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[Xen-users] Re: Setting CPSs per socket

From: PattiMichelle <miche1@xxxxxxxxxxxxx>

Date: Sat, 31 Jan 2009 09:26:19 -0800

Delivery-date: Sat, 31 Jan 2009 09:27:21 -0800

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List-id: Xen user discussion <xen-users.lists.xensource.com>

Thank you, James.  The version of Xen is 3.2.1, which seems *relatively* recent.

Yes, thank you James, that's about right, but domU seems to see all
cores, it's just the guest OS that sees only one core-per-socket.  To
overcome that, I'd like to convert all sockets (in the guest) to dual or
quad cores (AMD).  I found the guest's config file, not sure where the
domU config file is.

I bought, but didn't find any references to this subject in the book
"Running Xen."  I was confused by the position within the string of
"xxxx"-s of the apparently binary information in those structure
variables - is position important?  Now it's even more complicated since
AMDs are treated differently than Intel!  Thank you for the cut-n-paste
- I guess I can try fooling around with it and see if I get lucky, else
one of the Xen authors can help?

Now that I think about it, can I run WinXP and expose two 16-core
processors? (XP is supposed to support two sockets).  That would be /bonus./
Patti

> If I understand what you want correctly, you can do this by specifying
> the cpuid option in your domU config. The following is cut&paste from
> xmexample.hvm
>
> # Expose to the guest multi-core cpu instead of multiple processors
> # Example for intel, expose a 8-core processor :
> #cpuid=['1:edx=xxx1xxxxxxxxxxxxxxxxxxxxxxxxxxxx,
> #          ebx=xxxxxxxx00010000xxxxxxxxxxxxxxxx',
> #     '4,0:eax=001111xxxxxxxxxxxxxxxxxxxxxxxxxx']
> #  - CPUID.1[EDX][HT] : Enable HT
> #  - CPUID.1[EBX] : Number of vcpus * 2
> #  - CPUID.4,0[EAX] : Number of vcpus * 2 - 1
> #vcpus=8
> #
> # Example for amd, expose a 5-core processor :
> # cpuid = ['1:ebx=xxxxxxxx00001010xxxxxxxxxxxxxxxx,
> #             edx=xxx1xxxxxxxxxxxxxxxxxxxxxxxxxxxx',
> # '0x80000001:ecx=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx1x',
> # '0x80000008:ecx=xxxxxxxxxxxxxxxxxxxxxxxxxx001001']
> #   - CPUID.1[EBX] : Threads per Core * Cores per Socket (2 * #vcpus)
> #   - CPUID.1[EDX][HT] : Enable HT
> #   - CPUID.0x80000001[CmpLegacy] : Use legacy method
> #   - CPUID.0x80000008[ECX] : #vcpus * 2 - 1
> #vcpus=5
>
> I'm not sure what version of xen you get with OpenSuse 11, and I'm not
> exactly sure when the cpuid option first appeared.
>
> James
>
>
>
>

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