[PATCH RESEND RFC 08/10] migration: Introduce cpu-responsive-throttle parameter

[Hyman Huang <yong.huang@smartx.com>]

To enable the responsive throttle that will be implemented
in the next commit, introduce the cpu-responsive-throttle
parameter.

Signed-off-by: Hyman Huang <yong.huang@smartx.com>
---
 migration/migration-hmp-cmds.c |  8 ++++++++
 migration/options.c            | 20 ++++++++++++++++++++
 migration/options.h            |  1 +
 qapi/migration.json            | 16 +++++++++++++++-
 4 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index f7b8e06bb4..a3d4d3f62f 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -273,6 +273,10 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
             MigrationParameter_str(
                 MIGRATION_PARAMETER_CPU_PERIODIC_THROTTLE_INTERVAL),
             params->cpu_periodic_throttle_interval);
+        assert(params->has_cpu_responsive_throttle);
+        monitor_printf(mon, "%s: %s\n",
+            MigrationParameter_str(MIGRATION_PARAMETER_CPU_RESPONSIVE_THROTTLE),
+            params->cpu_responsive_throttle ? "on" : "off");
         assert(params->has_max_cpu_throttle);
         monitor_printf(mon, "%s: %u\n",
             MigrationParameter_str(MIGRATION_PARAMETER_MAX_CPU_THROTTLE),
@@ -529,6 +533,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
         p->has_cpu_periodic_throttle_interval = true;
         visit_type_uint8(v, param, &p->cpu_periodic_throttle_interval, &err);
         break;
+    case MIGRATION_PARAMETER_CPU_RESPONSIVE_THROTTLE:
+        p->has_cpu_responsive_throttle = true;
+        visit_type_bool(v, param, &p->cpu_responsive_throttle, &err);
+        break;
     case MIGRATION_PARAMETER_MAX_CPU_THROTTLE:
         p->has_max_cpu_throttle = true;
         visit_type_uint8(v, param, &p->max_cpu_throttle, &err);
diff --git a/migration/options.c b/migration/options.c
index 2dbe275ba0..aa233684ee 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -110,6 +110,8 @@ Property migration_properties[] = {
     DEFINE_PROP_UINT8("x-cpu-periodic-throttle-interval", MigrationState,
                       parameters.cpu_periodic_throttle_interval,
                       DEFAULT_MIGRATE_CPU_PERIODIC_THROTTLE_INTERVAL),
+    DEFINE_PROP_BOOL("x-cpu-responsive-throttle", MigrationState,
+                      parameters.cpu_responsive_throttle, false),
     DEFINE_PROP_SIZE("x-max-bandwidth", MigrationState,
                       parameters.max_bandwidth, MAX_THROTTLE),
     DEFINE_PROP_SIZE("avail-switchover-bandwidth", MigrationState,
@@ -715,6 +717,13 @@ bool migrate_periodic_throttle(void)
     return s->parameters.cpu_periodic_throttle;
 }
 
+bool migrate_responsive_throttle(void)
+{
+    MigrationState *s = migrate_get_current();
+
+    return s->parameters.cpu_responsive_throttle;
+}
+
 bool migrate_cpu_throttle_tailslow(void)
 {
     MigrationState *s = migrate_get_current();
@@ -899,6 +908,8 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
     params->has_cpu_periodic_throttle_interval = true;
     params->cpu_periodic_throttle_interval =
         s->parameters.cpu_periodic_throttle_interval;
+    params->has_cpu_responsive_throttle = true;
+    params->cpu_responsive_throttle = s->parameters.cpu_responsive_throttle;
     params->tls_creds = g_strdup(s->parameters.tls_creds);
     params->tls_hostname = g_strdup(s->parameters.tls_hostname);
     params->tls_authz = g_strdup(s->parameters.tls_authz ?
@@ -967,6 +978,7 @@ void migrate_params_init(MigrationParameters *params)
     params->has_cpu_throttle_tailslow = true;
     params->has_cpu_periodic_throttle = true;
     params->has_cpu_periodic_throttle_interval = true;
+    params->has_cpu_responsive_throttle = true;
     params->has_max_bandwidth = true;
     params->has_downtime_limit = true;
     params->has_x_checkpoint_delay = true;
@@ -1208,6 +1220,10 @@ static void migrate_params_test_apply(MigrateSetParameters *params,
             params->cpu_periodic_throttle_interval;
     }
 
