Validating {sno} cluster tuning for vDU application workloads

Before you can deploy virtual distributed unit (vDU) applications, you need to tune and configure the cluster host firmware and various other cluster configuration settings. Use the following information to validate the cluster configuration to support vDU workloads.

Additional resources

Recommended firmware configuration for vDU cluster hosts

Use the following table as the basis to configure the cluster host firmware for vDU applications running on OpenShift Container Platform 4.19.

Note

The following table is a general recommendation for vDU cluster host firmware configuration. Exact firmware settings will depend on your requirements and specific hardware platform. Automatic setting of firmware is not handled by the zero touch provisioning pipeline.

Table 1. Recommended cluster host firmware settings
Firmware setting	Configuration	Description
HyperTransport (HT)	Enabled	HyperTransport (HT) bus is a bus technology developed by AMD. HT provides a high-speed link between the components in the host memory and other system peripherals.
UEFI	Enabled	Enable booting from UEFI for the vDU host.
CPU Power and Performance Policy	Performance	Set CPU Power and Performance Policy to optimize the system for performance over energy efficiency.
Uncore Frequency Scaling	Disabled	Disable Uncore Frequency Scaling to prevent the voltage and frequency of non-core parts of the CPU from being set independently.
Uncore Frequency	Maximum	Sets the non-core parts of the CPU such as cache and memory controller to their maximum possible frequency of operation.
Performance P-limit	Disabled	Disable Performance P-limit to prevent the Uncore frequency coordination of processors.
Enhanced Intel® SpeedStep Tech	Enabled	Enable Enhanced Intel SpeedStep to allow the system to dynamically adjust processor voltage and core frequency that decreases power consumption and heat production in the host.
Intel® Turbo Boost Technology	Enabled	Enable Turbo Boost Technology for Intel-based CPUs to automatically allow processor cores to run faster than the rated operating frequency if they are operating below power, current, and temperature specification limits.
Intel Configurable TDP	Enabled	Enables Thermal Design Power (TDP) for the CPU.
Configurable TDP Level	Level 2	TDP level sets the CPU power consumption required for a particular performance rating. TDP level 2 sets the CPU to the most stable performance level at the cost of power consumption.
Energy Efficient Turbo	Disabled	Disable Energy Efficient Turbo to prevent the processor from using an energy-efficiency based policy.
Hardware P-States	Enabled or Disabled	Enable OS-controlled P-States to allow power saving configurations. Disable `P-states` (performance states) to optimize the operating system and CPU for performance over power consumption.
Package C-State	C0/C1 state	Use C0 or C1 states to set the processor to a fully active state (C0) or to stop CPU internal clocks running in software (C1).
C1E	Disabled	CPU Enhanced Halt (C1E) is a power saving feature in Intel chips. Disabling C1E prevents the operating system from sending a halt command to the CPU when inactive.
Processor C6	Disabled	C6 power-saving is a CPU feature that automatically disables idle CPU cores and cache. Disabling C6 improves system performance.
Sub-NUMA Clustering	Disabled	Sub-NUMA clustering divides the processor cores, cache, and memory into multiple NUMA domains. Disabling this option can increase performance for latency-sensitive workloads.

Note

Enable global SR-IOV and VT-d settings in the firmware for the host. These settings are relevant to bare-metal environments.

Note

Enable both C-states and OS-controlled P-States to allow per pod power management.

Recommended cluster configurations to run vDU applications

Clusters running virtualized distributed unit (vDU) applications require a highly tuned and optimized configuration. The following information describes the various elements that you require to support vDU workloads in OpenShift Container Platform 4.19 clusters.

Recommended cluster MachineConfig CRs for single-node OpenShift clusters

Check that the MachineConfig custom resources (CRs) that you extract from the ztp-site-generate container are applied in the cluster. The CRs can be found in the extracted out/source-crs/extra-manifest/ folder.

