Multi-level queue scheduling in Operating System

Multi-level queue scheduling and we have seen how it works so there we saw that we have classified our processes into different groups and these groups were made into different queues and there were scheduling is happening between processes within the queues and also they were scheduling happening among the queues.
One process is assigned to a particular queue it was always assigned to that queue itself that means a process that is assigned to ascertain queue will not be moved to another queue it always belongs to that same queue and that same queue alone so the main difference that we are going to see between multi-level queue scheduling and the multi-level feedback.
Scheduling that we are discussing now is that here in multi-level feedback you scheduling we are going to be able to move the processes between queues that means one process will not always belong to one certain queue but it can move from one queue to another the multi-level feedback your scheduling algorithm allows a process to move between queues.
Two separate processes according to the characteristics of their cpu burst so different processes will have different characteristics of the CPU burst some may take longer time some may take lesser time so depending upon these characteristics we are going to separate the processes and allow them to move between certain cues so if a process uses too much of the CPU time it will be moved to a lower priority queue so this is a good example of how processes can be moved between queues so let’s say that we are having certain cues here with certain levels of priorities and let’s say that there is a process that belongs to a high priority queue which is using the CPU for a very long time then what happens we know that processes that belongs to the lower priority queue are always waiting for the processes in the higher priority queues to complete their execution so that they will get a chance but if the process in the higher priority queue is using the CPU for a very long time then what happens all the other processes end up waiting for a long time so in this kind of a scenario in case of a multi-level queue.
Multi-level feedback queue scheduling which is the one that we are discussing nowhere what we can do is we can move that process that is using the CPU for a long time from the higher priority queue to a lower priority queue so that the other processes can complete their execution and everybody will get a chance so this is an example of how processes will be moved between queues so this scheme leaves IO-bound and interactive processes in the higher priority queues so we know that the input/output bound operations and the interactive processes are the ones that belong to the higher priority queues and also they are the processes that will not be taking a very long time so we have discussed about this interactive processes in the previous lecture so if you have not watched the previous lecture of multi-level queue scheduling.

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