Chapter 7. Using the Node Tuning Operator

Procedure

1. Create a config map that contains a valid tuned manifest, and reference the manifest in a node pool. In the following example, a

   Tuned

   manifest defines a profile that sets

   vm.dirty_ratio

   to 55 on nodes that contain the

   tuned-1-node-label

   node label with any value. Save the following

   ConfigMap

   manifest in a file named

   tuned-1.yaml

   :

       apiVersion: v1
       kind: ConfigMap
       metadata:
         name: tuned-1
         namespace: clusters
       data:
         tuning: |
           apiVersion: tuned.openshift.io/v1
           kind: Tuned
           metadata:
             name: tuned-1
             namespace: openshift-cluster-node-tuning-operator
           spec:
             profile:
             - data: |
                 [main]
                 summary=Custom OpenShift profile
                 include=openshift-node
                 [sysctl]
                 vm.dirty_ratio="55"
               name: tuned-1-profile
             recommend:
             - priority: 20
               profile: tuned-1-profile

   Note

   If you do not add any labels to an entry in the

   spec.recommend

   section of the Tuned spec, node-pool-based matching is assumed, so the highest priority profile in the

   spec.recommend

   section is applied to nodes in the pool. Although you can achieve more fine-grained node-label-based matching by setting a label value in the Tuned

   .spec.recommend.match

   section, node labels will not persist during an upgrade unless you set the

   .spec.management.upgradeType

   value of the node pool to

   InPlace

   .

2. Create the

   ConfigMap

   object in the management cluster:

   $ oc --kubeconfig="$MGMT_KUBECONFIG" create -f tuned-1.yaml

3. Reference the

   ConfigMap

   object in the

   spec.tuningConfig

   field of the node pool, either by editing a node pool or creating one. In this example, assume that you have only one

   NodePool

   , named

   nodepool-1

   , which contains 2 nodes.

       apiVersion: hypershift.openshift.io/v1alpha1
       kind: NodePool
       metadata:
         ...
         name: nodepool-1
         namespace: clusters
       ...
       spec:
         ...
         tuningConfig:
         - name: tuned-1
       status:
       ...

   Note

   You can reference the same config map in multiple node pools. In hosted control planes, the Node Tuning Operator appends a hash of the node pool name and namespace to the name of the Tuned CRs to distinguish them. Outside of this case, do not create multiple TuneD profiles of the same name in different Tuned CRs for the same hosted cluster.

1. List the

   Tuned

   objects in the hosted cluster:

   $ oc --kubeconfig="$HC_KUBECONFIG" get tuned.tuned.openshift.io -n openshift-cluster-node-tuning-operator

   Example output

   NAME       AGE
   default    7m36s
   rendered   7m36s
   tuned-1    65s

2. List the

   Profile

   objects in the hosted cluster:

   $ oc --kubeconfig="$HC_KUBECONFIG" get profile.tuned.openshift.io -n openshift-cluster-node-tuning-operator

   Example output

   NAME                           TUNED            APPLIED   DEGRADED   AGE
   nodepool-1-worker-1            tuned-1-profile  True      False      7m43s
   nodepool-1-worker-2            tuned-1-profile  True      False      7m14s

   Note

   If no custom profiles are created, the

   openshift-node

   profile is applied by default.

3. To confirm that the tuning was applied correctly, start a debug shell on a node and check the sysctl values:

   $ oc --kubeconfig="$HC_KUBECONFIG" debug node/nodepool-1-worker-1 -- chroot /host sysctl vm.dirty_ratio

   Example output

   vm.dirty_ratio = 55

Procedure

1. Create a

   ConfigMap

   object that contains a

   Tuned

   object manifest for creating 10 huge pages that are 2 MB in size. Save this

   ConfigMap

   manifest in a file named

   tuned-hugepages.yaml

   :

       apiVersion: v1
       kind: ConfigMap
       metadata:
         name: tuned-hugepages
         namespace: clusters
       data:
         tuning: |
           apiVersion: tuned.openshift.io/v1
           kind: Tuned
           metadata:
             name: hugepages
             namespace: openshift-cluster-node-tuning-operator
           spec:
             profile:
             - data: |
                 [main]
                 summary=Boot time configuration for hugepages
                 include=openshift-node
                 [bootloader]
                 cmdline_openshift_node_hugepages=hugepagesz=2M hugepages=50
               name: openshift-node-hugepages
             recommend:
             - priority: 20
               profile: openshift-node-hugepages

   Note

   The

   .spec.recommend.match

   field is intentionally left blank. In this case, this

   Tuned

   object is applied to all nodes in the node pool where this

   ConfigMap

   object is referenced. Group nodes with the same hardware configuration into the same node pool. Otherwise, TuneD operands can calculate conflicting kernel parameters for two or more nodes that share the same node pool.

