IPA IP 2020 Question 59
A question IPA Japan published in 令和2年度 10月 ITパスポート試験 公開問題 問59, translated into English. ITPEC is based on the same exams.
In a computer that uses virtual memory, it was found that the processing performance is decreasing because contents are frequently swapped between main memory and auxiliary storage. Which of the following is the most appropriate countermeasure to remove the cause of this decrease in processing performance? Here, the computer has only one (1) auxiliary storage device.
Explanation
Increasing the capacity of the main memory unit — frequent swapping means main memory is too small for the pages in use, so more main memory removes the cause.
Virtual memory lets programs use more memory than is physically installed by keeping part of it on auxiliary storage and moving pages in and out of main memory (paging). When the pages being used do not fit in main memory, page-ins and page-outs happen constantly and the computer spends its time on slow disk transfers instead of processing: thrashing. Adding main memory lets more pages stay resident, so the swapping falls.
Answer (c)
Why not others:
- •(a) — a faster CPU does not reduce the swapping; the CPU is waiting for the auxiliary storage
- •(b) — a larger virtual memory gives more room on auxiliary storage but does not let more pages stay in main memory
- •(d) — the auxiliary storage's capacity is not the bottleneck; a bigger device still swaps as often
Key rule: Thrashing comes from too little real memory for the working set; the remedy is more main memory (or fewer programs running at once), not more virtual memory.
Software · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.