Thanks Gianluca On Wed, Jan 11, 2017 at 1:46 PM, Gianluca Cecchi <gianluca.cecchi@gmail.com> wrote:
On Wed, Jan 11, 2017 at 6:31 AM, TranceWorldLogic . < tranceworldlogic@gmail.com> wrote:
Thanks Ondra that link is useful, Do you have any Idea why VDSM disable balloon concept for RHEV and use for all non-RHEV ?
Please refer to below link. https://www.ovirt.org/documentation/sla/memory-balloon/
*"Currently the balloon memory device is being created by default by libvirt for non RHEV environments, and VDSM disables it by default for RHEV."* Is there different technique use by RHEV ? Please provide me link for it detail. It will help me to compare ovirt and RHEV *.*
Thanks, ~Rohit
In effect it is strange. Inside official docs for RHEV 4.0 we have: Administration Guide https://access.redhat.com/documentation/en/red-hat- virtualization/4.0/paged/administration-guide/52-cluster-tasks
" 5.2.2.2. Optimization Settings Explained Memory Balloon Selecting the Enable Memory Balloon Optimization check box enables memory overcommitment on virtual machines running on the hosts in this cluster. When this option is set, the Memory Overcommit Manager (MoM) will start ballooning where and when possible, with a limitation of the guaranteed memory size of every virtual machine. ... It is important to understand that in some scenarios ballooning may collide with KSM. In such cases MoM will try to adjust the balloon size to minimize collisions. Additionally, in some scenarios ballooning may cause sub- optimal performance for a virtual machine. Administrators are advised to use ballooning optimization with caution. "
So it seems it is indeed possible to enable ballooning (note the considerations about KSM that could partially answer to your question...)
But then in Virtual Machine Management Guide here https://access.redhat.com/documentation/en/red-hat- virtualization/4.0/paged/virtual-machine-management- guide/33-installing-guest-agents-and-drivers
I see " 3.3.1. Red Hat Virtualization Guest Agents and Drivers
virtio-balloon
Virtio-balloon is used to control the amount of memory a guest actually accesses. It offers improved memory over-commitment. The balloon drivers are installed for future compatibility but not used by default in Red Hat Virtualization. "
So it seems it is not possible to enable it for guests.... Any clarification?
Thanks, Gianluca