结合vmstat分析iostat输出结果

man vmstat

FIELD DESCRIPTION FOR VM MODE

Procs

• r: The number of processes waiting for run time.

  r 表示运行队列 (就是说多少个进程真的分配到CPU). 当这个值超过了CPU数目, 就会出现CPU瓶颈.

• b: The number of processes in uninterruptible sleep.

Memory

• swpd: the amount of virtual memory used.
• free: the amount of idle memory.
• buff: the amount of memory used as buffers.
• cache: the amount of memory used as cache.
• inact: the amount of inactive memory. (-a option)
• active: the amount of active memory. (-a option)

Swap

• si: Amount of memory swapped in from disk (/s).
• so: Amount of memory swapped to disk (/s).

IO

• bi: Blocks received from a block device (blocks/s).
• bo: Blocks sent to a block device (blocks/s).

System

• in: The number of interrupts per second, including the clock.
• cs: The number of context switches per second.

CPU

• These are percentages of total CPU time.
• us: Time spent running non-kernel code. (user time, including nice time)
• sy: Time spent running kernel code. (system time)
• id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.

• wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.

  wa 列显示了IO等待所占用的CPU时间的百分比。这里wa的参考值为30%，如果wa超过30%，说明IO等待严重，这可能是磁盘大量随机访问造成的，也可能磁盘或者磁盘访问控制器的带宽瓶颈造成的(主要是块操作)

• st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.