man: add note about operation without swap in systemd-oomd

diff --git a/man/systemd-oomd.service.xml b/man/systemd-oomd.service.xml
index 86c47e5b572c39373af9da33afe941ec4cb616de..e87a753987abf9c66657dfe9e7962197239418d7 100644 (file)
--- a/man/systemd-oomd.service.xml
+++ b/man/systemd-oomd.service.xml
@@ -60,7 +60,9 @@
     Without swap, the system enters a livelocked state much more quickly and may prevent <command>systemd-oomd</command>
     from responding in a reasonable amount of time. See
     <ulink url="https://chrisdown.name/2018/01/02/in-defence-of-swap.html">"In defence of swap: common misconceptions"</ulink>
-    for more details on swap.</para>
+    for more details on swap. Any swap-based actions on systems without swap will be ignored. While
+    <command>systemd-oomd</command> can perform pressure-based actions on a system without swap, the pressure increases
+    will be more abrupt and may require more tuning to get the desired thresholds and behavior.</para>
 
     <para>Be aware that if you intend to enable monitoring and actions on <filename>user.slice</filename>,
     <filename>user-$UID.slice</filename>, or their ancestor cgroups, it is highly recommended that your programs be