iowait的形成原因和内核分析
经常我们碰到一些问题,进程的写文件,写入的速度非常慢,而且当时总的IO的数量(BI,BO)也非常低,但是vmstat显示的iowait却非常高,就是下图中的wa选项。
man vmstat手册如下解释:
wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
CPU花费到IO等待上的时间,也就是说进程的io被CPU调度出...
a Linux kernel virtualization developer, the contributor to KVM/Xen community, expert in VT-x, VT-d and X86 architecture, familiar with kernel development in KVM, XEN, Filesystem, IO storage, memory, schedule, etc.