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Is there any possibility to create a custom CPU model for KVM Linux guests, or at least to modify parameters such as cache size and model name?

I know I can set CPU features, topology and pinning and choose from one of available models. The problem is that there are Intel Xeon X7560 CPUs with 24 MiB of cache each, and I couldn't find anything even quite similar.

I'm not sure whether it can have a huge impact on computation speed with LAPACK, ATLAS, etc. but users will probably expect to see CPUs identical to these on the host machine.

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1 Answer 1

you can use the "host" option to pass the host CPU features to the VM instead of a set of flags and a name.

EDIT: this used to be a command line option, probably removed by now. Have a look at http://libvirt.org/formatdomain.html#elementsCPU for the current possibilities

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I don't see any place to set the "host" option. I cannot set it as model and I see no such thing in libvirt documentation. What do you exactly mean by "host" option? –  konradstrack Aug 11 '11 at 20:07
see the EDIT I just added –  dyasny Aug 12 '11 at 10:37
This host flag does not always work. When I use it on a system with Intel Xeon E5-2650 processors, the cpuinfo tells me it has 4096KB on the guest whereas the host reports 20 MB. –  user158877 Feb 13 '13 at 22:15
I'd take this specific issue to the libvirt mailing lists –  dyasny Feb 14 '13 at 4:54

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