[otterley]

It depends. If the second pod requests 4 CPUs, it doesn't necessarily mean that the first pod can't use all the CPUs in the uncontended case.

A lot of this depends on policy and cooperation, which is true for any multitenant system. If the policy is that nobody requests CPU, then the behavior will be like an ordinary shared Linux server under load - the scheduler will manage it as fairly as possible. OTOH, if there are pods that are greedy and pods that are parsimonious in terms of their requests, the greedy pods will get the lion's share of the resources if it needs them.

The flip side of overallocating CPU requests is cost. This value is subtracted from the available resources, making the node unavailable to do other useful work. Most of the time I see customers making the opposite mistake - overallocating CPU requests so much that their overall CPU utilization is well under 25% during peak periods.

[jeffbee]

Most people would be thrilled to get anything close to 25% CPU util. I guess one of the big missing pieces fro Borg that hasn't landed in k8s is node resource estimation. If you have a functional estimator, setting requests and limits becomes a bit less critical.