+    if (params->has_cpu_responsive_throttle) {
+        dest->cpu_responsive_throttle = params->cpu_responsive_throttle;
+    }
+
     if (params->tls_creds) {
         assert(params->tls_creds->type == QTYPE_QSTRING);
         dest->tls_creds = params->tls_creds->u.s;
@@ -1325,6 +1341,10 @@ static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
             params->cpu_periodic_throttle_interval;
     }
 
+    if (params->has_cpu_responsive_throttle) {
+        s->parameters.cpu_responsive_throttle = params->cpu_responsive_throttle;
+    }
+
     if (params->tls_creds) {
         g_free(s->parameters.tls_creds);
         assert(params->tls_creds->type == QTYPE_QSTRING);
diff --git a/migration/options.h b/migration/options.h
index efeac01470..613d675003 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -70,6 +70,7 @@ uint8_t migrate_cpu_throttle_increment(void);
 uint8_t migrate_cpu_throttle_initial(void);
 uint8_t migrate_periodic_throttle_interval(void);
 bool migrate_periodic_throttle(void);
+bool migrate_responsive_throttle(void);
 bool migrate_cpu_throttle_tailslow(void);
 bool migrate_direct_io(void);
 uint64_t migrate_downtime_limit(void);
diff --git a/qapi/migration.json b/qapi/migration.json
index 6d8358c202..9f52ed1899 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -734,6 +734,10 @@
 # @cpu-periodic-throttle-interval: Interval of the periodic CPU throttling.
 #     (Since 9.1)
 #
+# @cpu-responsive-throttle: Make CPU throttling more responsively by
+#                           introduce an extra detection metric of
+#                           migration convergence. (Since 9.1)
+#
 # @tls-creds: ID of the 'tls-creds' object that provides credentials
 #     for establishing a TLS connection over the migration data
 #     channel.  On the outgoing side of the migration, the credentials
@@ -855,7 +859,7 @@
            'throttle-trigger-threshold',
            'cpu-throttle-initial', 'cpu-throttle-increment',
            'cpu-throttle-tailslow', 'cpu-periodic-throttle',
-           'cpu-periodic-throttle-interval',
+           'cpu-periodic-throttle-interval', 'cpu-responsive-throttle',
            'tls-creds', 'tls-hostname', 'tls-authz', 'max-bandwidth',
            'avail-switchover-bandwidth', 'downtime-limit',
            { 'name': 'x-checkpoint-delay', 'features': [ 'unstable' ] },
@@ -916,6 +920,10 @@
 # @cpu-periodic-throttle-interval: Interval of the periodic CPU throttling.
 #     (Since 9.1)
 #
+# @cpu-responsive-throttle: Make CPU throttling more responsively by
+#                           introduce an extra detection metric of
+#                           migration convergence. (Since 9.1)
+#
 # @tls-creds: ID of the 'tls-creds' object that provides credentials
 #     for establishing a TLS connection over the migration data
 #     channel.  On the outgoing side of the migration, the credentials
@@ -1045,6 +1053,7 @@
             '*cpu-throttle-tailslow': 'bool',
             '*cpu-periodic-throttle': 'bool',
             '*cpu-periodic-throttle-interval': 'uint8',
+            '*cpu-responsive-throttle': 'bool',
             '*tls-creds': 'StrOrNull',
             '*tls-hostname': 'StrOrNull',
             '*tls-authz': 'StrOrNull',
@@ -1132,6 +1141,10 @@
 # @cpu-periodic-throttle-interval: Interval of the periodic CPU throttling.
 #     (Since 9.1)
 #
+# @cpu-responsive-throttle: Make CPU throttling more responsively by
+#                           introduce an extra detection metric of
+#                           migration convergence. (Since 9.1)
+#
 # @tls-creds: ID of the 'tls-creds' object that provides credentials
 #     for establishing a TLS connection over the migration data
 #     channel.  On the outgoing side of the migration, the credentials
@@ -1254,6 +1267,7 @@
             '*cpu-throttle-tailslow': 'bool',
             '*cpu-periodic-throttle': 'bool',
             '*cpu-periodic-throttle-interval': 'uint8',
+            '*cpu-responsive-throttle': 'bool',
             '*tls-creds': 'str',
             '*tls-hostname': 'str',
             '*tls-authz': 'str',
-- 
2.39.1