The following MachineConfig CRs from the ztp-site-generate container configure the cluster host:

Table 2. Recommended GitOps ZTP MachineConfig CRs
MachineConfig CR	Description
`01-container-mount-ns-and-kubelet-conf-master.yaml` `01-container-mount-ns-and-kubelet-conf-worker.yaml`	Configures the container mount namespace and kubelet configuration.
`03-sctp-machine-config-master.yaml` `03-sctp-machine-config-worker.yaml`	Loads the SCTP kernel module. These `MachineConfig` CRs are optional and can be omitted if you do not require this kernel module.
`06-kdump-master.yaml` `06-kdump-worker.yaml`	Configures kdump crash reporting for the cluster.
`07-sriov-related-kernel-args-master.yaml`	Configures SR-IOV kernel arguments in the cluster.
`08-set-rcu-normal-master.yaml` `08-set-rcu-normal-worker.yaml`	Disables `rcu_expedited` mode after the cluster has rebooted.
`99-crio-disable-wipe-master.yaml` `99-crio-disable-wipe-worker.yaml`	Disables the automatic CRI-O cache wipe following cluster reboot.
`99-sync-time-once-master.yaml` `99-sync-time-once-worker.yaml`	Configures the one-time check and adjustment of the system clock by the Chrony service.
`enable-crun-master.yaml` `enable-crun-worker.yaml`	Enables the `crun` OCI container runtime.
`extra-manifest/enable-cgroups-v1.yaml` `source-crs/extra-manifest/enable-cgroups-v1.yaml`	Enables cgroups v1 during cluster installation and when generating RHACM cluster policies.

Note

In OpenShift Container Platform 4.14 and later, you configure workload partitioning with the cpuPartitioningMode field in the ClusterInstance CR.

Additional resources

Recommended cluster Operators

The following Operators are required for clusters running virtualized distributed unit (vDU) applications and are a part of the baseline reference configuration:

Node Tuning Operator (NTO). NTO packages functionality that was previously delivered with the Performance Addon Operator, which is now a part of NTO.
PTP Operator
SR-IOV Network Operator
Red Hat OpenShift Logging Operator
Local Storage Operator

Recommended cluster kernel configuration

Always use the latest supported real-time kernel version in your cluster. Ensure that you apply the following configurations in the cluster:

Ensure that the following additionalKernelArgs are set in the cluster performance profile:

apiVersion: performance.openshift.io/v2
kind: PerformanceProfile
# ...
spec:
  additionalKernelArgs:
  - "rcupdate.rcu_normal_after_boot=0"
  - "efi=runtime"
  - "vfio_pci.enable_sriov=1"
  - "vfio_pci.disable_idle_d3=1"
  - "module_blacklist=irdma"

  # ...

Optional: Set the CPU frequency under the hardwareTuning field:

You can use hardware tuning to tune CPU frequencies for reserved and isolated core CPUs. For FlexRAN like applications, hardware vendors recommend that you run CPU frequencies below the default provided frequencies. It is highly recommended that, before setting any frequencies, you refer to the hardware vendor’s guidelines for maximum frequency settings for your processor generation. This example sets the frequencies for reserved and isolated CPUs to 2500 MHz:
```
apiVersion: performance.openshift.io/v2
kind: PerformanceProfile
metadata:
  name: openshift-node-performance-profile
spec:
      cpu:
        isolated: "2-19,22-39"
        reserved: "0-1,20-21"
      hugepages:
        defaultHugepagesSize: 1G
        pages:
          - size: 1G
            count: 32
      realTimeKernel:
          enabled: true
      hardwareTuning:
          isolatedCpuFreq: 2500000
          reservedCpuFreq: 2500000
```

Ensure that the performance-patch profile in the Tuned CR configures the correct CPU isolation set that matches the isolated CPU set in the related PerformanceProfile CR, for example:

apiVersion: tuned.openshift.io/v1
kind: Tuned
metadata:
  name: performance-patch
  namespace: openshift-cluster-node-tuning-operator
  annotations:
    ran.openshift.io/ztp-deploy-wave: "10"
spec:
  profile:
    - name: performance-patch
      # The 'include' line must match the associated PerformanceProfile name, for example:
      # include=openshift-node-performance-${PerformanceProfile.metadata.name}
      # When using the standard (non-realtime) kernel, remove the kernel.timer_migration override from the [sysctl] section
      data: |
        [main]
        summary=Configuration changes profile inherited from performance created tuned
        include=openshift-node-performance-openshift-node-performance-profile
        [scheduler]
        group.ice-ptp=0:f:10:*:ice-ptp.*
        group.ice-gnss=0:f:10:*:ice-gnss.*
        group.ice-dplls=0:f:10:*:ice-dplls.*
        [service]
        service.stalld=start,enable
        service.chronyd=stop,disable
# ...

