On Fri, Oct 16, 2009 at 12:08 PM, Dustin Henning <Dustin.Henning@xxxxxxxxxxx>
wrote:
Does
KVM have similar options that allow for communication directly between VMs?
I only used KVM once, with one VM, to determine fully-virtualized
performance was too poor (the same as in Xen, but with less driver support).
If so, I don't know why it doesn't suffer from the same issue, and I
should hope Xen could be fixed. Regardless, I am disappointed by RedHat's
decision to jump ship and go to KVM. I think xen makes more sense, and
pvops would be ideal. The primary reason I use Xen, though, is because I
use Windows and KVM doesn't have the drivers yet, so I get better performance
in Xen.
Dustin
Things are different in KVM and there's less isolation
between "DomUs" since they're basically processes. Theoretically KVM
should have much faster Guest to Guest networking then Xen but less isolation.
However a PV on Xen should cream KVM in just about every other aspect. I've
heard and I haven't finished my testing yet to confirm this that KVM is faster
than a Xen HVM doing the same tasks if they both have PV drivers which means
KVM may be better solution for virtualizing Windows. I have a contract for
Virtualizing 75 Window 2K systems so I'll be doing a great deal of testing in
the coming months to know for sure. The KVM method is attactive because it does
things the "Linux Way" though as apposed to being very invasive like
Xen. For Enterprise projects I only use Xen and use KVM for development work
but I keep my mind open. Most all Enterprise solutions are either ESX or Xen
based which tells you something. However, it's getting harder all the time to
stick with Xen because most distributions are dropping it. I'm now using Debian
Lenny kernels in my Ubuntu DomUs. It may end up being only Suse that supports
Xen at some point. I think Xen is a great product but if KVM can manage to do
the same thing and be easier to manage Xen will sadly go away. I've sort of
given up hope that it will ever have decent Dom0 support in the kernel. By the
time that happens KVM will have taken over the entire Linux VM world (which
makes the conspiracy theory part of my brain buzz).
Grant McWilliams
