[libvirt] RFC: add <currentVcpu> element

Eric Blake eblake at redhat.com
Tue Sep 28 22:36:51 UTC 2010


On 09/27/2010 11:20 AM, Eric Blake wrote:
>>
>> Another question I had, is there a way in QEmu to specifiy a different
>> cpu count from the -smp indicating the startup count ?
>
> I wish I knew off-hand, as it would make it easier for me to implement
> when I get to that part of the patch series :) But even if there isn't,
> I think that starting with the maximum via -smp and immediately after
> hot-unplugging to the current count is better than nothing.

Answering my own question: with qemu 0.12.5, 'qemu -help' lists:

-smp n[,maxcpus=cpus][,cores=cores][,threads=threads][,sockets=sockets]
                 set the number of CPUs to 'n' [default=1]
                 maxcpus= maximum number of total cpus, including
                   offline CPUs for hotplug etc.

So it looks like '-smp 1,maxcpus=2' maps nicely to <vcpu 
current='1'>2</vcpu>.

But per tests/qemuhelpdata, qemu 0.11.0 lacks this, so I also have to 
code up a qemu feature test.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org




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