Checking the realtime kernel version

Always use the latest version of the realtime kernel in your OpenShift Container Platform clusters. If you are unsure about the kernel version that is in use in the cluster, you can compare the current realtime kernel version to the release version with the following procedure.

Prerequisites

You have installed the OpenShift CLI (oc).
You are logged in as a user with cluster-admin privileges.
You have installed podman.

Procedure

Run the following command to get the cluster version:

$ OCP_VERSION=$(oc get clusterversion version -o jsonpath='{.status.desired.version}{"\n"}')

Get the release image SHA number:

$ DTK_IMAGE=$(oc adm release info --image-for=driver-toolkit quay.io/openshift-release-dev/ocp-release:$OCP_VERSION-x86_64)

Run the release image container and extract the kernel version that is packaged with cluster’s current release:
```
$ podman run --rm $DTK_IMAGE rpm -qa | grep 'kernel-rt-core-' | sed 's#kernel-rt-core-##'
```
Example output
```
4.18.0-305.49.1.rt7.121.el8_4.x86_64
```
This is the default realtime kernel version that ships with the release.

Note

The realtime kernel is denoted by the string .rt in the kernel version.

Verification

Check that the kernel version listed for the cluster’s current release matches actual realtime kernel that is running in the cluster. Run the following commands to check the running realtime kernel version:

Open a remote shell connection to the cluster node:
```
$ oc debug node/<node_name>
```

Check the realtime kernel version:

sh-4.4# uname -r

Example output

4.18.0-305.49.1.rt7.121.el8_4.x86_64

Checking that the recommended cluster configurations are applied

You can check that clusters are running the correct configuration. The following procedure describes how to check the various configurations that you require to deploy a DU application in OpenShift Container Platform 4.19 clusters.

Prerequisites

You have deployed a cluster and tuned it for vDU workloads.
You have installed the OpenShift CLI (oc).
You have logged in as a user with cluster-admin privileges.

Procedure

Check that the default OperatorHub sources are disabled. Run the following command:
```
$ oc get operatorhub cluster -o yaml
```
Example output
```
spec:
    disableAllDefaultSources: true
```
Check that all required CatalogSource resources are annotated for workload partitioning (PreferredDuringScheduling) by running the following command:
```
$ oc get catalogsource -A -o jsonpath='{range .items[*]}{.metadata.name}{" -- "}{.metadata.annotations.target\.workload\.openshift\.io/management}{"\n"}{end}'
```
Example output
```
certified-operators -- {"effect": "PreferredDuringScheduling"}
community-operators -- {"effect": "PreferredDuringScheduling"}
ran-operators 
redhat-marketplace -- {"effect": "PreferredDuringScheduling"}
redhat-operators -- {"effect": "PreferredDuringScheduling"}
```
1. CatalogSource resources that are not annotated are also returned. In this example, the ran-operators CatalogSource resource is not annotated and does not have the PreferredDuringScheduling annotation.
  Note
  
  In a properly configured vDU cluster, only a single annotated catalog source is listed.
Check that all applicable OpenShift Container Platform Operator namespaces are annotated for workload partitioning. This includes all Operators installed with core OpenShift Container Platform and the set of additional Operators included in the reference DU tuning configuration. Run the following command:
```
$ oc get namespaces -A -o jsonpath='{range .items[*]}{.metadata.name}{" -- "}{.metadata.annotations.workload\.openshift\.io/allowed}{"\n"}{end}'
```
Example output
```
default --
openshift-apiserver -- management
openshift-apiserver-operator -- management
openshift-authentication -- management
openshift-authentication-operator -- management
```
Important

Additional Operators must not be annotated for workload partitioning. In the output from the previous command, additional Operators should be listed without any value on the right side of the -- separator.

