Re: XEN Proposal

[Juergen Gross <juergen.gross@fujitsu-siemens.com>]

Chris wrote:
> Grouping domains for the purpose of sharing scheduler credits was the
> intent of the sched-groups project done by Mike Day at IBM:
> 
> http://xen.markmail.org/search/?q=sched-groups&x=0&y=0#query
> <http://xen.markmail.org/search/?q=sched-groups&x=0&y=0#query>:sched-groups%20from%3A%22Mike%20D.%20Day%22+page:1+mid:k36x7tqjy3zquqv7+state:results).
>  
> 
> A related project called Domain Groups (domgrps for short) also exists:
> 
> http://xen.markmail.org/search/?q=%22domain+group%22#query:%22domain%20group%22%20from%3AChris%20date%3A200702%20+page:1+mid:b525tcfzvfgv3gzo+state:results
> 
> The primary difference is that domgrps is a general-purpose domain
> grouping framework with integration into both the VMM and userspace
> tools.  It does group migration, moving domains b/w groups, etc..  
> 
> To demonstrate the flexibility of the domgrps architecture, I merged
> domgrps and schedgrps:
> 
> http://xen.markmail.org/search/?q=domgrps+schedgrps#query:domgrps
> schedgrps from%3A"Chris"+page:1+mid:rvetcmnmm7bkgexp+state:results
> 
> It should be equally straightforward to adapt domgrps to accommodate
> this newly proposed pooling concept.  I'd be happy to get involved if
> Keir suggests which grouping features are of interest.  If we first need
> a discussion to define the potential grouping features that's OK too,
> but I'll delay that effort until I'm asked.  

Chris, thanks for your support.
I think Keir's main interest is adding only features that are really needed.
So let me explain WHY we want to implement a pool concept:

We have a mainframe operating system called BS2000 originally designed for
/390 machines. As our customers often require small machines (software
prices are based on machine power) we decided some years ago to port BS2000
to other architectures as /390 machines are rather expensive.
We did ports to MIPS (we had MIPS UNIX machines in these times), to SPARC
(after our UNIX strategy switched to SPARC/Solaris), and now to x86_64.
We always had a virtual machine concept in BS2000 called VM2000 which is
quite important for our customers.
On x86_64 we decided to use XEN as base for our virtual machines to be able
to share the hardware with other systems as well.
The software prices for BS2000 will be still related to the machine power.
But often customers need only a small portion of the complete x86 machine
power for BS2000, so we added a license scheme to limit the power available
to BS2000 by pinning the domains with BS2000 to a subset of cpus.

BTW: on /390 and SPARC we already support VM-pools, so adding pools to XEN
would make this feature available to our customers who are still using it
today on other platforms.


Juergen

-- 
Juergen Gross                             Principal Developer
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Fujitsu Siemens Computers         e-mail: juergen.gross@fujitsu-siemens.com
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