Re: [Qemu-devel] [QEMU 7/7] migration: skip free pages during live migration

[Li, Liang Z]

> On Mon, Jun 13, 2016 at 06:16:49PM +0800, Liang Li wrote:
> > After sending out the request for free pages, live migration process
> > will start without waiting for the free page bitmap is ready. If the
> > free page bitmap is not ready when doing the 1st
> > migration_bitmap_sync() after ram_save_setup(), the free page bitmap
> > will be ignored, this means the free pages will not be filtered out in
> > this case.
> > The current implementation can not work with post copy, if post copy
> > is enabled, we simply ignore the free pages. Will make it work later.
> >
> > Signed-off-by: Liang Li <address@hidden>
> 
> Tying migration to balloon in this way seems rather ugly.
> So with request ID, the logic would basically be
> 
>       - add memory listener with high priority
>       - before sync bitmap, increment request id
>       - when we get response, if it has latest request id,
>         clear qemu migration bitmap
>         otherwise, ignore

Use the request ID is good. 
Could you elaborate the meaning of ' add memory listener with high priority ' ?

Thanks!
Liang