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Added CPU Manager content to 4.0
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Ashley Hardin
@@ -361,6 +361,8 @@ Topics:
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File: using-node-tuning-operator
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- Name: Using Cluster Loader
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File: using-cluster-loader
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- Name: Using CPU Manager
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File: using-cpu-manager
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- Name: Scaling the Cluster Monitoring Operator
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File: scaling-cluster-monitoring-operator
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- Name: Planning your environment according to object limits
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218
modules/setting-up-cpu-manager.adoc
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218
modules/setting-up-cpu-manager.adoc
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@@ -0,0 +1,218 @@
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// Module included in the following assemblies:
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//
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// * scaling_and_performance/using-cpu-manager.adoc
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[id='seting_up_cpu_manager_{context}']
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= Setting up CPU Manager
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.Procedure
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. Optionally, label a node:
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+
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----
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# oc label node perf-node.example.com cpumanager=true
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----
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. Edit the `MachineConfigPool` of the nodes where CPU Manager should be enabled.
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In this example, all workers have CPU Manager enabled:
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+
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----
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# oc edit machineconfigpool worker
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----
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. Add a label to the worker `MachineConfigPool`:
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+
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----
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metadata:
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creationTimestamp: 2019-xx-xxx
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generation: 3
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labels:
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custom-kubelet: cpumanager-enabled
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----
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. Create a `KubeletConfig`, `cpumanager-kubeletconfig.yaml`, custom resource (CR).
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Refer to the label created in the previous step to have the correct nodes
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updated with the new `KubeletConfig`. See the `machineConfigPoolSelector`
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section:
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+
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----
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apiVersion: machineconfiguration.openshift.io/v1
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kind: KubeletConfig
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metadata:
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name: cpumanager-enabled
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spec:
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machineConfigPoolSelector:
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matchLabels:
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custom-kubelet: cpumanager-enabled
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kubeletConfig:
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cpuManagerPolicy: static
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cpuManagerReconcilePeriod: 5s
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----
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. Create the dynamic `KubeletConfig`:
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+
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----
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# oc create -f cpumanager-kubeletconfig.yaml
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----
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+
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This adds the CPU Manager feature to the `KubeletConfig` and, if needed, the
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Machine Config Operator (MCO) reboots the node. To enable CPU Manager, a reboot
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is not needed.
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. Check for the merged `KubeletConfig`:
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+
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----
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# oc get machineconfig 99-worker-XXXXXX-XXXXX-XXXX-XXXXX-kubelet -o json | grep ownerReference -A7
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"ownerReferences": [
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{
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"apiVersion": "machineconfiguration.openshift.io/v1",
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"kind": "KubeletConfig",
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"name": "cpumanager-enabled",
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"uid": "7ed5616d-6b72-11e9-aae1-021e1ce18878"
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}
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],
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----
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. Check the worker for the updated `kubelet.conf`:
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+
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----
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# oc debug node/perf-node.example.com
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sh-4.4# cat /host/etc/kubernetes/kubelet.conf | grep cpuManager
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cpuManagerPolicy: static <1>
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cpuManagerReconcilePeriod: 5s <1>
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----
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<1> These settings were defined when you created the `KubeletConfig` CR.
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. Create a Pod that requests a core or multiple cores. Both limits and requests
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must have their CPU value set to a whole integer. That is the number of cores
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that will be dedicated to this Pod:
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+
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----
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# cat cpumanager-pod.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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generateName: cpumanager-
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spec:
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containers:
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- name: cpumanager
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image: gcr.io/google_containers/pause-amd64:3.0
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resources:
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requests:
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cpu: 1
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memory: "1G"
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limits:
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cpu: 1
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memory: "1G"
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nodeSelector:
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cpumanager: "true"
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----
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. Create the Pod:
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+
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----
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# oc create -f cpumanager-pod.yaml
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----
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. Verify that the Pod is scheduled to the node that you labeled:
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+
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----
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# oc describe pod cpumanager
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Name: cpumanager-6cqz7
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Namespace: default
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Priority: 0
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PriorityClassName: <none>
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Node: perf-node.example.com/xxx.xx.xx.xxx
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...
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Limits:
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cpu: 1
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memory: 1G
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Requests:
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cpu: 1
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memory: 1G
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...
