On 11.06.2015 10:13, Daniel P. Berrange wrote:
On Wed, Jun 10, 2015 at 09:20:40PM +0000, Vivi L wrote:
Michal Privoznik <mprivozn <at> redhat.com> writes:
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.
I thought setting hugepages per NUMA node is a nice-to-have feature. Is it required to enable the use of hugepages for the guest?
No, it should not be mandatory. You should be able to use
<memoryBacking> <hugepages/> </memoryBacking>
With pretty much any KVM/QEMU version that exists. If that's broken then its a libvit bug.
Unless hugepages are requested for guest NUMA nodes. In that case memory-backend-file object is required. From my investigation, this seems to be the case. Michal