linux – top命令第一次迭代总是返回相同的结果

运行top -b -n 1时,该命令始终返回相同的CPU值.
连续5次考虑以下测试运行：

[user@server ~]$top -b -n 5 -d.2 | grep "Cpu(s)"
Cpu(s): 18.5%us,10.0%sy,0.0%ni,67.0%id,4.2%wa,0.0%hi,0.2%si,0.1%st
Cpu(s): 39.8%us,27.7%sy,31.3%id,0.0%wa,1.2%si,0.0%st
Cpu(s): 39.0%us,35.4%sy,23.2%id,1.2%st
Cpu(s): 41.2%us,34.1%sy,15.3%id,1.2%wa,2.4%si,5.9%st
Cpu(s): 59.0%us,30.1%sy,4.8%id,3.6%si,2.4%st
[user@server ~]$top -b -n 5 -d.2 | grep "Cpu(s)"
Cpu(s): 18.5%us,0.1%st
Cpu(s): 18.9%us,17.8%sy,63.3%id,0.0%si,0.0%st
Cpu(s): 18.8%us,21.2%sy,55.3%id,2.4%wa,1.2%st
Cpu(s): 29.4%us,24.7%sy,45.9%id,0.0%st
Cpu(s): 60.5%us,24.4%sy,11.6%id,1.2%st
[user@server ~]$top -b -n 5 -d.2 | grep "Cpu(s)"
Cpu(s): 18.5%us,0.1%st
Cpu(s): 43.4%us,38.6%sy,15.7%id,1.2%st
Cpu(s): 55.3%us,40.0%sy,4.7%id,0.0%st
Cpu(s): 39.5%us,48.8%sy,5.8%id,3.5%st
Cpu(s): 40.7%us,55.6%sy,2.5%id,0.1%st
Cpu(s): 27.1%us,10.6%sy,61.2%id,0.0%st
Cpu(s): 25.3%us,5.7%sy,67.8%id,1.1%st
Cpu(s): 15.5%us,16.7%sy,64.3%id,3.6%st
Cpu(s): 57.3%us,11.2%sy,30.3%id,1.1%st
[user@server ~]$top -b -n 5 -d.2 | grep "Cpu(s)"
Cpu(s): 18.5%us,0.1%st
Cpu(s): 44.0%us,6.0%sy,42.9%id,3.6%st
Cpu(s): 45.8%us,9.6%sy,44.6%id,0.0%st
Cpu(s): 34.5%us,8.3%sy,57.1%id,0.0%st
Cpu(s): 38.6%us,14.5%sy,45.8%id,1.2%st

知道这里有什么问题吗？