Re: virtio scsi host draft specification, v3

[Paolo Bonzini <pbonzini@redhat.com>]

On 06/29/2011 12:31 PM, Michael S. Tsirkin wrote:
> On Wed, Jun 29, 2011 at 12:06:29PM +0200, Paolo Bonzini wrote:
>> On 06/29/2011 12:03 PM, Christoph Hellwig wrote:
>>>>   I agree here, in fact I misread Hannes's comment as "if a driver
>>>>   uses more than one queue it is responsibility of the driver to
>>>>   ensure strict request ordering".  If you send requests to different
>>>>   queues, you know that those requests are independent.  I don't think
>>>>   anything else is feasible in the virtio framework.
>>>
>>> That doesn't really fit very well with the SAM model.  If we want
>>> to use multiple queues for a single LUN it has to be transparent to
>>> the SCSI command stream.  Then again I don't quite see the use for
>>> that anyway.
>>
>> Agreed, I see a use for multiple queues (MSI-X), but not for
>> multiple queues shared by a single LUN.
>
> Then let's make it explicit in the spec?

What, forbid it or say ordering is not guaranteed?  The latter is 
already explicit with the wording suggested in the thread.

Paolo