试题与答案

设系统缓冲区和用户工作区均采用单缓冲,从外设读入1个数据块到系统缓冲区的时间为100

题型:单项选择题

题目:

设系统缓冲区和用户工作区均采用单缓冲,从外设读入1个数据块到系统缓冲区的时间为100,从系统缓冲区读入1个数据块到用户工作区的时间为5,对用户工作区中的1个数据块进行分析的时间为90(如下图所示)。进程从外设读入并分析2个数据块的最短时间是()

A.200

B.295

C.300

D.390

答案:

参考答案:C

解析:

数据块1从外设到用户工作区的总时间为105,在这段时间中,数据块2没有进行操作。在数据块1进行分析处理时,数据块2从外设到用户工作区的总时间为105,这段时间是并行的。再加上数据块2进行处理的时间90,总共是300,答案为C。

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