Re: Interpreting FreeBSD 'vmstat' output

[Sunday Folayan <sfolayan at skannet.com.ng>]

Brian,

And you want me to believe you do not know this? I guess you are asking
the wrong list. Try nanog ;-)

Happy New year!

Sunday.


On Mon, 6 Jan 2003, Brian Candler wrote:

> Date: Mon, 6 Jan 2003 18:35:43 +0000
> From: Brian Candler <B.Candler at pobox.com>
> To: afnog at afnog.org
> Subject: Interpreting FreeBSD 'vmstat' output
>
> Hello,
>
> I wonder if one of the deep kernel experts on this list can explain to me
> how to interpret the output of 'vmstat' in FreeBSD.
>
> I have a box here which has 1GB of RAM (running FreeBSD-4.5-RELEASE):
>
> Mar 19 14:46:15 radius-b-lond /kernel: real memory  = 1073676288 (1048512K bytes)
> Mar 19 14:46:15 radius-b-lond /kernel: avail memory = 1040379904 (1015996K bytes)
>
> This is what 'vmstat' shows:
>
> # vmstat 2
>  procs      memory      page                    disks     faults      cpu
>  r b w     avm    fre  flt  re  pi  po  fr  sr da0 da1   in   sy  cs us sy id
>  0 0 0   27908  32100  129   0   0   0 121   2   0   0   54   92  39 -3 -1 104
>  1 0 0   27908  32084  224   0   0   0 187   0   0   0  347 1018  90  7  2 91
>  0 0 0   27908  32052    2   0   0   0  29   0   2   0  381  939  94  9  1 90
>  0 0 0   28320  32036  223   0   0   0 198   0   3   0  365  987 109  7  2 92
>  0 0 0   28320  32004  224   0   0   0 201   0   0   0  381 1207 108  8  3 89
>  0 0 0   28320  31972    2   0   0   0  15   0   1   0  346  816  84  8  2 90
>  1 0 0   28320  31940  224   0   0   0 201   0   0   0  394 1340 114 11  2 86
>  0 0 0   28320  31908  224   0   0   0 201   0   1   0  388 1265 113 10  3 87
>
> I'm not sure how to interpret the 'fre' column - surely there is more than
> 32MB of available RAM? And the number of page faults seems high, if 'page
> fault' means 'event where I had to go to disk or swap to read a page' -
> although the level of disk I/O is low.
>
> 'top' reports:
>
> Mem: 29M Active, 800M Inact, 139M Wired, 33M Cache, 112M Buf, 3476K Free
> Swap: 1024M Total, 40K Used, 1024M Free
>
> This looks a bit more sensible. This machine is only running one main user
> process (a radius daemon) with 'SIZE' and 'RES' both about 15MB. Yes, I
> know that a 1GB machine is overkill for this application :-)
>
> Also, what does 'Inact' and 'Wired' mean? What is the difference between
> RAM in this state and RAM which is 'Free'?
>
> Thanks...
>
> Brian.
>
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