vmstat and iostat us/sy/id numbers wrong?

[Stefan Bethke]

Am 07.12.2009 um 16:10 schrieb John Baldwin:

> On Saturday 05 December 2009 9:19:06 am Stefan Bethke wrote:
>> I'm confused about the numbers shown in the last three columns in  
>> both
> vmstat and iostat. They should reflect percent of CPU time spent on  
> user
> processes, system threads, and the idle thread (or something like  
> that).
>>
>> On multiple machines running 8-stable from the last couple of days,  
>> the
> numbers do not agree with actual system usage and with numbers shown  
> by top,
> at all.  I'm seeing 7 7 87 on one box, 0 0 100 on another, and 10 3  
> 87 on a
> third.  The numbers stay the same even under different loads.
>>
>> Am I misunderstanding what those numbers should represent?
>
> Are you just running vmstat once or using 'vmstat 1' to have it  
> poll?  If you
> are running it once, note that the numbers vmstat report are the  
> percentage of
> system/user/idle time since boot rather than during the previous  
> second which
> is what top reports (and what 'vmstat 1' reports after the first  
> line).

Thanks, I figured that out eventually (also by the nice help received  
from David Wolfskill).

I'm now using "vmstat 30 2" and using the last line to get "current"  
numbers, instead of "vmstat 1".

There seems to be some problem with the numbers though, as the since- 
boot output of vmstat does not seems to add up to 100%, at least in  
some cases.  I'll see if I can find out more details later in the month.


Stefan

-- 
Stefan Bethke <stb at lassitu.de>   Fon +49 151 14070811