Merge pull request #70180 from mburke5678/node-cgroup-characteristic-note

GH65982 - Add note: cgroupsv2 has different characteristics than cgroupsv1

Author: mburke5678

installing/install_config/enabling-cgroup-v1.adoc

@@ -9,7 +9,7 @@ toc::[]
 
 As of {product-title} 4.14, {product-title} uses link:https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html[Linux control group version 2] (cgroup v2) in your cluster. If you are using cgroup v1 on {product-title} 4.13 or earlier, migrating to {product-title} 4.14 will not automatically update your cgroup configuration to version 2. A fresh installation of {product-title} 4.14 will use cgroup v2 by default. However, you can enable link:https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v1/index.html[Linux control group version 1] (cgroup v1) upon installation. Enabling cgroup v1 in {product-title} disables all cgroup v2 controllers and hierarchies in your cluster.
 
-cgroup v2 is the current version of the Linux cgroup API. cgroup v2 offers several improvements over cgroup v1, including a unified hierarchy, safer sub-tree delegation, new features such as link:https://www.kernel.org/doc/html/latest/accounting/psi.html[Pressure Stall Information], and enhanced resource management and isolation.
+include::snippets/cgroupv2-vs-cgroupv1.adoc[]
 
 ifndef::openshift-origin[]
 You can switch between cgroup v1 and cgroup v2, as needed, by editing the `node.config` object. For more information, see "Configuring the Linux cgroup on your nodes" in the "Additional resources" of this section.

modules/nodes-clusters-cgroups-2.adoc

@@ -26,7 +26,7 @@ endif::post[]
 endif::openshift-origin[]
 
 ifdef::post[]
-cgroup v2 is the current version of the Linux cgroup API. cgroup v2 offers several improvements over cgroup v1, including a unified hierarchy, safer sub-tree delegation, new features such as link:https://www.kernel.org/doc/html/latest/accounting/psi.html[Pressure Stall Information], and enhanced resource management and isolation.
+include::snippets/cgroupv2-vs-cgroupv1.adoc[]
 
 You can change between cgroup v1 and cgroup v2, as needed. Enabling cgroup v1 in {product-title} disables all cgroup v2 controllers and hierarchies in your cluster. 
 endif::post[]

nodes/clusters/nodes-cluster-cgroups-2.adoc

@@ -13,7 +13,7 @@ ifdef::openshift-origin[]
 {product-title} uses link:https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html[Linux control group version 2] (cgroup v2) in your cluster.
 endif::openshift-origin[]
 
-cgroup v2 is the current version of the Linux cgroup API. cgroup v2 offers several improvements over cgroup v1, including a unified hierarchy, safer sub-tree delegation, new features such as link:https://www.kernel.org/doc/html/latest/accounting/psi.html[Pressure Stall Information], and enhanced resource management and isolation.
+include::snippets/cgroupv2-vs-cgroupv1.adoc[]
 
 You can change between cgroup v1 and cgroup v2, as needed. Enabling cgroup v1 in {product-title} disables all cgroup v2 controllers and hierarchies in your cluster. 
 

snippets/cgroupv2-vs-cgroupv1.adoc

@@ -0,0 +1,10 @@
+// Text snippet included in the following modules:
+//
+// * installing/install-config/enabling-cgroup-v1.adoc
+// * modules/nodes-clusters-cgroups-2.adoc
+// * nodes/clusters/nodes-cluster-cgroups-2.adoc 
+
+:_mod-docs-content-type: SNIPPET
+
+cgroup v2 is the current version of the Linux cgroup API. cgroup v2 offers several improvements over cgroup v1, including a unified hierarchy, safer sub-tree delegation, new features such as link:https://www.kernel.org/doc/html/latest/accounting/psi.html[Pressure Stall Information], and enhanced resource management and isolation. However, cgroup v2 has different CPU, memory, and I/O management characteristics than cgroup v1. Therefore, some workloads might experience slight differences in memory or CPU usage on clusters that run cgroup v2.
+