Re: [PATCH v5 3/3] cpus-common: implement dirty limit on vCPU

[Markus Armbruster <armbru@redhat.com>]

Hyman Huang <huangy81@chinatelecom.cn> writes:

> 在 2021/11/24 23:33, Markus Armbruster 写道:
>> huangy81@chinatelecom.cn writes:
>> 
>>> From: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
>>>
>>> Implement dirtyrate calculation periodically basing on
>>> dirty-ring and throttle vCPU until it reachs the quota
>>> dirtyrate given by user.
>>>
>>> Introduce qmp commands set-dirty-limit/cancel-dirty-limit to
>>> set/cancel dirty limit on vCPU.
>>>
>>> Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>

[...]

>>> diff --git a/qapi/migration.json b/qapi/migration.json
>>> index bbfd48c..42b260e 100644
>>> --- a/qapi/migration.json
>>> +++ b/qapi/migration.json
>>> @@ -1850,6 +1850,49 @@
>>>   { 'command': 'query-dirty-rate', 'returns': 'DirtyRateInfo' }
>>>     ##
>>> +# @set-dirty-limit:
>>> +#
>>> +# Set the upper limit of dirty page rate for the interested vCPU.
>> "for a vCPU"
>> 
>>> +#
>>> +# This command could be used to cap the vCPU memory load, which is also
>>> +# refered as "dirty page rate". Users can use set-dirty-limit unconditionally,
>>> +# but if one want to know which vCPU is in high memory load and which vCPU
>>> +# should be limited, "calc-dirty-rate" with "dirty-ring" mode maybe an
>>> +# availiable method.
>> I think you should mention that the command fails unless dirty ring
>> is
>> enabled, and a pointer to its documentation.
>> 
> Emm, it seems that there's no documentation about dirty ring in qemu，
> should i metion the commit b4420f19 "KVM: Dirty ring support" for
> dirty-ring?

I think the best you can do then is something like 'Property
"dirty-ring-size" of accelerator object "kvm" must be set.'

[...]