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[Qemu-devel] [PATCH] Postcopy vs xbzrle: Don't send xbzrle pages once in
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [PATCH] Postcopy vs xbzrle: Don't send xbzrle pages once in postcopy [for 2.8] |
Date: |
Wed, 24 Aug 2016 18:15:46 +0100 |
From: "Dr. David Alan Gilbert" <address@hidden>
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 <address@hidden>
---
migration/ram.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/migration/ram.c b/migration/ram.c
index a3d70c4..79fdc94 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -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) {
--
2.7.4
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- [Qemu-devel] [PATCH] Postcopy vs xbzrle: Don't send xbzrle pages once in postcopy [for 2.8],
Dr. David Alan Gilbert (git) <=