Re: [PATCH v2 06/11] migration: Introduce dirty-limit capability

[Markus Armbruster <armbru@redhat.com>]

huangy81@chinatelecom.cn writes:

> From: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
>
> Introduce migration dirty-limit capability, which can
> be turned on before live migration and limit dirty
> page rate durty live migration.
>
> Introduce migrate_dirty_limit function to help check
> if dirty-limit capability enabled during live migration.
>
> Meanwhile, refactor vcpu_dirty_rate_stat_collect
> so that period can be configured instead of hardcoded.
>
> dirty-limit capability is kind of like auto-converge
> but using dirty limit instead of traditional cpu-throttle
> to throttle guest down. To enable this feature, turn on
> the dirty-limit capability before live migration using
> migratioin-set-capabilities, and set the parameters

migrate-set-capabilities

> "x-vcpu-dirty-limit-period", "vcpu-dirty-limit" suitably
> to speed up convergence.
>
> Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
> ---

[...]

> diff --git a/migration/migration.h b/migration/migration.h
> index cdad8ac..7fbb9f8 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -409,6 +409,7 @@ bool migrate_ignore_shared(void);
>  bool migrate_validate_uuid(void);
>  
>  bool migrate_auto_converge(void);
> +bool migrate_dirty_limit(void);
>  bool migrate_use_multifd(void);
>  bool migrate_pause_before_switchover(void);
>  int migrate_multifd_channels(void);
> diff --git a/qapi/migration.json b/qapi/migration.json
> index dd667dd..af6b2da 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -477,6 +477,8 @@
>  #                    will be handled faster.  This is a performance feature and
>  #                    should not affect the correctness of postcopy migration.
>  #                    (since 7.1)
> +# @dirty-limit: Use dirty-limit to throttle down guest if enabled.
> +#               (since 7.1)

8.0

>  #
>  # Features:
>  # @unstable: Members @x-colo and @x-ignore-shared are experimental.
> @@ -492,7 +494,7 @@
>             'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate',
>             { 'name': 'x-ignore-shared', 'features': [ 'unstable' ] },
>             'validate-uuid', 'background-snapshot',
> -           'zero-copy-send', 'postcopy-preempt'] }
> +           'zero-copy-send', 'postcopy-preempt', 'dirty-limit'] }
>  
>  ##
>  # @MigrationCapabilityStatus:

[...]