线程处理输入输出时，报告中的wio可能会达到90%的比例，而不考虑cpu的数量。
The kernel maintains statistics for kernel threads, paging, and interrupt activity, which the vmstat command accesses through the use of the the perfstat kernel extension. The disk input/output statistics are maintained by device drivers. For disks, the average transfer rate is determined by using the active time and number of transfers information. The percent active time is computed from the amount of time the drive is busy during the report.
The PhysicalVolume parameter can be used to specify one to four names. Transfer statistics are given for each specified drive in the order specified. This count represents requests to the physical device. It does not imply an amount of data that was read or written. Several logical requests can be combined into one physical request. If the PhysicalVolume parameter is used, the physical volume names are printed at the beginning of command execution.
vmstat通过perfstat内核扩展来维护内核线程，分页和中断活动的统计信息。而硬盘输入输入的统计信息是有磁盘启动类维护的，对于磁盘来说，平均传输速率是有活动时间和传输数量来决定的。活动时间是报告生成期间启动处于忙状态的时间。
我们可以指定1-4个物理卷，磁盘传输统计是根据指定的物理卷参数顺序来显示的。统计信息体现了对物理设备的请求，与发生的读或者写请求是不一致的，因为多个逻辑请求可能会合并为单个物理请求。
Beginning with AIX 5.3, the vmstat command reports the number of physical processors consumed (pc), and the percentage of entitlement consumed (ec), in Micro-Partitioning environments. These metrics will only be displayed on Micro-Partitioning environments.
下面是对各个统计信息字段的含义解释
kthr: information about kernel thread states.
| r |
Average number of runnable kernel threads over the sampling interval. Runnable refers to threads that are ready but waiting to run and to those threads already running. 如果超过cpu数量过多，则系统繁忙 |
| b |
Average number of kernel threads placed in the VMM wait queue (awaiting resource, awaiting input/output) over the sampling interval. |
Memory: information about the usage of virtual and real memory. Virtual pages are considered active if they have been accessed. A page is 4096 bytes.
| avm |
Active virtual pages. |
| fre |
Size of the free list. Note: A large portion of real memory is utilized as a cache for file system data. It is not unusual for the size of the free list to remain small. |
Page: information about page faults and paging activity. These are averaged over the interval and given in units per second.
| re |
Pager input/output list. |
| pi |
Pages paged in from paging space. |
| po |
Pages paged out to paging space. |
| fr |
Pages freed (page replacement). |
| sr |
Pages scanned by page-replacement algorithm. |
| cy |
Clock cycles by page-replacement algorithm. |
Faults: trap and interrupt rate averages per second over the sampling interval.
| in |
Device interrupts. |
| sy |
System calls. |
| cs |
Kernel thread context switches. |
Cpu: breakdown of percentage usage of processor time.
| us |
User time. |
| sy |
System time. |
| id |
Processor idle time. |
| wa |
Processor idle time during which the system had outstanding disk/NFS I/O request(s). See detailed description above. |
| pc |
Number of physical processors consumed. Displayed only if the partition is running with shared processor. |
| ec |
The percentage of entitled capacity consumed. Displayed only if the partition is running with shared processor. Because the time base over which this data is computed can vary, the entitled capacity percentage can sometimes exceed 100%. This excess is noticeable only with small sampling intervals. |
Disk: Provides the number of transfers per second to the specified physical volumes