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Re: [Xen-devel] CPU utilization



The default BVT scheduler is weighted fair share with extensions to better support I/O. If you add extra domains then the existing ones will get proportionally less CPU, assuming all domains are CPU bound.

More directly answering your question: most sane CPU schedulers are work conserving, meaning that if there is work to be done then they will schedule it in preference to idling. This means that if, say, domain0 is the only domain with work to do then it will get 100% of the CPU, even if its 'fair share' is, say, 50%. Now, however strict you are in scheduling a runnable domU onto the same processor it is clearly going to have some negative impact on domain0's CPU allocation compared with dom0 getting all the CPU.

 -- Keir

On 1 May 2005, at 14:51, Brian Hays wrote:

A question about CPU utilization...

If I have a domU that is under heavy processing load will it affect
the performance of other domU's or dom0? ...or is processing divided
in such a way that one domU will have no effect on others no matter
what load it is under?

Thank you,
Brian

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