Arjan van de Ven wrote: > On Thu, 2007-04-12 at 10:05 -0500, Anthony Liguori wrote: > >> Why not drive the backend from userspace? >> > > (nothing in the concept requires it to be in the kernel, it just makes > things a lot easier) > > Because I think the trend forward is to reduce the userspace dependency > of kvm, not increase it.
There's no increase in dependency since block IO is already done in userspace. Besides, I think the general Linux trend of moving things to userspace when there's no compelling reason to have them in kernel space trumps all other trends ;-) > And because you add context switches etc etc > There's no context switch just a privilege transition. Granted, privilege transitions aren't free but they're aren't that much compared to the cost of processing an IO request. >> Are you using a ring queue to >> transmit bio's from the guest to the host? >> > > sort of; it's not quite a real ring (I'm using the block layer tagged > queueing which is more efficient than a ring actually) > I'm not sure I understand. I guess I can just read the code. What I was wondering was whether you put the bio's into a shared ring queue or whether you issued a hypercall per bio. >> What are you using for >> discovery (I assume PCI)? >> > > I just added a hypercall to enumerate. Adding a dummy PCI is probably > needed for OS installers to auto-load the drivers. > Ah, okay. >> Could you post a copy of your driver on the list? I think it would be >> good to discuss. >> > > I'll dig it up > Excellent. Thank you! Regards, Anthony Liguori ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ kvm-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/kvm-devel
