Re: [PATCH v3 1/7] migration/multifd: Add new migration option zero-page-detection.

[Markus Armbruster]

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..1e66272f8f 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -653,6 +653,18 @@
>  { 'enum': 'MigMode',
>    'data': [ 'normal', 'cpr-reboot' ] }
>  
> +##
> +# @ZeroPageDetection:
> +#
> +# @none: Do not perform zero page checking.
> +#
> +# @legacy: Perform zero page checking from main migration thread.
> +#
> +# Since: 9.0
> +##
> +{ 'enum': 'ZeroPageDetection',
> +  'data': [ 'none', 'legacy' ] }
> +
>  ##
>  # @BitmapMigrationBitmapAliasTransform:
>  #
> @@ -874,6 +886,9 @@
>  # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
>  #        (Since 8.2)
>  #
> +# @zero-page-detection: Whether and how to detect zero pages. More details
> +#     see description in @ZeroPageDetection. Default is 'legacy'.  (since 
> 9.0)
> +#

I'm not sure we need to point to the member's type.  If we want to, we
better fix the prose: "For additional information, see
@ZeroPageDetection" or similar.

Two spaces between sentences for consistency, please.  Also, limit line
length 70 characters.

Together:

   # @zero-page-detection: Whether and how to detect zero pages.  For
   #     additional information, see @ZeroPageDetection.  Default is
   #     'multifd'.  (since 9.0)

Same for the other two copies.

>  # Features:
>  #
>  # @deprecated: Member @block-incremental is deprecated.  Use
> @@ -907,7 +922,8 @@
>             'block-bitmap-mapping',
>             { 'name': 'x-vcpu-dirty-limit-period', 'features': ['unstable'] },
>             'vcpu-dirty-limit',
> -           'mode'] }
> +           'mode',
> +           'zero-page-detection'] }
>  
>  ##
>  # @MigrateSetParameters:
> @@ -1066,6 +1082,9 @@
>  # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
>  #        (Since 8.2)
>  #
> +# @zero-page-detection: Whether and how to detect zero pages. More details
> +#     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: Whether and how to detect zero pages. More details
> +#     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: