Re: [Xen-devel] [PATCH RFC 5/8] libxl: introduce smt field

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Feb 22, 2016 at 09:02:11PM +0000, Joao Martins wrote:
> By setting it to true, it enables the vcpus set by the guest
> to be seen as a SMT-enabled topology. It uses then
> libxl__cpuid_set_topology() to change the cpuid accordingly.
> This setting is made *before* the cpuid is set so that
> any changes could be overwritten. The number of SMT threads
> are the ones supported by the host. And for that it adds
> another helper routine libxl__count_threads_per_core to fetch
> it.
> 
> This feature is useful in HT-enabled hosts so that hard
> pinned domains can see the right topology (i.e. SMT cores exposed
> as SMT cores) which in return would lead guest scheduler making
> better decisions.
> 

I think we need more sophisticated configuration options then just a
bool. If we're doing this, there is no reason why we shouldn't allow
administrator to set arbitrary topology for the guest.

Wei.

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