Re: [Qemu-devel] [PATCH] xbzrle: don't check the value in the vm ram repeatedly

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* ???? (chenliang0016@icloud.com) wrote:

> It is ok, we just need to guarantee that the pages in cache are same to the page in dest side. 
> Don??t care about whether they are same to src side. Because the modified pages during this
> time will be sent at next time.

It's an interesting, if unusual, observation; it means we can send
completely bogus data at this point because we know it will get
overwritten later; I think the requirements are:

  1) That we meet the protocol (which seems to require that the run lengths are
     not allowed to be 0)
  2) That we don't get stuck in any loops or go over the end of the page
     (I think this means we have to be careful of those byte loops within
     the word-at-a-time cases)
  3) The page that ends up in our xbzrle cache must match the destination
     page, since the next cycle of xbzrle will use it as reference.

Dave
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK