qapi/migration: Introduce x-vcpu-dirty-limit-period parameter

Introduce "x-vcpu-dirty-limit-period" migration experimental
parameter, which is in the range of 1 to 1000ms and used to
make dirtyrate calculation period configurable.

Currently with the "x-vcpu-dirty-limit-period" varies, the
total time of live migration changes, test results show the
optimal value of "x-vcpu-dirty-limit-period" ranges from
500ms to 1000 ms. "x-vcpu-dirty-limit-period" should be made
stable once it proves best value can not be determined with
developer's experiments.

Signed-off-by: Hyman Huang(黄勇) <yong.huang@smartx.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-Id: <168618975839.6361.17407633874747688653-2@git.sr.ht>
Signed-off-by: Juan Quintela <quintela@redhat.com>

migration/migration-hmp-cmds.c

@@ -364,6 +364,10 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
                 }
             }
         }
+
+        monitor_printf(mon, "%s: %" PRIu64 " ms\n",
+        MigrationParameter_str(MIGRATION_PARAMETER_X_VCPU_DIRTY_LIMIT_PERIOD),
+        params->x_vcpu_dirty_limit_period);
     }
 
     qapi_free_MigrationParameters(params);
@@ -620,6 +624,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
         error_setg(&err, "The block-bitmap-mapping parameter can only be set "
                    "through QMP");
         break;
+    case MIGRATION_PARAMETER_X_VCPU_DIRTY_LIMIT_PERIOD:
+        p->has_x_vcpu_dirty_limit_period = true;
+        visit_type_size(v, param, &p->x_vcpu_dirty_limit_period, &err);
+        break;
     default:
         assert(0);
     }

migration/options.c

@@ -80,6 +80,8 @@
 #define DEFINE_PROP_MIG_CAP(name, x)             \
     DEFINE_PROP_BOOL(name, MigrationState, capabilities[x], false)
 
+#define DEFAULT_MIGRATE_VCPU_DIRTY_LIMIT_PERIOD     1000    /* milliseconds */
+
 Property migration_properties[] = {
     DEFINE_PROP_BOOL("store-global-state", MigrationState,
                      store_global_state, true),
@@ -163,6 +165,9 @@ Property migration_properties[] = {
     DEFINE_PROP_STRING("tls-creds", MigrationState, parameters.tls_creds),
     DEFINE_PROP_STRING("tls-hostname", MigrationState, parameters.tls_hostname),
     DEFINE_PROP_STRING("tls-authz", MigrationState, parameters.tls_authz),
+    DEFINE_PROP_UINT64("x-vcpu-dirty-limit-period", MigrationState,
+                       parameters.x_vcpu_dirty_limit_period,
+                       DEFAULT_MIGRATE_VCPU_DIRTY_LIMIT_PERIOD),
 
     /* Migration capabilities */
     DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE),
@@ -908,6 +913,9 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
                        s->parameters.block_bitmap_mapping);
     }
 
+    params->has_x_vcpu_dirty_limit_period = true;
+    params->x_vcpu_dirty_limit_period = s->parameters.x_vcpu_dirty_limit_period;
+
     return params;
 }
 
@@ -940,6 +948,7 @@ void migrate_params_init(MigrationParameters *params)
     params->has_announce_max = true;
     params->has_announce_rounds = true;
     params->has_announce_step = true;
+    params->has_x_vcpu_dirty_limit_period = true;
 }
 
 /*
@@ -1100,6 +1109,15 @@ bool migrate_params_check(MigrationParameters *params, Error **errp)
     }
 #endif
 
+    if (params->has_x_vcpu_dirty_limit_period &&
+        (params->x_vcpu_dirty_limit_period < 1 ||
+         params->x_vcpu_dirty_limit_period > 1000)) {
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
+                   "x-vcpu-dirty-limit-period",
+                   "a value between 1 and 1000");
+        return false;
+    }
+
     return true;
 }
 
