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xen-users
Re: [Xen-users] Why does DomU CPU usage increase during live migration?
S. Ercan Yüzbasioglu wrote:
> I would expect that Dom0 should be the only domain whose CPU usage is
> supposed to increase. The migration process is supposed to be transparent to
> the DomU, right? So I cannot justify this behaviour. Does anybody have an
> idea about this?
two ideas:
1- Xen's Hypervisor is doing a heavy work, and charges it to the DomU's credit,
therefore the scheduler gives less CPU time to the 'real' DomU, so it gets less
idle time, so higher CPU usage.
2- the migration system uses MMU facilities to mark which pages have changed
after copied (so they have to be recopied). that marking makes the whole DomU
RAM look a bit like virtual memory (backed by real RAM), temporarily increasing
overhead, and making all processes in DomU slightly slower.
--
Javier
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