On Mon, Nov 26, 2012 at 04:28:33PM +0000, Chris Wilson wrote: > On Mon, 26 Nov 2012 14:48:18 +0200, ville.syrjala at linux.intel.com wrote: > > From: Ville Syrj?l? <ville.syrjala at linux.intel.com> > > > > According to BSpec the ring head and tail pointers must not be > > on the same cacheline when head > tail. The easiest way to enforce > > this is to reduce the reported ring space. > > I'm going to admit blindness because I don't see that warning in the > gen2-gen7 bspecs. Can you please give chapter and verse, and check to > see if there is a rationale? It's always the last thing in the section titled 'Ring Buffer Use'. I believe it's present in all the pre-snb internal bspecs, and it's also in all the public docs. I can't find it in the internal snb+ bspec but then again those don't seem to include the relevant chapter at all. Of course I can't be sure if it's a valid issue, or just something that got faithfully copypasted from one document to the next. -- Ville Syrj?l? Intel OTC
