Re: virtio scsi host draft specification, v3

[Paolo Bonzini]

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
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