Re: [Qemu-devel] [PATCH v10 7/7] vhost-user: add a new message to disable/enable a specific virt queue.

[Eric Blake]

On 09/22/2015 08:05 PM, Yuanhan Liu wrote:

>>> + * VHOST_USER_SET_VRING_ENABLE
>>> +
>>> +      Id: 18
>>> +      Equivalent ioctl: N/A
>>> +      Master payload: vring state description
>>> +
>>> +      Signal slave to enable or disable corresponding vring.
>>
>> Does there need to be any QMP control to manually change a given queue,
>> or is it all used under the hood with no need for management apps to
>> care other than their initial request of max queues?
> 
> TBH, I don't know. As far as I know, there is only one queue pair will
> be enabled by default, and it's user's job to enable (or disable) more
> queue pairs, say, by ethtool:
> 
>     # ethtool -L eth0 combined <queue pair number>
> 
> Which ends up sending the VHOST_USER_SET_VRING_ENABLE to actually enable
> (or disable) a specific queue pairs.

So if I'm understanding, it is ethtool, not qemu, that is used to turn
on additional queues, and therefore we don't need a QMP command in qemu
to control things.

> 
> Does that answer your question?

I think so, but I'll let other reviewers more familiar with this area of
code give a final say.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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