Re: [PATCH v8 08/12] s390x/cpu_topology: implementing numa for the s390x topology

[Pierre Morel]

On 7/21/22 10:16, Janis Schoetterl-Glausch wrote:
> On 7/21/22 09:58, Pierre Morel wrote:
> >

...snip...

> > You are right, numa is redundant for us as we specify the topology using the 
> > core-id.
> > The roadmap I would like to discuss is using a new:
> >
> > (qemu) cpu_move src dst
> >
> > where src is the current core-id and dst is the destination core-id.
> >
> > I am aware that there are deep implication on current cpu code but I do not 
> > think it is not possible.
> > If it is unpossible then we would need a new argument to the device_add for cpu to define 
> > the "effective_core_id"
> > But we will still need the new hmp command to update the topology.
> I don't think core-id is the right one, that's the guest visible CPU address, 
> isn't it?

Yes, the topology is the one seen by the guest.

> Although it seems badly named then, since multiple threads are part of the same 
> core (ok, we don't support threads).

I guess that threads will always move with the core or... we do not 
support threads.

> Instead socket-id, book-id could be changed dynamically instead of being 
> computed from the core-id.

What becomes of the core-id ?




--
Pierre Morel
IBM Lab Boeblingen