Fabiano Rosas <faro...@suse.de> writes:
> Add the direct-io migration parameter that tells the migration code to
> use O_DIRECT when opening the migration stream file whenever possible.
Why is that useful?
> This is currently only used with fixed-ram migration for the multifd
> channels that transfer the RAM pages. Those channels only transfer the
> pages and are guaranteed to perform aligned writes.
>
> However the parameter could be made to affect other types of
> file-based migrations in the future.
>
> Signed-off-by: Fabiano Rosas <faro...@suse.de>
[...]
> diff --git a/qapi/migration.json b/qapi/migration.json
> index 3b93e13743..1d38619842 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -878,6 +878,9 @@
> # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
> # (Since 8.2)
> #
> +# @direct-io: Open migration files with O_DIRECT when possible. This
> +# requires that the 'fixed-ram' capability is enabled. (since 9.0)
Two spaces between sentences for consistency, please.
> +#
> # Features:
> #
> # @deprecated: Member @block-incremental is deprecated. Use
> @@ -911,7 +914,8 @@
> 'block-bitmap-mapping',
> { 'name': 'x-vcpu-dirty-limit-period', 'features': ['unstable'] },
> 'vcpu-dirty-limit',
> - 'mode'] }
> + 'mode',
> + 'direct-io'] }
>
> ##
> # @MigrateSetParameters:
> @@ -1066,6 +1070,9 @@
> # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
> # (Since 8.2)
> #
> +# @direct-io: Open migration files with O_DIRECT when possible. This
> +# requires that the 'fixed-ram' capability is enabled. (since 9.0)
> +#
> # Features:
> #
> # @deprecated: Member @block-incremental is deprecated. Use
> @@ -1119,7 +1126,8 @@
> '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
> 'features': [ 'unstable' ] },
> '*vcpu-dirty-limit': 'uint64',
> - '*mode': 'MigMode'} }
> + '*mode': 'MigMode',
> + '*direct-io': 'bool' } }
>
> ##
> # @migrate-set-parameters:
> @@ -1294,6 +1302,9 @@
> # @mode: Migration mode. See description in @MigMode. Default is 'normal'.
> # (Since 8.2)
> #
> +# @direct-io: Open migration files with O_DIRECT when possible. This
> +# requires that the 'fixed-ram' capability is enabled. (since 9.0)
> +#
> # Features:
> #
> # @deprecated: Member @block-incremental is deprecated. Use
> @@ -1344,7 +1355,8 @@
> '*x-vcpu-dirty-limit-period': { 'type': 'uint64',
> 'features': [ 'unstable' ] },
> '*vcpu-dirty-limit': 'uint64',
> - '*mode': 'MigMode'} }
> + '*mode': 'MigMode',
> + '*direct-io': 'bool' } }
>
> ##
> # @query-migrate-parameters:
[...]
