Changing Power settings

On Power® Systems, you must change the simultaneous multithreading (SMT) settings for Kernel-based Virtual Machine (KVM) capable systems and big core, PowerVM® capable systems.

Installation phase: Setting up a client workstation; Collecting required information; Preparing your cluster; Installing the Cloud Pak for Data platform and services
Who needs to complete this task?: A cluster administrator must complete this task.
When do you need to complete this task?: When you plan to install some services, you must change node settings to configure your cluster so those services run properly.

Procedure

Complete the following steps to change the simultaneous multithreading (SMT) settings for Kernel-based Virtual Machine (KVM) capable (LC922, IC922, AC922) systems, and big core, PowerVM capable systems (L922, E950, E980, S922, S1022, S1024, E1050, and E1080).

Label all small core KVM capable worker nodes by using one of the following options:
- If the worker node is not running Db2® Warehouse workloads, use SMT=2, as shown in the following example:
```
oc label node <node> SMT=2 --overwrite
```
- If the worker node is running Db2 Warehouse workloads, use SMT=4, as shown in the following example:
```
oc label node <node> SMT=4 --overwrite
```
Label all big core PowerVM capable worker nodes by using one of the following options:
- If the worker node is not running Db2 Warehouse workloads, use SMT=4, as shown in the following example:
```
oc label node <node> SMT=4 --overwrite
```
- If the worker node is running Db2 Warehouse workloads, use SMT=8, as shown in the following example:
```
oc label node <node> SMT=8 --overwrite 
```

Create a YAML file, smt.yaml, with the following content:

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  labels:
    machineconfiguration.openshift.io/role: worker
  name: 99-worker-smt
spec:
  config:
    ignition:
      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:text/plain;charset=utf-8;base64,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
          verification: {}
        filesystem: root
        mode: 0755
        overwrite: true
        path: /usr/local/bin/powersmt
    systemd:
      units:
        - name: smt.service
          enabled: true
          contents: |
            [Unit]
            Description=Set SMT
            After=network-online.target
            Before= crio.service
            [Service]
            Type=oneshot
            RemainAfterExit=yes
            ExecStart=/usr/local/bin/powersmt
            [Install]
            WantedBy=multi-user.target

Run the oc create command to apply the changes.

Note: You must ensure that the cluster master nodes (or control plane) are in Ready status before you issue this command.
```
oc create -f smt.yaml
```
Your worker nodes perform a rolling restart action to update the kernel argument slub_max_order and set the labeled SMT level.
Note:
- All the worker nodes are rebooted after the command is issued. The slub_max_order=0 kernel argument and the specified SMT level are applied to all the worker nodes after the restart completes. The SMT level on the worker nodes that are not labeled are set to the default value.
- If the SMT level on a particular worker node needs to be changed, you must label that worker node with the new SMT level, and manually restart it.