Consider the following justifications for commonly using the two-level CPU scheduling:
Consider the following justifications for commonly using the two-level CPU scheduling:
I. It is used when memory is too small to hold all the ready processes
II. Because its performance is same as that of the FIFO.
III. Because it facilitates putting some set of processes into memory and a choice is made from that.
IV. Because it does not allow to adjust the set of in-core processes
Which of the following is true?
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Correct answer: (D) I and III
Explanation
Two-level scheduling is used to schedule efficiently when some processes are swapped out. A lower-level scheduler (e.g. round robin) selects only among the processes in memory, while a higher-level scheduler swaps processes in and out of memory. Hence I and III are correct.