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Thank you for the clarification.

Il Gio 12 Gen 2023, 03:09 Sean Mooney <smooney at redhat.com> ha scritto:

> On Wed, 2023-01-11 at 23:10 +0100, Ignazio Cassano wrote:
> > Hello All,
> > I would like to know if with numa in kvm hypervisor I must disable merge
> > across nodes ? If yes, is there any metadata to do it ?
> no nova has numa toplogy awareness for vms with a virutal numa toplogy
>
> i.e. if you want vms ot have numa affinity you can request a numa toplogy
> explcitly by using hw:numa_nodes=<number of virutal numa nodes for the vm>
> it can also be done via the image with hw_numa_nodes.
>
> nova will also generate a request for a singel numa node if  you use
> specific feature like cpu pinnign or hugepages  to name two cases. i belive
> pmem
> also does it so that is not ment to be an exaustive list.
>
> all vms that have an implciet or explict numa toplogy should have
> hw:mem_page_size or hw_mem_page_size set to an allowed value
> (small,large,any,<intager_page_size[KMG]>) for example
> hw:mem_page_size=small will create a singel numa node guest using implcit
> numa request as a
> result of specifying
> a page size and small will ensure that hugepages are not used for the vm.
> on must cpu archtecutres small means the default 4k pages are uesed.
> such a vm will be pinned to a spcific host numa ndoe but will float over
> cpu on that numa node sicne cpu pinnign is not enabeld.
>
> if the vm does not request a numa topology we will not do any numa aware
> placment or affinity enforcement.
>
> nova does not support mixing numa and non numa vms on the same host and
> its left to the operator to ensure that useing any of the means supproted
> by placement or schduler filters.
>
> > Ignazio
>
>
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