What are process scheduling queues?

Question :

What are process scheduling queues?

The OS maintains all PCBs in Process Scheduling Queues. The OS maintains a separate queue for each of the process states and PCBs of all processes in the same execution state are placed in the same queue. When the state of a process is changed, its PCB is unlinked from its current queue and moved to its new state queue.

The Operating System maintains the following important process scheduling queues −

•  Job queue − This queue keeps all the processes in the system.
•  Ready queue − This queue keeps a set of all processes residing in main memory, ready and waiting to execute. A new process is always put in this queue.
•  Device queues − The processes which are blocked due to unavailability of an I/O device constitute this queue.
•