Re: CPU Utilization

[Andrew Theurer <habanero@us.ibm.com>]

Dave Thompson (davetho) wrote:

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>>-----Original Message-----
>>From: Anthony Liguori [mailto:aliguori@us.ibm.com] 
>>Sent: Monday, December 12, 2005 5:01 PM
>>To: Dave Thompson (davetho)
>>Cc: Rob Gardner; xen-devel@lists.xensource.com
>>Subject: Re: [Xen-devel] CPU Utilization
>>
>>top isn't smart enough to realize that for a portion of the running 
>>time, a domain has been pre-empted out and is not running.
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>>top will then charge whatever was running at pre-emption time for the 
>>time that other domain running.
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>But what else is running?  In this case I only have dom0 configured,
>there is no domU.  The only other possibility would be the hypervisor
>and I hope the hypervisor is not accounting for the other 30%.
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If xend is started, you may have the software bridge running which can 
use as much as 10% cpu. Also, I don't see soft ints in that top output.  
That could also be another ~7% cpu.  Also xen is doing some work, 
receiving the real interrupts and generating virtual interrupts to dom0, 
so with all this, it is possible that you are using another 30% unseen 
in top.  Best way to confirm this would be to use xenoprofile.

-Andrew

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