"Dr. David Alan Gilbert (git)" <dgilb...@redhat.com> wrote: > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > > Postcopy detects accesses to pages that haven't been transferred yet > using userfaultfd, and it causes exceptions on pages that are 'not > present'. > Ballooning also causes pages to be marked as 'not present' when the > guest inflates the balloon. > Potentially a balloon could be inflated to discard pages that are > currently inflight during postcopy and that may be arriving at about > the same time. > > To avoid this confusion, disable ballooning during postcopy. > > When disabled we drop balloon requests from the guest. Since ballooning > is generally initiated by the host, the management system should avoid > initiating any balloon instructions to the guest during migration, > although it's not possible to know how long it would take a guest to > process a request made prior to the start of migration. > > Queueing the requests until after migration would be nice, but is > non-trivial, since the set of inflate/deflate requests have to > be compared with the state of the page to know what the final > outcome is allowed to be. > > Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
Reviewed-by: Juan Quintela <quint...@redhat.com>
