Linux常用命令之vmstat--rainnyzhong的博客

.vmstatvmstat是Virtual Meomory Statistics（虚拟内存统计）的缩写，可用来纪录 processes, memory, paging, block IO, traps, 与 cpu activity [root@raclinux1 ~]# vmstat --help
usage: vmstat [-V] [-n] [delay [count]]
              -V prints version.
              -n causes the headers not to be reprinted regularly.
              -a print inactive/active page stats.
              -d prints disk statistics
              -D prints disk table
              -p prints disk partition statistics
              -s prints vm table
              -m prints slabinfo
              -S unit size
              delay is the delay between updates in seconds.
              unit size k:1000 K:1024 m:1000000 M:1048576 (default is K)
              count is the number of updates. 其中红色部分是新选项，2.5.70及以上内核适用 2.举例：[oracle@raclinux1 ~]$ vmstat 3
procs -----------------memory---------------swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache       si   so     bi    bo   in    cs us sy id wa
 0  0      0   1672  29032 108664    0    0    66    16 1012   259  2  7 87  3
 0  0      0   1672  29040 108664    0    0     0    11  930   199  1  4 95  0
 0  0      0   1676  29040 108664    0    0     0    39  949   202  1  3 96  0
 0  0      0   1680  29048 108664    0    0     0     4  937   199  1  3 96  0
 0  0      0   1680  29048 108664    0    0     0    25  932   198  1  4 95  0
 0  0      0   1680  29056 108664    0    0     0     4  944   206  1  3 96  0
 0  0      0   1680  29056 108664    0    0     0     0  932   198  1  3 96  0
 0  0      0   1680  29064 108664    0    0     0     4  935   196  1  3 96  0
 0  0      0   1680  29064 108664    0    0     0     0  941   198  1  3 96  0
 0  0      0   1680  29072 108664    0    0     0     4  949   202  1  2 96  0
 0  0      0   1680  29072 108664    0    0     0     0  938   196  1  3 96  0 其中：   Procs
       r: The number of processes waiting for run time.在运行队列中等候运行
       b: The number of processes in uninterruptible sleep.被资源阻塞(I/0,页面调度,等等)

                                                                                
   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, shown as zero. 3.解读：A.CPU问题：下面几列需要被察看，以确定cpu是否有问题 Processes in the run queue (procs r)
User time (cpu us)
System time (cpu sy)
Idle time (cpu id)
 问题情况:
1.) 如果processes in run queue (procs r)的数量远大于系统中cpu的数量，将会使系统便慢。
2.) 如果这个数量是cpu的4倍的话，说明系统正面临cpu能力短缺,这将使系统运行速度大幅度降低
3.) 如果cpu的idle时间经常为0的话，或者系统占用时间(cpu sy)是用户占用时间(cpu us)两辈的话，系统面临缺少cpu资源 解决方案 :
解决这些情况，涉及到调整应用程序，使其能更有效的使用cpu，同时增加cpu的能力或数量 B.内存问题：主要查看页导入的数值（swap中的si），如果该值比较大就要考虑内存，大概方法如下：1).最简单的，加大RAM　　
2).改小SGA，使得对RAM需求减少　　
3).减少RAM的需求（如：减少PGA）  4.新参数： 1）.vmstat -D 显示磁盘信息(只能一次性，delay参数无效）[oracle@raclinux1 ~]$ vmstat -D
           25 disks
            6  partitions 
     17577  total reads
      4140   merged reads  587320   read sectors
  248149   milli reading
     6889   writes
    13672  merged writes
  164444  written sectors
  167353  milli writing
           0  inprogress IO
        178 milli spent IO 2）.vmstat -d 查看磁盘统计信息  [oracle@raclinux1 ~]$ vmstat -d | grep -v ram
disk- ------------reads------------ ------------writes----------- -----IO------
       total merged sectors      ms  total merged sectors      ms    cur    sec
hdc       13     88     680     249      0      0       0       0      0      0
sda    17396   2644  580819  243635   6983  13749  165836  167797      0    178
sdb       46    657    1185    1808      0      0       0       0      0      0
sdc       53    420    1436    1667      6      4      56       7      0      1
sdd       24    132    1248     348      0      0       0       0      0      0
disk- ------------reads------------ ------------writes----------- -----IO------
       total merged sectors      ms  total merged sectors      ms    cur    sec
sde       36    135    1368     288      0      0       0       0      0      0
sdf        9     64     584     154      0      0       0       0      0      0
fd0        0      0       0       0      0      0       0       0      0      0
md0        0      0       0       0      0      0       0       0      0      0 3）.vmstat -s （一次性，delay参数无效） [oracle@raclinux1 ~]$ vmstat -s
       256044  total memory
       254428  used memory
       153584  active memory
        70960  inactive memory
         1616  free memory
        33976  buffer memory
       104140  swap cache
      1044184  total swap
            0  used swap
      1044184  free swap
        13214 non-nice user cpu ticks
         3759 nice user cpu ticks
        43122 system cpu ticks
       827934 idle cpu ticks
        14246 IO-wait cpu ticks
           98 IRQ cpu ticks
        27960 softirq cpu ticks
       293660 pages paged in
        83714 pages paged out
            0 pages swapped in
            0 pages swapped out
      9369649 interrupts
      2217323 CPU context switches
   1143195570 boot time
        29804 forks