Version: 1.0
Date: October 2025
Author: AI-assisted analysis of Nova functional test infrastructure
This comprehensive guide documents Nova's functional test infrastructure and provides a blueprint for replicating this pattern in other OpenStack projects. It covers fixture architecture, RPC/messaging, database management, external service mocking, and CI/CD integration.
A frequent topic of discussion for OpenStack administrators is how to properly configure CPU allocation to balance performance and density. This blog post, inspired by a recent internal chat, will walk you through the key configuration options in OpenStack Nova for managing CPU overcommitment, with pointers to the official upstream documentation.
CPU overcommitment allows you to present more virtual CPUs (vCPUs) to your instances than the number of physical CPU cores available on the compute host. This is a common practice in virtualized environments, leveraging the fact that most instances don't use 100% of their assigned CPU all the time.
It's important to remember that in Nova, CPU overcommitment only applies to instances with a shared CPU policy (hw:cpu_policy='shared'). Instances that require dedicated CPUs (hw:cpu_policy='dedicated') get exclusive access to physical cores, and t