* Michael S. Tsirkin (m...@redhat.com) wrote: > On Mon, Apr 18, 2016 at 11:08:31AM +0000, Li, Liang Z wrote: > > 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 > > > > Both are ad-hoc solutions imho. > > c. put the bitmap in a ramblock, check it on destination before > requesting pages. > > This way it's migrated on-demand.
I can see where you're coming from, but I don't like this idea, because sending data controlling the RAM migration process in RAM blocks controlled by the same data just sounds too recursive to ever debug. Dave > > -- > MST -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
