The preempt mode requires the capability to assign channel for each of the
page, while the compression logic will currently assign pages to different
compress thread/local-channel so potentially they're incompatible.
Signed-off-by: Peter Xu <pet...@redhat.com>
---
migration/migration.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/migration/migration.c b/migration/migration.c
index fb4066dfb4..07c74a79a2 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1341,6 +1341,17 @@ static bool migrate_caps_check(bool *cap_list,
error_setg(errp, "Postcopy preempt requires postcopy-ram");
return false;
}
+
+ /*
+ * Preempt mode requires urgent pages to be sent in separate
+ * channel, OTOH compression logic will disorder all pages into
+ * different compression channels, which is not compatible with the
+ * preempt assumptions on channel assignments.
+ */
+ if (cap_list[MIGRATION_CAPABILITY_COMPRESS]) {
+ error_setg(errp, "Postcopy preempt not compatible with compress");
+ return false;
+ }
}
return true;
--
2.32.0
