Re: [Qemu-devel] [PATCH 22/22] add cpu-add qmp command and implement CPU hot-add for target-i386

[Eduardo Habkost]

On Thu, Apr 11, 2013 at 05:17:29PM +0200, Igor Mammedov wrote:
[...]
> > 
> > Now, my question is: suppose a caller starts QEMU as:
> > 
> >  $ qemu -smp 18,cores=3,threads=3,maxcpus=36 \
> >         -numa node,cpus=0-8   -numa node,cpus=9-17 \
> >         -numa node,cpus=18-26 -numa node,cpus=27-35
> > 
> > and the caller wants to hot-add all VCPUs in the last CPU socket (that
> > means: all the VCPUs in the last NUMA node, that means: CPU indexes
> > 27-35). What should the caller do to find out which of the
> > /machine/icc-bridge/cpu[0..N] links/IDs really correspond to those
> > VCPUs?
> If one wants plug in a specific CPU, It won't work with -numa yet.

OK, documenting it as unsupported by now would be enough to me. :-)

It looks like -numa is the only interface that requires CPUs to be
individually identified in the command-line, right?

> 
> to make it work we need to specify sockets on -numa cmd. line and then
> construct synthetic QOM containers tree that could looklike:
> 
> /machine/numa_nodes/[0..N]/sockets/[0..M]/cpus/[0..X]
> 
> then command line could look like:
> $ qemu -smp 18,cores=3,threads=3,maxcpus=36 \
>        -numa node,sockets=0-1 -numa node,sockets=2-3

Makes sense to me. Using socket numbers is one way of making the CPU
identifiers be topology-based (as mentioned on a previous message), and
also make it stricter to allow only topologies that actually make sense
for a "/machine/numa_nodes/.../sockets/.../threads/..." tree.

> [...]

-- 
Eduardo