One of our customers observed this issue. In order to reproduce, In my test cluster, I intentionally increased the overall CPU limits to over 200% and monitored the cluster for more than 2 days. However, I did not see the KubeCPUOvercommit alert, which ideally should trigger after 10 minutes of overcommitment. 

Allocated resources:
  (Total limits may be over 100 percent, i.e., overcommitted.)
  Resource                       Requests      Limits
  --------                          --------            ------
  cpu                                2654m (75%)        8450m (241%)
  memory                         5995Mi (87%)  12264Mi (179%)
  ephemeral-storage         0 (0%)        0 (0%)
  hugepages-1Gi             0 (0%)        0 (0%)
  hugepages-2Mi             0 (0%)        0 (0%)

OCP console --> Observe --> alerting --> alert rule and select for the `KubeCPUOvercommit` alert.

Expression:

sum by (cluster) (namespace_cpu:kube_pod_container_resource_requests:sum{job="kube-state-metrics"}) - (sum by (cluster) (kube_node_status_allocatable{job="kube-state-metrics",resource="cpu"}) - max by (cluster) (kube_node_status_allocatable{job="kube-state-metrics",resource="cpu"})) > 0 and (sum by (cluster) (kube_node_status_allocatable{job="kube-state-metrics",resource="cpu"}) - max by (cluster) (kube_node_status_allocatable{job="kube-state-metrics",resource="cpu"})) > 0