[libvirt PATCH 1/3] Introduce VIR_MIGRATE_POSTCOPY_PREEMPT flag

During post-copy migration (once it actually switches to post-copy mode) dirty memory pages are continued to be migrated iteratively, while the destination can explicitly request a specific page to be migrated before the iterative process gets to it (which happens when a guest wants to read a page that was not migrated yet). Without this flag explicitly requested pages need to wait until all other pages already queued are transferred. Enabling this flag will instruct the hypervisor to create a separate migration channel for explicitly requested pages so that they can preempt the queue. Signed-off-by: Jiri Denemark <jdenemar(a)redhat.com&gt; --- include/libvirt/libvirt-domain.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h index 30cce85b29..ee23ae97a5 100644 --- a/include/libvirt/libvirt-domain.h +++ b/include/libvirt/libvirt-domain.h @@ -1100,6 +1100,14 @@ typedef enum { * Since: 8.5.0 */ VIR_MIGRATE_ZEROCOPY = (1 << 20), + + /* Allow post-copy requests to preempt normal migration stream. This way + * page faults on the destination hosts caused by accessing a memory page + * that was not migrated yet should be handled faster. + * + * Since: 10.0.0 + */ + VIR_MIGRATE_POSTCOPY_PREEMPT = (1 << 21), } virDomainMigrateFlags; -- 2.43.0