man: similar → similarly

[thirdparty/systemd.git] / man / systemd.service.xml

diff --git a/man/systemd.service.xml b/man/systemd.service.xml
index 95cb0aca3d467e07e782ac779e4ae4d130f71f0d..98c8bf8c6d3c73f718625fb9f0565ec0cf5e10fc 100644 (file)
--- a/man/systemd.service.xml
+++ b/man/systemd.service.xml
@@ -1103,7 +1103,7 @@
         <term><varname>USBFunctionDescriptors=</varname></term>
         <listitem><para>Configure the location of a file containing
         <ulink
-        url="https://www.kernel.org/doc/Documentation/usb/functionfs.txt">USB
+        url="https://docs.kernel.org/usb/functionfs.html">USB
         FunctionFS</ulink> descriptors, for implementation of USB
         gadget functions. This is used only in conjunction with a
         socket unit with <varname>ListenUSBFunction=</varname>
@@ -1123,15 +1123,25 @@
       <varlistentry>
         <term><varname>OOMPolicy=</varname></term>
 
-        <listitem><para>Configure the Out-Of-Memory (OOM) killer policy. On Linux, when memory becomes scarce
-        the kernel might decide to kill a running process in order to free up memory and reduce memory
+        <listitem><para>Configure the out-of-memory (OOM) kernel killer policy. Note that the userspace OOM
+        killer
+        <citerefentry><refentrytitle>systemd-oomd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+        is a more flexible solution that aims to prevent out-of-memory situations for the userspace, not just
+        the kernel.</para>
+
+        <para>On Linux, when memory becomes scarce to the point that the kernel has trouble allocating memory
+        for itself, it might decide to kill a running process in order to free up memory and reduce memory
         pressure. This setting takes one of <constant>continue</constant>, <constant>stop</constant> or
         <constant>kill</constant>. If set to <constant>continue</constant> and a process of the service is
         killed by the kernel's OOM killer this is logged but the service continues running. If set to
         <constant>stop</constant> the event is logged but the service is terminated cleanly by the service
         manager. If set to <constant>kill</constant> and one of the service's processes is killed by the OOM
-        killer the kernel is instructed to kill all remaining processes of the service, too. Defaults to the
-        setting <varname>DefaultOOMPolicy=</varname> in
+        killer the kernel is instructed to kill all remaining processes of the service too, by setting the
+        <filename>memory.oom.group</filename> attribute to <constant>1</constant>; also see <ulink
+        url="https://docs.kernel.org/admin-guide/cgroup-v2.html">kernel documentation</ulink>.
+        </para>
+
+        <para>Defaults to the setting <varname>DefaultOOMPolicy=</varname> in
         <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
         is set to, except for services where <varname>Delegate=</varname> is turned on, where it defaults to
         <constant>continue</constant>.</para>
@@ -1140,7 +1150,11 @@
         shall be considered preferred or less preferred candidates for process termination by the Linux OOM
         killer logic. See
         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
-        details.</para></listitem>
+        details.</para>
+
+        <para>This setting also applies to <command>systemd-oomd</command>. Similarly to the kernel OOM
+        kills, this setting determines the state of the service after <command>systemd-oomd</command> kills a
+        cgroup associated with the service.</para></listitem>
       </varlistentry>
 
     </variablelist>