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Postcopy vs xbzrle: Don't send xbzrle pages once in postcopy [for 2.8]

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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>
This commit is contained in:
Dr. David Alan Gilbert 2016-08-24 18:15:46 +01:00 committed by Juan Quintela
parent 091ecc8b69
commit 2ebeaec012
1 changed files with 3 additions and 1 deletions
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4
migration/ram.c
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@ -771,7 +771,9 @@ static int ram_save_page(QEMUFile *f, PageSearchStatus *pss,
* 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) {