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

[Zheng Chuan <zhengchuan@huawei.com>]

On 2020/9/24 3:03, Dr. David Alan Gilbert wrote:
> * Eric Blake (eblake@redhat.com) wrote:
>> 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.
> 
Hi, Eric.
Thanks for your review.
Yeah, it could be optional.
and should it need keep start-time and calc-time when omit dirtyrate?
like:
{"return":{"status":"measuring","start-time":3718293,"calc-time":1},"id":"libvirt-15"}
or
{"return":{"status":"unstarted","start-time":3718293,"calc-time":1},"id":"libvirt-15"}

> I've already got it queued; I'll fix up the grammar; if someone wants to
> send a change to make it optional before this version freezes that's OK.
> 
> Dave
> 
>>
>>> +#
>>> +# @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