[libvirt] Problem with setting up KVM guests to use HugePages

[Michal Privoznik]

On 10.06.2015 01:05, Vivi L wrote:
> Kashyap Chamarthy <kchamart <at> redhat.com> writes:
> 
> 
>> You might want re-test by explicitly setting the 'page' element and
>> 'size' attribute? From my test, I had something like this:
>>
>>     $ virsh dumpxml f21-vm | grep hugepages -B3 -A2 
>>       <memory unit='KiB'>2000896</memory>
>>       <currentMemory unit='KiB'>2000000</currentMemory>
>>       <memoryBacking>
>>         <hugepages>
>>           <page size='2048' unit='KiB' nodeset='0'/>
>>         </hugepages>
>>       </memoryBacking>
>>       <vcpu placement='static'>8</vcpu>
>>
>> I haven't tested this exhaustively, but some basic test notes here:
>>
>>     https://kashyapc.fedorapeople.org/virt/test-hugepages-with-libvirt.txt
> 
> Current QEMU does not support setting <page> element. Could it be the 
> cause of my aforementioned problem?
> 
> unsupported configuration: huge pages per NUMA node are not supported 
> with this QEMU
> 

So this is explanation why the memory for you guest is not backed by
hugepages.

Can you please share the qemu command line that libvirt generated for
your guest?

Michal