@@ -1199,6 +1217,11 @@ static void migrate_params_test_apply(MigrateSetParameters *params,
         dest->has_block_bitmap_mapping = true;
         dest->block_bitmap_mapping = params->block_bitmap_mapping;
     }
+
+    if (params->has_x_vcpu_dirty_limit_period) {
+        dest->x_vcpu_dirty_limit_period =
+            params->x_vcpu_dirty_limit_period;
+    }
 }
 
 static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
@@ -1317,6 +1340,11 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
             QAPI_CLONE(BitmapMigrationNodeAliasList,
                        params->block_bitmap_mapping);
     }
+
+    if (params->has_x_vcpu_dirty_limit_period) {
+        s->parameters.x_vcpu_dirty_limit_period =
+            params->x_vcpu_dirty_limit_period;
+    }
 }
 
 void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)

qapi/migration.json

@@ -789,9 +789,14 @@
 #     Nodes are mapped to their block device name if there is one, and
 #     to their node name otherwise.  (Since 5.2)
 #
+# @x-vcpu-dirty-limit-period: Periodic time (in milliseconds) of dirty limit during
+#                             live migration. Should be in the range 1 to 1000ms,
+#                             defaults to 1000ms. (Since 8.1)
+#
 # Features:
 #
-# @unstable: Member @x-checkpoint-delay is experimental.
+# @unstable: Members @x-checkpoint-delay and @x-vcpu-dirty-limit-period
+#            are experimental.
 #
 # Since: 2.4
 ##
@@ -809,8 +814,9 @@
            'multifd-channels',
            'xbzrle-cache-size', 'max-postcopy-bandwidth',
            'max-cpu-throttle', 'multifd-compression',
-           'multifd-zlib-level' ,'multifd-zstd-level',
+           'multifd-zlib-level', 'multifd-zstd-level',
-           'block-bitmap-mapping' ] }
+           'block-bitmap-mapping',
+           { 'name': 'x-vcpu-dirty-limit-period', 'features': ['unstable'] } ] }
 
 ##
 # @MigrateSetParameters:
@@ -945,9 +951,14 @@
 #     Nodes are mapped to their block device name if there is one, and
 #     to their node name otherwise.  (Since 5.2)
 #
+# @x-vcpu-dirty-limit-period: Periodic time (in milliseconds) of dirty limit during
+#                             live migration. Should be in the range 1 to 1000ms,
+#                             defaults to 1000ms. (Since 8.1)
+#
 # Features:
 #
-# @unstable: Member @x-checkpoint-delay is experimental.
+# @unstable: Members @x-checkpoint-delay and @x-vcpu-dirty-limit-period
+#            are experimental.
 #
 # TODO: either fuse back into MigrationParameters, or make
 #     MigrationParameters members mandatory
@@ -982,7 +993,9 @@
             '*multifd-compression': 'MultiFDCompression',
             '*multifd-zlib-level': 'uint8',
             '*multifd-zstd-level': 'uint8',
-            '*block-bitmap-mapping': [ 'BitmapMigrationNodeAlias' ] } }
+            '*block-bitmap-mapping': [ 'BitmapMigrationNodeAlias' ],
+            '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
+                                            'features': [ 'unstable' ] } } }
 
 ##
 # @migrate-set-parameters:
@@ -1137,9 +1150,14 @@
 #     Nodes are mapped to their block device name if there is one, and
 #     to their node name otherwise.  (Since 5.2)
 #
+# @x-vcpu-dirty-limit-period: Periodic time (in milliseconds) of dirty limit during
+#                             live migration. Should be in the range 1 to 1000ms,
+#                             defaults to 1000ms. (Since 8.1)
+#
 # Features:
 #
-# @unstable: Member @x-checkpoint-delay is experimental.
+# @unstable: Members @x-checkpoint-delay and @x-vcpu-dirty-limit-period
+#            are experimental.
 #
 # Since: 2.4
 ##
@@ -1171,7 +1189,9 @@
             '*multifd-compression': 'MultiFDCompression',
             '*multifd-zlib-level': 'uint8',
             '*multifd-zstd-level': 'uint8',
-            '*block-bitmap-mapping': [ 'BitmapMigrationNodeAlias' ] } }
+            '*block-bitmap-mapping': [ 'BitmapMigrationNodeAlias' ],
+            '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
+                                            'features': [ 'unstable' ] } } }
 
 ##
 # @query-migrate-parameters: