Page History

...

Discussions with community 3 days.
updating functional spec 1 days.
Coding 4 days.
testing 2 days.

Prerequisites to use cpu and ram overcommit.

The feature is dependent on the OS type ,Hypervisor capabilities, and some scripts.

1.) All VMs should have a ballon driver installed in them. The hypervisor communicates with the ballon driver to free up and make the memory available to a guest. So in case of
*XenSever.
The ballon driver can be found as a part of xen pv or PVHVM drivers. The xen pvhvm drivers are included in upstream linux kernels 2.6.36+.
*VMware.
In case of VMware the ballon deiver can be found as a part of the vmware tools. All the guests that are deployed in a overcommit cluster should have the vmware tools installed.
*KVM
All the guest are required to support the virtio drivers. All the linux kernels>= 2.6.25 have them installed. Admin needs to activate it. It can be done by setting CONFIG_VIRTIO_BALLOON=y in the virtio configuration.

2.) Hypervisor capabilities.
The hypervisor should be capable of using the memory ballooning. Each of the hypervisor provides their own feature to support ballooning.
*xenserver
The DMC (Dynamic Memory Control)capability of the hypervisor should be enabled. only xenserver Advanced and above versions have this feature.

*VMware & KVM.
The memory ballooning is supported by default.