Re: [Qemu-devel] [QEMU 4/7] balloon: get free page info from guest

[Li, Liang Z]

> On Mon, Jun 13, 2016 at 06:16:46PM +0800, Liang Li wrote:
> > Add a new feature to get the free page information from guest, the
> > free page information is saved in a bitmap. Please note that 'free
> > page' only means these pages are free before the request, some of the
> > pages will become no free during the process of sending the free page
> > bitmap to QEMU.
> >
> > Signed-off-by: Liang Li <address@hidden>
> 
> 
> I don't much like this request interface.
> The meaning of free page is rather fuzzy too - so at what point are they free?
> 
> 
> My suggestion would be:
>       report free page request ID to guest
>       include request ID when guest sends free page list
> 
> the definition is then:
>       page was free sometime after host set this value of request
>       ID and before it received response with the same ID

That's better. I will change in next version.
And there is another issue similar as we solved to speed up the 
inflating/deflating process.
Should we use a large page bitmap or a small one ? I used a big one in the 
patch.

If we chose to use a small page bitmap, then we have to traverse the free page 
list for many times,
and the meaning of free page will be more fuzzy.

But if we use a big map bitmap, people may ask, why a small one here and a big 
one there?

Thanks!

Liang