Cluster Node Tuning Operator
The Cluster Node Tuning Operator manages cluster node-level tuning for OpenShift.
The majority of high-performance applications require some level of kernel tuning. The operator provides a unified management interface to users of node-level sysctls and more flexibility to add custom tuning specified by user needs. The operator manages the containerized tuned daemon for OpenShift as a Kubernetes DaemonSet. It ensures custom tuning specification is passed to all containerized tuned daemons running in the cluster in the format that the daemons understand. The daemons run on all nodes in the cluster, one per node.
Deploying the node tuning operator
The operator is deployed by applying the
*.yaml manifests in the operator's
/manifests directory in alphanumeric order. It automatically creates a default deployment
and custom resource
for the tuned daemons. The following shows the default CR created
by the operator on a cluster with the operator installed.
$ oc get Tuned NAME AGE default 1h
Custom tuning specification
For an example of a tuning specification, refer to
/assets/tuned/07-cr-tuned.yaml in the operator's directory or to
the resource created in a live cluster by:
$ oc get Tuned/default -o yaml
The CR for the operator has two major sections. The first
profile:, is a list of tuned profiles and their names. The
recommend:, defines the profile selection logic.
Multiple custom tuning specifications can co-exist as multiple CRs in the operator's namespace. The existence of new CRs or the deletion of old CRs is detected by the operator. All existing custom tuning specifications are merged and appropriate objects for the containerized tuned daemons are updated.
profile: section lists tuned profiles and their names.
profile: - name: tuned_profile_1 data: | # Tuned profile specification [main] summary=Description of tuned_profile_1 profile [sysctl] net.ipv4.ip_forward=1 # ... other sysctl's or other tuned daemon plugins supported by the containerized tuned # ... - name: tuned_profile_n data: | # Tuned profile specification [main] summary=Description of tuned_profile_n profile # tuned_profile_n profile settings
Refer to a list of (tuned plugins supported by the operator)[#supported-tuned-daemon-plugins].
profile: selection logic is defined by the
recommend: section of the CR.
recommend: - match: # optional; if omitted, profile match is assumed unless a profile with a higher matches first <match> # an optional array priority: <priority> # profile ordering priority, lower numbers mean higher priority (0 is the highest priority) profile: <tuned_profile_name> # e.g. tuned_profile_1 # ... - match: <match> priority: <priority> profile: <tuned_profile_name> # e.g. tuned_profile_n
<match> is omitted, a profile match (i.e. true) is assumed.
<match> is an optional array recursively defined as follows:
- label: <label_name> # node or pod label name value: <label_value> # optional node or pod label value; if omitted, the presence of <label_name> is enough to match type: <label_type> # optional node or pod type ("node" or "pod"); if omitted, "node" is assumed <match> # an optional <match> array
<match> is not omitted, all nested
<match> sections must
also evaluate to true. Otherwise, false is assumed and the
profile with the respective
<match> section will not be applied or
recommended. Therefore, the nesting (child
<match> sections) works as logical
and operator. Conversely, if any item of the
<match> array matches,
<match> array evaluates to true. Therefore, the array
acts as logical or operator.
- match: - label: tuned.openshift.io/elasticsearch match: - label: node-role.kubernetes.io/master - label: node-role.kubernetes.io/infra type: pod priority: 10 profile: openshift-control-plane-es - match: - label: node-role.kubernetes.io/master - label: node-role.kubernetes.io/infra priority: 20 profile: openshift-control-plane - priority: 30 profile: openshift-node
The CR above is translated for the containerized tuned daemon into
its recommend.conf file based on the profile priorities. The profile
with the highest priority (10) is openshift-control-plane-es and,
therefore, it is considered first. The containerized tuned daemon
running on a given node looks to see if there is a pod running on the
same node with the tuned.openshift.io/elasticsearch label set. If not,
<match> section evaluates as false. If there is such a
pod with the label, in order for the
<match> section to evaluate to
true, the node label also needs to be node-role.kubernetes.io/master
If the labels for the profile with priority 10 matched, openshift-control-plane-es profile is applied and no other profile is considered. If the node/pod label combination did not match, the second highest priority profile (openshift-control-plane) is considered. This profile is applied if the containerized tuned pod runs on a node with labels node-role.kubernetes.io/master or node-role.kubernetes.io/infra.
Finally, the profile
openshift-node has the lowest priority of 30.
It lacks the
<match> section and, therefore, will always match. It
acts as a profile catch-all to set openshift-node profile, if no other
profile with higher priority matches on a given node.
Supported tuned daemon plugins
with the exception of dynamic tuning functionality provided by some of the plugins.
The following Tuned plugins are currently not supported: