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Re: [Xen-devel] SMP guest support in unstable tree.

> SMP guests can use between
> 1 and 32 virtual cpus, even if the machine has fewer physical cpus.

I note that the Xen-2.1 roadmap aims for the ability to transparently & 
dynamically reassign a VM to a new real processor on the same node ("CPU 
load balancing").  Is this already in place?

What are the proposed models for assigning virtual processors to real 
processors?  In particular, is there an aim toward gang scheduling of 
virtual processors?

Are there thoughts on how virtual-multiprocessor guests change resource 
allocation?  For example, if I have a two-virtual-processor guest [A] and 
a four-virtual-processor guest [B], and I assign them each a 50% share, is 
it more "correct" for: 

1. Each virtual processor to get 1/6 of the total real processor 
2. Each virtual processor of A to get 1/4, each of B to get 1/8;
3. The sum of the virtual processors of A to get no more than 1/2, etc.;
4. Something else?

I realize all these are easily configurable & nothing needs to be set in 
stone; am mainly interested if there's been any off-list discussion of 
this sort of thing.

Dr. John Linwood Griffin
Research Staff Member, Secure Systems Department
IBM T.J. Watson Research Center, Hawthorne, New York, USA
JLG at us.ibm.com, http://www.research.ibm.com/people/j/jlg/

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