Check that the ClusterLogging configuration is correct. Run the following commands:

Validate that the appropriate input and output logs are configured:

$ oc get -n openshift-logging ClusterLogForwarder instance -o yaml

Example output

apiVersion: logging.openshift.io/v1
kind: ClusterLogForwarder
metadata:
  creationTimestamp: "2022-07-19T21:51:41Z"
  generation: 1
  name: instance
  namespace: openshift-logging
  resourceVersion: "1030342"
  uid: 8c1a842d-80c5-447a-9150-40350bdf40f0
spec:
  inputs:
  - infrastructure: {}
    name: infra-logs
  outputs:
  - name: kafka-open
    type: kafka
    url: tcp://10.46.55.190:9092/test
  pipelines:
  - inputRefs:
    - audit
    name: audit-logs
    outputRefs:
    - kafka-open
  - inputRefs:
    - infrastructure
    name: infrastructure-logs
    outputRefs:
    - kafka-open
...

Check that the curation schedule is appropriate for your application:

$ oc get -n openshift-logging clusterloggings.logging.openshift.io instance -o yaml

Example output

apiVersion: logging.openshift.io/v1
kind: ClusterLogging
metadata:
  creationTimestamp: "2022-07-07T18:22:56Z"
  generation: 1
  name: instance
  namespace: openshift-logging
  resourceVersion: "235796"
  uid: ef67b9b8-0e65-4a10-88ff-ec06922ea796
spec:
  collection:
    logs:
      fluentd: {}
      type: fluentd
  curation:
    curator:
      schedule: 30 3 * * *
    type: curator
  managementState: Managed
...

Check that the web console is disabled (managementState: Removed) by running the following command:
```
$ oc get consoles.operator.openshift.io cluster -o jsonpath="{ .spec.managementState }"
```
Example output
```
Removed
```

Check that chronyd is disabled on the cluster node by running the following commands:

$ oc debug node/<node_name>

Check the status of chronyd on the node:

sh-4.4# chroot /host

sh-4.4# systemctl status chronyd

Example output

● chronyd.service - NTP client/server
    Loaded: loaded (/usr/lib/systemd/system/chronyd.service; disabled; vendor preset: enabled)
    Active: inactive (dead)
      Docs: man:chronyd(8)
            man:chrony.conf(5)

Check that the PTP interface is successfully synchronized to the primary clock using a remote shell connection to the linuxptp-daemon container and the PTP Management Client (pmc) tool:

Set the $PTP_POD_NAME variable with the name of the linuxptp-daemon pod by running the following command:
```
$ PTP_POD_NAME=$(oc get pods -n openshift-ptp -l app=linuxptp-daemon -o name)
```

Run the following command to check the sync status of the PTP device:

$ oc -n openshift-ptp rsh -c linuxptp-daemon-container ${PTP_POD_NAME} pmc -u -f /var/run/ptp4l.0.config -b 0 'GET PORT_DATA_SET'

Example output

sending: GET PORT_DATA_SET
  3cecef.fffe.7a7020-1 seq 0 RESPONSE MANAGEMENT PORT_DATA_SET
    portIdentity            3cecef.fffe.7a7020-1
    portState               SLAVE
    logMinDelayReqInterval  -4
    peerMeanPathDelay       0
    logAnnounceInterval     1
    announceReceiptTimeout  3
    logSyncInterval         0
    delayMechanism          1
    logMinPdelayReqInterval 0
    versionNumber           2
  3cecef.fffe.7a7020-2 seq 0 RESPONSE MANAGEMENT PORT_DATA_SET
    portIdentity            3cecef.fffe.7a7020-2
    portState               LISTENING
    logMinDelayReqInterval  0
    peerMeanPathDelay       0
    logAnnounceInterval     1
    announceReceiptTimeout  3
    logSyncInterval         0
    delayMechanism          1
    logMinPdelayReqInterval 0
    versionNumber           2

Run the following pmc command to check the PTP clock status:

$ oc -n openshift-ptp rsh -c linuxptp-daemon-container ${PTP_POD_NAME} pmc -u -f /var/run/ptp4l.0.config -b 0 'GET TIME_STATUS_NP'

Example output

sending: GET TIME_STATUS_NP
  3cecef.fffe.7a7020-0 seq 0 RESPONSE MANAGEMENT TIME_STATUS_NP
    master_offset              10 
    ingress_time               1657275432697400530
    cumulativeScaledRateOffset +0.000000000
    scaledLastGmPhaseChange    0
    gmTimeBaseIndicator        0
    lastGmPhaseChange          0x0000'0000000000000000.0000
    gmPresent                  true 
    gmIdentity                 3c2c30.ffff.670e00

master_offset should be between -100 and 100 ns.
Indicates that the PTP clock is synchronized to a master, and the local clock is not the grandmaster clock.

