Re: [PATCH v2 1/7] migration/multifd: Add new migration option zero-page-detection.

[Markus Armbruster <armbru@redhat.com>]

Hao Xiang <hao.xiang@bytedance.com> writes:

> This new parameter controls where the zero page checking is running.
> 1. If this parameter is set to 'legacy', zero page checking is
> done in the migration main thread.
> 2. If this parameter is set to 'none', zero page checking is disabled.
>
> Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>

[...]

> diff --git a/qapi/migration.json b/qapi/migration.json
> index 5a565d9b8d..99843a8e95 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -653,6 +653,17 @@
>  { 'enum': 'MigMode',
>    'data': [ 'normal', 'cpr-reboot' ] }
>  
> +##
> +# @ZeroPageDetection:
> +#
> +# @legacy: Perform zero page checking from main migration thread. (since 9.0)
> +#
> +# @none: Do not perform zero page checking.
> +#
> +##

The entire type is since 9.0.  Thus:

   ##
   # @ZeroPageDetection:
   #
   # @legacy: Perform zero page checking from main migration thread.
   #
   # @none: Do not perform zero page checking.
   #
   # Since: 9.0
   ##

> +{ 'enum': 'ZeroPageDetection',
> +  'data': [ 'legacy', 'none' ] }
> +
>  ##
>  # @BitmapMigrationBitmapAliasTransform:
>  #
> @@ -874,6 +885,9 @@
>  # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
>  #        (Since 8.2)
>  #
> +# @zero-page-detection: See description in @ZeroPageDetection.
> +#     Default is 'legacy'. (Since 9.0)

The description feels a bit lazy :)

Suggest

   # @zero-page-detection: Whether and how to detect zero pages.  Default
   #     is 'legacy'.  (since 9.0)

Same for the other two copies.

> +#
>  # Features:
>  #
>  # @deprecated: Member @block-incremental is deprecated.  Use
> @@ -907,7 +921,8 @@
>             'block-bitmap-mapping',
>             { 'name': 'x-vcpu-dirty-limit-period', 'features': ['unstable'] },
>             'vcpu-dirty-limit',
> -           'mode'] }
> +           'mode',
> +           'zero-page-detection'] }
>  
>  ##
>  # @MigrateSetParameters:
> @@ -1066,6 +1081,10 @@
>  # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
>  #        (Since 8.2)
>  #
> +# @zero-page-detection: See description in @ZeroPageDetection.
> +#     Default is 'legacy'. (Since 9.0)
> +#
> +#
>  # Features:
>  #
>  # @deprecated: Member @block-incremental is deprecated.  Use
> @@ -1119,7 +1138,8 @@
>              '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
>                                              'features': [ 'unstable' ] },
>              '*vcpu-dirty-limit': 'uint64',
> -            '*mode': 'MigMode'} }
> +            '*mode': 'MigMode',
> +            '*zero-page-detection': 'ZeroPageDetection'} }
>  
>  ##
>  # @migrate-set-parameters:
> @@ -1294,6 +1314,9 @@
>  # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
>  #        (Since 8.2)
>  #
> +# @zero-page-detection: See description in @ZeroPageDetection.
> +#     Default is 'legacy'. (Since 9.0)
> +#
>  # Features:
>  #
>  # @deprecated: Member @block-incremental is deprecated.  Use
> @@ -1344,7 +1367,8 @@
>              '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
>                                              'features': [ 'unstable' ] },
>              '*vcpu-dirty-limit': 'uint64',
> -            '*mode': 'MigMode'} }
> +            '*mode': 'MigMode',
> +            '*zero-page-detection': 'ZeroPageDetection'} }
>  
>  ##
>  # @query-migrate-parameters: