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Re: [Xen-devel] PV-vNUMA issue: topology is misinterpreted by the guest

On 07/24/2015 06:44 PM, Boris Ostrovsky wrote:
On 07/24/2015 12:39 PM, Juergen Gross wrote:

I don't say mangling cpuids can't solve the scheduling problem. It
surely can. But it can't solve the scheduling problem without hiding
information like number of sockets or cores which might be required
for license purposes. If we don't care, fine.

(this is somewhat repeating the email I just sent)

Why can's we construct socket/core info with CPUID (and *possibly* ACPI
changes) that we present a reasonable (licensing-wise) picture?

Can you suggest an example where it will not work and then maybe we can
figure something out?

Let's assume a software with license based on core count. You have a
system with a 2 8 core processors and hyperthreads enabled, summing up
to 32 logical processors. Your license is valid for up to 16 cores, so
running the software on bare metal on your system is fine.

Now you are running the software inside a virtual machine with 24 vcpus
in a cpupool with 24 logical cpus limited to 12 cores (6 cores of each
processor). As we have to hide hyperthreading in order to not to have
to pin each vcpu to just a single logical processor, the topology
resulting from this picture will have to present 24 cores. The license
will not cover this hardware.


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