Re: [Qemu-devel] [PATCH 2.1 00/28] Current state of NUMA series, and hostmem improvements

[Paolo Bonzini]

Il 07/03/2014 12:59, Andreas Färber ha scritto:
> Am 05.03.2014 12:30, schrieb Paolo Bonzini:
> > Il 05/03/2014 12:05, Andreas Färber ha scritto:
> > > I didn't review it in-depth yet, but minor technical issues apart, I
> > > think we need to keep NUMA and CPU separate,
> >
> > I agree.
>
> Here you agreed ...
>
> > > Compare that to:
> > >
> > > /machine
> > >   /node[0] # This is not really telling!
> > >     /socket[0]
> > >       /core[0]
> > >         /thread[0] # So CPUState != thread?
> > >           cpu -> /machine/unassigned/device[0]
> > >   /unassigned
> > >     /device[0]
> >
> > I think this is better; in our world we can have multiple sockets in the
> > same NUMA node.  But CPUState == thread, so you can have just /thread[0]
> > -> /machine/unassigned/device[0].
>
> ... but you seem to have missed my point about separation. Here the
> socket object is a child<> of the NUMA node and would get realized
> together with it but separate from the link<>ed CPUState.

Ah, I didn't think the socket object as anything but a container.  For 
me, "keep NUMA and CPU separate" meant "keep NUMA and CPUState separate".

> > Alternatively, and to keep CPU + NUMA even *more* separate:
> >
> >   /machine
> >     /node[0]
> >        /cpu[0] -> /machine/unassigned/device[0]
> >        ...
> >     /socket[0]
> >        /core[0]
> >           /thread[0] -> /machine/unassigned/device[0]
> >     /unassigned
> >        /device[0]
>
> Now this is pretty much my proposal ;) except that you retained the
> criticized "node" as name and moved "socket[0]" out of
> /machine/unassigned (I had /machine/peripheral in mind for -device) and
> keep the CPUState out of the socket object.
>
> Anthony had requested hot-add to happen via "device_add Xeon4242",
> adding a full socket object with 6 cores at once. In that case CPUState
> needs to be an integral part of that socket-derived device for recursive
> realization. Objects that are just link<>ed to wouldn't get
> automatically realized.

Yes, if you want to do this then you're right and /socket[n] needs to be 
a device.

However, I'd still like it to be mostly a container, and that is why I 
liked the idea of having /node[n] with "flat" links to the actual 
CPUStates (and also memdevs).

> > I think we can.  Children and links look exactly the same from the outside.
>
> Well, we can't qom-get/qom-set a path string from/to a child<> property,
> can we?

We can get it but not set it.  But Stefan's series provides a way to 
make links read-only too, and these links should be read-only I think.

Paolo