[libvirt-users] How to disable kvm_steal_time feature

[Martin Kletzander]

On Fri, Nov 27, 2015 at 04:25:55PM +0300, Vasiliy Tolstov wrote:
>27 нояб. 2015 г. 14:15 пользователь "Martin Kletzander" <mkletzan at redhat.com>
>написал:
>>
>> On Fri, Nov 20, 2015 at 04:31:56PM +0100, Piotr Rybicki wrote:
>>>
>>> Hi.
>>>
>>> I would like to workaround a bug, when after live-migration of KVM
>>> guest, there is a 100% steal time shown in guest.
>>>
>>> I've read, that disabling 'kvm_steal_time' feature should workarund
>>> this bug, but i can't find a way to disable it in libvirt's domain xml
>>> file.
>>>
>>
>> There is no support for that in libvirt.  Either we must addit ad a
>> feature (patches welcome), but if that's there just for a workaround,
>> I would suggest chasing the original bug.
>>
>> If you just want to check that the workaround works, you could check
>> how the '-cpu ' parameter looks like when the domain is running and
>> then use the unsupported way of adding parameters to the qemu
>> commandline to specify the -cpu parameter again (qemu should use the
>> last one, so it should work), something like this:
>>
>> <domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0
>'>
>> ...
>>  <qemu:commandline>
>>    <qemu:arg value='-cpu'/>
>>    <qemu:arg value='${CPU_SPEC},-kvm_steal_time'/>
>>  </qemu:commandline>
>> </domain>
>>
>> where ${CPU_SPEC} is the next parameter after the '-cpu' one from the
>> command line, so for qemu command line similar to this:
>>
>>  qemu-kvm ... -cpu Nehalem,+feat,something ...
>>
>> the line in XML would be:
>>
>>  <qemu:arg value='Nehalem,+feat,something,-kvm_steal_time'/>
>>
>> HTH,
>>
>> Martin
>>
>>> Tried in <cpu> section:
>>> <feature policy='disable' name='kvm_steal_time'/>
>>> but that doesn't work.
>>>
>>> Also, couldn't find any related information in libvirt documentation.
>>> Google helps neither.
>>>
>>> How can I disable this feature?
>>>
>>> Thanks in advance.
>>> Piotr Rybicki
>>>
>>>
>
>Does it possible to calculate steal time for  vm if I have libvirt and
>domain stats?

I don't think we report that in domain stats, but top/virt-top could
help with that.

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>>
>>
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