What is the difference between CPU contention and CPU ready queue?

'CPU contention’ and 'CPU ready queue’ are two related terms, but they address slightly different aspects of the same problem.

'CPU contention’ describes conflicts between different virtual machines in a virtualized hardware system where they are competing for the same resources. The term 'CPU contention’ might describe an event or series of events, or it might generically refer to situations where these kinds of conflicts occur.

By contrast, 'CPU ready queue’ is a term used to describe a facility in virtualization as well as a metric that can be affected by CPU contention. VMWare, a major distributor of virtualization software, has defined CPU ready queue as "the time a virtual machine must wait in a ready-to-run state before it can be scheduled on a CPU."

In other words, CPU contention is the problem, and CPU ready queue is a way to measure it. If CPU ready queue or wait time is too high, IT professionals must investigate and figure out what’s happening — for instance, whether virtual machines are correctly placed in a virtual environment, whether overall resources are sufficient for good operation, and whether there is specific CPU contention, or bottlenecks related to system calibration or setup.