In the following output from top, which processes contribute to the percentage of time that the CPU spends in the state of wa?



Tasks: 193 total, 1 running, 190 sleeping, 2 stopped, 0 zombie
Cpu(s): 0.5%us, 0.3%sy, 0.0%ni, 98.2%id, 1.0%wa, 0.0%hi, 0.0%si, 0.0%st

A. Processes waiting for user interaction.
B. Processes that were already closed and are waiting to be launched again.
C. Processes that have not been scheduled yet because they haven't been fully loaded into RAM or are in swap.
D. Processes waiting for IO operations to complete.

題解

「top」指令用來顯示目前行程的資訊、系統運行時間和負載情形。有關於CPU的資訊，各個欄位的意義如下：

  • us：執行nice值等於0的使用者行程所花費的CPU時間。
  • sy：執行Kernel行程所花費的CPU時間。
  • ni：執行nice值不等於0的使用者行程所花費的CPU時間。
  • id：Kernel閒置的時間。
  • wa：等待IO的時間。
  • hi：等待硬體中斷的時間。
  • si：等待軟體中斷的時間。
  • st：等待虛擬機的管理程式(hypervisor)處理其它虛擬機的時間。

所以答案是選項「D」。