Re: [Qemu-devel] [RFC Design Doc]Speed up live migration by skipping free pages

[Li, Liang Z]

Hi Dave,

I am now working on how to benefit post-copy by skipping the free pages, 
and I remember you have said we should let the destination know the info
of free pages so as to avoid request the free pages from the source. 

We have two solutions:

a. send the migration dirty page bitmap to destination before post
copy start, so the destination can decide whether to request the pages or 
place zero pages by checking the migration dirty page bitmap. The advantage
is that we can avoid sending the free pages. the disadvantage is that we have 
to send extra data to destination.

b. Check the page request on the source side, if it's not a dirty page, send a 
zero
page header to the destination.

What's your opinion about them?

Liang