[libvirt] [PATCH v2 01/12] Introduce /domain/devices/interface/driver/@queues attribute

[Osier Yang]

On 14/05/13 17:33, Michal Privoznik wrote:
> On 13.05.2013 22:38, Laine Stump wrote:
>> On 05/13/2013 01:22 PM, Michal Privoznik wrote:
>>> This attribute is going to represent number of queues for
>>> multique vhost network interface. This commit implements XML
>>> extension part of the feature and add one test as well. For now,
>>> we can only do xml2xml test as qemu command line generation code
>>> is not adapted yet.
>>> ---
>>>   docs/formatdomain.html.in                          | 11 ++++-
>>>   docs/schemas/domaincommon.rng                      |  5 +++
>>>   src/conf/domain_conf.c                             | 15 +++++++
>>>   src/conf/domain_conf.h                             |  1 +
>>>   src/qemu/qemu_domain.c                             | 27 +++++++-----
>>>   tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml  |  2 +-
>>>   .../qemuxml2argv-net-virtio-device.xml             |  2 +-
>>>   .../qemuxml2argvdata/qemuxml2argv-vhost_queues.xml | 51 ++++++++++++++++++++++
>>>   tests/qemuxml2argvdata/qemuxml2argv-virtio-lun.xml |  2 +-
>>>   tests/qemuxml2xmltest.c                            |  1 +
>>>   10 files changed, 103 insertions(+), 14 deletions(-)
>>>   create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-vhost_queues.xml
>>>
>>> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
>>> index 8004428..d671491 100644
>>> --- a/docs/schemas/domaincommon.rng
>>> +++ b/docs/schemas/domaincommon.rng
>>> @@ -1990,6 +1990,11 @@
>>>                   </attribute>
>>>                 </optional>
>>>                 <optional>
>>> +                <attribute name='queues'>
>>> +                  <ref name="positiveInteger"/>
>>
>> Should a lower limit be put on it in the RNG? (does qemu have a
>> documented limit?)
> I don't think so. QEMU doesn't have anything documented, but they are
> using uint16_t to store the max_queues internally. However, when setting
> it in virtio_net_device_init they use:
>
> n->max_queues = MAX(n->nic_conf.queues, 1);
>
> where n->nic_conf.queues is int32_t. Maybe we should ask on the qemu list.
>
This means we want qemu to either document the limits or expose them
in some manner.

See commit log of 0d70656afded421e434a03c4af4d004a0fbcde47, I was
annoyed about to find out the limits of the various qemu device.

Osier