Postcopy vs xbzrle: Don't send xbzrle pages once in postcopy [for 2.8]
xbzrle relies on reading pages that have already been sent
to the destination and then applying the modifications; we can't
do that in postcopy because the destination may well have
modified the page already or the page has been discarded.
I already didn't allow reception of xbzrle pages, but I
forgot to add the test to stop them being sent.
Enabling both xbzrle and postcopy can make some sense;
if you think that your migration might finish if you
have xbzrle, then when it doesn't complete you flick
over to postcopy and stop xbzrle'ing.
This corresponds to RH bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1368422
Symptom is:
Unknown combination of migration flags: 0x60 (postcopy mode)
(either 0x60 or 0x40)
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
diff --git a/migration/ram.c b/migration/ram.c
index c8ec9f2..bc6154f 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -771,7 +771,9 @@
* page would be stale
*/
xbzrle_cache_zero_page(current_addr);
- } else if (!ram_bulk_stage && migrate_use_xbzrle()) {
+ } else if (!ram_bulk_stage &&
+ !migration_in_postcopy(migrate_get_current()) &&
+ migrate_use_xbzrle()) {
pages = save_xbzrle_page(f, &p, current_addr, block,
offset, last_stage, bytes_transferred);
if (!last_stage) {
