If a thread is not finished running, perhaps because it had to wait or it was preempted, it is typically restarted on the same processor that previously ran it. What is this known as?

processor affinity

Explanation: processor affinity is the ability or privilege afforded to a user which enables the user to specify the processor or the cores a given thread or process should run on. Processor affinity is also called processor pinning meaning a user can designate a particular process or thread to run on a specified processor. Processor affinity is used to improve performance as it reduces cache load. However, the pinned process or thread cannot use any other core apart from the designated core unless the process affinity setting is reversed.