Write an algorithm for Round Robin CPU scheduling using?

Answer 1

On each system clock tick, at interval set by design...

• If no other runnable threads, return from clock interrupt.
• Save the currently running thread's context.
• Restore the next runnable thread's context.
• Return from clock tick interrupt.

Note: Most modern schedulers combine round-robin with priority. In the priority scheme, any runnable thread with a higher priority than the interrupted thread takes precedence. If there are none, then round-robin applies at the current priority. If there are no runnable threads at the current priority, lower priorities are considered until we reach the idle priority thread, which, by the way, is always runnable.

Also, there is usually an algorithm that adjusts thread priority dynamically. As the thread runs, if it stays runnable its priority slowly drops from its initial base priority. If it is constantly blocking and then then becoming runnable, its priority increases, often faster than it decreases. This makes interactive threads appear to be very responsive, while CPU intensive threads slowly defer to interactive threads. This is usually a good compromise between responsiveness and throughput.