Re: [PATCH v11 4/4] softmmu/dirtylimit: implement dirty page rate limit

[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 "set-vcpu-dirty-limit",
> "cancel-vcpu-dirty-limit", "query-vcpu-dirty-limit"
> to enable, disable, query dirty page limit for virtual CPU.
>
> Meanwhile, introduce corresponding hmp commands
> "set_vcpu_dirty_limit", "cancel_vcpu_dirty_limit",
> "info vcpu_dirty_limit" so the feature can be more usable.
>
> Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>

[...]

> diff --git a/qapi/migration.json b/qapi/migration.json
> index ac5fa56..9d406f4 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -1869,6 +1869,66 @@
>              'current-rate': 'int64' } }
>  
>  ##
> +# @set-vcpu-dirty-limit:
> +#
> +# Set the upper limit of dirty page rate for virtual CPU.

"for virtual CPUs"

> +#
> +# 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.
> +#
> +# @cpu-index: index of virtual CPU, default is all.
> +#
> +# @dirty-rate: upper limit of dirty page rate for virtual CPU.

Lacks a unit.  Is it bytes per second?  pages per second?

> +#
> +# Since: 7.0
> +#
> +# Example:
> +#   {"execute": "set-vcpu-dirty-limit"}
> +#    "arguments": { "dirty-rate": 200,
> +#                   "cpu-index": 1 } }
> +#
> +##
> +{ 'command': 'set-vcpu-dirty-limit',
> +  'data': { '*cpu-index': 'uint64',

Use 'int' for consistency with cpu-index arguments elsewhere.

> +            'dirty-rate': 'uint64' } }
> +
> +##
> +# @cancel-vcpu-dirty-limit:
> +#
> +# Cancel the upper limit of dirty page rate for virtual CPU.

"for virtual CPUs"

> +#
> +# Cancel the dirty page limit for the vCPU which has been set with
> +# set-vcpu-dirty-limit command. Note that this command requires
> +# support from dirty ring, same as the "set-vcpu-dirty-limit".
> +#
> +# @cpu-index: index of virtual CPU, default is all.
> +#
> +# Since: 7.0
> +#
> +# Example:
> +#   {"execute": "cancel-vcpu-dirty-limit"}
> +#    "arguments": { "cpu-index": 1 } }
> +#
> +##
> +{ 'command': 'cancel-vcpu-dirty-limit',
> +  'data': { '*cpu-index': 'uint64'} }

Use 'int' for consistency with cpu-index arguments elsewhere.

> +
> +##
> +# @query-vcpu-dirty-limit:
> +#
> +# Returns information about all virtual CPU dirty limit if enabled.

Suggest "about virtual CPU dirty page rate limits, if any".

> +#
> +# Since: 7.0
> +#
> +# Example:
> +#   {"execute": "query-vcpu-dirty-limit"}
> +#
> +##
> +{ 'command': 'query-vcpu-dirty-limit',
> +  'returns': [ 'DirtyLimitInfo' ] }
> +
> +##
>  # @snapshot-save:
>  #
>  # Save a VM snapshot

[...]