Re: [Qemu-devel] Re: [PATCH] virtio-blk: add SGI_IO passthru support

[Paul Brook]

On Wednesday 29 April 2009, Christoph Hellwig wrote:
> On Tue, Apr 28, 2009 at 11:37:01AM -0500, Anthony Liguori wrote:
> > Ah, excellent.  I think that's a great thing to do.  So do you think
> > virtio-scsi would deprecate virtio-blk?
>
> I don't think so.  If you have an image format or a non-scsi blockdevice
> underneath virtio-block avoids the encoding into SCSI CDBs and back and
> should be faster.

Is this actually measurably faster, or just infinitesimally faster in theory?

I can maybe see that virtio-blk is slightly simpler for dumb drivers, though 
even then a basic scsi host is pretty straightforward and I find it hard to 
believe there's much real benefit.

Paul