Dan Linder’s problem with KVM performance sounds like he created his virtual machine hard drive as qcow2, which has bad bad performance with ext4 and xfs due to Red Hat (the owner of qemu) *forcing* write-through mode to “avoid disk corruption”. If I create my virtual machine with a ‘raw’ drive in write-back mode, it runs significantly faster. If I partition my hard drive to have a LVM physical volume, create a logical volume group ‘virtgroup’, and create a logical volume ‘win7′ and assign /dev/virtgroup/win7 as the hard drive for my virtual machine, it runs at virtually the speed of the hardware, significantly faster than userland solutions like VMWare Workstation and VirtualBox, especially after installing the virtio drivers in Windows. Well, until you want to display something. At which point using rdesktop to access your Windows virtual machine runs *much* faster than using the pathetic graphics console that KVM provides.

spice-space.org looks like they’re creating a new incompatible screen display protocol to do the exact same things that RDP does (i.e., pass sound and such as well as screen info over the Internet). Remotely logged into a Windows machine using an official Microsoft RDP viewer I can hear the sound, and even attach virtual drives to the remote machine to install software. It always amuses me when Microsoft re-invents Unix, badly, but here it appears Linux is re-inventing Microsoft, badly — for no good reason, because Microsoft has published the specs on RDP and there’s already the beginnings of a good viewer for Linux (rdesktop). Siiiiiiiigh…..

it’s early, but the scenario is changing

http://www.spice-space.org/home.html

@Christopher Tozzi

http://sourceforge.net/projects/aqemu/

it’s early, but the scenario is changing

http://www.spice-space.org/home.html

VirtualBox have full support for OpenGL 2, and with WineD3D even some DX8/DX9 games should work, but the DX support is still experimental. There might be problems playing HD videos in Windows 7 guest, I managed to play it with smplayer and opengl driver on integrated intel card (720p only), but I think the faster the gpu, the faster the video (but why to play it there anyway? Only if you are thinking of making multiterminal for a school or so, but than you can buy better mainboard with vt-d support and the cheapest graphics card)

If gaming is not a priority, or only OpenGL games are to be played, then it seems better option to buy a cheaper mainboard without vt-d, and buy SSD for extra performance, and use VirtualBox on that. It might be even possible to install some glide wrapper for oldest games, supposing that OpenGL support is really full.

On my four core AMD Phenom II 945 (four core, 6M L3 cache) system, KVM is as good as VirtualBox.

I think we’ll see KVM win for server use and VirtualBox win for desktop users. A lot of this has to do with how Oracle handles VirtualBox in the future: tightening of licensing could be a huge boost for KVM.

Lucid user here.

That’s pretty much the same experience I had.

But I’m not sure if it’s related to disk flushing issues; from what I understand, VirtualBox’s disk config is writeback by default, while KVM’s is writetrough, but I could be Oh-So-Wrong…

If, on the other hand, you have headless servers and services that must always be available but preferably not too visible, then KVM with libvirt is a clear winner. If you run desktop guest systems on KVM, then you’ll certainly want to drop VNC as quickly as possible. Using RDP for Windows and NX for GNU+Linux, is _far_ superior.

You cannot run accelerated VirtualBox and KVM at the same time, but if you close down all the guests from one, then it’s no problem to run the other.