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Re: [Xen-devel] Cpu pools discussion

To: George Dunlap <dunlapg@xxxxxxxxx>
Subject: Re: [Xen-devel] Cpu pools discussion
From: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
Date: Tue, 28 Jul 2009 15:57:26 +0200
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Zhigang Wang <zhigang.x.wang@xxxxxxxxxx>, Tim Deegan <Tim.Deegan@xxxxxxxxxx>, Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>
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George Dunlap wrote:
> On Tue, Jul 28, 2009 at 2:39 PM, Juergen
> Gross<juergen.gross@xxxxxxxxxxxxxx> wrote:
>> 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 :-)
> 
> If I recall your use case, Juergen, I thought the whole point was to
> keep some set of VMs limited to just a subset of CPUs?  So the first
> point is a feature for you, not a bug. :-)

Indeed.
I just like to think about further enhancements, even if my company isn't
requiring them...

> 
> If we ever do find someone who wants cpu pools, perhaps to use
> different schedulers, but wants to be able to dynamically adjust pool
> size, then they can work on such a project.  Until then, no point
> spending time on something no one's going to use.

Absolutely true.
OTOH I see pools as an interesting way to support large NUMA systems in an
effective way. And for this usage you would need such a project :-)
I think it is very important to check the possible future enhancements, as
they might influence decisions today.


Juergen

-- 
Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 636 47950
Fujitsu Technolgy Solutions               e-mail: juergen.gross@xxxxxxxxxxxxxx
Otto-Hahn-Ring 6                        Internet: ts.fujitsu.com
D-81739 Muenchen                 Company details: ts.fujitsu.com/imprint.html

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