From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Tue, 18 May 2010 04:19:31 +0300

With PUBLISH_USED_IDX, guest tells us which used entries
it has consumed. This can be used to reduce the number
of interrupts: after we write a used entry, if the guest has not yet
consumed the previous entry, or if the guest has already consumed the
new entry, we do not need to interrupt.
This imporves bandwidth by 30% under some workflows.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Rusty, Dave, this patch depends on the patch
"virtio: put last seen used index into ring itself"
which is currently destined at Rusty's tree.
Rusty, if you are taking that one for 2.6.35, please
take this one as well.
Dave, any objections?

None:

Acked-by: David S. Miller <davem@davemloft.net>