From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Wilson Subject: Re: [PATCH 1/2] drm/i915: Don't allow ring tail to reach the same cacheline as head Date: Mon, 26 Nov 2012 20:24:10 +0000 Message-ID: References: <1353934099-18685-1-git-send-email-ville.syrjala@linux.intel.com> <1353934099-18685-2-git-send-email-ville.syrjala@linux.intel.com> <20121126180200.GA21547@intel.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1784574153==" Return-path: Received: from mga14.intel.com (mga14.intel.com [143.182.124.37]) by gabe.freedesktop.org (Postfix) with ESMTP id 91AB2E62FD for ; Mon, 26 Nov 2012 12:24:17 -0800 (PST) In-Reply-To: <20121126180200.GA21547@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Cc: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org --===============1784574153== Content-Type: text/plain On Mon, 26 Nov 2012 20:02:00 +0200, Ville Syrjälä wrote: > On Mon, Nov 26, 2012 at 04:28:33PM +0000, Chris Wilson wrote: > > On Mon, 26 Nov 2012 14:48:18 +0200, ville.syrjala@linux.intel.com wrote: > > > From: Ville Syrjälä > > > > > > 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. Gotcha. Yes, nice catch. Reviewed-by: Chris Wilson -Chris -- Chris Wilson, Intel Open Source Technology Centre --===============1784574153== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx --===============1784574153==--