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Is starvation possible in priority scheduling?
In priority-based scheduling algorithms, a major problem is indefinite block, or starvation. A process that is ready to run but waiting for the CPU can be considered blocked. A priority scheduling algorithm can leave some low-priority processes waiting indefinitely.
What is the disadvantage of priority scheduling?
The major disadvantage of priority scheduling is the process of indefinite blocking or starvation. This problem appears when a process is ready to be executed but it has to wait for the long time for execution by CPU because other high priority processes are executed by the CPU.
What happens if Q is too large in RR scheduling?
If time quantum is too large, the response time of the processes is too much which may not be tolerated in interactive environment. If time quantum is too small, it causes unnecessarily frequent context switch leading to more overheads resulting in less throughput.
How lower priority task executes in a preemptive scheduler?
Preemptive scheduling is used in real-time systems where the tasks are usually configured with different priorities and time critical tasks are given higher priorities. A higher priority task can stop a lower priority one and grab and use the CPU until it releases it.
What is starvation in priority scheduling?
Starvation or indefinite blocking is phenomenon associated with the Priority scheduling algorithms, in which a process ready to run for CPU can wait indefinitely because of low priority. As we see in the above example process having higher priority than other processes getting CPU earlier.
How many types of priority scheduling are there?
There are two types of priority scheduling algorithm exists. One is Preemptive priority scheduling while the other is Non Preemptive Priority scheduling. The priority number assigned to each of the process may or may not vary.
What will happen if the time quantum for RR scheduling is 20 milliseconds?
If a process’s CPU burst exceeds 1 time quantum, that process is preempted and is put back in the ready queue. The RR scheduling algorithm is thus preemptive. For example, with five processes and a time quantum of 20 milliseconds, each process will get up to 20 milliseconds every 100 milliseconds.
What is the waiting time using priority scheduling?
Priority scheduling is a non-preemptive algorithm and one of the most common scheduling algorithms in batch systems. Each process is assigned first arrival time (less arrival time process first) if two processes have same arrival time, then compare to priorities (highest process first).
What is the the average waiting time if priority scheduling is followed?
Average waiting time is defined as the sum of total time waited before starting of the processes divided by the total number of processes. Here, average waiting time = (6 + 0 + 16 + 18 + 1) / 5 = 41 / 5 = 8.2.