Balloon Driver Kvm

Introduction. VirtIO Drivers are paravirtualized drivers for kvm/Linux see In short, they enable direct paravirtualized.

Oct 08, 2015  Overview. This page describes how to obtain and use virtio drivers for Windows virtual machines running on KVM, and additional software agents for.

Lots of people have heard this word ballooning and had a thought about it. . In computer world, this word is mostly aligned with virtualization. .

Jul 17, 2010  This post explains what the KVM virtio_balloon driver is all about. Richard WM Jones Virtualization, tools and tips Blog at WordPress.com.

Virtio Paravirtualized drivers for kvm/Linux. Virtio was chosen to be the main platform for IO virtualization in KVM; The idea behind it is to have a common framework.

Optimized and effective memory management is a key factor in virtualization environments. KSM and Auto-Ballooning enables sophisticated and economic configurations for physical RAM utilization.

KSM Kernel Samepage Merging is running in the Linux kernel and scans the memory of all the virtual machines running on a single host, looking for duplication and consolidating. With KSM we re able to improve virtual machine density by as much as 300 without impacting performance. One of the great benefits of using Linux as the hypervisor means KSM is not limited to KVM and virtual machines, but can also reduce memory pressure with normal Linux applications.

It was integrated in PVE since version 1.5, and is implemented with the package ksm-control-daemon check your version with the cli command pveversion -v.

Just install several KVM virtual machines with the same OS using at least 80 of your physical memory on the host and wait a few minutes. You will notice higher CPU activities on the host ksm daemon and the used memory on the host will be lowered significantly see start page showing the overall memory usage.

Howto verify that KSM is working how many pages are being shared between your KVM guests :

watch cat /sys/kernel/mm/ksm/pages_sharing

The file /etc/ksmtuned.conf allows for some customization of its behaviour.

Memory ballooning KVM only allows you to have your guest dynamically change it s memory usage by evicting unused memory during run time. It reduces the impact your guest can have on memory usage of your host by giving up unused memory back to the host.

The Proxmox VE host can loan ballooned memory to a busy VM. The VM decides which processes or cache pages to swap out to free up memory for the balloon. The VM Windows or Linux knows best which memory regions it can give up without impacting performance of the VM.

See Windows_VirtIO_Drivers to get info about

changelog and guest OS compatibility

other kind of guest devices supported

Download the latest drivers ISO as suggested by the page Windows_VirtIO_Drivers to your desktop.

Then upload the ISO to your Proxmox VE server:

logon to the Proxmox VE web interface

select a ISO-enabled storage see Storage_Model Storage_type_Content

just use the upload button on the menu bar.

Follow the link: Windows_VirtIO_Drivers Choose_the_right_driver

Enable Auto-Ballooning on Windows 2012/Win8

More or less the same instructions as Windows 2008r2.

Enable Auto-Ballooning on Windows 2008r2

Set the VM memory to Automatically allocate memory within this range - I choose 4096/2048 as example see screenshot

Start the VM and install all virtio drivers, including the balloon driver see screenshot

Copy and rename as Administrator the WIN7 AMD64 directory from the virtio.iso to c:/Program files/Balloon

Open a CMD as Administrator and cd into  c:/Program Files/Balloon

Install the BLNSVR with BLNSVR.exe -i

As soon as the service is started, also the memory information displayed on the Proxmox VE GUI is identical to the value shown in the windows task manager see screenshot.

If you need details about ballooning stats for this VM, go to the KVM monitor and enter info balloon

VirtIO drivers: KVM project wiki downloads

Enable Auto-Ballooning on Windows 2003 / Windows Xp

You need to install the balloon service with BLNSVR, like for win2008.

You also need to install the driver manually

Download the devcon software on microsoft website

Then install the balloon driver with

devcon install BALLOON.inf PCI VEN_1AF4 DEV_1002 SUBSYS_00051AF4 REV_00

Modern Linux Kernels does include the Balloon drivers by default. It works out of the box, and you only need to set the VM to Automatically allocate memory within this range

tbd: Proxmox VE Youtube channel.

Windows VirtIO Drivers. The source for the Windows drivers is hosted in a repository on GIT hub. Anonymous users can clone the repository git clone git://github.com.

After someone asked me a question about balloons in the virtualization sense today, I noticed that there is not very much documentation around. This post explains what the KVM virtio_balloon driver is all about.

First of all, what is a balloon driver if you ve never even heard of the concept. It s a way to give or take RAM from a guest. In theory at least, if your guest needs more RAM, you can use the balloon driver to give it more RAM. Or if the host needs to take RAM away from guests, it can do so. All of this is done without needing to pause or reboot the guest.

You might think that this would work as a RAM hot add feature, rather like hot adding disks to a guest. Although RAM hot add would IMHO be much better, currently this is not how ballooning works.

What we have is a kernel driver inside the guest called virtio_balloon. This driver acts like a kind of weird process, either expanding its own memory usage or shrinking down to nearly nothing, as in the diagrams below:

When the balloon driver expands, normal applications running in the guest suddenly have a lot less memory and the guest does the usual things it does when there s not much memory, including swapping stuff out and starting up the OOM killer. The balloon itself is non-swappable and un-killable in case you were wondering.

So what s the point of a kernel driver which wastes memory. There are two points: Firstly, the driver communicates with the host over the virtio channel, and the host gives it instructions expand to this size, shrink down now. The guest cooperates, but doesn t directly control the balloon.

Secondly, memory pages in the balloon are unmapped from the guest and handed back to the host, so the host can hand them out to other guests. It s like the guest s memory has a chunk missing from it:

Libvirt has two settings you can control called currentMemory and maxMemory memory in the libvirt XML :

maxMemory or just is the memory allocated at boot time to a guest. KVM and Xen guests currently cannot exceed this. currentMemory controls what memory you re requesting to give to the guest s applications. The balloon fills the rest of the memory and gives it back to the host for the host to use elsewhere.

You can adjust this manually for your guests, either by editing the XML, or by using the virsh setmem command.

Hi, I m toying with the latest windows driver release virtio-win-1.1.11-0.iso and I noticed that in addition to the network and disk drivers there are two new ones.