MLQ

MLQ is an acronym that most commonly refers to Multi-Level Queue, a concept used in computer science to organize process scheduling in operating systems and related queueing models. In a typical MLQ design, the ready set is divided into several distinct queues, each representing a category of processes with similar characteristics or requirements. Processes are assigned to a queue on admission and, in the classic form, do not move between queues during execution. Each queue is governed by its own scheduling policy, and a fixed priority scheme determines which queue’s processes are chosen for execution before those in lower-priority queues.

In operation, the system selects a process from the highest-priority nonempty queue and applies the queue’s chosen policy (for example, first-come, first-served or round-robin) to determine the order of service within that queue. The use of multiple queues allows the system to tailor CPU allocation to different types of workloads, such as interactive versus batch processes, or short versus long tasks. Some variations introduce aging or dynamic adjustments to mitigate starvation of lower-priority queues, or allow limited migration of processes between queues in order to balance responsiveness and throughput.

MLQ is related to, but distinct from, multi-level feedback queue (MLFQ) scheduling. In MLFQ, processes can migrate between queues based on observed behavior, whereas classical MLQ emphasizes fixed allocation to predefined queues.

Outside operating systems, MLQ can appear as an acronym for other terms or organizations, and its meaning is context-dependent. In any given discussion, the intended definition should be inferred from subject matter and usage.