[ovirt-users] Bad performance with Windows 2012 guests

Sven Achtelik Sven.Achtelik at mailpool.us
Sun May 3 11:48:32 UTC 2015

Hi Doron,

I've also noticed that there seems to be a difference in performance between Win2k8 R2/Linux and Windows Server 2012. After reading Martijns post I've done some speed test regarding the drive speeds and was looking for a way to compare the VMs on a more professional way. My tests showed, that on the same hardware, the Win2k8 R2 was faster in response and throughput on the disks. I found a utility that somehow measures the latency on a system and that also showed a significant difference. What is the correct way to do a performance test on a VM running in KVM ? 


-----Ursprüngliche Nachricht-----
Von: users-bounces at ovirt.org [mailto:users-bounces at ovirt.org] Im Auftrag von Doron Fediuck
Gesendet: Samstag, 2. Mai 2015 10:50
An: Martijn Grendelman
Cc: Karen Noel; users at ovirt.org; Vadim Rozenfeld
Betreff: Re: [ovirt-users] Bad performance with Windows 2012 guests

On Apr 30, 2015 14:03, Martijn Grendelman <martijn.grendelman at isaac.nl> wrote:
> Hi,
> Ever since our first Windows Server 2012 deployment on oVirt (3.4 back 
> then, now 3.5.1), I have noticed that working on these VMs via RDP or 
> on the console via VNC is noticeably slower than on Windows 2008 
> guests on the same oVirt environment.
> Basic things like starting an application (even the Server Manager 
> that get started automatically on login) take a very long time, 
> sometimes minutes. Everything is just... slow.
> We have recently deployed Microsoft Exchange on a Windows Server 2012 
> guest on RHEV, and it doesn't perform well at all.
> I haven't been able to find the cause for this slowness; CPU usage is 
> not excessive and it doesn't seem I/O related. Moreover, other types 
> of guests (Linux and even Windows 2008) do not have this problem.
> We have 3 different environments: 
> - oVirt 3.5.1, on old Dell servers with Penryn Family CPUs with fairly 
> slow storage on replicated GlusterFS, running CentOS 6.6
> - oVirt 3.5.1, on modern 6-core SandyBridge servers with local storage 
> via NFS, running CentOS 7.0)
> - RHEV 3.4.4 on modern 10-core SandyBridge servers with an iSCSI SAN 
> behind it, running on RHEV Hypervisor 6.5
> All of these -very different- environments expose the same behaviour: 
> Linux, Windows 2008 fast (or as fast as can be expected given the 
> hardware), Windows 2012 painfully slow.
> All Windows 2012 servers use VirtIO disk and network. I think all 
> drivers are from the virtio-win-0.1-74 ISO.
> Does anyone share this experience? 
> Any idea why this could happen and how it can be fixed? 
> Any other information I should share to get a better idea? 
> Btw, for the guests on the RHEV environment, we have a case with 
> RedHat support, but that doesn't seem to lead to a quick solution, 
> hence I'm writing here, too.
> Thanks for any help. 
> Regards,
> Martijn Grendelman

Hi Martijn,
Can you please provide the QEMU command line, together with kvm and qemu version?

This information will be helpful for reproducing the problem. However, if the problem is not reproducible on a local setup, we will probably need to ask collecting some performance information with xperf tool. 

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