Re: [PATCH 3/3] numa: Initialize node initiator with respect to .has_cpu

[Tao Xu]

On 6/1/2020 4:10 PM, Michal Privoznik wrote:
> On 5/29/20 5:09 PM, Igor Mammedov wrote:
> > On Fri, 29 May 2020 15:33:48 +0200
> > Michal Privoznik <mprivozn@redhat.com> wrote:
> >
> > > The initiator attribute of a NUMA node is documented as the 'NUMA
> > > node that has best performance to given NUMA node'. If a NUMA
> > > node has at least one CPU there can hardly be a different node
> > > with better performace and thus all NUMA nodes which have a CPU
> > > are initiators to themselves. Reflect this fact when initializing
> > > the attribute.
> >
> > It is not true in case of the node is memory-less
>
> Are you saying that if there's a memory-less NUMA node, then it needs to
> have initiator set too? Asking mostly out of curiosity because we don't
> allow memory-less NUMA nodes in Libvirt just yet. Nor cpu-less, but my
> patches that I'm referring to in cover letter will allow at least
> cpu-less nodes. Should I allow both?
QEMU now is not support memory-less NUMA node, but in hardware may be 
supported. So we reserve this type of NUMA node for future usage. And 
QEMU now can support cpu-less NUMA node, for emulating some "slow" 
memory(like some NVDIMM).

> Also, can you shed more light into why machine_set_cpu_numa_node() did
> not override the .initiator?
>
> Thanks,
> Michal