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Chapter 20. Debugging low latency node tuning status
Use the PerformanceProfile custom resource (CR) status fields for reporting tuning status and debugging latency issues in the cluster node.
20.1. Debugging low latency CNF tuning status
The PerformanceProfile custom resource (CR) contains status fields for reporting tuning status and debugging latency degradation issues. These fields report on conditions that describe the state of the operator’s reconciliation functionality.
A typical issue can arise when the status of machine config pools that are attached to the performance profile are in a degraded state, causing the PerformanceProfile status to degrade. In this case, the machine config pool issues a failure message.
The Node Tuning Operator contains the performanceProfile.spec.status.Conditions status field:
The Status field contains Conditions that specify Type values that indicate the status of the performance profile:
Available- All machine configs and Tuned profiles have been created successfully and are available for cluster components are responsible to process them (NTO, MCO, Kubelet).
Upgradeable- Indicates whether the resources maintained by the Operator are in a state that is safe to upgrade.
Progressing- Indicates that the deployment process from the performance profile has started.
DegradedIndicates an error if:
- Validation of the performance profile has failed.
- Creation of all relevant components did not complete successfully.
Each of these types contain the following fields:
Status-
The state for the specific type (
trueorfalse). Timestamp- The transaction timestamp.
Reason string- The machine readable reason.
Message string- The human readable reason describing the state and error details, if any.
20.1.1. Machine config pools
A performance profile and its created products are applied to a node according to an associated machine config pool (MCP). The MCP holds valuable information about the progress of applying the machine configurations created by performance profiles that encompass kernel args, kube config, huge pages allocation, and deployment of rt-kernel. The Performance Profile controller monitors changes in the MCP and updates the performance profile status accordingly.
The only conditions returned by the MCP to the performance profile status is when the MCP is Degraded, which leads to performanceProfile.status.condition.Degraded = true.
Example
The following example is for a performance profile with an associated machine config pool (worker-cnf) that was created for it:
The associated machine config pool is in a degraded state:
oc get mcp
# oc get mcpCopy to Clipboard Copied! Toggle word wrap Toggle overflow Example output
NAME CONFIG UPDATED UPDATING DEGRADED MACHINECOUNT READYMACHINECOUNT UPDATEDMACHINECOUNT DEGRADEDMACHINECOUNT AGE master rendered-master-2ee57a93fa6c9181b546ca46e1571d2d True False False 3 3 3 0 2d21h worker rendered-worker-d6b2bdc07d9f5a59a6b68950acf25e5f True False False 2 2 2 0 2d21h worker-cnf rendered-worker-cnf-6c838641b8a08fff08dbd8b02fb63f7c False True True 2 1 1 1 2d20h
NAME CONFIG UPDATED UPDATING DEGRADED MACHINECOUNT READYMACHINECOUNT UPDATEDMACHINECOUNT DEGRADEDMACHINECOUNT AGE master rendered-master-2ee57a93fa6c9181b546ca46e1571d2d True False False 3 3 3 0 2d21h worker rendered-worker-d6b2bdc07d9f5a59a6b68950acf25e5f True False False 2 2 2 0 2d21h worker-cnf rendered-worker-cnf-6c838641b8a08fff08dbd8b02fb63f7c False True True 2 1 1 1 2d20hCopy to Clipboard Copied! Toggle word wrap Toggle overflow The
describesection of the MCP shows the reason:oc describe mcp worker-cnf
# oc describe mcp worker-cnfCopy to Clipboard Copied! Toggle word wrap Toggle overflow Example output
Message: Node node-worker-cnf is reporting: "prepping update: machineconfig.machineconfiguration.openshift.io \"rendered-worker-cnf-40b9996919c08e335f3ff230ce1d170\" not found" Reason: 1 nodes are reporting degraded status on syncMessage: Node node-worker-cnf is reporting: "prepping update: machineconfig.machineconfiguration.openshift.io \"rendered-worker-cnf-40b9996919c08e335f3ff230ce1d170\" not found" Reason: 1 nodes are reporting degraded status on syncCopy to Clipboard Copied! Toggle word wrap Toggle overflow The degraded state should also appear under the performance profile
statusfield marked asdegraded = true:oc describe performanceprofiles performance
# oc describe performanceprofiles performanceCopy to Clipboard Copied! Toggle word wrap Toggle overflow Example output
Copy to Clipboard Copied! Toggle word wrap Toggle overflow
20.2. Collecting low latency tuning debugging data for Red Hat Support
When opening a support case, it is helpful to provide debugging information about your cluster to Red Hat Support.
The must-gather tool enables you to collect diagnostic information about your OpenShift Container Platform cluster, including node tuning, NUMA topology, and other information needed to debug issues with low latency setup.
For prompt support, supply diagnostic information for both OpenShift Container Platform and low latency tuning.
20.2.1. About the must-gather tool
The oc adm must-gather CLI command collects the information from your cluster that is most likely needed for debugging issues, such as:
- Resource definitions
- Audit logs
- Service logs
You can specify one or more images when you run the command by including the --image argument. When you specify an image, the tool collects data related to that feature or product. When you run oc adm must-gather, a new pod is created on the cluster. The data is collected on that pod and saved in a new directory that starts with must-gather.local. This directory is created in your current working directory.
20.2.2. Gathering low latency tuning data
Use the oc adm must-gather CLI command to collect information about your cluster, including features and objects associated with low latency tuning, including:
- The Node Tuning Operator namespaces and child objects.
-
MachineConfigPooland associatedMachineConfigobjects. - The Node Tuning Operator and associated Tuned objects.
- Linux kernel command-line options.
- CPU and NUMA topology
- Basic PCI device information and NUMA locality.
Prerequisites
-
Access to the cluster as a user with the
cluster-adminrole. - The OpenShift Container Platform CLI (oc) installed.
Procedure
-
Navigate to the directory where you want to store the
must-gatherdata. Collect debugging information by running the following command:
oc adm must-gather
$ oc adm must-gatherCopy to Clipboard Copied! Toggle word wrap Toggle overflow Example output
Copy to Clipboard Copied! Toggle word wrap Toggle overflow Create a compressed file from the
must-gatherdirectory that was created in your working directory. For example, on a computer that uses a Linux operating system, run the following command:tar cvaf must-gather.tar.gz must-gather-local.5421342344627712289
$ tar cvaf must-gather.tar.gz must-gather-local.54213423446277122891 Copy to Clipboard Copied! Toggle word wrap Toggle overflow - 1
- Replace
must-gather-local.5421342344627712289//with the directory name created by themust-gathertool.
NoteCreate a compressed file to attach the data to a support case or to use with the Performance Profile Creator wrapper script when you create a performance profile.
- Attach the compressed file to your support case on the Red Hat Customer Portal.
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