Check that the expected master offset value corresponding to the value in /var/run/ptp4l.0.config is found in the linuxptp-daemon-container log:

$ oc logs $PTP_POD_NAME -n openshift-ptp -c linuxptp-daemon-container

Example output

phc2sys[56020.341]: [ptp4l.1.config] CLOCK_REALTIME phc offset  -1731092 s2 freq -1546242 delay    497
ptp4l[56020.390]: [ptp4l.1.config] master offset         -2 s2 freq   -5863 path delay       541
ptp4l[56020.390]: [ptp4l.0.config] master offset         -8 s2 freq  -10699 path delay       533

Check that the SR-IOV configuration is correct by running the following commands:

Check that the disableDrain value in the SriovOperatorConfig resource is set to true:

$ oc get sriovoperatorconfig -n openshift-sriov-network-operator default -o jsonpath="{.spec.disableDrain}{'\n'}"

Example output

true

Check that the SriovNetworkNodeState sync status is Succeeded by running the following command:

$ oc get SriovNetworkNodeStates -n openshift-sriov-network-operator -o jsonpath="{.items[*].status.syncStatus}{'\n'}"

Example output

Succeeded

Verify that the expected number and configuration of virtual functions (Vfs) under each interface configured for SR-IOV is present and correct in the .status.interfaces field. For example:

$ oc get SriovNetworkNodeStates -n openshift-sriov-network-operator -o yaml

Example output

apiVersion: v1
items:
- apiVersion: sriovnetwork.openshift.io/v1
  kind: SriovNetworkNodeState
...
  status:
    interfaces:
    ...
    - Vfs:
      - deviceID: 154c
        driver: vfio-pci
        pciAddress: 0000:3b:0a.0
        vendor: "8086"
        vfID: 0
      - deviceID: 154c
        driver: vfio-pci
        pciAddress: 0000:3b:0a.1
        vendor: "8086"
        vfID: 1
      - deviceID: 154c
        driver: vfio-pci
        pciAddress: 0000:3b:0a.2
        vendor: "8086"
        vfID: 2
      - deviceID: 154c
        driver: vfio-pci
        pciAddress: 0000:3b:0a.3
        vendor: "8086"
        vfID: 3
      - deviceID: 154c
        driver: vfio-pci
        pciAddress: 0000:3b:0a.4
        vendor: "8086"
        vfID: 4
      - deviceID: 154c
        driver: vfio-pci
        pciAddress: 0000:3b:0a.5
        vendor: "8086"
        vfID: 5
      - deviceID: 154c
        driver: vfio-pci
        pciAddress: 0000:3b:0a.6
        vendor: "8086"
        vfID: 6
      - deviceID: 154c
        driver: vfio-pci
        pciAddress: 0000:3b:0a.7
        vendor: "8086"
        vfID: 7

Check that the cluster performance profile is correct. The cpu and hugepages sections will vary depending on your hardware configuration. Run the following command:

$ oc get PerformanceProfile openshift-node-performance-profile -o yaml

Example output

apiVersion: performance.openshift.io/v2
kind: PerformanceProfile
metadata:
  creationTimestamp: "2022-07-19T21:51:31Z"
  finalizers:
  - foreground-deletion
  generation: 1
  name: openshift-node-performance-profile
  resourceVersion: "33558"
  uid: 217958c0-9122-4c62-9d4d-fdc27c31118c
spec:
  additionalKernelArgs:
  - idle=poll
  - rcupdate.rcu_normal_after_boot=0
  - efi=runtime
  cpu:
    isolated: 2-51,54-103
    reserved: 0-1,52-53
  hugepages:
    defaultHugepagesSize: 1G
    pages:
    - count: 32
      size: 1G
  machineConfigPoolSelector:
    pools.operator.machineconfiguration.openshift.io/master: ""
  net:
    userLevelNetworking: true
  nodeSelector:
    node-role.kubernetes.io/master: ""
  numa:
    topologyPolicy: restricted
  realTimeKernel:
    enabled: true
status:
  conditions:
  - lastHeartbeatTime: "2022-07-19T21:51:31Z"
    lastTransitionTime: "2022-07-19T21:51:31Z"
    status: "True"
    type: Available
  - lastHeartbeatTime: "2022-07-19T21:51:31Z"
    lastTransitionTime: "2022-07-19T21:51:31Z"
    status: "True"
    type: Upgradeable
  - lastHeartbeatTime: "2022-07-19T21:51:31Z"
    lastTransitionTime: "2022-07-19T21:51:31Z"
    status: "False"
    type: Progressing
  - lastHeartbeatTime: "2022-07-19T21:51:31Z"
    lastTransitionTime: "2022-07-19T21:51:31Z"
    status: "False"
    type: Degraded
  runtimeClass: performance-openshift-node-performance-profile
  tuned: openshift-cluster-node-tuning-operator/openshift-node-performance-openshift-node-performance-profile

