Re: [Qemu-devel] [PATCH 7/8] migration: new migration test mode

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Denis V. Lunev (den@openvz.org) wrote:
> On 10/07/2015 04:56 PM, Dr. David Alan Gilbert wrote:
> >* Denis V. Lunev (den@openvz.org) wrote:
> >>From: Igor Redko <redkoi@virtuozzo.com>
> >>
> >>In this patch the ability to start a migration with test-only
> >>capability was added. It allows to gather the guest VM’s memory
> >>usage statistics avoiding time and memory overheads and real
> >>data transmission.  New MIGRATION_STATUS_TEST_COMPLETED was
> >>added to distinguish between test migration and true migration
> >>success states.
> >Why isn't this just a new transport? i.e. I could do this just by doing
> >a migrate to test:   ?
> >
> >It seems simpler and avoids some of the special casing?
> >
> >Dave
> we would like to avoid VM pause in the migration_thread when
> the process is finished. Thus we should have a capability
> for this in the rest of the code.

Ah OK.

> Though we can setup the capability here or in the suitable
> place and check that capability in the migration thread
> using transport here as a distinction.
> 
> Will it be OK for you?

Yes, that works for me I think.

Dave

> 
> Den
> 
> >>Signed-off-by: Igor Redko <redkoi@virtuozzo.com>
> >>Reviewed-by: Anna Melekhova <annam@virtuozzo.com>
> >>Signed-off-by: Denis V. Lunev <den@openvz.org>
> >>---
> >>  migration/migration.c | 12 ++++++++++--
> >>  qapi-schema.json      |  4 +++-
> >>  2 files changed, 13 insertions(+), 3 deletions(-)
> >>
> >>diff --git a/migration/migration.c b/migration/migration.c
> >>index 3182e15..3470d39 100644
> >>--- a/migration/migration.c
> >>+++ b/migration/migration.c
> >>@@ -790,7 +790,9 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
> >>      s = migrate_init(&params);
> >>-    if (strstart(uri, "tcp:", &p)) {
> >>+    if (migrate_is_test()) {
> >>+        test_start_migration(s, p, &local_err);
> >>+    } else if (strstart(uri, "tcp:", &p)) {
> >>          tcp_start_outgoing_migration(s, p, &local_err);
> >>  #ifdef CONFIG_RDMA
> >>      } else if (strstart(uri, "rdma:", &p)) {
> >>@@ -1054,8 +1056,14 @@ static void *migration_thread(void *opaque)
> >>          }
> >>          if (qemu_file_get_error(s->file)) {
> >>-            migrate_set_state(s, MIGRATION_STATUS_ACTIVE,
> >>+            /*FIXME replace magic number with smth legit*/
> >>+            if (migrate_is_test() && qemu_file_get_error(s->file) == -42) {
> >>+                migrate_set_state(s, MIGRATION_STATUS_ACTIVE,
> >>+                              MIGRATION_STATUS_TEST_COMPLETED);
> >>+            } else {
> >>+                migrate_set_state(s, MIGRATION_STATUS_ACTIVE,
> >>                                MIGRATION_STATUS_FAILED);
> >>+            }
> >>              break;
> >>          }
> >>diff --git a/qapi-schema.json b/qapi-schema.json
> >>index 38bf199..e022f9c 100644
> >>--- a/qapi-schema.json
> >>+++ b/qapi-schema.json
> >>@@ -432,6 +432,8 @@
> >>  #
> >>  # @completed: migration is finished.
> >>  #
> >>+# @test-completed: migration time estimation finished.
> >>+#
> >>  # @failed: some error occurred during migration process.
> >>  #
> >>  # Since: 2.3
> >>@@ -439,7 +441,7 @@
> >>  ##
> >>  { 'enum': 'MigrationStatus',
> >>    'data': [ 'none', 'setup', 'cancelling', 'cancelled',
> >>-            'active', 'completed', 'failed' ] }
> >>+            'active', 'completed', 'test-completed', 'failed' ] }
> >>  ##
> >>  # @MigrationInfo
> >>-- 
> >>2.1.4
> >>
> >>
> >--
> >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK