vmstat

仮想メモリの統計情報の表示
仮想メモリはコンピュータの黎明期よりある仕組み
- プロセスは 0 番地から始まる仮想メモリ上で動くように作られる (実メモリ上のどこに配置されるかは考えなくていい)
- 本当にCPUから使われるときだけ実メモリにマッピングされて CPU で実行される
- その仲立ちをやるのが OS ってやつ

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$ vmstat -h

Usage:
 vmstat [options] [delay [count]]

Options:
 -a, --active           active/inactive memory
 -f, --forks            number of forks since boot
 -m, --slabs            slabinfo
 -n, --one-header       do not redisplay header
 -s, --stats            event counter statistics 
 -d, --disk             disk statistics
 -D, --disk-sum         summarize disk statistics
 -p, --partition <dev>  partition specific statistics
 -S, --unit <char>      define display unit
 -w, --wide             wide output
 -t, --timestamp        show timestamp
 -y, --no-first         skips first line of output

 -h, --help     display this help and exit
 -V, --version  output version information and exit

For more details see vmstat(8).

vmstat, vmstat -a メモリの状況を表示

引数無し、-a オプション付きで実行すると、現在のメモリの状況を取得できる

ubuntu@www4250uj:~$ vmstat
procs -----------memory---------- ---swap-- -----io---- -system-- -------cpu-------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st gu
 2  0 359168  97780  50032 713320    9  329  1144   435  803    3  2  1 97  0  0  0
ubuntu@www4250uj:~$ vmstat -a
procs -----------memory---------- ---swap-- -----io---- -system-- -------cpu-------
 r  b   swpd   free  inact active   si   so    bi    bo   in   cs us sy id wa st gu
 0  0 357632  93468 485080 587088    8  296  1037   397  781    3  2  1 97  0  0  0

-S m オプションをつけると MB 単位で表示 (単位は k 1000, K 1024, m 1000000, M 1048576 が指定可能)

ubuntu@www4250uj:~$ vmstat -S m
procs -----------memory---------- ---swap-- -----io---- -system-- -------cpu-------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st gu
 1  0    371     91     52    760    0    0   910   354  760    3  2  1 97  0  0  0
ubuntu@www4250uj:~$ vmstat -a -S m
procs -----------memory---------- ---swap-- -----io---- -system-- -------cpu-------
 r  b   swpd   free  inact active   si   so    bi    bo   in   cs us sy id wa st gu
 1  0    371     91    493    610    0    0   908   354  760    3  2  1 97  0  0  0

-表示内容 (manより引用)

FIELD DESCRIPTION FOR VM MODE
   Procs
       r: The number of runnable processes (running or waiting for run time).
       b: The number of processes blocked waiting for I/O to complete.

   Memory
       These are affected by the --unit option.
       swpd: the amount of swap 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
       These are affected by the --unit option.
       si: Amount of memory swapped in from disk (/s).
       so: Amount of memory swapped to disk (/s).

   IO
       bi: Kibibyte received from a block device (KiB/s).
       bo: Kibibyte sent to a block device (KiB/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.
       st: Time stolen from a virtual machine.  Prior to Linux 2.6.11, unknown.
       gu: Time spent running KVM guest code (guest time, including guest nice).

vmstat -f fork回数

システム稼働からの fork　回数 = 起動してからどんだけプロセスを作ったか

ubuntu@www4250uj:~$ vmstat -f
         2738 forks

vmsrat -m メモリ断片化の状況

Linuxカーネルが、プロセスに割り当てたページのうち未使用な領域 (slub)
Linuxカーネルは、slub領域が30%を超えると、メモリのデフラグを行って、なるべく連続領域がプロセスにわたるようにする

ubuntu@www4250uj:~$ sudo vmstat -m

vmstart -s 統計情報の表示

vmstat で出せるデータ全部盛り

ubuntu@www4250uj:~$ vmstat -s
      2014808 K total memory
      1646040 K used memory
       466056 K active memory
       572376 K inactive memory
       126256 K free memory
        19516 K buffer memory
       550860 K swap cache
      6291452 K total swap
       397568 K used swap
      5893884 K free swap
        12462 non-nice user cpu ticks
            0 nice user cpu ticks
         3680 system cpu ticks
       888314 idle cpu ticks
         2601 IO-wait cpu ticks
            0 IRQ cpu ticks
          298 softirq cpu ticks
          127 stolen cpu ticks
            0 non-nice guest cpu ticks
            0 nice guest cpu ticks
      1590521 K paged in
       654100 K paged out
         3277 pages swapped in
       100950 pages swapped out
      2186383 interrupts
      3109658 CPU context switches
   1718467490 boot time
         4227 forks

vmstat -d, -D ディスク情報表示

ubuntu@www4250uj:~$ vmstat -d
disk- ------------reads------------ ------------writes----------- -----IO------
       total merged sectors      ms  total merged sectors      ms    cur    sec
loop0      0      0       0       0      0      0       0       0      0      0
loop1      0      0       0       0      0      0       0       0      0      0
loop2      0      0       0       0      0      0       0       0      0      0
loop3      0      0       0       0      0      0       0       0      0      0
loop4      0      0       0       0      0      0       0       0      0      0
loop5      0      0       0       0      0      0       0       0      0      0
loop6      0      0       0       0      0      0       0       0      0      0
loop7      0      0       0       0      0      0       0       0      0      0
vda    62993  18928 3233706   28781  32493 116577 1344688  153725      0     43
sr0        0      0       0       0      0      0       0       0      0      0
ubuntu@www4250uj:~$ vmstat -D
           10 disks
            2 partitions
        63078 total reads
        18928 merged reads
      3240170 read sectors
        28805 milli reading
        32498 writes
       116779 merged writes
      1346344 written sectors
       153740 milli writing
            0 inprogress IO
           43 milli spent IO
          182 milli weighted IO

表示内容 (manより引用)

   Reads
       total: Total reads completed successfully
       merged: grouped reads (resulting in one I/O)
       sectors: Sectors read successfully
       ms: milliseconds spent reading

   Writes
       total: Total writes completed successfully
       merged: grouped writes (resulting in one I/O)
       sectors: Sectors written successfully
       ms: milliseconds spent writing

   IO
       cur: I/O in progress
       s: seconds spent for I/O

vmstat -p パーティション読み書き回数

ubuntu@www4250uj:~$ sudo fdisk -l
Disk /dev/vda: 200 GiB, 214748364800 bytes, 419430400 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: B1D9F0C9-5071-4302-9F9F-029CFDE73E1D

Device     Start       End   Sectors  Size Type
/dev/vda1   2048      4095      2048    1M BIOS boot
/dev/vda2   4096 419427967 419423872  200G Linux filesystem
ubuntu@www4250uj:~$ vmstat -p /dev/vda2
vda2            reads      read sectors      writes  requested writes
                63398           3254002       33964           1372808