diff --git a/specs/template.rst b/specs/template.rst index 6b9d36e09..a8f45f41c 100644 --- a/specs/template.rst +++ b/specs/template.rst @@ -120,6 +120,30 @@ Aside from the API, are there other ways a user will interact with this feature? - Does this change have an impact on python-novaclient? What does the user interface there look like? +Performance Impact +------------------ + +Describe any potential performance impact on the system, for example +how often will new code be called, and is there a major change to the calling +pattern of existing code. + +Examples of things to consider here include: +- A periodic task might look like a small addition but if it calls conductor or + another service the load is multiplied by the number of nodes in the system. + +- Scheduler filters get called once per host for every instance being created, so + any latency they introduce is linear with the size of the system. + +- A small change in a utility function or a commonly used decorator can have a + large impacts on performance. + +- Calls which result in a database queries (whether direct or via conductor) can + have a profound impact on performance when called in critical sections of the + code. + +- Will the change include any locking, and if so what considerations are there on + holding the lock? + Deployer impact ---------------