[Engine-devel] VmDynamic kvm_enable

[Dan Kenigsberg]

On Tue, Mar 12, 2013 at 10:37:41AM -0400, Laszlo Hornyak wrote:
> Hi,
> 
> I came across a VmDynamic property 'kvm_enable'. It sounds strange for me, because ovirt is very colsely integrated with kvm. So a short dig into this flag...
> There is a similar thing for the VDS, it is set to true by vdsm is the host CPU has a VT flag. It is actually used to check if the host is OK to run VMS.
> 
> But the one for Vm it looks like a distributed logical loop in vdsm: it is set when constructing a VM object (vdsm/vm.py:~343) from the data sent by the client (engine) and then reported back in vm stats, so it is just a roundtrip between vdsm and it's client.
> In the engine side, it is just keeps sending it between the frontend DB and vdsm, never part of a decision.
> 
> Is this still needed here? Can I remove?
> VDSM guys?

I have a vague memeory that once upon at time, qemu occasionally failed
to enable kvm support - even though it was asked to. I then silently
switched to emulated mode, which was grindingly slow. Engine wanted to
know about such occasions.

I believe that a better technical approach would have been to kill the
violating process, and not let it run at all (unless qemu emulation was
strictly requested by management).

Anyway, as you have noted, this has rotten away throuh the years, and
unless older Engine versions are expecting this value in any way, I am
all for dropping it.

Dan.