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SubjectRe: [PATCH v3 3/6] vbus: add a "vbus-proxy" bus model for vbus_driver objects
On 08/18/2009 04:08 AM, Anthony Liguori wrote:
> I believe strongly that we should avoid putting things in the kernel
> unless they absolutely have to be. I'm definitely interested in
> playing with vhost to see if there are ways to put even less in the
> kernel. In particular, I think it would be a big win to avoid
> knowledge of slots in the kernel by doing ring translation in
> userspace. This implies a userspace transition in the fast path.
> This may or may not be acceptable. I think this is going to be a very
> interesting experiment and will ultimately determine whether my
> intuition about the cost of dropping to userspace is right or wrong.

I believe with a perfectly scaling qemu this should be feasible.
Currently qemu is far from scaling perfectly, but inefficient userspace
is not a reason to put things into the kernel.

Having a translated ring is also a nice solution for migration -
userspace can mark the pages dirty while translating the receive ring.

Still, in-kernel translation is simple enough that I think we should
keep it.

--
error compiling committee.c: too many arguments to function



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