Re: [Xen-devel] Cpu pools discussion

[Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>]

Tim Deegan wrote:
> At 14:24 +0100 on 28 Jul (1248791073), Juergen Gross wrote:
>>> Does strict partitioning of CPUs like this satisfy everyone's
>>> requirements?  Bearing in mind that 
>>>
>>>  - It's not work-conserving, i.e. it doesn't allow best-effort
>>>    scheduling of pool A's vCPUs on the idle CPUs of pool B.
>>>
>>>  - It restricts the maximum useful number of vCPUs per guest to the size
>>>    of a pool rather than the size of the machine. 
>>>
>>>  - dom0 would be restricted to a subset of CPUs.  That seems OK to me
>>>    but occasionally people talk about having dom0's vCPUs pinned 1-1 on 
>>>    the physical CPUs.
>> You don't have to define other pools. You can just live with the default pool
>> extended to all cpus and everything is as today.
> 
> Yep, all I'm saying is you can't do both.  If the people who want this
> feature (so far I count two of you) want to do both, then this
> solution's good not enough, and we should think about that before going
> ahead with it.

Okay.

I think your first point is the most important one.
It might be possible to build a load balancing scheme to shift cpus between
pools dynamically, but this should be step 2, I think :-)
But it would be a nice project :-)


Juergen

-- 
Juergen Gross                 Principal Developer Operating Systems
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