<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Wed, Jan 11, 2017 at 6:31 AM, TranceWorldLogic . <span dir="ltr"><<a href="mailto:tranceworldlogic@gmail.com" target="_blank">tranceworldlogic@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>Thanks Ondra that link is useful,<br></div><div>Do you have any Idea why VDSM disable balloon concept for RHEV and use for all non-RHEV ?<br><br></div><div>Please refer to below link.<br><a href="https://www.ovirt.org/documentation/sla/memory-balloon/" target="_blank">https://www.ovirt.org/<wbr>documentation/sla/memory-<wbr>balloon/</a><i><br>"Currently the balloon memory device is being created by default by libvirt for non RHEV environments,
and VDSM disables it by default for RHEV."<br><br></i></div><div>Is there different technique use by RHEV ? Please provide me link for it detail.<i><br></i></div><div>It will help me to compare ovirt and RHEV<i>.<br></i></div><div><i><br></i></div><div>Thanks,<br></div><div>~Rohit<i><br></i></div></div><div class="gmail-HOEnZb"><div class="gmail-h5"><div class="gmail_extra"><br></div></div></div></blockquote><div><br></div><div>In effect it is strange.</div><div>Inside official docs for RHEV 4.0 we have:</div><div>Administration Guide</div><div><a href="https://access.redhat.com/documentation/en/red-hat-virtualization/4.0/paged/administration-guide/52-cluster-tasks">https://access.redhat.com/documentation/en/red-hat-virtualization/4.0/paged/administration-guide/52-cluster-tasks</a><br></div><div><br></div><div>"</div><div>5.2.2.2. Optimization Settings Explained<br></div><div>Memory Balloon</div><div><div>Selecting the Enable Memory Balloon</div><div>Optimization check box enables memory</div><div>overcommitment on virtual machines running</div><div>on the hosts in this cluster. When this option</div><div>is set, the Memory Overcommit Manager</div><div>(MoM) will start ballooning where and when</div><div>possible, with a limitation of the guaranteed</div><div>memory size of every virtual machine.</div><div>...</div><div>It is important to understand that in some</div><div>scenarios ballooning may collide with KSM. In</div><div>such cases MoM will try to adjust the balloon</div><div>size to minimize collisions. Additionally, in</div><div>some scenarios ballooning may cause sub-</div><div>optimal performance for a virtual machine.</div><div>Administrators are advised to use ballooning</div><div>optimization with caution.</div></div><div>"</div><div><br></div><div>So it seems it is indeed possible to enable ballooning (note the considerations about KSM that could partially answer to your question...)</div><div><br></div><div>But then in Virtual Machine Management Guide here</div><div><a href="https://access.redhat.com/documentation/en/red-hat-virtualization/4.0/paged/virtual-machine-management-guide/33-installing-guest-agents-and-drivers">https://access.redhat.com/documentation/en/red-hat-virtualization/4.0/paged/virtual-machine-management-guide/33-installing-guest-agents-and-drivers</a><br></div><div><br></div><div>I see</div><div>"</div><div><div>3.3.1. Red Hat Virtualization Guest Agents and Drivers</div><div><br></div><div>virtio-balloon</div><div><br></div><div>Virtio-balloon is used to</div><div>control the amount of</div><div>memory a guest actually</div><div>accesses. It offers improved</div><div>memory over-commitment.</div><div>The balloon drivers are</div><div>installed for future</div><div>compatibility but not used by</div><div>default in Red Hat</div><div>Virtualization.</div></div><div>"</div><div><br></div><div>So it seems it is not possible to enable it for guests....</div><div>Any clarification?</div><div><br></div><div>Thanks,</div><div>Gianluca</div><div><br></div></div></div></div>