Re: [Xen-devel] CPU Utilization

Andrew Theurer
Tue, 13 Dec 2005 03:23:56 -0000

>>-----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.
>>
>>top will then charge whatever was running at pre-emption time for the
>>time that other domain running.
>>
>>
>
>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%.
>
>
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