Re: [Qemu-devel] balloon driver

[Jamie Lokier]

Mark Williamson wrote:
> > Even if the guest has to swap, the reasoning is that the guest is in a
> > much better position to figure out what to swap than if the host were
> > forced to.
> 
> Worse, the guest might decide to swap out a page that's already
> swapped in by the host, forcing it to be read in again only to be
> immediately written out to disk by the guest :-(

...unless the guest's disk I/O is with simulated DMA or recognisable
block-copy instruction sequences, and doesn't look at the data.  In
that case the emulator can, in principle, keep track of where pages
are copied around without being examined, and avoid actually swapping
them in.

Probably not worth the complexity.

-- Jamie