Re: [Qemu-devel] vm state save/restore question

[Benjamin Herrenschmidt]

On Tue, 2012-06-19 at 23:00 +0200, Alexander Graf wrote:
> How is the problem different from RAM? It's a 16MB region that can be
> accessed by the guest even during transfer time, so it can get dirty
> during the migration. But we only need to really transfer the last
> small delta at the end of the migration, right?

Because with -M pseries it's not mapped into guest space but instead is
a chunk of physically contiguous memory accessed directly in real mode
by KVM. So no dirty tracking here.

We could keep track manually maybe using some kind of dirty bitmap of
changes to the hash table but that would add overhead to things like
H_ENTER.

Cheers,
Ben.