On Wed, May 19, 2010 at 08:04:51PM +0300, Avi Kivity wrote: > On 05/18/2010 04:19 AM, Michael S. Tsirkin wrote: >> 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@xxxxxxxxxx> >> --- >> >> 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? >> > > I object: I think the index should have its own cacheline, The issue here is that host/guest do not know each other's cache line size. I guess we could just put it at offset 128 or something like that ... Rusty? > and that it should be documented before merging. I think you meant to object to the virtio patch, not this one. This patch does not introduce new layout, just implements host support. virtio spec patch will follow: it is not part of linux tree so there is no patch dependency. > -- > Do not meddle in the internals of kernels, for they are subtle and quick to panic. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
