[Qemu-devel] [v5 11/12] migration: Add interface to control compression

[Liang Li <liang.z.li@intel.com>]

The multiple compression threads can be turned on/off through
qmp and hmp interface before doing live migration.

Signed-off-by: Liang Li <liang.z.li@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>
Reviewed-by: Dr.David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 migration/migration.c | 7 +++++--
 qapi-schema.json      | 7 ++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 8e15a79..55f749e 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -590,8 +590,11 @@ bool migrate_zero_blocks(void)
 
 bool migrate_use_compression(void)
 {
-    /* Disable compression before the patch series are applied */
-    return false;
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_COMPRESS];
 }
 
 int migrate_compress_level(void)
diff --git a/qapi-schema.json b/qapi-schema.json
index e16f8eb..0dfc4ce 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -491,13 +491,18 @@
 #          to enable the capability on the source VM. The feature is disabled by
 #          default. (since 1.6)
 #
+# @compress: Use multiple compression threads to accelerate live migration.
+#          This feature can help to reduce the migration traffic, by sending
+#          compressed pages. The feature is disabled by default. (since 2.3)
+#
 # @auto-converge: If enabled, QEMU will automatically throttle down the guest
 #          to speed up convergence of RAM migration. (since 1.6)
 #
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
-  'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks'] }
+  'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
+           'compress'] }
 
 ##
 # @MigrationCapabilityStatus
-- 
1.9.1