[Qemu-devel] [PULL 07/27] migration: introduce postcopy-blocktime capability

[Juan Quintela <quintela@redhat.com>]

From: Alexey Perevalov <a.perevalov@samsung.com>

Right now it could be used on destination side to
enable vCPU blocktime calculation for postcopy live migration.
vCPU blocktime - it's time since vCPU thread was put into
interruptible sleep, till memory page was copied and thread awake.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 migration/migration.c | 9 +++++++++
 migration/migration.h | 1 +
 qapi/migration.json   | 6 +++++-
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/migration/migration.c b/migration/migration.c
index 19917a4b5b..fb876e9fca 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1499,6 +1499,15 @@ bool migrate_zero_blocks(void)
     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
 }
 
+bool migrate_postcopy_blocktime(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_POSTCOPY_BLOCKTIME];
+}
+
 bool migrate_use_compression(void)
 {
     MigrationState *s;
diff --git a/migration/migration.h b/migration/migration.h
index 663415fe48..9ab8d07004 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -201,6 +201,7 @@ int migrate_compress_level(void);
 int migrate_compress_threads(void);
 int migrate_decompress_threads(void);
 bool migrate_use_events(void);
+bool migrate_postcopy_blocktime(void);
 
 /* Sending on the return path - generic and then for each message type */
 void migrate_send_rp_shut(MigrationIncomingState *mis,
diff --git a/qapi/migration.json b/qapi/migration.json
index 4cd3d13158..4d8ccdf776 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -352,12 +352,16 @@
 #
 # @x-multifd: Use more than one fd for migration (since 2.11)
 #
+# @postcopy-blocktime: Calculate downtime for postcopy live migration
+#                     (since 2.12)
+#
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
   'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
            'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
-           'block', 'return-path', 'pause-before-switchover', 'x-multifd' ] }
+           'block', 'return-path', 'pause-before-switchover', 'x-multifd',
+           'postcopy-blocktime' ] }
 
 ##
 # @MigrationCapabilityStatus:
-- 
2.14.3