On Fri, 4 Jun 2010 08:05:43 pm Michael S. Tsirkin wrote: > On Fri, Jun 04, 2010 at 12:04:57PM +0930, Rusty Russell wrote: > > On Wed, 2 Jun 2010 12:17:12 am Michael S. Tsirkin wrote: > > > This adds an (unused) option to put available ring before control (avail > > > index, flags), and adds padding between index and flags. This avoids > > > cache line sharing between control and ring, and also makes it possible > > > to extend avail control without incurring extra cache misses. > > > > > > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > > > > No no no no. 254? You're trying to Morton me![1] > > Hmm, I wonder what will we do if we want a 3rd field on > a separate chacheline. But ok. > > > How's this (untested): > > I think we also want to put flags there as well, > they are used on interrupt path, together with last used index. I'm uncomfortable with moving a field. We haven't done that before and I wonder what will break with old code. Should we instead just abandon the flags field and use last_used only? Or, more radically, put flags == last_used when the feature is on? Thoughts? Rusty. -- 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
