Re: [PATCH v10 3/3] cpus-common: implement dirty page limit on virtual CPU

[Markus Armbruster <armbru@redhat.com>]

huangy81@chinatelecom.cn writes:

> From: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
>
> Implement dirtyrate calculation periodically basing on
> dirty-ring and throttle virtual CPU until it reachs the quota
> dirty page rate given by user.
>
> Introduce qmp commands "vcpu-dirty-limit", "query-vcpu-dirty-limit"
> to enable, disable, query dirty page limit for virtual CPU.
>
> Meanwhile, introduce corresponding hmp commands "vcpu_dirty_limit",
> "info vcpu_dirty_limit" so developers can play with them easier.
>
> Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>

[...]

> diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
> index 96d0148..04879a2 100644
> --- a/include/monitor/hmp.h
> +++ b/include/monitor/hmp.h
> @@ -131,6 +131,8 @@ void hmp_replay_delete_break(Monitor *mon, const QDict *qdict);
>  void hmp_replay_seek(Monitor *mon, const QDict *qdict);
>  void hmp_info_dirty_rate(Monitor *mon, const QDict *qdict);
>  void hmp_calc_dirty_rate(Monitor *mon, const QDict *qdict);
> +void hmp_info_vcpu_dirty_limit(Monitor *mon, const QDict *qdict);
> +void hmp_vcpu_dirty_limit(Monitor *mon, const QDict *qdict);
>  void hmp_human_readable_text_helper(Monitor *mon,
>                                      HumanReadableText *(*qmp_handler)(Error **));
>  
> diff --git a/qapi/migration.json b/qapi/migration.json
> index ac5fa56..7d8da4f 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -1869,6 +1869,50 @@
>              'current-rate': 'int64' } }
>  
>  ##
> +# @vcpu-dirty-limit:
> +#
> +# Set or cancel the upper limit of dirty page rate for a virtual CPU.
> +#
> +# Requires KVM with accelerator property "dirty-ring-size" set.
> +# A virtual CPU's dirty page rate is a measure of its memory load.
> +# To observe dirty page rates, use @calc-dirty-rate.
> +#
> +# @enable: true to enable, false to disable.
> +#
> +# @cpu-index: index of virtual CPU, default is all.

Suggest

    # @cpu-index: The vCPU to act upon (all by default).

(I'm stealing this from trace.json)

> +#
> +# @dirty-rate: upper limit of dirty page rate for virtual CPU, to
> +#              cancel dirty limit, this field will be ignored.
> +#
> +# Since: 7.0
> +#
> +# Example:
> +#   {"execute": "vcpu-dirty-limit"}
> +#    "arguments": { "enable": true,
> +#                   "cpu-index": 1,
> +#                   "dirty-rate": 200 } }
> +#
> +##
> +{ 'command': 'vcpu-dirty-limit',
> +  'data': { 'enable': 'bool',
> +            '*cpu-index': 'uint64',
> +            '*dirty-rate': 'uint64'} }

Drop @enable, please.

If @dirty-rate is present, set the limit to its value.

If it's absent, cancel the limit.

> +
> +##
> +# @query-vcpu-dirty-limit:
> +#
> +# Returns information about all virtual CPU dirty limit if enabled.
> +#
> +# Since: 7.0
> +#
> +# Example:
> +#   {"execute": "query-vcpu-dirty-limit"}
> +#
> +##
> +{ 'command': 'query-vcpu-dirty-limit',
> +  'returns': [ 'DirtyLimitInfo' ] }
> +
> +##
>  # @snapshot-save:
>  #
>  # Save a VM snapshot