Re: [Xen-devel] Re: Domain Groups - VMM Support

[Chris <hap10@xxxxxxxxxxxxxx>]

On Jan 31, 2008, at 3:04 PM, Mike D. Day wrote:
> I looked at creating a new hypervisor for scheduling groups, but found
> it much simpler to add a new sub-function under the dom_ctl
> hypercall. It markedly reduced the size of the patch and I didn't see
> any downside. It might make sense to do the same thing here. That way
> you wouldn't need to add the new hypercall to every jump table.
I  have no objection to making domgrpctl become a set of sub-ops to  
the existing domain management hypercall.  In fact, with the  
predecessor to domctl (dom0_op) that's how it was implemented.   
During the domctl developmental churn I separated them to make my  
life easier, but now it's just an artifact.
> To merge with scheduling groups, it may be nice to have an  
> extensible structure like we do with schedulers in Xen.
I agree.  There's more to groups than what the two of us have  
released thus far and adding new features should be made as painless  
as possible.  My suggestion is to save this type of overhaul until we  
settle on an agreeable functionality merge.
> I think its worth an attempt to merge the scheduling groups with
> domain groups. I'll start looking at some of the ideas I mentioned
> above, be happy to work with anyone else who wants to have a go.
I'm also having a go at the merge and will release a patch set RFC  
hopefully well before leaving on travel at the end of next week.
With regard to the merge, I've got a question for you.  In schedgrps,  
when a domain joins a group the assumption is that credits are  
thereafter shared among group members (for as long as it's a  
member).  I think there are cases where it makes sense to group  
domains without implicitly sharing credits (the null-group in domgrps  
is such a case).  So, I'd like to make it optional for members to  
delegate their VCPUs to the group.  The question is, do you have an  
opinion whether domains should have to opt-in or opt-out of sharing  
their credits when joining a group?
Cheers,
Chris

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