Re: [PATCH v2 1/3] qmp: Support for querying stats

[Mark Kanda <mark.kanda@oracle.com>]

On 1/18/2022 6:52 AM, Daniel P. Berrangé wrote:
> On Tue, Jan 18, 2022 at 01:26:32PM +0100, Paolo Bonzini wrote:
>> On 1/17/22 16:17, Mark Kanda wrote:
>>>> I agree except that I think this and StatsResults should be unions,
>>>> even if it means running multiple query-stats commands.
>>> IIUC, making StatsResults a union implies the filter is a required
>>> argument (currently it is optional - omitting it dumps all VM and VCPU
>>> stats). Just to confirm - we want the filter to be required?
>> Yeah, I think at least the "kind" (vcpu, vm, perhaps in the future block or
>> net) should be mandatory.  If the caller doesn't know of a "kind", chances
>> are it won't be able to understand what object the stats refer to, for
>> example the vcpu "id" here:
>>
>> { 'union': 'StatsResults',
>>     'base': { 'target': 'StatsTarget', stats: ['StatsResultsEntry'] },
>>     'discriminator': 'target',
>>     'data': { 'vcpu': ['id': 'int'] }
>> }
>>
>> (which is another different between Daniel's proposal and mine; his just
>> placed all vcpus into an array with no explicit id, if I understand
>> correctly).
> An explicit ID isn't strictly required, since the caller can assume
> the results are ordered on CPU ID, so even if they gave a request
> for a sparse subset of CPUs, the results can be interpreted.  None
> the less having a vCPU id included is more friendly, so worth
> having.
>
>
> Regards,
> Daniel
OK. Thank you Daniel and Paolo. I'll implement these changes for v3.

Best regards,
-Mark