ISRO2016-51

Question

For the real time operating system, which of the following is the most suitable scheduling scheme?

• A. Round robin
• B. First come first serve
• C. Pre-emptive
• D. Random scheduling

Answer 1

Answer C :

Preemptive Scheduling is suitable for Real-Time Programming, as it will allow a real-time process to preempt a process currently running in the Kernel. A preemptive Kernel may be more responsive, since there is less risk that a Kernal-mode process will run for arbitrarily long period before relinquishing the processor to waiting proces. Real-time systems requires that results be produced within a specified deadline.One of the key feature of Real-time system is its ability to respond to real-time process as soon as process requires CPU .As a result the scheduler for real-time system must support priority-based algorithm with preemption.

Round Robin Scheduling is used in Time Sharing Systems . (Refer Galvin)

Comments

But these cases also possible with pre-emptive scheduling like a important or urgent process may starve .

so on this way we can also reject c option

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Real time implies any new process must get immediate priority. This should be given in any standard text book.

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So in context of this question with pre-emptive you mean a system where a currently running program could be pre-empted to serve an urgent process.

whereas in round robin it will go until time quantum or process completion so we are not getting immediate response ..

Answer 2

https://en.wikipedia.org/wiki/Real-time_operating_system

nice explanation.