In this topic, you will learn about, Round-Robin scheduling.
Round-Robin (RR) Scheduling:
The Round-Robin scheduling algorithm is designed especially for the time-sharing systems. It is similar to FCFS, but preemption is added to switch between processes a small unit of time, called time Quantum or Time Slice is defined. A time Quantum is generally 10-100 milliseconds. The ready queue is treated as a circular queue. The CPU scheduler circular goes around the ready queue allocating the CPU for each process for a time interval of up to one-time quantum.
To implement Round-Robin scheduling, we keep the ready queue as a FIFO queue of processes. The CPU scheduler picks the first process from the ready queue, shakes the timer to interrupt after 1 quantum and dispatches a process.
In Round-Robin scheduling, one of two things will then happen:
- The process may have a CPU burst of less than 1-time quantum. In this case, the process itself will release the CPU voluntarily. The scheduler will then proceed to the next process, otherwise
- If the CPU burst of the currently running process is longer than one-time quantum, the timer will go off and will cause an interrupt to the Operating System (OS).
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