Multilevel queue Scheduling in operating system-computer world

 

Multilevel queue Scheduling in operating system

Multilevel queue Scheduling 

Multilevel queue Scheduling algorithms has been created for situation in which processes are easily classified into different groups. A common division is made between foreground processes and background processes. In this scheduling algorithm, process in the ready queue can be divided into different classes where each class has its own scheduling needs. In other word we can say that a multilevel queue scheduling algorithm partition the ready queue into several separate queue. The process are permanently assigned to one queue, generally based on some property of the process, such as memory size, process priority, or process type. Each queue it's own scheduling algorithm. For example, a common process division is a foreground process and background process. The foreground queue is scheduled by an RR algorithm, while the background queue is scheduled by an FCFS algorithm. The process scheduler is alternately select jobs from each queue and assign them to the CPU based on the algorithm assigned to the queue. 

Order of priority

1. System process queue
2. Interactive process queue
3. Batch process queue 
4. Each queue has absolute priority over lower-priority queues.