Re: [PATCH QEMU v7 2/9] qapi/migration: Introduce x-vcpu-dirty-limit-period parameter

[Markus Armbruster <armbru@redhat.com>]

~hyman <hyman@git.sr.ht> writes:

> From: Hyman Huang(黄勇) <yong.huang@smartx.com>
>
> 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>
> ---
>  migration/migration-hmp-cmds.c |  8 ++++++++
>  migration/options.c            | 28 ++++++++++++++++++++++++++++
>  qapi/migration.json            | 34 +++++++++++++++++++++++++++-------
>  3 files changed, 63 insertions(+), 7 deletions(-)
>
> diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
> index 9885d7c9f7..352e9ec716 100644
> --- a/migration/migration-hmp-cmds.c
> +++ b/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);
>      }
> diff --git a/migration/options.c b/migration/options.c
> index 5a9505adf7..1de63ba775 100644
> --- a/migration/options.c
> +++ b/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)
> diff --git a/qapi/migration.json b/qapi/migration.json
> index 47dfef0278..384b768e03 100644
> --- a/qapi/migration.json
> +++ b/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.

Please format like

   # @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: Members @x-checkpoint-delay and
   #     @x-vcpu-dirty-limit-period are experimental.

to blend in with recent commit a937b6aa739 (qapi: Reformat doc comments
to conform to current conventions).

>  #
>  # 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',
> -           'block-bitmap-mapping' ] }
> +           'multifd-zlib-level', 'multifd-zstd-level',
> +           '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.
>  #

Likewise.

>  # 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.
>  #

Likewise.

>  # 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: