Re: [Qemu-devel] [PATCH v2 3/3] virtio-balloon: add a timer to limit the free page report waiting time

[Liang Li <liliang.opensource@gmail.com>]

On Tue, Feb 27, 2018 at 06:10:47PM +0800, Wei Wang wrote:
> On 02/27/2018 08:50 AM, Michael S. Tsirkin wrote:
> > On Mon, Feb 26, 2018 at 12:35:31PM +0800, Wei Wang wrote:
> > > On 02/09/2018 08:15 PM, Dr. David Alan Gilbert wrote:
> > > > * Wei Wang (wei.w.wang@intel.com) wrote:
> > 
> > I think all this is premature optimization. It is not at all clear that
> > anything is gained by delaying migration. Just ask for hints and start
> > sending pages immediately.  If guest tells us a page is free before it's
> > sent, we can skip sending it.  OTOH if migration is taking less time to
> > complete than it takes for guest to respond, then we are better off just
> > ignoring the hint.
> 
> OK, I'll try to create a thread for the free page optimization. We create
> the thread to poll for free pages at the beginning of the bulk stage, and
> stops at the end of bulk stage.
> There are also comments about postcopy support with this feature, I plan to
> leave that as the second step (that support seems not urgent for now).
> 
> 
> Best,
> Wei

you can make use the current migration thread instead of creating a new one.

Liang