問53
頻出度★☆☆
マルチコアプロセッサに関する記述のうち, 適切なものはどれか。
平成26年度 秋期 ITパスポート試験 問53
テクノロジ系コンピュータ構成要素 › プロセッサ
This question's explanation and your answers so far.
解説
問 53
- ア
正解 A multi-core processor is a single processor (CPU) that contains multiple cores for performing computation. The OS assigns processes and threads to the individual cores, and each core runs a different task at the same time, which increases the amount of work that can be completed per unit of time (throughput) and raises the processing capability of the system as a whole. It is also worth knowing the background: continuing to raise the clock frequency ran into the limits of increased power consumption and heat, so the direction shifted to increasing the number of cores and improving performance through parallel processing. Therefore ア, which states “By having each core execute a different process simultaneously, it aims to improve the overall processing capability of the system”, is appropriate.
Incorrectイ
Having several units perform the same processing and comparing the results to raise reliability is the idea behind a dual system or a fault-tolerant design; it is not the original purpose of a multi-core processor. The aim of going multi-core is not to raise reliability by running the same processing redundantly, but to raise performance (processing capability) by dividing different tasks among the cores. Note also that a duplex system is a configuration with an active system and a standby system that switches over when a failure occurs; the standby system does not run the same processing and compare results, so it is a different concept and should not be confused with this.
Incorrectウ
To make effective use of multiple cores, the OS must manage which process or thread is assigned to which core, so scheduling functions that support multiprocessor / multi-core operation are indispensable. The statement that the cores are controlled by hardware alone and that the OS needs no special functions is incorrect. If the OS and the applications do not support parallel processing, performance will not improve even if the number of cores is increased.
Incorrectエ
The processing capability of a processor is not determined by the number of cores alone: the higher the clock frequency, the more instructions a single core can execute per unit of time. Actual performance is determined by several factors together, including the number of cores, the clock frequency, instruction execution efficiency, cache capacity, and how far the software is parallelized, so the statement that it does not depend on the clock frequency is incorrect.
ここがポイント
- Multi-core processor = a technology that places multiple computation cores in one CPU, assigns a different task to each core, and runs them in parallel, thereby improving the processing capability (throughput) of the system as a whole.
- Even if the number of cores is increased, performance will not improve without OS support (multi-core-aware scheduling) and parallelization of the software. Performance also depends not only on the number of cores but on factors such as the clock frequency.
用語