2. Create the

   ConfigMap

   object in the management cluster:

   $ oc --kubeconfig="<management_cluster_kubeconfig>" create -f tuned-hugepages.yaml 

   1

   1

   Replace <management_cluster_kubeconfig> with the name of your management cluster kubeconfig file.

3. Create a

   NodePool

   manifest YAML file, customize the upgrade type of the

   NodePool

   , and reference the

   ConfigMap

   object that you created in the

   spec.tuningConfig

   section. Create the

   NodePool

   manifest and save it in a file named

   hugepages-nodepool.yaml

   by using the

   hcp

   CLI:

   $ hcp create nodepool aws \
     --cluster-name <hosted_cluster_name> \

   1

   
     --name <nodepool_name> \

   2

   
     --node-count <nodepool_replicas> \

   3

   
     --instance-type <instance_type> \

   4

   
     --render > hugepages-nodepool.yaml

   1

   Replace <hosted_cluster_name> with the name of your hosted cluster.

   2

   Replace <nodepool_name> with the name of your node pool.

   3

   Replace <nodepool_replicas> with the number of your node pool replicas, for example, 2.

   4

   Replace <instance_type> with the instance type, for example, m5.2xlarge.

   Note

   The

   --render

   flag in the

   hcp create

   command does not render the secrets. To render the secrets, you must use both the

   --render

   and the

   --render-sensitive

   flags in the

   hcp create

   command.

4. In the

   hugepages-nodepool.yaml

   file, set

   .spec.management.upgradeType

   to

   InPlace

   , and set

   .spec.tuningConfig

   to reference the

   tuned-hugepages

   ConfigMap

   object that you created.

       apiVersion: hypershift.openshift.io/v1alpha1
       kind: NodePool
       metadata:
         name: hugepages-nodepool
         namespace: clusters
         ...
       spec:
         management:
           ...
           upgradeType: InPlace
         ...
         tuningConfig:
         - name: tuned-hugepages

   Note

   To avoid the unnecessary re-creation of nodes when you apply the new

   MachineConfig

   objects, set

   .spec.management.upgradeType

   to

   InPlace

   . If you use the

   Replace

   upgrade type, nodes are fully deleted and new nodes can replace them when you apply the new kernel boot parameters that the TuneD operand calculated.

5. Create the

   NodePool

   in the management cluster:

   $ oc --kubeconfig="<management_cluster_kubeconfig>" create -f hugepages-nodepool.yaml

1. List the

   Tuned

   objects in the hosted cluster:

   $ oc --kubeconfig="<hosted_cluster_kubeconfig>" get tuned.tuned.openshift.io -n openshift-cluster-node-tuning-operator

   Example output

   NAME                 AGE
   default              123m
   hugepages-8dfb1fed   1m23s
   rendered             123m

2. List the

   Profile

   objects in the hosted cluster:

   $ oc --kubeconfig="<hosted_cluster_kubeconfig>" get profile.tuned.openshift.io -n openshift-cluster-node-tuning-operator

   Example output

   NAME                           TUNED                      APPLIED   DEGRADED   AGE
   nodepool-1-worker-1            openshift-node             True      False      132m
   nodepool-1-worker-2            openshift-node             True      False      131m
   hugepages-nodepool-worker-1    openshift-node-hugepages   True      False      4m8s
   hugepages-nodepool-worker-2    openshift-node-hugepages   True      False      3m57s

   Both of the worker nodes in the new

   NodePool

   have the

   openshift-node-hugepages

   profile applied.

3. To confirm that the tuning was applied correctly, start a debug shell on a node and check

   /proc/cmdline

   .

   $ oc --kubeconfig="<hosted_cluster_kubeconfig>" debug node/nodepool-1-worker-1 -- chroot /host cat /proc/cmdline

   Example output

   BOOT_IMAGE=(hd0,gpt3)/ostree/rhcos-... hugepagesz=2M hugepages=50