A Multilevel Feedback Queue scheduler allows a process to move between different priority queues based on its observed behaviour during execution. Which specific behaviour typically causes a process to be demoted to a lower-priority queue?

A Multilevel Feedback Queue uses a process's actual behaviour as feedback to adjust its priority dynamically. A process that consumes its entire allotted CPU time quantum without voluntarily yielding (e.g., for I/O) demonstrates that it is CPU-bound and likely to need substantial further CPU time — such a process is demoted to a lower-priority queue, which typically has a longer time quantum (suited to longer-running jobs) but is scheduled less frequently, keeping the higher-priority queues responsive for short, interactive, I/O-bound processes that voluntarily give up the CPU quickly (which are instead promoted or kept in high-priority queues).