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Re: [Xen-users] CPU activity: top and xm top

To: "Petersson, Mats" <Mats.Petersson@xxxxxxx>
Subject: Re: [Xen-users] CPU activity: top and xm top
From: Igor Chubin <igor@xxxxxxx>
Date: Wed, 11 Apr 2007 12:32:53 +0300
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Mats, 

thank you for your answer.


Now I know that domain 0 CPU activity consists of 
hypervisor activity and domain 0 kernel with its processes.

You suppose that this 20% (or 14% to be more correct)
hypervisor spends processing interrupts.

But my machine is idle.
It does nothing: it has no network activity and presumable no disk
activity.

I wanted to inspect interrupts activity using sar, 
but without success. Unfortunately sar doesn't report interrupts
activity under Xen :(
(May be I can use /proc/interrupts and get information from this
file? Will it be correct?)

So my machine is idle but I have 20% of CPU activity for domain 0.
The question is: How can I get exactly know for what is this 20% spending?
What tools (or interfaces e.g. /proc files) can I use for this?


...
> > I have only domain 0 running. No U-domains at all.
> > 
> >     $ sudo xm list
> >     Name     ID Mem(MiB) VCPUs State  Time(s)
> >     Domain-0 0  192      2     r----- 184.0
> > 
> > How does xm top calculate cpu activity?
> > Is there any way to access low level information that xm top uses in
> > its calculations?
> 
> Yes there is, but I don't know how (it's been discussed before on Xen
> Users and/or Xen Devel, so google should be able to find it). 
> 
> Xm top is just a python script, and you can get the information that the
> python-code is fetching from the hypervisor. 
> 

I know this.
But may be somebody have done this already
and knows where this low-level information lies.

Ok, I will Google for this.


-- 
WBR, i.m.chubin


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