Re: [Qemu-devel] [PATCH 02/12] migration: fix counting normal page for compression

[Xiao Guangrong]

On 06/13/2018 11:51 PM, Dr. David Alan Gilbert wrote:
> * address@hidden (address@hidden) wrote:
> > From: Xiao Guangrong <address@hidden>
> >
> > The compressed page is not normal page
>
> Is this the right reason?

I think the 'normal' page shouldn't include the compressed
page and XBZRLE-ed page (the current code does not treat
xbzrle pages are normal as well).

> I think we always increment some counter for a page - so
> what gets incremented for a compressed page?

In the later patch, we will introduce the statistics of
compression which contains "pages":
   @pages: amount of pages compressed and transferred to the target VM

> Is the real answer that we do:
>
>    ram_save_target_page
>       control_save_page
>       compress_page_with_multi_thread
>
> and control_save_page already increments the counter?

No :), control_save_page increments the counter only if it posted
data out, under that case, the compression path is not invoked.

Thanks!