ksmd allows you to oversubscribe your compute nodes by sharing memory pages between your instances running on a compute node.
A CPU tax is to be expected for this process to do his job. That said, I have been running into an issue where the CPU tax was over 50%. This is obviously not acceptable.
Here is how to disable ksmd
echo "KSM_ENABLED=0" > /etc/default/qemu-kvm reboot
Unfortunately, this will mean that you will not be sharing memory pages between instances anymore, using more memory on each node.
ksmd can also be fine-tuned in the following configuration file:
But finding the right parameters for your specific configuration can be a time consuming task.
More information can be found here: