Comment 5 for bug 1623871

@mveenasl asked that I describe my testing process - here it is:

I pushed this change to a PPA:
  https://launchpad.net/~ce-hyperscale/+archive/ubuntu/cloud-mitaka

I then deployed OpenStack across a cluster of Cavium ThunderX CRB1s systems
using the current Mitaka Juju charms. I configured the nova-compute charm to pull
packages from this overlay PPA:

  openstack-origin: ppa:ce-hyperscale/cloud-mitaka

I logged into each of the 3 nova-compute nodes and created hugepages:

  $ echo 4096 | sudo tee /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages

And restarted libvirt/nova-compute just to be sure they were detected:

  $ sudo service libvirt-bin restart; sudo service nova-compute restart

I configured the m1.small flavor type to use hugepages:
  $ nova flavor-key m1.small set hw:mem_page_size=2048

I then launched a guest:
  $ nova boot --image xenial-uefi --flavor m1.small --nic net-id=0fed1d06-2c7c-48ab-b81b-112af6d362d7 uefi

Then found the corresponding hypervisor node and logged in.

I verified that QEMU was started w/ the appropriate memory-backend settings:

$ ps -ef | grep qemu
libvirt+ 850307 1 42 16:17 ? 00:00:12 /usr/bin/qemu-system-aarch64 -name instance-00000001 -S -machine virt,accel=kvm,usb=off,gic-version=3 -cpu host -drive file=/usr/share/AAVMF/AAVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on -drive file=/var/lib/libvirt/qemu/nvram/instance-00000001_VARS.fd,if=pflash,format=raw,unit=1 -m 2048 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -object memory-backend-file,id=ram-node0,prealloc=yes,mem-path=/dev/hugepages/libvirt/qemu,share=yes,size=2147483648,host-nodes=0,policy=bind -numa node,nodeid=0,cpus=0,memdev=ram-node0 [...]

And that the hugepage pool was actually depleted:
 $ cat /sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages
 3072

And finally, checked the console log to make sure the guest OS actually booted:

ubuntu@ubuntu:~$ nova console-log uefi | tail -2
[ 196.813164] cloud-init[1242]: Cloud-init v. 0.7.7 finished at Fri, 30 Sep 2016 16:21:21 +0000. Datasource DataSourceEc2. Up 196.73 seconds