Messages in this thread | | | Date | Tue, 18 Aug 2009 10:38:39 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH v3 3/6] vbus: add a "vbus-proxy" bus model for vbus_driver objects |
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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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