On Fri, 2006-03-24 at 15:55 +0000, Alan Cox wrote: > On Gwe, 2006-03-24 at 07:38 -0500, Jeff Garzik wrote: > > > A pure SCSI abstraction doesn't allow for shared head scheduling which > > > you will need to scale Xen sanely on typical PC boxes. > > > > Not true at all. If you can do it with a block device, you can do it > > with a SCSI block device. > > I don't believe this is true. The complexity of expressing sequences of > command ordering between virtual machines acting in a co-operative but > secure manner isn't as far as I can see expressable sanely in SCSI TCQ I thought usb_scsi taught us that SCSI was overkill for a block abstraction? I have a much simpler Xen block-device implementation which seems to perform OK, and is a lot less LOC than the in-tree one, so I don't think the "SCSI would be better than what's there" (while possibly true) is valid. Cheers! Rusty. -- ccontrol: http://ozlabs.org/~rusty/ccontrol
