KSM and Auto-Ballooning in OpenNebula


I am wondering, Dose OpenNebula support KSM and Auto-Ballooning? I use virsh command for show dominfo but the value of “Max memory” and “Used memory” are the same.

root@hv002:~# virsh dominfo one-26
Id: 3
Name: one-26
UUID: ace938d1-8327-477e-9f7c-1c12d5d36d56
OS Type: hvm
State: running
CPU(s): 1
CPU time: 25.9s
Max memory: 262144 KiB
Used memory: 262144 KiB
Persistent: no
Autostart: disable
Managed save: no
Security model: apparmor
Security DOI: 0
Security label: libvirt-ace938d1-8327-477e-9f7c-1c12d5d36d56 (enforcing)

Opennebula is just an orchestration tool, controlling KVM or VMware or Xen. What you probably want to know is how your hypervisor is setup by default. Looked into this because of this recent news: https://www.vusec.net/projects/flip-feng-shui/
In your case, here you can check what’s in use: http://www.linux-kvm.org/page/KSM

and specifically:

You can verify KSM is in action, by checking for the existence of some of its /sys files, under /sys/kernel/mm/ksm/
They are:


how many shared pages are being used


how many more sites are sharing them i.e. how much saved


how many pages unique but repeatedly checked for merging


how many pages changing too fast to be placed in a tree


how many times all mergeable areas have been scanned

1 Like

Hi VURoland,

Thank you so much for your valuable information, especially Flip Feng Shui attack.

Hello, but what about memory ballooning? How it could be implemented for VMs?