Merge pull request #39246 from Amrita42/BZ2018364

BZ2018364: Re-defining steps and modify/add yaml file examples

Author: lpettyjo

modules/cnf-provisioning-real-time-and-low-latency-workloads.adoc

@@ -34,36 +34,75 @@ Establishing the right performance expectations refers to the fact that the real
 == Provisioning a worker with real-time capabilities
 
 . Install Performance Addon Operator to the cluster.
+
 . Optional: Add a node to the {product-title} cluster.
 See link:https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux_for_real_time/8/html-single/tuning_guide/index#Setting_BIOS_parameters[Setting BIOS parameters].
-. Optional: Create a new machine config pool for real-time nodes.
-. Add the node to the proper machine config pool, using node role labels.
-+
-You must decide which nodes will be configured with real-time workloads. It could be all of the nodes in the cluster or a subset of the nodes. The Performance Addon Operator expects all of the nodes are part of a dedicated machine config pool. If you use all of the nodes, you just point the Performance Addon Operator to the worker node role label. If you use a subset, you must group the nodes into a new machine config pool.
 
-. Create the `PerformanceProfile` with the proper set of housekeeping cores and `realTimeKernel: enabled: true`.
+. Add the label `worker-rt` to the worker nodes that require the real-time capability by using the `oc` command.
 
-. Specify a node selector in the `PerformanceProfile`, as shown here:
+. Create a new machine config pool for real-time nodes:
 +
 [source,yaml]
 ----
-apiVersion: performance.openshift.io/v2
-kind: PerformanceProfile
+apiVersion: machineconfiguration.openshift.io/v1
+kind: MachineConfigPool
 metadata:
- name: example-performanceprofile
+  name: worker-rt
+  labels:
+    machineconfiguration.openshift.io/role: worker-rt
 spec:
-...
-  realTimeKernel:
-    enabled: true
+  machineConfigSelector:
+    matchExpressions:
+      - {
+           key: machineconfiguration.openshift.io/role,
+           operator: In,
+           values: [worker, worker-rt],
+        }
+  paused: false
   nodeSelector:
-    node-role.kubernetes.io/worker-rt: ""
+    matchLabels:
+      node-role.kubernetes.io/worker-rt: ""
 ----
+Note that a machine config pool worker-rt is created for group of nodes that have the label `worker-rt`.
+
+. Add the node to the proper machine config pool by using node role labels.
++
+[NOTE]
+====
+You must decide which nodes are configured with real-time workloads. You could configure all of the nodes in the cluster, or a subset of the nodes. The Performance Addon Operator that expects all of the nodes are part of a dedicated machine config pool. If you use all of the nodes, you must point the Performance Addon Operator to the worker node role label. If you use a subset, you must group the nodes into a new machine config pool.
+====
+. Create the `PerformanceProfile` with the proper set of housekeeping cores and `realTimeKernel: enabled: true`.
 
+. You must set `machineConfigPoolSelector` in `PerformanceProfile`:
++
+[source,yaml]
+----
+  apiVersion: performance.openshift.io/v2
+  kind: PerformanceProfile
+  metadata:
+   name: example-performanceprofile
+  spec:
+  ...
+    realTimeKernel:
+      enabled: true
+    nodeSelector:
+       node-role.kubernetes.io/worker-rt: ""
+    machineConfigPoolSelector:
+       machineconfiguration.openshift.io/role: worker-rt
+----
 . Verify that a matching machine config pool exists with a label:
 +
-[source,bash]
+[source,terminal]
+----
+$ oc describe mcp/worker-rt
+----
++
+.Example output
+[source,yaml]
 ----
-machineconfiguration.openshift.io/role=worker-rt
+Name:         worker-rt
+Namespace:
+Labels:       machineconfiguration.openshift.io/role=worker-rt
 ----
 
 . {product-title} will start configuring the nodes, which might involve multiple reboots. Wait for the nodes to settle. This can take a long time depending on the specific hardware you use, but 20 minutes per node is expected.
@@ -87,7 +126,7 @@ Note the worker with the role `worker-rt` that contains the string `4.18.0-211.r
 NAME                               	STATUS   ROLES           	AGE 	VERSION                  	INTERNAL-IP
 EXTERNAL-IP   OS-IMAGE                                       	KERNEL-VERSION
 CONTAINER-RUNTIME
-cnf-worker-0.example.com	          Ready	 worker,worker-rt   5d17h   v1.22.1
+rt-worker-0.example.com	          Ready	 worker,worker-rt   5d17h   v1.22.1
 128.66.135.107   <none>    	        Red Hat Enterprise Linux CoreOS 46.82.202008252340-0 (Ootpa)
 4.18.0-211.rt5.23.el8.x86_64   cri-o://1.22.1-90.rhaos4.9.git4a0ac05.el8-rc.1
 [...]