Note

CPU settings are dependent on the number of cores available on the server and should align with workload partitioning settings. hugepages configuration is server and application dependent.

Check that the PerformanceProfile was successfully applied to the cluster by running the following command:

$ oc get performanceprofile openshift-node-performance-profile -o jsonpath="{range .status.conditions[*]}{ @.type }{' -- '}{@.status}{'\n'}{end}"

Example output

Available -- True
Upgradeable -- True
Progressing -- False
Degraded -- False

Check the Tuned performance patch settings by running the following command:

$ oc get tuneds.tuned.openshift.io -n openshift-cluster-node-tuning-operator performance-patch -o yaml

Example output

apiVersion: tuned.openshift.io/v1
kind: Tuned
metadata:
  creationTimestamp: "2022-07-18T10:33:52Z"
  generation: 1
  name: performance-patch
  namespace: openshift-cluster-node-tuning-operator
  resourceVersion: "34024"
  uid: f9799811-f744-4179-bf00-32d4436c08fd
spec:
  profile:
  - data: |
      [main]
      summary=Configuration changes profile inherited from performance created tuned
      include=openshift-node-performance-openshift-node-performance-profile
      [bootloader]
      cmdline_crash=nohz_full=2-23,26-47 
      [sysctl]
      kernel.timer_migration=1
      [scheduler]
      group.ice-ptp=0:f:10:*:ice-ptp.*
      [service]
      service.stalld=start,enable
      service.chronyd=stop,disable
    name: performance-patch
  recommend:
  - machineConfigLabels:
      machineconfiguration.openshift.io/role: master
    priority: 19
    profile: performance-patch

The cpu list in cmdline=nohz_full= will vary based on your hardware configuration.

Check that cluster networking diagnostics are disabled by running the following command:
```
$ oc get networks.operator.openshift.io cluster -o jsonpath='{.spec.disableNetworkDiagnostics}'
```
Example output
```
true
```

Check that the Kubelet housekeeping interval is tuned to slower rate. This is set in the containerMountNS machine config. Run the following command:

$ oc describe machineconfig container-mount-namespace-and-kubelet-conf-master | grep OPENSHIFT_MAX_HOUSEKEEPING_INTERVAL_DURATION

Example output

Environment="OPENSHIFT_MAX_HOUSEKEEPING_INTERVAL_DURATION=60s"

Check that Grafana and alertManagerMain are disabled and that the Prometheus retention period is set to 24h by running the following command:
```
$ oc get configmap cluster-monitoring-config -n openshift-monitoring -o jsonpath="{ .data.config\.yaml }"
```
Example output
```
grafana:
  enabled: false
alertmanagerMain:
  enabled: false
prometheusK8s:
   retention: 24h
```
1. Use the following commands to verify that Grafana and alertManagerMain routes are not found in the cluster:
  $ oc get route -n openshift-monitoring alertmanager-main
  $ oc get route -n openshift-monitoring grafana
  Both queries should return Error from server (NotFound) messages.
Check that there is a minimum of 4 CPUs allocated as reserved for each of the PerformanceProfile, Tuned performance-patch, workload partitioning, and kernel command-line arguments by running the following command:
```
$ oc get performanceprofile -o jsonpath="{ .items[0].spec.cpu.reserved }"
```
Example output
```
0-3
```
Note

Depending on your workload requirements, you might require additional reserved CPUs to be allocated.