Re: [Qemu-devel] [RFC qemu 0/4] A PV solution for live migration optimization

[Roman Kagan]

On Wed, Mar 09, 2016 at 02:38:52PM -0500, Rik van Riel wrote:
> On Wed, 2016-03-09 at 20:04 +0300, Roman Kagan wrote:
> > On Wed, Mar 09, 2016 at 05:41:39PM +0200, Michael S. Tsirkin wrote:
> > > On Wed, Mar 09, 2016 at 05:28:54PM +0300, Roman Kagan wrote:
> > > > For (1) I've been trying to make a point that skipping clean
> > > > pages is
> > > > much more likely to result in noticable benefit than free pages
> > > > only.
> > > 
> > > I guess when you say clean you mean zero?
> > 
> > No I meant clean, i.e. those that could be evicted from RAM without
> > causing I/O.
> > 
> 
> Programs in the guest may have that memory mmapped.
> This could include things like libraries and executables.
> 
> How do you deal with the guest page cache containing
> references to now non-existent memory?
> 
> How do you re-populate the memory on the destination
> host?

I guess the confusion is due to the context I stripped from the previous
messages...  Actually I've been talking about doing full-fledged balloon
inflation before the migration, so, when it's deflated the guest will
fault in that data from the filesystem as usual.

Roman.