On 08.08.2011, at 15:29, Anthony Liguori wrote:
One thing that strikes me about this algorithm is that it's very good for a
particular type of workload--shockingly good really.
I think workload aware migration compression is possible for a lot of different
types of workloads. That makes me a bit wary of QEMU growing quite a lot of
compression mechanisms.
It makes me think that this logic may really belong at a higher level where
more information is known about the workload. For instance, I can imagine
XBZRLE living in something like libvirt.
Today, parsing migration traffic is pretty horrible but I think we're pretty
strongly committed to fixing that in 1.0. That makes me wonder if it would be
nicer architecturally for a higher level tool to own something like this.
Originally, when I added migration, I had the view that we would have transport
plugins based on the exec: protocol. That hasn't really happened since libvirt
really owns migration but I think having XBZRLE as a transport plugin for
libvirt is something worth considering.
I'm curious what people think about this type of approach. CC'ing libvirt to
get their input.
In general, I believe it's a good idea to keep looking at libvirt as a vm
management layer and only a vm management layer. Directly working with the
migration protocol basically ties us to libvirt if we want to do migration,
killing competition in the management stack. Just look at how xm is tied to xen
- it's one of the major points I dislike about it :).