rmeggins at my company)</p>
</article>
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