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Re: Cores, Hyperthreads, and KVM

On 13/03/18 21:13, Richard Hector wrote:

> Hi all,

Hi, Richard.

> When I configure a KVM guest to have 2 vcpus, will that be 2 full cores?
> Or will it give the guest both threads on the same real core? Or might
> it use half of each of 2 different cores?
> I guess the same applies to physical CPUs, too - there's presumably an
> advantage in giving a VM a set of cores all on the same CPU, to take
> advantage of shared caching - is that dealt with automatically?
> I've always assumed that I should allocate even numbers of vcpus on an
> HT capable machine, so that it keeps the threads together.
> Does any of this matter?

I think these 2 VCPUs can run on any core however you can configure the
affinity of processors by limiting the execution using taskset.

By the way, it looks like your GPG key is expired.

Kind regards,

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