Merge pull request #14259 from ahardin-rh/recommended-host-practices-40

Added Recommended node host practices information

Author: ahardin-rh

modules/recommended-node-host-practices.adoc

@@ -0,0 +1,48 @@
+// Module included in the following assemblies:
+//
+// * scalability_and_performance/recommended-host-practices.adoc
+
+[id="recommended-node-host-practices-{context}"]
+= Recommended node host practices
+
+The {product-title} node configuration file contains important options. For
+example, two parameters control the maximum number of pods that can be scheduled
+to a node: `podsPerCore` and `maxPods`.
+
+When both options are in use, the lower of the two values limits the number of
+pods on a node. Exceeding these values can result in:
+
+* Increased CPU utilization.
+* Slow pod scheduling.
+* Potential out-of-memory scenarios, depending on the amount of memory in the node.
+* Exhausting the pool of IP addresses.
+* Resource overcommitting, leading to poor user application performance.
+
+[IMPORTANT]
+====
+In Kubernetes, a pod that is holding a single container actually uses two
+containers. The second container is used to set up networking prior to the
+actual container starting. Therefore, a system running 10 pods will actually
+have 20 containers running.
+====
+
+`podsPerCore` sets the number of pods the node can run based on the number of
+processor cores on the node. For example, if `podsPerCore` is set to `10` on a
+node with 4 processor cores, the maximum number of pods allowed on the node will
+be `40`.
+
+----
+kubeletConfig:
+  podsPerCore: 10
+----
+
+Setting `podsPerCore` to `0` disables this limit. The default is `0`.
+`podsPerCore` cannot exceed `maxPods`.
+
+`maxPods` sets the number of pods the node can run to a fixed value, regardless
+of the properties of the node.
+
+----
+ kubeletConfig:
+    maxPods: 250
+----

scalability_and_performance/recommended-host-practices.adoc

@@ -7,4 +7,11 @@ toc::[]
 
 This topic provides recommended host practices for {product-title}.
 
+include::modules/recommended-node-host-practices.adoc[leveloffset=+1]
+
 include::modules/create-a-kubeletconfig-crd-to-edit-kubelet-parameters.adoc[leveloffset=+1]
+
+== Additional resources
+
+* xref:../scalability_and_performance/planning-your-environment-according-to-object-limits.adoc#planning-your-environment-according-to-object-limits[{product-title}
+cluster limits]