On Thu, 20 May 2010 07:57:18 am Michael S. Tsirkin wrote: > 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<m...@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? > >> > > > > 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?
I was assuming you'd put it at the end of the padding. I think it's a silly optimization, but Avi obviously feels strongly about it and I respect his opinion. Please resubmit... Thanks, Rusty. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
