Let's say you are attempting to deploy a pod on OpenShift, and something like this is being returned. Notice in this example that 2 nodes have insufficient CPU.

Events:
  Type     Reason            Age   From               Message
  ----     ------            ----  ----               -------
  Warning  FailedScheduling  28s   default-scheduler  0/13 nodes are available: 2 Insufficient cpu, 3 node(s) had untolerated taint {node-role.kubernetes.io/master: }, 8 node(s) didn't match Pod's node affinity/selector. preemption: 0/13 nodes are available: 11 Preemption is not helpful for scheduling, 2 No preemption victims found for incoming pod.

Almost always, pods are deployed to worker nodes, thus it's probably the worker nodes that have insufficient CPU. The oc get nodes command can be used to list your nodes.

~]$ oc get nodes
NAME                  STATUS   ROLES            AGE    VERSION
my-node-edge-lm6wz     Ready    infra,worker     519d   v1.23.5+012e945
my-node-edge-pmlls     Ready    infra,worker     519d   v1.23.5+012e945
my-node-infra-c4v5h    Ready    infra,worker     519d   v1.23.5+012e945
my-node-infra-mc8rc    Ready    infra,worker     519d   v1.23.5+012e945
my-node-infra-p9cjv    Ready    infra,worker     519d   v1.23.5+012e945
my-node-master-0       Ready    master           522d   v1.23.5+012e945
my-node-master-1       Ready    master           522d   v1.23.5+012e945
my-node-master-2       Ready    master           522d   v1.23.5+012e945
my-node-worker-lk5vm   Ready    compute,worker   61d    v1.23.5+012e945
my-node-worker-pj4r4   Ready    compute,worker   61d    v1.23.5+012e945

The oc adm top command can be used to display the current, real time amount of CPU and memory being used by nodes.

~]$ oc adm top node
NAME                       CPU(cores)   CPU%   MEMORY(bytes)   MEMORY%
my-edge-78v55              139m         3%     5634Mi          65%
my-edge-tk6gm              143m         4%     5514Mi          63%
my-infra-7hpsl             751m         13%    12094Mi         24%
my-infra-jld8v             1091m        19%    45008Mi         92%
my-infra-wxjgn             323m         5%     12444Mi         25%
my-master-0                499m         6%     15022Mi         23%
my-master-1                647m         8%     15334Mi         24%
my-master-2                327m         4%     11125Mi         17%
my-worker-4ccvr            195m         5%     6821Mi          11%
my-worker-flbcp            181m         5%     8027Mi          13%
my-worker-jchnk            178m         5%     8204Mi          13%

And by pods in the currently selected namespace.

~]$ oc adm top pods
NAME                        CPU(cores)   MEMORY(bytes)
my-pod-5ff96b69cd-v6pv5     1m           36Mi
my-pod-66f68d8884-vbp6g     0m           121Mi
my-pod-84d6fdb8c-5zczs      1m           221Mi

Or in a specific namespace.

~]$ oc adm top pods --namespace my-project
NAME                        CPU(cores)   MEMORY(bytes)
my-pod-5ff96b69cd-v6pv5     1m           36Mi
my-pod-66f68d8884-vbp6g     0m           121Mi
my-pod-84d6fdb8c-5zczs      1m           221Mi

Or in all namespaces.

~]$ oc adm top pods --all-namespaces
NAMESPACE          NAME                          CPU(cores)   MEMORY(bytes)
foo-project        my-pod-7478b76dcc-2ql98       1m           77Mi
foo-project        my-pod-5ffbb5f99-vclqf        1m           9Mi
foo-project        my-pod-94d49d56d-n9g26        1m           42Mi
bar-project        my-pod-7cf56894f6-5w4qp       1m           167Mi
bar-project        my-pod-56d6b9b59c-j5z7b       1m           22Mi
bar-project        my-pod-5d47f598cb-cc5nd       1m           53Mi

You can view the node YAML to determine how much allocatable and capacity CPU the node has.

~]$ oc get node my-node-worker-lk5vm --output yaml
status:
  allocatable:
    cpu: 3500m
    ephemeral-storage: "114396791822"
    hugepages-1Gi: "0"
    hugepages-2Mi: "0"
    memory: 62447948Ki
    pods: "250"
  capacity:
    cpu: "4"
    ephemeral-storage: 125293548Ki
    hugepages-1Gi: "0"
    hugepages-2Mi: "0"
    memory: 65696076Ki
    pods: "250"

And you can view the pod YAML to see if the containers in the pod have CPU requests/limits. In this example, there are 3 containers in the pod, each requesting 500m of CPU. That's quite a bit of CPU to be requesting.

~]$ oc get pod my-pod-kzz2w --output yaml
spec:
  containers:
  - name: my-container
    resources:
      requests:
        cpu: 500m
        memory: 128Mi
  initContainers:
  - name: my-first-init-container
    resources:
      requests:
        cpu: 500m
        memory: 128Mi
  - name: my-second-init-container
    resources:
      requests:
        cpu: 500m        

If the pod is managed by a deployment, you can try reducing the CPU requests in the deployment, to see if the pod is able to be scheduled on the node with less CPU. Of course, the pod may not function probably if it actually needs 500m of CPU requests, but you can at least try this change to see what the result it.