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QoS Class: Guaranteed
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Node-Selectors: cpumanager=true
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----
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. Verify that the `cgroups` are set up correctly. Get the process ID (PID) of the
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`pause` process:
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+
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----
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# ├─init.scope
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│ └─1 /usr/lib/systemd/systemd --switched-root --system --deserialize 17
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└─kubepods.slice
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├─kubepods-pod69c01f8e_6b74_11e9_ac0f_0a2b62178a22.slice
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│ ├─crio-b5437308f1a574c542bdf08563b865c0345c8f8c0b0a655612c.scope
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│ └─32706 /pause
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----
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+
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Pods of quality of service (QoS) tier `Guaranteed` are placed within the
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`kubepods.slice`. Pods of other QoS tiers end up in child `cgroups` of
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`kubepods`:
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+
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----
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# cd /sys/fs/cgroup/cpuset/kubepods.slice/kubepods-pod69c01f8e_6b74_11e9_ac0f_0a2b62178a22.slice/crio-b5437308f1ad1a7db0574c542bdf08563b865c0345c86e9585f8c0b0a655612c.scope
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# for i in `ls cpuset.cpus tasks` ; do echo -n "$i "; cat $i ; done
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cpuset.cpus 1
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tasks 32706
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----
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. Check the allowed CPU list for the task:
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+
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----
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# grep ^Cpus_allowed_list /proc/32706/status
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Cpus_allowed_list: 1
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----
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. Verify that another pod (in this case, the pod in the `burstable` QoS tier) on
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the system cannot run on the core allocated for the `Guaranteed` pod:
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+
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----
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# cat /sys/fs/cgroup/cpuset/kubepods.slice/kubepods-besteffort.slice/kubepods-besteffort-podc494a073_6b77_11e9_98c0_06bba5c387ea.slice/crio-c56982f57b75a2420947f0afc6cafe7534c5734efc34157525fa9abbf99e3849.scope/cpuset.cpus
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0
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----
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+
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----
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# oc describe node perf-node.example.com
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...
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Capacity:
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attachable-volumes-aws-ebs: 39
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cpu: 2
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ephemeral-storage: 124768236Ki
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hugepages-1Gi: 0
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hugepages-2Mi: 0
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memory: 8162900Ki
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pods: 250
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Allocatable:
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attachable-volumes-aws-ebs: 39
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cpu: 1500m
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ephemeral-storage: 124768236Ki
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hugepages-1Gi: 0
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hugepages-2Mi: 0
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memory: 7548500Ki
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pods: 250
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------- ---- ------------ ---------- --------------- ------------- ---
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default cpumanager-6cqz7 1 (66%) 1 (66%) 1G (12%) 1G (12%) 29m
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Allocated resources:
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(Total limits may be over 100 percent, i.e., overcommitted.)
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Resource Requests Limits
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-------- -------- ------
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cpu 1440m (96%) 1 (66%)
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----
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+
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This VM has two CPU cores. You set `kube-reserved` to 500 millicores, meaning half
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of one core is subtracted from the total capacity of the node to arrive at the
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`Node Allocatable` amount. You can see that `Allocatable CPU` is 1500 millicores.
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This means you can run one of the CPU Manager pods since each will take one whole
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core. A whole core is equivalent to 1000 millicores. If you try to schedule a
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second pod, the system will accept the pod, but it will never be scheduled:
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+
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----
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NAME READY STATUS RESTARTS AGE
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cpumanager-6cqz7 1/1 Running 0 33m
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cpumanager-7qc2t 0/1 Pending 0 11s
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----
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18
scalability_and_performance/using-cpu-manager.adoc
Normal file
18
scalability_and_performance/using-cpu-manager.adoc
Normal file
@@ -0,0 +1,18 @@
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[id='using-cpu-manager']
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= Using CPU Manager
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include::modules/common-attributes.adoc[]
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:context:
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toc::[]
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CPU Manager manages groups of CPUs and constrains workloads to specific CPUs.
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CPU Manager is useful for workloads that have some of these attributes:
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* Require as much CPU time as possible.
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* Are sensitive to processor cache misses.
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* Are low-latency network applications.
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* Coordinate with other processes and benefit from sharing a single processor
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cache.
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include::modules/setting-up-cpu-manager.adoc[leveloffset=+1]
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