iostat之CPU统计

iostat是I/O statistics（输入/输出统计）的缩写，iostat工具将对系统的磁盘操作活动进行监视。它的特点是汇报磁盘活动统计情况，同时也会汇报出CPU使用情况。同vmstat一样，iostat也有一个弱点，就是它不能对某个进程进行深入分析，仅对系统的整体情况进行分析。

【CPU Utilization Report】

  %user --Show the percentage of CPU utilization that occurred while executing at the user level (application).

  %nice --Show the percentage of CPU utilization that occurred while executing at the user level with nice priority.

  %system --Show the percentage of CPU utilization that occurred while executing at the system level (kernel).

  %iowait --Show the percentage of time that the CPU or CPUs were idle during which the system had an outstanding disk I/O request.

  %steal --Show the percentage of time spent in involuntary wait by the virtual CPU or CPUs while the hypervisor was servicing another virtual processor.

  %idle --Show the percentage of time that the CPU or CPUs were idle and the system did not have an outstanding disk I/O request.