Re: [PATCH v10 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function

[Eric Blake <eblake@redhat.com>]

On 9/16/20 1:22 AM, Chuan Zheng wrote:
> Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function which could be called
> 
> Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
> ---

> +++ b/qapi/migration.json
> @@ -1737,3 +1737,53 @@
>   ##
>   { 'enum': 'DirtyRateStatus',
>     'data': [ 'unstarted', 'measuring', 'measured'] }
> +
> +##
> +# @DirtyRateInfo:
> +#
> +# Information about current dirty page rate of vm.
> +#
> +# @dirty-rate: @dirtyrate describing the dirty page rate of vm
> +#          in units of MB/s.
> +#          If this field return '-1', it means querying is not
> +#          start or not complete.

Grammar:

it means querying has not yet started or completed.

Should this field instead be optional, and omitted for those cases?  In 
which case, I'd suggest:

...in units of MB/s, present only when querying the rate has completed.

> +#
> +# @status: status containing dirtyrate query status includes
> +#          'unstarted' or 'measuring' or 'measured'
> +#
> +# @start-time: start time in units of second for calculation
> +#
> +# @calc-time: time in units of second for sample dirty pages
> +#
> +# Since: 5.2
> +#
> +##
> +{ 'struct': 'DirtyRateInfo',
> +  'data': {'dirty-rate': 'int64',
> +           'status': 'DirtyRateStatus',
> +           'start-time': 'int64',
> +           'calc-time': 'int64'} }
> +
> +##
> +# @calc-dirty-rate:
> +#
> +# start calculating dirty page rate for vm
> +#
> +# @calc-time: time in units of second for sample dirty pages
> +#
> +# Since: 5.2
> +#
> +# Example:
> +#   {"command": "calc-dirty-rate", "data": {"calc-time": 1} }
> +#
> +##
> +{ 'command': 'calc-dirty-rate', 'data': {'calc-time': 'int64'} }
> +
> +##
> +# @query-dirty-rate:
> +#
> +# query dirty page rate in units of MB/s for vm
> +#
> +# Since: 5.2
> +##
> +{ 'command': 'query-dirty-rate', 'returns': 'DirtyRateInfo' }
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org